Improving flow distribution in influent channels using computational fluid dynamics.
Park, No-Suk; Yoon, Sukmin; Jeong, Woochang; Lee, Seungjae
2016-10-01
Although the flow distribution in an influent channel where the inflow is split into each treatment process in a wastewater treatment plant greatly affects the efficiency of the process, and a weir is the typical structure for the flow distribution, to the authors' knowledge, there is a paucity of research on the flow distribution in an open channel with a weir. In this study, the influent channel of a real-scale wastewater treatment plant was used, installing a suppressed rectangular weir that has a horizontal crest to cross the full channel width. The flow distribution in the influent channel was analyzed using a validated computational fluid dynamics model to investigate (1) the comparison of single-phase and two-phase simulation, (2) the improved procedure of the prototype channel, and (3) the effect of the inflow rate on flow distribution. The results show that two-phase simulation is more reliable due to the description of the free-surface fluctuations. It should first be considered for improving flow distribution to prevent a short-circuit flow, and the difference in the kinetic energy with the inflow rate makes flow distribution trends different. The authors believe that this case study is helpful for improving flow distribution in an influent channel.
A data-mining approach to predict influent quality.
Kusiak, Andrew; Verma, Anoop; Wei, Xiupeng
2013-03-01
In wastewater treatment plants, predicting influent water quality is important for energy management. The influent water quality is measured by metrics such as carbonaceous biochemical oxygen demand (CBOD), potential of hydrogen, and total suspended solid. In this paper, a data-driven approach for time-ahead prediction of CBOD is presented. Due to limitations in the industrial data acquisition system, CBOD is not recorded at regular time intervals, which causes gaps in the time-series data. Numerous experiments have been performed to approximate the functional relationship between the input and output parameters and thereby fill in the missing CBOD data. Models incorporating seasonality effects are investigated. Four data-mining algorithms-multilayered perceptron, classification and regression tree, multivariate adaptive regression spline, and random forest-are employed to construct prediction models with the maximum prediction horizon of 5 days.
Specific methanogenic activity test for anaerobic degradation of influents
NASA Astrophysics Data System (ADS)
Hussain, Athar; Dubey, Shashi Kant
2017-05-01
Specific methanogenic activity (SMA) determines the methane-producing capability of the sludge for a specific substrate. Methanogenic activity test can be used to delineate the operating conditions for anaerobic systems and a parameter to assess the system performance by giving a better perceptive of the system and its stability. At the beginning of the start-up period of a new digester, the SMA is of great importance for the determination of proper initial organic loading rate. In different phases, a regular determination of SMA also ascertains the development stages of the sludge. Also, a change in SMA indicates an inhibition or an accumulation of slow degradable or even non-biodegradable organic matter from the influents. This paper reviews the SMA of anaerobic sludge under different operating conditions using different substrates.
Temporal dynamics of antibiotics in wastewater treatment plant influent.
Coutu, Sylvain; Wyrsch, V; Wynn, H K; Rossi, L; Barry, D A
2013-08-01
A yearlong field experimental campaign was conducted to reveal time scales over which antibiotic fluxes vary in the influent of a wastewater treatment plant (WTP). In particular, sampling was carried out to ascertain the amplitudes of monthly, daily and hourly fluctuations of several antibiotics. A total of 180 samples was collected at the entrance of a WTP in Lausanne, Switzerland. Sample concentrations were multiplied by flow rate to obtain monthly, daily and hourly mass fluxes of six antibiotics (trimethoprim, norfloxacin, ciprofloxacin, ofloxacin, clindamycin and metronidazole). Seasonality in mass fluxes was observed for all substances, with maximum values in winter being up to an order of magnitude higher than in summer. The hourly measurements of the mass flux of antibiotics were found to have a period of 12h. This was due to peaks in toilet use in the morning and early evening. In particular, the morning peak in flushing coincided with high concentrations (and hence high mass fluxes) due to overnight accumulation of substances in urine. However, little variation was observed in the average daily flux. Consequently, fluctuations in mass fluxes of antibiotics were mainly evident at the monthly and hourly time scales, with little variation on the day-week time scale. These results can aid in optimizing removal strategies and future sampling campaigns focused on antibiotics in wastewater. Copyright © 2013 Elsevier B.V. All rights reserved.
Detailed PCB congener characterization of influent and effluent at New York and New Jersey WPCPs
Durell, G.S.; Lizotte, R.D. Jr.; Solomon, M.H.; Green, J.W.; Spadone, J.; Pires, L.
1995-12-31
The waste streams at 26 New York City and New Jersey water pollution control plants (WPCP) were characterized for PCB. Time-integrated influent and effluent samples were collected during normal and high (storm) flow conditions; high flow influent simulated what may by-pass the plant and be discharged through combined sewer overflows. State-of-the-art congener-specific analytical methods were used to achieve detection limits from 0.05 to 0.3 ng/L. Concentrations of 71 individual PCB congeners that constitute approximately 95% of the total PCB in Aroclors and environmental samples were determined. The PCB concentrations and congener distributions varied notably among plants. Individual congener concentrations were typically well below 1 ng/L in the effluent, with a few congeners being detected at 5 to 10 ng/L levels in some samples. The concentrations were under 1 ng/L in most influent samples, with occasional determinations above 10 ng/L. The average total PCB concentration, defined as the sum of the 71 individual congener concentrations, at the 26 WPCPs were 27, 110, and 160 ng/L for normal flow effluent, normal flow influent, and high flow influent, respectively. The results indicate that PCB levels in New York City and New Jersey WPCP discharges are generally low, with most effluent having total PCB concentrations below 0.05 {micro}g/L. The PCB levels in the influent were commonly under 0.1 {micro}g/L and became slightly elevated at most plants during storms while at some plants the increase in flow appeared to dilute the PCB in the influent. The WPCPs remove, on average, approximately 75% of the PCB received in the influent.
Rossmann, Maike; Matos, Antonio Teixeira; Abreu, Edgar Carneiro; Silva, Fabyano Fonseca; Borges, Alisson Carraro
2013-10-15
The aim of the present study was to evaluate the influence of aeration and vegetation on the removal of organic matter in coffee processing wastewater (CPW) treated in 4 constructed wetlands (CWs), characterized as follows: (i) ryegrass (Lolium multiflorum) cultivated system operating with an aerated influent; (ii) non-cultivated system operating with an aerated influent, (iii) ryegrass cultivated system operating with a non-aerated influent; and (iv) non-cultivated system operating with a non-aerated influent. The lowest average chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of 87, 84 and 73%, respectively, were obtained in the ryegrass cultivated system operating with a non-aerated influent. However, ryegrass cultivation did not influence the removal efficiency of organic matter. Artificial aeration of the CPW, prior to its injection in the CW, did not improve the removal efficiencies of organic matter. On other hand it did contribute to increase the instantaneous rate at which the maximum COD removal efficiency was reached. Although aeration did not result in greater organic matter removal efficiencies, it is important to consider the benefits of aeration on the removal of the other compounds.
Fan, Jinlin; Wang, Wengang; Zhang, Bo; Guo, Yeye; Ngo, Huu Hao; Guo, Wenshan; Zhang, Jian; Wu, Haiming
2013-09-01
The performance response of eight vertical flow constructed wetlands (VFCWs) to different influent COD/N ratios and intermittent aeration in domestic wastewater treatment was investigated. Almost complete nitrification was obtained by intermittent aeration, which well developed alternate anaerobic and aerobic conditions for nitrification and denitrification. Sufficient carbon source supply resulted from influent COD/N ratio of 10 simultaneously obtained high removals of COD (96%), ammonia nitrogen (99%) and total nitrogen (90%) in intermittently aerated VFCWs. In all non-aerated VFCWs, poor nitrification was observed due to oxygen deficiency whilst high COD/N ratios further led to lower COD and nitrogen removal efficiency. The results suggest that intermittent aeration combined with high influent COD/N ratios could achieve high nitrogen removal in VFCWs.
Influent of Borax Decahydrate Composition as Additional Flux into Stoneware Bodies
NASA Astrophysics Data System (ADS)
Bakil, Siti Natrah Abd; Hussin, Rosniza; Bakar Aramjat, Abu
2017-08-01
Stoneware is vitrified, has less porosity and requires high sintering temperature. The influent of borax decahydrate composition at sintering temperature 1050°C and 1150°C on the thermal analysis, fracture surface, linear shrinkage, water absorption and modular of rapture (MOR) were investigated. Rectangular sample were produced by uniaxially pressing at 40MPa. The thermal behavior was determined by thermogravimetric and different thermal analysis (TGA-DTA). The Scanning electron microscopy (SEM) was used for fracture surface analysis. The water absorption (%) of the sample were determined using Archimedes’ method. The experimental result showed that content of borax decahydrate have influent the properties of stoneware bodies.
The effect of alternating influent carbon source composition on activated sludge bioflocculation.
Van Dierdonck, J; Van den Broeck, R; Vervoort, E; Van Impe, J; Smets, I
2013-09-10
The impact of alternating influent carbon sources, i.e., glucose and starch, on activated sludge bioflocculation was investigated. To this end, four lab-scale reactors were operated during a long-term experiment. During this period the influent carbon source ratio (glucose/starch) was alternated every 7 or 35 days (i.e., a fast and slow switching frequency). Bioflocculation was monitored throughout the entire experiment using an extensive set of parameters, including macroscopic and microscopic activated sludge characteristics. Sludge hydrophobicity remained high (>80%) throughout the experiment indicating good bioflocculation. However, sludge settleability decreased for all four reactors after a 60 day adaptation period to the applied alternation in influent carbon source. During this adaptation period, floc size decreased due to the release of microcolonies. The subsequent period was characterized by a decrease in settleability, coinciding with a release of primary particles and an increase in floc size. The observed phenomena could be linked with the protein concentration near the floc surface. This fraction mainly consists of hydrolytic enzymes necessary for the degradation of starch and is responsible for a progressive deterioration of the EPS matrix. The results of this specific study indicate to be independent of the influent carbon source ratio or switching frequency.
Contaminant trends in reservoir sediment cores as records of influent stream quality
Van Metre, P.C.; Mahler, B.J.
2004-01-01
When reconstructing water-quality histories from lake and reservoir cores, it is sometimes assumed that the chemical signatures in the cores reflect historical water quality in the influent streams. To investigate this assumption, concentrations of metals, PAHs, and organochlorine compounds in sediment cores were compared to those associated with an influent-stream suspended sediment for three reservoirs in Fort Worth, TX, and two reservoirs in Boston, MA, U.S.A., and interpreted in light of land-use and regulation histories. In evaluating relations between suspended sediments and cores, three levels of preservation were indicated: (1) influent concentrations and historical trends are preserved in cores (metals at all sites; some organic contaminants at some sites); (2) some loss occurs during transport and initial deposition but relative historical trends are preserved in cores (some organic contaminants at some sites); and (3) neither stream concentrations nor relative historical trends are preserved (dieldrin and p,p???-DDT). The degree of preservation of influent concentration histories varied between lakes, particularly for PAHs. The results support the use of sediment cores to infer streamwater-quality histories for many contaminants but indicate that reservoir-bottom sediment samples might underestimate concentrations of organic contaminants in some streams.
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1995-01-01
Parametric cost analysis is a mathematical approach to estimating cost. Parametric cost analysis uses non-cost parameters, such as quality characteristics, to estimate the cost to bring forth, sustain, and retire a product. This paper reviews parametric cost analysis and shows how it can be used within the cost deployment process.
USDA-ARS?s Scientific Manuscript database
This study characterizes the performance of influent and effluent disinfection systems at Craig Brook National Fish Hatchery, a U.S. Fish and Wildlife Service (USFWS) Atlantic salmon (Salmo salar) restoration facility in East Orland, ME. Influent treatment of the hatchery’s water supply limits fish ...
Effect of influent substrate ratio on anammox granular sludge: performance and kinetics.
Zhu, Weiqiang; Li, Jin; Dong, Huiyu; Wang, Dan; Zhang, Peiyu
2017-09-27
Effect of influent substrate ratio on anammox process was studied in sequencing batch reactor. Operating temperature was fixed at 35 ± 1 °C. Influent pH and hydraulic retention time were 7.5 and 6 h, respectively. When influent NO2(-)-N/NH4(+)-N was no more than 2.0, total nitrogen removal rate (TNRR) increased whereas NH4(+)-N removal rate stabilized at 0.32 kg/(m(3) d). ΔNO2(-)-N/ΔNH4(+)-N increased with enhancing NO2(-)-N/NH4(+)-N. When NO2(-)-N/NH4(+)-N was 4.5, ΔNO2(-)-N/ΔNH4(+)-N was 1.98, which was much higher than theoretical value (1.32). The IC50 of NO2(-)-N was 289 mg/L and anammox activity was inhibited at high NO2(-)-N/NH4(+)-N ratio. With regard to influent NH4(+)-N/NO2(-)-N, the maximum NH4(+)-N removal rate was 0.36 kg/(m(3) d), which occurred at the ratio of 4.0. Anammox activity was inhibited when influent NH4(+)-N/NO2(-)-N was higher than 5.0. With influent NO3(-)-N/NH4(+)-N of 2.5-6.5, NH4(+)-N removal rate and NRR were stabilized at 0.33 and 0.40 kg/(m(3) d), respectively. When the ratio was higher than 6.5, nitrogen removal would be worsened. The inhibitory threshold concentration of NO2(-)-N was lower than NH4(+)-N and NO3(-)-N. Anammox bacteria were more sensitive to NO2(-)-N than NH4(+)-N and NO3(-)-N. TNRR would be enhanced with increasing nitrogen loading rate, but sludge floatation occurred at high nitrogen loading shock. The Han-Levenspiel could be applied to simulate nitrogen removal resulting from NO2(-)-N inhibition.
Actions taken in response to the potential for volatile organics in RLWTF influent tanks
DEL SIGNORE, JOHN C.
2007-01-01
Positive USQD-RL W -06.0729-JPS, titled "Potential for Volatile Organics in RLW" was signed Friday, 09-08-06, at 1600. It resulted from a Potentially Inadequate Safety Analysis (PISA) for the Radioactive Liquid Waste Treatment Facility (RLWTF) at Technical Area 50. The PISA posits that an unspecified accident occurs at a generator facility, and that said accident does not ignite the volatile organic liquid, but results instead in the release of a large volume of volatile organic liquid into an RLW drain. Once in the drain, the liquid flows unimpeded into the RLWTF influent tanks. After entering the influent tanks, a spark causes a deflagration or explosion. This report documents actions taken in response to the PISA.
Wei, Xiaorong; Shao, Mingan; Du, Lina; Horton, Robert
2014-12-01
Understanding the transport of humic acids (HAs) in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns. Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media.
Wu, Haiming; Fan, Jinlin; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Hu, Zhen; Liang, Shuang
2015-01-01
In this study, the removal performances of organic pollutants and nitrogen in vertical flow constructed wetlands (VFCWs) with and without intermittent aeration fed with different strengths of influent were evaluated as a possible treatment for decentralized domestic wastewater in northern China. The intermittent aeration strategy not only significantly increased removal efficiencies of organic pollutants and ammonium nitrogen (NH4(+)-N), but also successfully created alternate aerobic and anaerobic conditions resulting in high total nitrogen (TN) removal. Moreover, increasing influent strength did not affect the removal efficiencies of organic matters and nitrogen in aerated VFCWs. Compared with non-aerated VFCWs, much higher removal of organic pollutants (96%), NH4(+)-N (98%), and TN (85%) was obtained simultaneously in intermittent aeration VFCWs, especially at high influent strengths. The results suggest that the intermittent aeration could be an appropriate strategy for achieving the high removal performance in VFCWs, especially for in-situ treatment of high strength decentralized domestic wastewaters. Copyright © 2014 Elsevier Ltd. All rights reserved.
Fuentes, H.R.; Polzer, W.L.; Springer, E.P.
1987-04-01
In previous unsaturated transport studies at Los Alamos dispersion coefficients were estimated to be higher close to the tracer source than at greater distances from the source. Injection of tracers through discrete influent outlets could have accounted for those higher dispersions. Also, a lack of conservation of mass of the tracers was observed and suspected to be due to spatial variability in transport. In the present study experiments were performed under uniform influent (ponded) conditions in which breakthrough of tracers was monitored at four locations at each of four depths. All other conditions were similar to those of the unsaturated transport experiments. A comparison of results from these two sets of experiments indicates differences in the parameter estimates. Estimates were made for the dispersion coefficient and the retardation factor by the one-dimensional steady flow computer code, CFITIM. Estimates were also made for mass and for velocity and the dispersion coefficient by the method of moments. The dispersion coefficient decreased with depth under discrete influent application and increased with depth under ponded influent application. Retardation was predicted better under the discrete influent application than under ponded influent application. Differences in breakthroughs and in estimated parameters among locations at the same depth were observed under ponded influent application. Those differences indicate that there is a lack of conservation of mass as well as significant spatial variability across the experimental domain. 14 refs., 9 figs., 8 tabs.
Chen, Chuan; Xu, Xi-Jun; Xie, Peng; Yuan, Ye; Zhou, Xu; Wang, Ai-Jie; Lee, Duu-Jong; Ren, Nan-Qi
2017-03-01
Integrated simultaneous desulfurization and denitrification (ISDD) process has proven to be feasible for the coremoval of sulfate, nitrate, and chemical oxygen demand (COD). In this study, we aimed to reveal the microbial community dynamics in the ISDD process with different influent nitrate (NO3(-)) concentrations. For all tested scenarios, full denitrification was accomplished while sulfate removal efficiency decreased along with increased influent NO3(-) concentrations. The proportion of S(0) to influent SO4(2-) maintained a low level (5.6-17.0%) regardless of the increased influent NO3(-) concentrations. Microbial community analysis results showed that higher influent NO3(-) concentrations affected the microbial community structure greatly. Phyla Proteobacteria, Spirochaetae, Firmicutes, Synergistetes, and Chloroflexi dominated in all the community compositions, of which Proteobacteria exhibited a clear difference among eight microbial samples. Members of δ-Proteobacteria, with 16S rRNA gene sequences related to Desulfobulbus, were clearly decreased at influent NO3(-) = 3000 and 3500 mg/L, suggesting an inhibitory effect of NO3(-) on sulfate reduction. In contrast, as influent NO3(-) concentration increased, microbial community was notably enriched in γ-Proteobacteria and ε-Proteobacteria, which revealed the enrichment of 16S rRNA gene sequences related to Pseudomonas (γ-Proteobacteria), and Arcobacteria and Sulfurospirillum (ε-Proteobacteria).
Parametrically defined differential equations
NASA Astrophysics Data System (ADS)
Polyanin, A. D.; Zhurov, A. I.
2017-01-01
The paper deals with nonlinear ordinary differential equations defined parametrically by two relations. It proposes techniques to reduce such equations, of the first or second order, to standard systems of ordinary differential equations. It obtains the general solution to some classes of nonlinear parametrically defined ODEs dependent on arbitrary functions. It outlines procedures for the numerical solution of the Cauchy problem for parametrically defined differential equations.
Parametric Resonance Revisited
NASA Astrophysics Data System (ADS)
van den Broeck, C.; Bena, I.
The phenomenon of parametric resonance is revisited. Several physical examples are reviewed and an exactly solvable model is discussed. A mean field theory is presented for globally coupled parametric oscillators with randomly distributed phases. A new type of collective instability appears, which is similar in nature to that of noise induced phase transitions.
Heinonen, M; Jokelainen, M; Fred, T; Koistinen, J; Hohti, H
2013-01-01
Municipal wastewater treatment plant (WWTP) influent is typically dependent on diurnal variation of urban production of liquid waste, infiltration of stormwater runoff and groundwater infiltration. During wet weather conditions the infiltration phenomenon typically increases the risk of overflows in the sewer system as well as the risk of having to bypass the WWTP. Combined sewer infrastructure multiplies the role of rainwater runoff in the total influent. Due to climate change, rain intensity and magnitude is tending to rise as well, which can already be observed in the normal operation of WWTPs. Bypass control can be improved if the WWTP is prepared for the increase of influent, especially if there is some storage capacity prior to the treatment plant. One option for this bypass control is utilisation of on-line weather-radar-based forecast data of rainfall as an input for the on-line influent model. This paper reports the Viikinmäki WWTP wet weather influent modelling project results where gridded exceedance probabilities of hourly rainfall accumulations for the next 3 h from the Finnish Meteorological Institute are utilised as on-line input data for the influent model.
McLellan, S.L.; Huse, S.M.; Mueller-Spitz, S.R.; Andreishcheva, E.N.; Sogin, M.L.
2009-01-01
The release of untreated sewage introduces non-indigenous microbial populations of uncertain composition into surface waters. We used massively parallel 454 sequencing of hypervariable regions in rRNA genes to profile microbial communities from eight untreated sewage influent samples of two wastewater treatment plants (WWTP) in metropolitan Milwaukee. The sewage profiles included a discernable human fecal signature made up of several taxonomic groups including multiple Bifidobacteriaceae, Coriobacteriaceae, Bacteroidaceae, Lachnospiraceae, and Ruminococcaceae genera. The fecal signature made up a small fraction of the taxa present in sewage but the relative abundance of these sequence tags mirrored the population structures of human fecal samples. These genera were much more prevalent in the sewage influent than standard indicators species. High-abundance sequences from taxonomic groups within the Beta- and Gammaproteobacteria dominated the sewage samples but occurred at very low levels in fecal and surface water samples, suggesting that these organisms proliferate within the sewer system. Samples from Jones Island (JI – servicing residential plus a combined sewer system) and South Shore (SS – servicing a residential area) WWTPs had very consistent community profiles, with greater similarity between WWTPs on a given collection day than the same plant collected on different days. Rainfall increased influent flows at SS and JI WWTPs, and this corresponded to greater diversity in the community at both plants. Overall, the sewer system appears to be a defined environment with both infiltration of rainwater and stormwater inputs modulating community composition. Microbial sewage communities represent a combination of inputs from human fecal microbes and enrichment of specific microbes from the environment to form a unique population structure. PMID:19840106
McLellan, S L; Huse, S M; Mueller-Spitz, S R; Andreishcheva, E N; Sogin, M L
2010-02-01
The release of untreated sewage introduces non-indigenous microbial populations of uncertain composition into surface waters. We used massively parallel 454 pyrosequencing of hypervariable regions in rRNA genes to profile microbial communities from eight untreated sewage influent samples of two wastewater treatment plants (WWTPs) in metropolitan Milwaukee. The sewage profiles included a discernible human faecal signature made up of several taxonomic groups including multiple Bifidobacteriaceae, Coriobacteriaceae, Bacteroidaceae, Lachnospiraceae and Ruminococcaceae genera. The faecal signature made up a small fraction of the taxa present in sewage but the relative abundance of these sequence tags mirrored the population structures of human faecal samples. These genera were much more prevalent in the sewage influent than standard indicators species. High-abundance sequences from taxonomic groups within the Beta- and Gammaproteobacteria dominated the sewage samples but occurred at very low levels in faecal and surface water samples, suggesting that these organisms proliferate within the sewer system. Samples from Jones Island (JI--servicing residential plus a combined sewer system) and South Shore (SS--servicing a residential area) WWTPs had very consistent community profiles, with greater similarity between WWTPs on a given collection day than the same plant collected on different days. Rainfall increased influent flows at SS and JI WWTPs, and this corresponded to greater diversity in the community at both plants. Overall, the sewer system appears to be a defined environment with both infiltration of rainwater and stormwater inputs modulating community composition. Microbial sewage communities represent a combination of inputs from human faecal microbes and enrichment of specific microbes from the environment to form a unique population structure.
Seib, M D; Berg, K J; Zitomer, D H
2016-09-01
Sustainable municipal wastewater recovery scenarios highlight benefits of anaerobic membrane bioreactors (AnMBRs). However, influences of continuous seeding by influent wastewater and temperature on attached-growth AnMBRs are not well understood. In this study, four bench-scale AnMBR operated at 10 and 25°C were fed synthetic (SPE) and then real (PE) primary effluent municipal wastewater. Illumina sequencing revealed different bacterial communities in each AnMBR in response to temperature and bioreactor configuration, whereas differences were not observed in archaeal communities. Activity assays revealed hydrogenotrophic methanogenesis was the dominant methanogenic pathway at 10°C. The significant relative abundance of Methanosaeta at 10°C concomitant with low acetoclastic methanogenic activity may indicate possible Methanosaeta-Geobacter direct interspecies electron transfer. When AnMBR feed was changed to PE, continual seeding with wastewater microbiota caused AnMBR microbial communities to shift, becoming more similar to PE microbiota. Therefore, influent wastewater microbiota, temperature and reactor configuration influenced the AnMBR microbial community. Copyright © 2016 Elsevier Ltd. All rights reserved.
Ginige, Maneesha P; Kayaalp, Ahmet S; Cheng, Ka Yu; Wylie, Jason; Kaksonen, Anna H
2013-01-01
Removal of phosphorus (P) and nitrogen (N) from municipal wastewaters is required to mitigate eutrophication of receiving water bodies. While most treatment plants achieve good N removal using influent carbon (C), the use of influent C to facilitate enhanced biological phosphorus removal (EBPR) is poorly explored. A number of operational parameters can facilitate optimum use of influent C and this study investigated the effects of cycle length, dissolved oxygen (DO) concentration during aerobic period and influent solids on biological P and N removal in sequencing batch reactors (SRBs) using municipal wastewaters. Increasing cycle length from 3 to 6 h increased P removal efficiency, which was attributed to larger portion of N being removed via nitrite pathway and more biodegradable organic C becoming available for EBPR. Further increasing cycle length from 6 to 8 h decreased P removal efficiencies as the demand for biodegradable organic C for denitrification increased as a result of complete nitrification. Decreasing DO concentration in the aerobic period from 2 to 0.8 mg L(-1) increased P removal efficiency but decreased nitrification rates possibly due to oxygen limitation. Further, sedimented wastewater was proved to be a better influent stream than non-sedimented wastewater possibility due to the detrimental effect of particulate matter on biological nutrient removal.
Chen, Hong; Zhang, Can; Han, Jianbo; Yu, Yixuan; Zhang, Peng
2012-11-01
Concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in influents, effluents and sludges were investigated by analyzing the samples from twelve wastewater treatment plants (WWTPs) in China. The highest concentrations of PFOS and PFOA in influents were found to occur in municipal and industrial WWTPs, respectively. Relative to PFOS and PFOA concentrations in influents, elevated concentrations were observed in effluents from WWTPs applying anaerobic-anoxic-oxic wastewater treatment process. Importantly, application of previously reported organic carbon normalized partition coefficients (K(OC)) derived from sediment-based sorption experiments appear to underestimate the PFOS and PFOA levels in biosolids quantified in the current study. PFOS and PFOA levels in effluents were found to be approximately 27 and 2 times higher than those detected in the effluent-receiving seawater, respectively. However, their levels in this area of seawater haven't exceeded the provisional short-term health advisories in drinking water issued by U.S. EPA yet.
Ahnert, Markus; Marx, Conrad; Krebs, Peter; Kuehn, Volker
2016-12-01
This paper presents a simple method for the generation of continuous influent quality datasets for wastewater treatment plants (WWTPs) that is based on incomplete available routine data, only, without referring to any further measurement. In the approach, Weibull-distributed random data are fitted to the available routine data, such that the resulting distribution of influent quality data shows the identical statistical characteristics. Beside the description of the method, this paper contains a comprehensive analysis of robustness and universality of the approach. It is shown that incomplete datasets with only 10% remaining influent quality data can be filled with this method with nearly the same statistical parameters as the original data. In addition, the use with datasets of different WWTP plants sizes results always in a good agreement between original and filled datasets.
Kitajima, Masaaki; Rachmadi, Andri T; Iker, Brandon C; Haramoto, Eiji; Pepper, Ian L; Gerba, Charles P
2015-07-01
Human cosavirus (HCoSV) is a novel member of the family Picornaviridae. We investigated the prevalence and genetic diversity of HCoSV in influent and effluent wastewater in Arizona over a 12-month period, from August 2011 to July 2012. HCoSV sequences were identified in six (25%) influent samples and one (4%) effluent sample, with the highest concentration of 3.24 × 10(5) and 1.54 × 10(3) copies/liter in influent and effluent, respectively. The strains were characterized based on their 5' untranslated region and classified into species A and D, demonstrating that genetically heterogeneous HCoSV were circulating with a clear temporal shift of predominant strains in the study area.
Spérandio, Mathieu; Labelle, Marc-André; Ramdani, Abdellah; Gadbois, Alain; Paul, Etienne; Comeau, Yves; Dold, Peter L
2013-01-01
Activated sludge models have assumed that a portion of organic solids in municipal wastewater influent is unbiodegradable. Also, it is assumed that solids from biomass decay cannot be degraded further. The paper evaluates these assumptions based on data from systems operating at higher than typical sludge retention times (SRTs), including membrane bioreactor systems with total solids retention (no intentional sludge wastage). Data from over 30 references and with SRTs of up to 400 d were analysed. A modified model that considers the possible degradation of the two components is proposed. First order degradation rates of approximately 0.007 d(-1) for both components appear to improve sludge production estimates. Factors possibly influencing these degradation rates such as wastewater characteristics and bioavailability are discussed.
Bacteria isolated from sewage influent resistant to ciprofloxacin, chloramphenicol and tetracycline.
Zwenger, Sam R; Gillock, Eric T
2009-02-01
This study assessed the presence of antibiotic-resistant bacteria in sewage influent. Resistance was measured by determining the lowest concentration of antibiotic, in micrograms per milliliter (microg mL(- 1)). To determine the minimum inhibitory concentration (MIC), which is used in diagnostic laboratories, we used the Etest, a plastic strip containing an antibiotic concentration gradient. In total, we sampled five sewage treatment plants of various sizes in Kansas and isolated bacteria resistant to three broad-spectrum antibiotics; ciprofloxacin (1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-yl-quinoline-3-carboxylic acid), chloramphenicol 2,2-dichlor-N-[(aR, bR)-b-hydroxy-a-hydroxymethyl-4-nitrophenethyl] acetamide), and tetracycline (2-(amino-hydroxy-ethylidene)-4-dimethylamino-6,10,11,12a-tetrahydroxy-6-methyl-4,4a,5,5a-tetrahydrotetracene-1,3,12-trione). In total, 25 Gram-negative isolates were found to be resistant to at least one of the antibiotics tested. Some isolates were multi-drug resistant, regardless of the amount of influent the sewage treatment plant received. A Pseudomonas isolate from the smallest sewage treatment plant (approximately 2 million gallons treated per day) showed resistance to all three antibiotics, albeit at low levels (10 microg mL(- 1)). The largest number of bacteria (6 species) were isolated from the largest sewage treatment plant (45 million gallons per day). Regardless, the results of this study are in agreement with similar studies, antibiotic resistance can persist long after the antibiotics have been forgotten.
Herrmann, Inga; Jourak, Amir; Hedström, Annelie; Lundström, T. Staffan; Viklander, Maria
2013-01-01
Sorption by active filter media can be a convenient option for phosphorus (P) removal and recovery from wastewater for on-site treatment systems. There is a need for a robust laboratory method for the investigation of filter materials to enable a reliable estimation of their longevity. The objectives of this study were to (1) investigate and (2) quantify the effect of hydraulic loading rate and influent source (secondary wastewater and synthetic phosphate solution) on P binding capacity determined in laboratory column tests and (3) to study how much time is needed for the P to react with the filter material (reaction time). To study the effects of these factors, a 22 factorial experiment with 11 filter columns was performed. The reaction time was studied in a batch experiment. Both factors significantly (α = 0.05) affected the P binding capacity negatively, but the interaction of the two factors was not significant. Increasing the loading rate from 100 to 1200 L m−2 d−1 decreased P binding capacity from 1.152 to 0.070 g kg−1 for wastewater filters and from 1.382 to 0.300 g kg−1 for phosphate solution filters. At a loading rate of 100 L m−2 d−1, the average P binding capacity of wastewater filters was 1.152 g kg−1 as opposed to 1.382 g kg−1 for phosphate solution filters. Therefore, influent source or hydraulic loading rate should be carefully controlled in the laboratory. When phosphate solution and wastewater were used, the reaction times for the filters to remove P were determined to be 5 and 15 minutes, respectively, suggesting that a short residence time is required. However, breakthrough in this study occurred unexpectedly quickly, implying that more time is needed for the P that has reacted to be physically retained in the filter. PMID:23936313
Chimchirian, Robert F; Suri, Rominder P S; Fu, Hongxiang
2007-09-01
Three municipal wastewater treatment plants (WWTPs) in southeastern Pennsylvania were sampled to determine the presence and concentrations of 12 natural and synthetic estrogen hormones in the wastewater influent and effluent. The target estrogens were 17alpha-estradiol, estrone, estriol, equilin, 17alpha-dihydroequilin, 17beta-estradiol, 17alpha-ethinyl estradiol, gestodene, norgestrel, levonorgestrel, medrogestone, and trimegestone. One WWTP uses a biofilm reactor (packed-bed trickling filter),and the other two use suspended-growth media (continuously stirred activated sludge reactor and sequential batch reactor). Estrone was detected in all the three plants; estriol and estradiol were detected at two WWTPs; and 17 alpha-dihydroequilin and 17 alpha-ethinyl estradiol were detected at one WWTP. The concentration of estrogens in the influent and effluent of the three treatment plants ranged from 1.2 to 259 ng/L and 0.5 to 49 ng/L, respectively. The percentage removal of estrogens from the aqueous phase ranged from 41 to 99%, except in the case of 17alpha-dihydroequilin; the removal of 17alpha-dihydroequilin was negligible. The suspended-growth media systems showed higher removal efficiencies for estrogens than the biofilm system. The analytical method uses a Varian C-18 solid-phase extraction (Varian Inc., Palo Alto, California), followed by a derivatization with bis(trimethylsilyl)trifluoroacetamide. The detection limits for the estrogen compounds ranged from 0.1 to 10 ng/L using a sample size of 1 L. The method recoveries ranged from 71 to 120%, and the relative standard deviation ranged from 6 to 14% for all the hormones.
Gagné, F; Smyth, S A; André, C; Douville, M; Gélinas, M; Barclay, K
2013-03-01
The present study sought to examine the performance of six different wastewater treatment processes from 12 wastewater treatment plants using a toxicogenomic approach in rainbow trout hepatocytes. Freshly prepared rainbow trout hepatocytes were exposed to increasing concentrations of influent (untreated wastewaters) and effluent (C(18)) extracts for 48 h at 15 °C. A test battery of eight genes was selected to track changes in xenobiotic biotransformation, estrogenicity, heavy metal detoxification, and oxidative stress. The wastewaters were processed by six different treatment systems: facultative and aerated lagoons, activated sludge, biological aerated filter, biological nutrient removal, chemically assisted primary treated, and trickling filter/solids contact. Based on the chemical characteristics of the effluents, the treatment plants were generally effective in removing total suspended solids and chemical oxygen demand, but less so for ammonia and alkalinity. The 12 influents differed markedly with each other, which makes the comparison among treatment processes difficult. For the influents, both population size and flow rate influenced the increase in the following mRNA levels in exposed hepatocytes: metallothionein (MT), cytochrome P4503A4 (CYP3A4), and vitellogenin (VTG). Gene expression of glutathione S-transferase (GST) and the estrogen receptor (ER), were influenced only by population size in exposed cells to the influent extracts. The remaining genes-superoxide dismutase (SOD) and multidrug resistance transporter (MDR)-were not influenced by either population size or flow rate in exposed cells. It is noteworthy that the changes in MT, ER, and VTG in cells exposed to the effluents were significantly affected by the influents across the 12 cities examined. However, SOD, CYP1A1, CYP3A4, GST, and MDR gene expression were the least influenced by the incoming influents. The data also suggest that wastewater treatments involving biological or aeration
Plodinec, M.J.
1998-11-20
After being filled with glass, DWPF canistered waste forms will be welded closed using an upset resistance welding process. This final closure weld must be leaktight, and must remain so during extended storage at SRS. As part of the DWPF Startup Test Program, a parametric study (DWPF-WP-24) has been performed to determine a range of welder operating parameters which will produce acceptable welds. The parametric window of acceptable welds defined by this study is 90,000 + 15,000 lb of force, 248,000 + 22,000 amps of current, and 95 + 15 cycles* for the time of application of the current.
Eberhard, B.J.; Harbour, J.R.; Plodinec, M.J.
1994-06-01
As part of the DWPF Startup Test Program, a parametric study has been performed to determine a range of welder operating parameters which will produce acceptable final welds for canistered waste forms. The parametric window of acceptable welds defined by this study is 90,000 {plus_minus} 15,000 lb of force, 248,000 {plus_minus} 22,000 amps of current, and 95 {plus_minus} 15 cycles (@ 60 cops) for the time of application of the current.
Parametric Rietveld refinement
Stinton, Graham W.; Evans, John S. O.
2007-01-01
In this paper the method of parametric Rietveld refinement is described, in which an ensemble of diffraction data collected as a function of time, temperature, pressure or any other variable are fitted to a single evolving structural model. Parametric refinement offers a number of potential benefits over independent or sequential analysis. It can lead to higher precision of refined parameters, offers the possibility of applying physically realistic models during data analysis, allows the refinement of ‘non-crystallographic’ quantities such as temperature or rate constants directly from diffraction data, and can help avoid false minima. PMID:19461841
Parametric Differentiation and Integration
ERIC Educational Resources Information Center
Chen, Hongwei
2009-01-01
Parametric differentiation and integration under the integral sign constitutes a powerful technique for calculating integrals. However, this topic is generally not included in the undergraduate mathematics curriculum. In this note, we give a comprehensive review of this approach, and show how it can be systematically used to evaluate most of the…
Parametric Interpretation in Yorktalk.
ERIC Educational Resources Information Center
Ogden, Richard
The method of parametric interpretation used in the computer program "Yorktalk," software that creates synthetic parameter files from phonological representations of speech, is explained. First, the design of the program is described, and the concept of "exponency" in prosodic analysis is explained as it is applied in the…
Parametric Differentiation and Integration
ERIC Educational Resources Information Center
Chen, Hongwei
2009-01-01
Parametric differentiation and integration under the integral sign constitutes a powerful technique for calculating integrals. However, this topic is generally not included in the undergraduate mathematics curriculum. In this note, we give a comprehensive review of this approach, and show how it can be systematically used to evaluate most of the…
Majumder, Partha Sarathi; Gupta, S K
2009-03-01
This study was carried out to determine the effect of influent pH and alkalinity on the performance of sequential UASB and RBC reactors for the removal of 2-CP and 2,4-DCP from two different simulated wastewaters. The performance of methanogens at low (<6.0) to high (>8.0) pH values and at sufficiently high alkalinity (1500-3500 mg/l as CaCO(3)) is described in this paper. Sequential reactors were capable of handling wastewaters with influent pH, 5.5-8.5. However, with influent pH 7.0+/-0.1 UASB reactor showed best performance for 2-CP (99%) and 2,4-DCP (88%) removals. Increase in alkalinity/COD ratio in the influent (>1.1) caused gradual decrease in the chlorophenol removal in UASB reactors. The UASB reactors could not tolerate wastewater with higher alkalinity/COD ratio (2.6) and showed significant deterioration of its performance in terms of chlorophenols removal achieving only 74.7% 2-CP and 60% 2,4-DCP removals, respectively.
Heat Transfer Parametric System Identification
1993-06-01
Transfer Parametric System Identification 6. AUTHOR(S Parker, Gregory K. 7. PERFORMING ORGANIZATION NAME(S) AND AOORESS(ES) 8. PERFORMING ORGANIZATION...distribution is unlimited. Heat Transfer Parametric System Identification by Gregory K. Parker Lieutenant, United States Navy BS., DeVry Institute of...Modeling Concept ........ ........... 3 2. Lumped Parameter Approach ...... ......... 4 3. Parametric System Identification ....... 4 B. BASIC MODELING
Methane from cattle waste: effects of temperature, hydraulic retention time, and influent substrate
Hashimoto, A.G.
1982-09-01
The effects of temperature (35 and 55/sup 0/C), influent volatile solids (VS) concentration (S/sub 0/ = 43, 64, 82, 100, and 128 kg VS/m/sup 3/) and hydraulic retention time (HRT = 4, 5, 8, 10, 15, and 25 days) on methane (CH/sub 4/) production from cattle waste were evaluated using 3-dm/sup 3/ laboratory scale fermentors. The highest CH/sub 4/ production rate achieved was 6.11 m/sup 3/ CH/sub 4/ m/sup -3/ fermentor day/sup -1/ at 55/sup 0/C, four days HRT, and S/sub 0/ = 100 kg VS/m/sup 3/. Batch fermentations showed an ultimate CH/sub 4/ yield (B/sub 0/) of 0.42 m/sup 3/ CH/sub 4//kg VS fed. The maximum loading rates for unstressed fermentation were 7 kg VS m/sup -3/ day/sup -1/ at 35/sup 0/C and 20 kg VS m/sup -3/ day/sup -1/ at 55/sup 0/C. The kinetic parameter (K, an increasing K indicates inhibition of fermentation) increased exponentially.
Impact of influent COD/N ratio on disintegration of aerobic granular sludge.
Luo, Jinghai; Hao, Tianwei; Wei, Li; Mackey, Hamish R; Lin, Ziqiao; Chen, Guang-Hao
2014-10-01
Disintegration of aerobic granular sludge (AGS) is a challenging issue in the long-term operation of an AGS system. Chemical oxygen demand (COD)-to-nitrogen (N) ratio (COD/N), often variable in industrial wastewaters, could be a destabilizing factor causing granule disintegration. This study investigates the impact of this ratio on AGS disintegration and identifies the key causes, through close monitoring of AGS changes in its physical and chemical characteristics, microbial community and treatment performance. For specific comparison, two lab-scale air-lift type sequencing batch reactors, one for aerobic granular and the other for flocculent sludge, were operated in parallel with three COD/N ratios (4, 2, 1) applied in the influent of each reactor. The decreased COD/N ratios of 2 and 1 strongly influenced the stability of AGS with regard to physical properties and nitrification efficiency, leading to AGS disintegration when the ratio was decreased to 1. Comparatively the flocculent sludge maintained relatively stable structure and nitrification efficiency under all tested COD/N ratios. The lowest COD/N ratio resulted in a large microbial community shift and extracellular polymeric substances (EPS) reduction in both flocculent and granular sludges. The disintegration of AGS was associated with two possible causes: 1) reduction in net tyrosine production in the EPS and 2) a major microbial community shift including reduction in filamentous bacteria leading to the collapse of granule structure.
Chalcogenide optical parametric oscillator.
Ahmad, Raja; Rochette, Martin
2012-04-23
We demonstrate the first optical parametric oscillator (OPO) based on chalcogenide glass. The parametric gain medium is an As(2)Se(3) chalcogenide microwire coated with a layer of polymer. The doubly-resonant OPO oscillates simultaneously at a Stokes and an anti Stokes wavelength shift of >50 nm from the pump wavelength that lies at λ(P) = 1,552 nm. The oscillator has a peak power threshold of 21.6 dBm and a conversion efficiency of >19%. This OPO experiment provides an additional application of the chalcogenide microwire technology; and considering the transparency of As(2)Se(3) glass extending far in the mid-infrared (mid-IR) wavelengths, the device holds promise for realizing mid-IR OPOs utilizing existing optical sources in the telecommunications wavelength region.
Parametric Explosion Spectral Model
Ford, S R; Walter, W R
2012-01-19
Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.
NASA Astrophysics Data System (ADS)
Kakadiaris, Ioannis A.; Konstantinidis, Ioannis; Papadakis, Manos; Ding, Wei; Shen, Lixin
2005-08-01
Three dimensional (3D) surfaces can be sampled parametrically in the form of range image data. Smoothing/denoising of such raw data is usually accomplished by adapting techniques developed for intensity image processing, since both range and intensity images comprise parametrically sampled geometry and appearance measurements, respectively. We present a transform-based algorithm for surface denoising, motivated by our previous work on intensity image denoising, which utilizes a non-separable Parseval frame and an ensemble thresholding scheme. The frame is constructed from separable (tensor) products of a piecewise linear spline tight frame and incorporates the weighted average operator and the Sobel operators in directions that are integer multiples of 45°. We compare the performance of this algorithm with other transform-based methods from the recent literature. Our results indicate that such transform methods are suited to the task of smoothing range images.
Percent recovery of low influent concentrations of microorganism surrogates in small sand columns
NASA Astrophysics Data System (ADS)
Stevenson, M. E.; Blaschke, A. P.
2012-04-01
In order to develop a dependable method to calculate the setback distance of a drinking water well from a potential point of microbiological contamination, surrogates are used to perform field tests to avoid using pathogenic micro-organisms. One such surrogate used to model the potential travel time of microbial contamination is synthetic microspheres. The goal of this study is to examine the effect of differing influent colloid concentrations on the percent recovery of microbial surrogates after passing through a soil column. Similar studies have been done to investigate blocking of ideal attachment sites using concentrations between 106 and 1010 particles ml-1. These high concentrations were necessary due to the detection limit of the measuring technique used; however, our measuring technique allows us to test input concentrations ranging from 101 to 106 particles ml-1. These low concentrations are more similar to the concentrations of pathogenic microorganisms present in nature. We have tested the enumeration of 0.5 μm microspheres using a solid-phase cytometer and evaluated their transport in small sand columns. Fluorescent microspheres were purchased for this study with carboxylated surfaces. The soil columns consist of Plexiglas tubes, 30 cm long and 7 cm in diameter, both filled with the same coarse sand. Bromide was used as a conservative tracer, to estimate pore-water velocity and dispersivity, and bromide concentrations were analysed using ion chromatography and bromide probes. Numerical modelling was done using CXTFIT and HYDRUS-1D software programs. The 0.5 μm beads were enumerated in different environmental waters using solid-phase cytometry and compared to counts in sterile water in order to confirm the accuracy of the method. The solid-phase cytometer was able to differentiate the 0.5 μm beads from naturally present autofluorescent particles and bacteria, and therefore, is an appropriate method to enumerate this surrogate.
Ye, Fenxia; Peng, Ge; Li, Ying
2011-08-01
It is necessary to understand the bioflocculation, settling and dewatering characteristics in the activated sludge process in order to establish more efficient operational strategies. The influences of carbon source on the extracellular polymeric substances (EPS) and flocculation, settling and dewatering properties of the activated sludge were investigated. Laboratory-scale completely mixed activated sludge processes were used to grow the activated sludge with different carbon sources of starch, glucose and sodium acetate. The sludge fed with acetate had highest loosely bound EPS (LB-EPS) and that fed with starch lowest. The amount of tightly bound EPS (TB-EPS), protein content in LB-EPS, polysaccharide content and protein contents in TB-EPS, were independent of the influent carbon source. The polysaccharide content in LB-EPS of the activated sludge fed with sodium acetate was lower slightly than those of starch and glucose. The sludge also had a nearly consistent flocs size and the sludge volume index (SVI) value. ESS content of the sludge fed with sodium acetate was higher initially, although it was similar to those fed with glucose and starch finally. However, the specific resistance to filtration and normalized capillary suction time fluctuated first, but finally were stable at around 5.0×10(8)mkg(-1) and 3.5 s Lg(-1) SS, respectively. Only the protein content in LB-EPS weakly correlated with the flocs size and SVI of the activated sludge. But there was no correlation between any other EPS contents or components and the physicochemical properties of the activated sludge.
Liu, Yanchen; Shi, Hanchang; Shi, Huiming; Wang, Zhiqiang
2010-10-01
The aim of study was proposed a new control model feasible on-line implemented by Programmable Logic Controller (PLC) to enhance nitrogen removal against the fluctuation of influent in Carrousel oxidation ditch. The discrete-time control model was established by confirmation model of operational conditions based on a expert access, which was obtained by a simulation using Activated Sludge Model 2-D (ASM2-D) and Computation Fluid Dynamics (CFD), and discrete-time control model to switch between different operational stages. A full-scale example is provided to demonstrate the feasibility of the proposed operation and the procedure of the control design. The effluent quality was substantially improved, to the extent that it met the new wastewater discharge standards of NH(3)-N<5mg/L and TN<15 mg/L enacted in China throughout a one-day period with fluctuation of influent.
Kitajima, Masaaki; Haramoto, Eiji; Iker, Brandon C; Gerba, Charles P
2014-06-15
We investigated the occurrence of Cryptosporidium, Giardia, and Cyclospora at two wastewater treatment plants (WWTPs) in Arizona over a 12-month period, from August 2011 to July 2012. Influent and effluent wastewater samples were collected monthly, and protozoan (oo)cysts were concentrated using an electronegative filter, followed by the detection of protozoa using fluorescent microscopy (Cryptosporidium oocysts and Giardia cysts) and PCR-based methods (Cryptosporidium spp., Giardia intestinalis, and Cyclospora cayetanensis). The concentration of Giardia cysts in the influent was always higher than that of Cryptosporidium oocysts (mean concentration of 4.8-6.4×10(3) versus 7.4×10(1)-1.0×10(2)(oo)cysts/l) with no clear seasonality, and log10 reduction of Giardia cysts was significantly higher than that of Cryptosporidium oocysts for both WWTPs (P<0.05). Log10 reduction of Giardia cysts at the WWTP utilizing activated sludge was significantly higher than the other WWTP using trickling filter (P=0.014), while no statistically significant difference between the two WWTPs was observed for the log10 reduction of Cryptosporidium oocysts (P=0.207). Phylogenetic analysis revealed that G. intestinalis strains identified in wastewater belonged to two assemblages, AII and B, which are potentially infectious to humans. C. cayetanensis was also detected from both influent and effluent using a newly developed quantitative PCR, with the highest influent concentration of 1.2×10(4)copies/l. Our results demonstrated that these protozoan pathogens are prevalent in the study area and that efficacy of the conventional wastewater treatment processes at physically removing (oo)cysts is limited.
Bade, Richard; Bijlsma, Lubertus; Sancho, Juan V; Baz-Lomba, Jose A; Castiglioni, Sara; Castrignanò, Erika; Causanilles, Ana; Gracia-Lor, Emma; Kasprzyk-Hordern, Barbara; Kinyua, Juliet; McCall, Ann-Kathrin; van Nuijs, Alexander L N; Ort, Christoph; Plósz, Benedek G; Ramin, Pedram; Rousis, Nikolaos I; Ryu, Yeonsuk; Thomas, Kevin V; de Voogt, Pim; Zuccato, Ettore; Hernández, Félix
2017-02-01
The popularity of new psychoactive substances (NPS) has grown in recent years, with certain NPS commonly and preferentially consumed even following the introduction of preventative legislation. With the objective to improve the knowledge on the use of NPS, a rapid and very sensitive method was developed for the determination of ten priority NPS (N-ethylcathinone, methylenedioxypyrovalerone (MDPV), methylone, butylone, methedrone, mephedrone, naphyrone, 25-C-NBOMe, 25-I-NBOMe and 25-B-NBOMe) in influent wastewater. Sample clean-up and pre-concentration was made by off-line solid phase extraction (SPE) with Oasis MCX cartridges. Isotopically labelled internal standards were used to correct for matrix effects and potential SPE losses. Following chromatographic separation on a C18 column within 6 min, the compounds were measured by tandem mass spectrometry in positive ionization mode. The method was optimised and validated for all compounds. Limits of quantification were evaluated by spiking influent wastewater samples at 1 or 5 ng/L. An investigation into the stability of these compounds in influent wastewater was also performed, showing that, following acidification at pH 2, all compounds were relatively stable for up to 7 days. The method was then applied to influent wastewater samples from eight European countries, in which mephedrone, methylone and MDPV were detected. This work reveals that although NPS use is not as extensive as for classic illicit drugs, the application of a highly sensitive analytical procedure makes their detection in wastewater possible. The developed analytical methodology forms the basis of a subsequent model-based back-calculation of abuse rate in urban areas (i.e. wastewater-based epidemiology). Copyright © 2016 Elsevier Ltd. All rights reserved.
Daalkhaijav, Uranbileg; Nemati, Mehdi
2014-01-01
Anaerobic ammonium oxidation (ANAMMOX) is an innovative process for the treatment of ammonia-contaminated waters. ANNAMOX is usually preceded by a nitrifying step in which ammonia is partially oxidized to nitrite. The effectiveness of the overall process depends on control of the nitrification and creation of a suitable influent for ANAMMOX. In this work, impacts of ammonia concentration and loading rate on partial nitrification and composition of the resulting effluent were investigated in continuous stirred tank (CSTR) and biofilm reactors fed with various ammonia concentrations (17.6-61.5 mM; 299-1045 ppm). Regardless of ammonia concentration, loading rates from 3.1 to 5.4mM/h in the CSTR and 6.4-12.1 mM/h in the biofilm reactor generated effluents with nitrite to ammonia ratios of 1.2 +/- 0.3 (suitable ANAMMOX influent). Under these conditions, the highest ammonia loading and nitrite production rates in the CSTR and biofilm reactors were 5.4 and 2.5 mM/h (HRT: 3.7 h) and 12.1 and 6.5 mM/h (HRT: 1.6 h), respectively. Results reveal that ammonia loading rate can be used effectively to achieve suitable ANAMMOX influent without the need for precise control of dissolved oxygen (DO). Considering the difficulty in regulating DO in large-scale systems and the need for the nitrifying process to be flexible with respect to various ammonia concentrations, the loading rate appears to be a practical option to control partial nitrification. Verifying the range of ammonia loading rates that generate ANAMMOX influent allows operation of the nitrifying step with any level of ammonia in the feed, with the proper loading rate achieved through adjustment of hydraulic residence time.
NASA Technical Reports Server (NTRS)
Rosu, Grigore (Inventor); Chen, Feng (Inventor); Chen, Guo-fang; Wu, Yamei; Meredith, Patrick O. (Inventor)
2014-01-01
A program trace is obtained and events of the program trace are traversed. For each event identified in traversing the program trace, a trace slice of which the identified event is a part is identified based on the parameter instance of the identified event. For each trace slice of which the identified event is a part, the identified event is added to an end of a record of the trace slice. These parametric trace slices can be used in a variety of different manners, such as for monitoring, mining, and predicting.
Multicast Parametric Synchronous Sampling
2011-09-01
28, No. 23, pp. 3478-3487 (2010). [7] S. Moro, E. Myslivets, J.R. Windmiller, N. Alic, J.M. Chavez Boggio , S. Radic “Synthesis of Equalized...Broadband Parametric Gain by Localized Dispersion Mapping” IEEE Photonics Technology Letters, Vol. 20, No. 23, pp. 1971 – 1973 (2008). [8] J.C. Boggio , S...21 No. 10, pp. 612-614 (2009). [9] C.S. Bres, J.M. Chavez- Boggio , N. Alic, S. Radic, “1-to-40 10-Gb/s Channel Multicasting and Amplification in
Optical parametric loop mirror
NASA Astrophysics Data System (ADS)
Mori, K.; Morioka, T.; Saruwatari, M.
1995-06-01
A novel configuration for four-wave mixing (FWM) is proposed that offers the remarkable feature of inherently separating the FWM wave from the input pump and signal waves and suppressing their background amplified stimulated emission without optical filtering. In the proposed configuration, an optical parametric loop mirror, two counterpropagating FWM waves generated in a Sagnac interferometer interfere with a relative phase difference that is introduced deliberately. FWM frequency-conversion experiments in a polarization-maintaining fiber achieved more than 35 dB of input-wave suppression against the FWM wave.
Welles, Laurens; Abbas, Ben; Sorokin, Dimitry Y.; Lopez-Vazquez, Carlos M.; Hooijmans, Christine M.; van Loosdrecht, Mark C. M.; Brdjanovic, Damir
2017-01-01
The objective of this study was to investigate the ability of a culture highly enriched with the polyphosphate-accumulating organism, “Candidatus Accumulibacter phosphatis” clade IIC, to adjust their metabolism to different phosphate availabilities. For this purpose the biomass was cultivated in a sequencing batch reactor with acetate and exposed to different phosphate/carbon influent ratios during six experimental phases. Activity tests were conducted to determine the anaerobic kinetic and stoichiometric parameters as well as the composition of the microbial community. Increasing influent phosphate concentrations led to increased poly-phosphate content and decreased glycogen content of the biomass. In response to higher biomass poly-phosphate content, the biomass showed higher specific phosphate release rates. Together with the phosphate release rates, acetate uptake rates also increased up to an optimal poly-phosphate/glycogen ratio of 0.3 P-mol/C-mol. At higher poly-phosphate/glycogen ratios (obtained at influent P/C ratios above 0.051 P-mol/C-mol), the acetate uptake rates started to decrease. The stoichiometry of the anaerobic conversions clearly demonstrated a metabolic shift from a glycogen dominated to a poly-phosphate dominated metabolism as the biomass poly-phosphate content increased. FISH and DGGE analyses confirmed that no significant changes occurred in the microbial community, suggesting that the changes in the biomass activity were due to different metabolic behavior, allowing the organisms to proliferate under conditions with fluctuating phosphate levels. PMID:28111570
Liang, Yinxiu; Zhu, Hui; Bañuelos, Gary; Yan, Baixing; Shutes, Brian; Cheng, Xianwei; Chen, Xin
2017-11-01
This study aims to evaluate how plant species, influent loads and salinity levels affect the removal of nutrients from saline wastewater using constructed wetlands (CWs). CWs planted with Canna indica showed the greatest removal percentages among the four tested species for nitrogen (N) (∼100%) at both low and high influent loads, and ∼100% and 93.8% for phosphorus (P) at low and high influent loads, respectively at an electrical conductivity (EC) of 7 mS/cm (25 °C). The influence of different salinity levels on plant assimilation of N and P varied with their respective concentrations; salinity (e.g., EC at 7, 10 and 15 mS/cm) even enhanced plant absorption of N and P under specific conditions. In conclusion, CWs planted with selected species can be used for the removal of N and P under a range of different salinity levels (e.g., EC at 7, 10 and 15 mS/cm, 25 °C). Copyright © 2017. Published by Elsevier Ltd.
Hijosa-Valsero, María; Reyes-Contreras, Carolina; Domínguez, Carmen; Bécares, Eloy; Bayona, Josep M
2016-02-01
Seven mesocosm-scale constructed wetlands (CWs) with different design configurations, dealing with primary-treated urban wastewater, were assessed for the concentration, distribution and fate of ten pharmaceutical and personal care products (PPCPs) [ibuprofen, ketoprofen, naproxen, diclofenac, salicylic acid, caffeine, carbamazepine, methyl dihydrojasmonate, galaxolide and tonalide] and eight of their transformation products (TPs). Apart from influent and effluent, various CW compartments were analysed, namely, substrate, plant roots and pore water. PPCP content in pore water depended on the specific CW configuration. Macrophytes can take up PPCPs through their roots. Ibuprofen, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide were present on the root surface with a predominance of galaxolide and caffeine in all the planted systems. Naproxen, ibuprofen, salicylic acid, methyl dihydrojasmonate, galaxolide and tonalide were uptaken by the roots. In order to better understand the removal processes, biomass measurement and biodegradability studies through the characterization of internal-external isomeric linear alkylbenzenes present on the gravel bed were performed. Three TPs namely, ibuprofen-amide, 3-ethylbenzophenone and 4-hydroxy-diclofenac were identified for the first time in wetland pore water and effluent water, which suggests de novo formation (they were not present in the influent). Conversely, O-desmethyl-naproxen was degraded through the wetland passage since it was detected in the influent but not in the subsequent treatment stages. Biodegradation pathways are therefore suggested for most of the studied PPCPs in the assessed CWs. Copyright © 2015 Elsevier Ltd. All rights reserved.
Kouba, Vojtech; Catrysse, Michael; Stryjova, Hana; Jonatova, Ivana; Volcke, Eveline I P; Svehla, Pavel; Bartacek, Jan
2014-01-01
The application of nitrification-denitrification over nitrite (nitritation-denitritation) with municipal (i.e. diluted and cold (or low-temperature)) wastewater can substantially improve the energy balance of municipal wastewater treatment plants. For the accumulation of nitrite, it is crucial to inhibit nitrite-oxidizing bacteria (NOB) with simultaneous proliferation of ammonium-oxidizing bacteria (AOB). The present study describes the effect of the influent total ammonium nitrogen (TAN) concentration on AOB and NOB activity in two moving bed biofilm reactors operated as sequencing batch reactors (SBR) at 15 °C (SBR I) and 21 °C (SBR II). The reactors were fed with diluted reject water containing 600, 300, 150 and 75 mg TAN L(-1). The only factor limiting NOB activity in these reactors was the high concentrations of free ammonia and/or free nitrous acid (FNA) during the SBR cycles. Nitrite accumulation was observed with influents containing 600, 300 and 150 mg TAN L(-1) in SBR I and 600 and 300 in SBR II. Once nitrate production established in the reactors, the increase of influent TAN concentration up to the original 600 mg TAN L(-1) did not limit NOB activity. This was due to the massive development of NOB clusters throughout the biofilm that were able to cope with faster formation of FNA. The results of the fluorescence in situ hybridization analysis preliminarily showed the stratification of bacteria in the biofilm.
Wang, Xiaoyuan; Xie, Bing; Zhang, Chaoqun; Shen, Yiwen; Lu, Jun
2017-01-01
In this paper, Quantitative Polymerase Chain Reaction (qPCR), Illumina MiSeq sequencing and (15)N stable isotopic tracing methods were applied to study the effects of influent organic loading, BOD5/TN and NO2-N/NH4-N ratios on the combined nitrogen removal through denitrification and anammox. The results show that, the total nitrogen removal was above 90% at the optimum reaction condition: organic loading 0.04kg/m(3)·day, BOD5/TN 0.2, and NO2-N/NH4-N 1.0. Approximately 9.43% of the nitrogen removal occurred through anammox process when BOD5/TN was 0.1, and increased to 21.46% when BOD5/TN was 0.2. The anammox accounted for 10% when NO2-N/NH4-N was 0.5, and that increased to 20.72% when NO2-N/NH4-N was 1.0-1.5. hzsA was directly proportional to the influent BOD5/TN. A positive correlation between BOD5/TN and anammox microorganisms existed. Similarly, there was a positive correlation between NO2-N/NH4-N and denitrification microorganisms. Therefore, it is feasible to regulate the influent to improve nitrogen removal efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.
Progress in optical parametric oscillators
NASA Technical Reports Server (NTRS)
Fan, Y. X.; Byer, R. L.
1984-01-01
It is pointed out that tunable coherent sources are very useful for many applications, including spectroscopy, chemistry, combustion diagnostics, and remote sensing. Compared with other tunable sources, optical parametric oscillators (OPO) offer the potential advantage of a wide wavelength operating range, which extends from 0.2 micron to 25 microns. The current status of OPO is examined, taking into account mainly advances made during the last decade. Attention is given to early LiNbO3 parametric oscillators, problems which have prevented wide use of parametric oscillators, the demonstration of OPO's using urea and AgGaS2, progress related to picosecond OPO's, a breakthrough in nanosecond parametric oscillators, the first demonstration of a waveguide and fiber parametric amplification and generation, the importance of chalcopyrite crystals, and theoretical work performed with the aim to understand the factors affecting the parametric oscillator performance.
Wey, Andrew; Connett, John; Rudser, Kyle
2015-07-01
For estimating conditional survival functions, non-parametric estimators can be preferred to parametric and semi-parametric estimators due to relaxed assumptions that enable robust estimation. Yet, even when misspecified, parametric and semi-parametric estimators can possess better operating characteristics in small sample sizes due to smaller variance than non-parametric estimators. Fundamentally, this is a bias-variance trade-off situation in that the sample size is not large enough to take advantage of the low bias of non-parametric estimation. Stacked survival models estimate an optimally weighted combination of models that can span parametric, semi-parametric, and non-parametric models by minimizing prediction error. An extensive simulation study demonstrates that stacked survival models consistently perform well across a wide range of scenarios by adaptively balancing the strengths and weaknesses of individual candidate survival models. In addition, stacked survival models perform as well as or better than the model selected through cross-validation. Finally, stacked survival models are applied to a well-known German breast cancer study.
Monolithic optical parametric oscillators
NASA Astrophysics Data System (ADS)
Breunig, Ingo; Beckmann, Tobias; Buse, Karsten
2012-02-01
Stability and footprint of optical parametric oscillators (OPOs) strongly depend on the cavity used. Monolithic OPOs tend to be most stable and compact since they do not require external mirrors that have to be aligned. The most straightforward way to get rid of the mirrors is to coat the end faces of the nonlinear crystal. Whispering gallery resonators (WGRs) are a more advanced solution since they provide ultra-high reflectivity over a wide spectral range without any coating. Furthermore, they can be fabricated out of nonlinear-optical materials like lithium niobate. Thus, they are ideally suited to serve as a monolithic OPO cavity. We present the experimental realization of optical parametric oscillators based on whispering gallery resonators. Pumped at 1 μm wavelength, they generate signal and idler fields tunable between 1.8 and 2.5 μm wavelength. We explore different schemes, how to phase match the nonlinear interaction in a WGR. In particular, we show improvements in the fabrication of quasi-phase-matching structures. They enable great flexibility for the tuning and for the choice of the pump laser.
Short, Michael D; Daikeler, Alexander; Wallis, Kirsten; Peirson, William L; Peters, Gregory M
2017-12-01
Methane (CH4) is an important anthropogenic greenhouse gas and a by-product of urban sewage management. In recent years and contrary to international (IPCC) consensus, pressurised (anaerobic) sewers were identified as important CH4 sources, yet relatively little remains known regarding the role of gravity sewers in CH4 production and conveyance. Here we provide the results of a nine month study assessing dissolved CH4 levels in the raw influent of three large Australian wastewater treatment plants (WWTPs) fed by gravity sewers. Similar to recent international research and contrary to IPCC guidance, results show that gravity sewered wastewater contains moderate levels of CH4 (≈1mgL(-1)). Dissolved CH4 concentration correlated negatively with daily sewage flow rate (i.e. inversely proportional to sewer hydraulic residence time), with daily CH4 mass loads on average some two-fold greater under low flow (dry weather) conditions. Along with sewage hydraulic residence time, sewer sediments are thought to interact with sewage flow rate and are considered to play a key role in gravity sewer CH4 production. A per capita load of 78gCH4person(-1)y(-1) is offered for gravity sewered wastewater entering WWTPs, with a corresponding emission estimate of up to 62gCH4person(-1)y(-1), assuming 80% water-to-air transfer of inflowing CH4 in WWTPs with combined preliminary-primary plus secondary treatment. Results here support the emerging consensus view that hydraulic operation (i.e. gravity versus pressurised, sewage flow rate) is a key factor in determining sewer CH4 production, with gravity sewer segments likely to play a dominant role in total CH4 production potential for large metropolitan sewer networks. Further work is warranted to assess the scale and temporal dynamics of CH4 production in gravity sewers elsewhere, with more work needed to adequately capture and assess the scale of diffuse sewer network CH4 emissions from sprawling urban settlements globally. Copyright
NASA Astrophysics Data System (ADS)
Acomi, Nicoleta; Ancuţa, Cristian; Andrei, Cristian; Boştinǎ, Alina; Boştinǎ, Aurel
2016-12-01
Ships are mainly built to sail and transport cargo at sea. Environmental conditions and state of the sea are communicated to vessels through periodic weather forecasts. Despite officers being aware of the sea state, their sea time experience is a decisive factor when the vessel encounters severe environmental conditions. Another important factor is the loading condition of the vessel, which triggers different behaviour in similar marine environmental conditions. This paper aims to analyse the behaviour of a port container vessel in severe environmental conditions and to estimate the potential conditions of parametric roll resonance. Octopus software simulation is employed to simulate vessel motions under certain conditions of the sea, with possibility to analyse the behaviour of ships and the impact of high waves on ships due to specific wave encounter situations. The study should be regarded as a supporting tool during the decision making process.
Ebrahimzadeh, M
2003-12-15
Since its invention more than 40 years ago, the laser has become an indispensable optical tool, capable of transforming light from its naturally incoherent state to a highly coherent state in space and time. Yet, due to fundamental limitations, operation of the laser remains confined to restricted spectral and temporal regions. Nonlinear optics can overcome this limitation by allowing access to new spectral and temporal regimes through the exploitation of suitable dielectric materials in combination with the laser. In particular, optical parametric oscillators are versatile coherent light sources with unique flexibility that can provide optical radiation across an entire spectral range from the ultraviolet to the far-infrared and over all temporal scales from continuous wave to the ultrafast femtosecond domain.
Parametric lattice Boltzmann method
NASA Astrophysics Data System (ADS)
Shim, Jae Wan
2017-06-01
The discretized equilibrium distributions of the lattice Boltzmann method are presented by using the coefficients of the Lagrange interpolating polynomials that pass through the points related to discrete velocities and using moments of the Maxwell-Boltzmann distribution. The ranges of flow velocity and temperature providing positive valued distributions vary with regulating discrete velocities as parameters. New isothermal and thermal compressible models are proposed for flows of the level of the isothermal and thermal compressible Navier-Stokes equations. Thermal compressible shock tube flows are simulated by only five on-lattice discrete velocities. Two-dimensional isothermal and thermal vortices provoked by the Kelvin-Helmholtz instability are simulated by the parametric models.
Nanoscale electromechanical parametric amplifier
Aleman, Benjamin Jose; Zettl, Alexander
2016-09-20
This disclosure provides systems, methods, and apparatus related to a parametric amplifier. In one aspect, a device includes an electron source electrode, a counter electrode, and a pumping electrode. The electron source electrode may include a conductive base and a flexible conductor. The flexible conductor may have a first end and a second end, with the second end of the flexible conductor being coupled to the conductive base. A cross-sectional dimension of the flexible conductor may be less than about 100 nanometers. The counter electrode may be disposed proximate the first end of the flexible conductor and spaced a first distance from the first end of the flexible conductor. The pumping electrode may be disposed proximate a length of the flexible conductor and spaced a second distance from the flexible conductor.
Mechanical Parametric Oscillations and Waves
ERIC Educational Resources Information Center
Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.
2013-01-01
Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…
Mechanical Parametric Oscillations and Waves
ERIC Educational Resources Information Center
Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.
2013-01-01
Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…
NASA Technical Reports Server (NTRS)
Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.
1993-01-01
Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.
Li, Weihua; Sun, Yingjie; Bian, Rongxing; Wang, Huawei; Zhang, Dalei
2017-08-12
The carbon-nitrogen ratio (COD/NH4(+)-N) is an important factor affecting nitrification and denitrification in wastewater treatment; this factor also influences nitrous oxide (N2O) emissions. This study investigated two simulated intermittently aerated semi-aerobic aged refuse bioreactors (SAARB) filled with 8-year old aged refuse (AR). The research analyzed how differences in and the combination of influent COD and NH4(+)-N impact N2O emissions in leachate treatment. Experimental results showed that N2O emissions increased as the influent COD/NH4(+)-N decreased. The influent COD had a greater effect on N2O emissions than NH4(+)-N at the same influent ratios of COD/NH4(+)-N (2.7 and 8.0, respectively). The maximum N2O emission accounted for 8.82±2.65% of the total nitrogen removed from the influent leachate; the maximum level occurred when the COD was 2000mg/L. An analysis of differences in influent carbon sources at the same COD/NH4(+)-N ratios concluded that the availability of biodegradable carbon substrates (i.e. glucose) is an important factor affecting N2O emissions. At a low influent COD/NH4(+)-N ratio (2.7), the N2O conversion rate was greater when there were more biodegradable carbon substrates. Although the SAARB included the N2O generation and reduction processes, N2O reduction mainly occurred later in the process, after leachate recirculation. The maximum N2O emission rate occurred in the first hour of single-period (24h) experiments, as leachate contacted the surface AR. In practical SAARB applications, N2O emissions may be reduced by measures such as reducing the initial recirculation loading of NH4(+)-N substrates, adding a later supplement of biodegradable carbon substrates, and/or prolonging hydraulic retention time (HRT) of influent leachate. Copyright © 2017. Published by Elsevier Ltd.
Jordan, Mark A; Welsh, David T; John, Richard; Catterall, Kylie; Teasdale, Peter R
2013-02-01
Representative and fast monitoring of wastewater influent and effluent biochemical oxygen demand (BOD) is an elusive goal for the wastewater industry and regulatory bodies alike. The present study describes a suitable assay, which incorporates activated sludge as the biocatalyst and ferricyanide as the terminal electron acceptor for respiration. A number of different sludges and sludge treatments were investigated, primarily to improve the sensitivity of the assay. A limit of detection (LOD) (2.1 mg BOD₅ L⁻¹) very similar to that of the standard 5-day BOD₅ method was achieved in 4 h using raw influent sludge that had been cultured overnight as the biocatalyst. Reducing the microbial concentration was the most effective means to improve sensitivity and reduce the contribution of the sludge's endogenous respiration to total ferricyanide-mediated (FM) respiration. A strong and highly significant relationship was found (n = 33; R = 0.96; p < 0.001; slope = 0.94) between BOD₅ and FM-BOD equivalent values for a diverse range of samples including wastewater treatment plant (WWTP) influent and treated effluent, as well as several grey water samples. The activated sludge FM-BOD assay presented here is an exceptional surrogate method to the standard BOD₅ assay, providing representative, same-day BOD analysis of WWTP samples with a comparable detection limit, a 4-fold greater analytical range and much faster analysis time. The industry appeal of such an assay is tremendous given that ~90% of all BOD₅ analysis is dedicated to measurement of WWTP samples, for which this assay is specifically designed. Copyright © 2012 Elsevier Ltd. All rights reserved.
Vivancos, E; Healy, C; Mueller, F; Whalley, D
2001-05-09
Embedded systems often have real-time constraints. Traditional timing analysis statically determines the maximum execution time of a task or a program in a real-time system. These systems typically depend on the worst-case execution time of tasks in order to make static scheduling decisions so that tasks can meet their deadlines. Static determination of worst-case execution times imposes numerous restrictions on real-time programs, which include that the maximum number of iterations of each loop must be known statically. These restrictions can significantly limit the class of programs that would be suitable for a real-time embedded system. This paper describes work-in-progress that uses static timing analysis to aid in making dynamic scheduling decisions. For instance, different algorithms with varying levels of accuracy may be selected based on the algorithm's predicted worst-case execution time and the time allotted for the task. We represent the worst-case execution time of a function or a loop as a formula, where the unknown values affecting the execution time are parameterized. This parametric timing analysis produces formulas that can then be quickly evaluated at run-time so dynamic scheduling decisions can be made with little overhead. Benefits of this work include expanding the class of applications that can be used in a real-time system, improving the accuracy of dynamic scheduling decisions, and more effective utilization of system resources. This paper describes how static timing analysis can be used to aid in making dynamic scheduling decisions. The WCET of a function or a loop is represented as a formula, where the values affecting the execution time are parameterized. Such formulas can then be quickly evaluated at run-time so dynamic scheduling decisions can be made when scheduling a task or choosing algorithms within a task. Benefits of this parametric timing analysis include expanding the class of applications that can be used in a real-time system
NASA Astrophysics Data System (ADS)
Choi, Jongseong
The performance of a hypersonic flight vehicle will depend on existing materials and fuels; this work presents the performance of the ideal scramjet engine for three different combustion chamber materials and three different candidate fuels. Engine performance is explored by parametric cycle analysis for the ideal scramjet as a function of material maximum service temperature and the lower heating value of jet engine fuels. The thermodynamic analysis is based on the Brayton cycle as similarly employed in describing the performance of the ramjet, turbojet, and fanjet ideal engines. The objective of this work is to explore material operating temperatures and fuel possibilities for the combustion chamber of a scramjet propulsion system to show how they relate to scramjet performance and the seven scramjet engine parameters: specific thrust, fuel-to-air ratio, thrust-specific fuel consumption, thermal efficiency, propulsive efficiency, overall efficiency, and thrust flux. The information presented in this work has not been done by others in the scientific literature. This work yields simple algebraic equations for scramjet performance which are similar to that of the ideal ramjet, ideal turbojet and ideal turbofan engines.
Parametric Transformation Analysis
NASA Technical Reports Server (NTRS)
Gary, G. Allan
2003-01-01
Because twisted coronal features are important proxies for predicting solar eruptive events, and, yet not clearly understood, we present new results to resolve the complex, non-potential magnetic field configurations of active regions. This research uses free-form deformation mathematics to generate the associated coronal magnetic field. We use a parametric representation of the magnetic field lines such that the field lines can be manipulated to match the structure of EUV and SXR coronal loops. The objective is to derive sigmoidal magnetic field solutions which allows the beta greater than 1 regions to be included, aligned and non-aligned electric currents to be calculated, and the Lorentz force to be determined. The advantage of our technique is that the solution is independent of the unknown upper and side boundary conditions, allows non-vanishing magnetic forces, and provides a global magnetic field solution, which contains high- and low-beta regimes and is consistent with all the coronal images of the region. We show that the mathematical description is unique and physical.
Parametric Mass Reliability Study
NASA Technical Reports Server (NTRS)
Holt, James P.
2014-01-01
The International Space Station (ISS) systems are designed based upon having redundant systems with replaceable orbital replacement units (ORUs). These ORUs are designed to be swapped out fairly quickly, but some are very large, and some are made up of many components. When an ORU fails, it is replaced on orbit with a spare; the failed unit is sometimes returned to Earth to be serviced and re-launched. Such a system is not feasible for a 500+ day long-duration mission beyond low Earth orbit. The components that make up these ORUs have mixed reliabilities. Components that make up the most mass-such as computer housings, pump casings, and the silicon board of PCBs-typically are the most reliable. Meanwhile components that tend to fail the earliest-such as seals or gaskets-typically have a small mass. To better understand the problem, my project is to create a parametric model that relates both the mass of ORUs to reliability, as well as the mass of ORU subcomponents to reliability.
NASA Astrophysics Data System (ADS)
Duan, J. J.; Zhao, J. N.; Xue, L. H.; Yang, L. Z.
2016-08-01
Plant floating bed was adopted in this study to compare the purification effect of four plant species (Oenanthe javanica, Ipomoea aquatica, Hydrocotyle vulgaris, and Iris sibirica) receiving high and low treated domestic sewage. The experiment was conducted for eight months during the low temperature season. The results indicated that the average removal rates of TN and NH4+-N in I. aquatica floating bed were relatively high both under high and low influent concentration during the first stage of the experiment. During the second stage, H. vulgaris showed the best performance for nitrogen treatment, and the average removal rates of TN were 70.7% and 87.7% under high and low influent concentration, while the average removal rates of NH4 +-N were as high as 98.9% and 98.9%, accordingly. Moreover, H. vulgaris contributed most for plant assimilation to nitrogen removal among different plant floating systems. It was also found that the existence of hydrophytes effectively controlled the rise of water pH value and algae growth and reproduction, which helped to improve the aquatic environment. The results provide engineering parameters for the future design of an ecological remediation technology for low-pollution wastewater purification.
Tolksdorf, J; Cornel, P
2017-04-01
The SEMIZENTRAL infrastructure approach has been developed for fast growing cities, to meet their challenges regarding water supply as well as biowaste and wastewater (WW) treatment. The world's first full-scale SEMIZENTRAL Resource Recovery reference plant has been implemented in Qingdao (PR China). Greywater (GW) and blackwater (BW) are collected and treated separately. Measurement of influent concentrations revealed significant differences, compared with the design values. Values from the literature for GW and BW characteristics vary more markedly than for municipal WW; recommended design values are still lacking. Moreover, cross-connections between GW and BW can influence the influent characteristics considerably. Consequences for the design of GW and BW treatment are evaluated for boundary conditions, which require high effluent quality for both treatment modules. Model calculations illustrate the significant influence of uncertain WW characteristics on the required aeration basin volume and oxygen demand for GW and BW treatment; however, uncertainties are considerably reduced for the combination of these modules. Thus, a flexible design of the treatment plant is required. A possible concept for such a design is presented.
Jaranowska, Paulina; Cydzik-Kwiatkowska, Agnieszka; Zielińska, Magdalena
2013-07-01
The structure of microbial consortia in wastewater treatment facilities is a resultant of environmental conditions created by the operational parameters of the purification process. In the research, activated sludge from nine Polish wastewater treatment plants (WWTPs) was investigated at a molecular level to determine the impact of the complexity of biological treatment line and the influent composition on the species structure and the diversity of bacterial consortia. The community fingerprints and technological data were subjected to the canonical correspondence and correlation analyses. The number of separated biological processes realized in the treatment line and the presence of industrial wastewater in the influent were the key factors determining the species structure of total and ammonia-oxidizing bacteria in biomass. The N2O-reducers community composition depended significantly on the design of the facility; the highest species richness of denitrifiers was noted in the WWTPs with separated denitrification tanks. The contribution of industrial streams to the inflow affected the diversity of total and denitrifying bacterial consortia and diminished the diversity of ammonia oxidizers. The obtained data are valuable for engineers since they revealed the main factors, including the design of wastewater treatment plant, influencing the microbial groups critical for the stability of purification processes.
NASA Astrophysics Data System (ADS)
Hussey, Dennis Frank
2000-10-01
Scope and method of study. The purpose of this study was to develop a generalized rate model to handle multicomponent mixed-bed ion exchange (MBIE) with multivalent dissociative species and variable influent conditions. To achieve this goal, mass transfer mechanisms of weak electrolytes in ion exchange column have been studied; and based on which, rate expressions for weak electrolyte transfer have been proposed. In addition, the column material balance has been derived in terms of the constituent species concentrations only. Finally, generalized dissociation equilibrium equations for several types of weak electrolyte constituents were implemented, and the effluent concentrations were determined by solving column material balance equations along with the rate expressions. Findings and conclusions. The mixed bed ion exchange column model has been successfully programmed into a computer program and is capable of predicting the effluent concentration histories, dynamic resin loading, solution, and rate profiles. The column material balance has been satisfied to within 1% for all chemistries studied. The model is capable of simulating variable influent contaminant concentrations and flow rates by sequentially using the loading profiles of previous simulations. The model maintains electroneutrality at all times. Dissociative species transfer is adequate for many systems, but additional work is required to incorporate molecular constituent mass transfer.
Heffron, K T; Gaines, K F; Novak, J M; Canam, T; Collard, D A
2016-05-01
The concentration of 17β-estradiol (E2) was measured through stages of wastewater treatment at a central Illinois wastewater treatment plant (WWTP). E2 concentration was quantified using a competitive enzyme-linked immunosorbent assay (ELISA). The concentration of E2 was compared with demographic effects of a university; physical parameters of the wastewater (dissolved oxygen, pH, and temperature); and daily influent and effluent flow rates. Effluent concentrations ranged from 0 to 25.3 ng L(-1) with an average discharge of 3.6 ng L(-1). E2 concentration was shown to increase at the start of each university semester; however, this trend was not observed in the summer sessions. Low influent and effluent flow rates, which correspond to increased water retention time at the WWTP, were correlated to increased removal efficiency of E2, where low flow was linked to 91 % removal efficiency and high flow with 58 % removal efficiency. This study concludes that E2 was being discharged at concentrations known to cause ecological risk, and that the demographic changes in a university student body had a significant effect on E2 concentration throughout the treatment process.
D'Agostino, Fabio; Del Core, Marianna; Cappello, Simone; Mazzola, Salvatore; Sprovieri, Mario
2015-10-01
Here, we describe the methodologies adopted to ensure that natural seawater, used as "influent water" for the land test, complies with the requirement that should be fulfilled to show the efficacy of the new ballast water treatment system (BWTS). The new BWTS was located on the coast of SW Sicily (Italy), and the sampled seawater showed that bacteria and plankton were two orders of magnitude lower than requested. Integrated approaches for preparation of massive cultures of bacteria (Alcanivorax borkumensis and Marinobacter hydrocarbonoclasticus), algae (Tetraselmis suecica), rotifers (Brachionus plicatilis), and crustaceans (Artemia salina) suitable to ensure that 200 m(3) of water fulfilled the international guidelines of MEPC.174(58)G8 are here described. These methodologies allowed us to prepare the "influent water" in good agreement with guidelines and without specific problems arising from natural conditions (seasons, weather, etc.) which significantly affect the concentrations of organisms at sea. This approach also offered the chance to reliably run land tests once every two weeks.
Tian, Hailong; Yan, Yingchun; Chen, Yuewen; Wu, Xiaolei; Li, Baoan
2016-02-01
The membrane-aerated biofilm reactor (MABR) is a promising municipal wastewater treatment process. In this study, two cross-flow MABRs were constructed to explore the carbon and nitrogen removal performance and bacterial succession, along with changes of influent loading shock comprising flow velocity, COD, and NH4-N concentrations. Redundancy analysis revealed that the function of high flow velocity was mainly embodied in facilitating contaminants diffusion and biosorption rather than the success of overall bacterial populations (p > 0.05). In contrast, the influent NH4-N concentration contributed most to the variance of reactor efficiency and community structure (p < 0.05). Pyrosequencing results showed that Anaerolineae, and Beta- and Alphaproteobacteria were the dominant groups in biofilms for COD and NH4-N removal. Among the identified genera, Nitrosomonas and Nitrospira were the main nitrifiers, and Hyphomicrobium, Hydrogenophaga, and Rhodobacter were the key denitrifiers. Meanwhile, principal component analysis indicated that bacterial shift in MABR was probably the combination of stochastic and deterministic processes.
Parametric Equations, Maple, and Tubeplots.
ERIC Educational Resources Information Center
Feicht, Louis
1997-01-01
Presents an activity that establishes a graphical foundation for parametric equations by using a graphing output form called tubeplots from the computer program Maple. Provides a comprehensive review and exploration of many previously learned topics. (ASK)
Baker, C.
1994-10-01
The Department of Energy`s (DOE) Hanford site near Richland, Washington is being cleaned up after 50 years of nuclear materials production. One of the most serious problems at the site is the waste stored in single-shell underground storage tanks. There are 149 of these tanks containing the spent fuel residue remaining after the fuel is dissolved in acid and the desired materials (primarily plutonium and uranium) are separated out. The tanks are upright cylinders 75 ft. in diameter with domed tops. They are made of reinforced concrete, have steel liners, and each tank is buried under 7--12 ft. of overburden. The tanks are up to 40-ft. high, and have capacities of 500,000, 750,000, or 1,000,000 gallons of waste. As many as one-third of these tanks are known or suspected to leak. The waste form contained in the tanks varies in consistency from liquid supernatant to peanut-butter-like gels and sludges to hard salt cake (perhaps as hard as low-grade concrete). The current waste retrieval plan is to insert a large long-reach manipulator through a hole cut in the top of the tank, and use a variety of end-effectors to mobilize the waste and remove it from the tank. PNL has, with the assistance of Deneb robotics employees, developed a means of using the IGRIP code to perform parametric design of mechanical systems. This method requires no modifications to the IGRIP code, and all design data are stored in the IGRIP workcell. The method is presented in the context of development of a passive articulated mechanism that is used to deliver down-arm services to a gantry robot. The method is completely general, however, and could be used to design a fully articulated manipulator. Briefly, the method involves using IGCALC expressions to control manipulator joint angles, and IGCALC variables to allow user control of link lengths and offsets. This paper presents the method in detail, with examples drawn from PNL`s experience with the gantry robot service-providing mechanism.
NASA Technical Reports Server (NTRS)
Prince, Frank A.
2017-01-01
Building a parametric cost model is hard work. The data is noisy and often does not behave like we want it to. We need statistics to give us an indication of the goodness of our models, but; statistics can be manipulated and mislead. On top of all of that, our own very human biases can lead us astray; causing us to see patterns in the noise and draw false conclusions from the data. Yet, it is the data itself that is the foundation for making better cost estimates and cost models. I believe the mistake we often make is we believe that our models are representative of the data; that our models summarize the experiences, the knowledge, and the stories contained in the data. However, it is the opposite that is true. Our models are but imitations of reality. They give us trends, but not truth. The experiences, the knowledge, and the stories that we need in order to make good cost estimates is bound up in the data. You cannot separate good cost estimating from a knowledge of the historical data. One final thought. It is our attempts to make sense out of the randomness that leads us astray. In order to make progress as cost modelers and cost estimators, we must accept that there are real limitations on our ability to model the past and predict the future. I do not believe we should throw up our hands and say this is the best we can do. Rather, to see real improvement we must first recognize these limitations, avoid the easy but misleading solutions, and seek to find ways to better model the world we live in. I don't have any simple solutions. Perhaps the answers lie in better data or in a totally different approach to simulating how the world works. All I know is that we must do our best to speak truth to ourselves and our customers. Misleading ourselves and our customers will, in the end, result in an inability to have a positive impact on those we serve.
Rephasing invariant parametrization of flavor mixing
NASA Astrophysics Data System (ADS)
Lee, Tae-Hun
A new rephasing invariant parametrization for the 3 x 3 CKM matrix, called (x, y) parametrization, is introduced and the properties and applications of the parametrization are discussed. The overall phase condition leads this parametrization to have only six rephsing invariant parameters and two constraints. Its simplicity and regularity become apparent when it is applied to the one-loop RGE (renormalization group equations) for the Yukawa couplings. The implications of this parametrization for unification of the Yukawa couplings are also explored.
Parametric Resonance for Material Characterization
NASA Astrophysics Data System (ADS)
Adler, Laszlo; Rokhlin, Stanislav I.
2009-03-01
While studying finite amplitude ultrasonic wave resonance in a one dimensional liquid filled cavity, formed by a narrow band transducer and a plane reflector, fractional harmonics of the driver's frequency were observed in addition to the expected high harmonics. Subsequently it was realized that the system was one of the many examples where parametric resonance takes place and the observed fractional harmonics are parametrically generated. Parametric resonance occurs in any physical system which has a periodically modulated natural frequency. The generation mechanism also requires a sufficiently high threshold value of the driving amplitude and the system becomes nonlinear. Further increase of the driving amplitude above the threshold produces additional fractional harmonics and at a certain value an almost continuous spectrum is produced and the phenomenon becomes chaotic. Our recently developed frequency modulated angle beam ultrasonic method for adhesive bond evaluation is an additional example of the use of a resonance parametric system. The acoustic resonator is formed by an adhesive layer with the resonance frequency affected by the bond quality between the adhesive and the substrates. In this case the interfacial stresses (due to an external low frequency excitation) may or may not produce parametric shift of the resonance depending on the quality of the interfacial bond.
Parametric functional principal component analysis.
Sang, Peijun; Wang, Liangliang; Cao, Jiguo
2017-09-01
Functional principal component analysis (FPCA) is a popular approach in functional data analysis to explore major sources of variation in a sample of random curves. These major sources of variation are represented by functional principal components (FPCs). Most existing FPCA approaches use a set of flexible basis functions such as B-spline basis to represent the FPCs, and control the smoothness of the FPCs by adding roughness penalties. However, the flexible representations pose difficulties for users to understand and interpret the FPCs. In this article, we consider a variety of applications of FPCA and find that, in many situations, the shapes of top FPCs are simple enough to be approximated using simple parametric functions. We propose a parametric approach to estimate the top FPCs to enhance their interpretability for users. Our parametric approach can also circumvent the smoothing parameter selecting process in conventional nonparametric FPCA methods. In addition, our simulation study shows that the proposed parametric FPCA is more robust when outlier curves exist. The parametric FPCA method is demonstrated by analyzing several datasets from a variety of applications. © 2017, The International Biometric Society.
Hoffmann, C; Christofi, N
2001-10-01
To protect the bioceonosis within activated sludge, a method of predicting the toxic effect of influents to the biological treatment stage of waste water treatment plants, based on DIN method 38412 L 34, has been developed. A population of the luminescent marine bacterium Vibrio fischeri was incorporated into a sludge testing matrix derived from a model laboratory and real activated sludge plants. The sludge was challenged with different concentrations of pure toxicants and complex aqueous samples, and light output by V. fischeri monitored. The results were compared to toxicant testing in the absence of sludge (standard test). The modified method was found to be less sensitive for some toxicants tested than the standard DIN and other bioluminescent tests, but considered more realistic as it provides buffering and takes into account sorption which can affect the sensitivity of the test towards some compounds. The method is comparable in terms of ease of use, speed, reproducibility and cost effectiveness to standard V. fischeri luminescence methods.
Fernández-Ramos, C; Ballesteros, O; Blanc, R; Zafra-Gómez, A; Jiménez-Díaz, I; Navalón, A; Vílchez, J L
2012-08-30
In the present paper, we developed an accurate method for the analysis of alcohol sulfates (AS) in wastewater samples from wastewater treatment plant (WWTP) influents and effluents. Although many methodologies have been published in the literature concerning the study of anionic surfactants in environmental samples, at present, the number of analytical methodologies that focus in the determination of AS by gas chromatography in the different environmental compartments is limited. The reason for this is that gas chromatography-mass spectrometry (GC-MS) technique requires a previous hydrolysis reaction followed by derivatization reactions. In the present work, we proposed a new procedure in which the hydrolysis and derivatization reactions take place in one single step and AS are directly converted to trimethylsilyl derivatives. The main factors affecting solid-phase extraction (SPE), hydrolysis/derivatization and GC-MS procedures were accurately optimised. Quantification of the target compounds was performed by using GC-MS in selected ion monitoring (SIM) mode. The limits of detection (LOD) obtained ranged from 0.2 to 0.3 μg L(-1), and limits of quantification (LOQ) from 0.5 to 1.0 μg L(-1), while inter- and intra-day variability was under 5%. A recovery assay was also carried out. Recovery rates for homologues in spiked samples ranged from 96 to 103%. The proposed method was successfully applied for the determination of anionic surfactants in wastewater samples from one WWTP located in Granada (Spain). Concentration levels for the homologues up to 39.4 μg L(-1) in influent and up to 8.1 μg L(-1) in effluent wastewater samples.
Parametric infrared tunable laser system
NASA Technical Reports Server (NTRS)
Garbuny, M.; Henningsen, T.; Sutter, J. R.
1980-01-01
A parametric tunable infrared laser system was built to serve as transmitter for the remote detection and density measurement of pollutant, poisonous, or trace gases in the atmosphere. The system operates with a YAG:Nd laser oscillator amplifier chain which pumps a parametric tunable frequency converter. The completed system produced pulse energies of up to 30 mJ. The output is tunable from 1.5 to 3.6 micrometers at linewidths of 0.2-0.5 /cm (FWHM), although the limits of the tuning range and the narrower line crystals presently in the parametric converter by samples of the higher quality already demonstrated is expected to improve the system performance further.
Polarization mixing optical parametric oscillator.
Pearl, Shaul; Smith, Arlee Virgil; Arie, Ady; Blau, Pinhas; Kalmani, Gal
2005-05-01
We report the experimental realization of a new type of optical parametric oscillator in which oscillation is achieved by polarization rotation in a linear retarder, followed by nonlinear polarization mixing. The mixing is performed by a type II degenerate parametric downconversion in a periodically poled KTP crystal pumped by a 1064 nm pulsed Nd:YAG pump. A single, linearly polarized beam, precisely at the degenerate wavelength is generated. The output spectrum has a narrow linewidth (below the instrumentation bandwidth of 1 nm) and is highly stable with respect to variations in the crystal temperature.
Biological Parametric Mapping WITH Robust AND Non-Parametric Statistics
Yang, Xue; Beason-Held, Lori; Resnick, Susan M.; Landman, Bennett A.
2011-01-01
Mapping the quantitative relationship between structure and function in the human brain is an important and challenging problem. Numerous volumetric, surface, regions of interest and voxelwise image processing techniques have been developed to statistically assess potential correlations between imaging and non-imaging metrices. Recently, biological parametric mapping has extended the widely popular statistical parametric mapping approach to enable application of the general linear model to multiple image modalities (both for regressors and regressands) along with scalar valued observations. This approach offers great promise for direct, voxelwise assessment of structural and functional relationships with multiple imaging modalities. However, as presented, the biological parametric mapping approach is not robust to outliers and may lead to invalid inferences (e.g., artifactual low p-values) due to slight mis-registration or variation in anatomy between subjects. To enable widespread application of this approach, we introduce robust regression and non-parametric regression in the neuroimaging context of application of the general linear model. Through simulation and empirical studies, we demonstrate that our robust approach reduces sensitivity to outliers without substantial degradation in power. The robust approach and associated software package provide a reliable way to quantitatively assess voxelwise correlations between structural and functional neuroimaging modalities. PMID:21569856
Biological parametric mapping with robust and non-parametric statistics.
Yang, Xue; Beason-Held, Lori; Resnick, Susan M; Landman, Bennett A
2011-07-15
Mapping the quantitative relationship between structure and function in the human brain is an important and challenging problem. Numerous volumetric, surface, regions of interest and voxelwise image processing techniques have been developed to statistically assess potential correlations between imaging and non-imaging metrices. Recently, biological parametric mapping has extended the widely popular statistical parametric mapping approach to enable application of the general linear model to multiple image modalities (both for regressors and regressands) along with scalar valued observations. This approach offers great promise for direct, voxelwise assessment of structural and functional relationships with multiple imaging modalities. However, as presented, the biological parametric mapping approach is not robust to outliers and may lead to invalid inferences (e.g., artifactual low p-values) due to slight mis-registration or variation in anatomy between subjects. To enable widespread application of this approach, we introduce robust regression and non-parametric regression in the neuroimaging context of application of the general linear model. Through simulation and empirical studies, we demonstrate that our robust approach reduces sensitivity to outliers without substantial degradation in power. The robust approach and associated software package provide a reliable way to quantitatively assess voxelwise correlations between structural and functional neuroimaging modalities. Copyright © 2011 Elsevier Inc. All rights reserved.
Graphical functions in parametric space
NASA Astrophysics Data System (ADS)
Golz, Marcel; Panzer, Erik; Schnetz, Oliver
2016-12-01
Graphical functions are positive functions on the punctured complex plane Csetminus {0,1} which arise in quantum field theory. We generalize a parametric integral representation for graphical functions due to Lam, Lebrun and Nakanishi, which implies the real analyticity of graphical functions. Moreover, we prove a formula that relates graphical functions of planar dual graphs.
Parametric Identification of Systems Via Linear Operators.
1978-09-01
A general parametric identification /approximation model is developed for the black box identification of linear time invariant systems in terms of... parametric identification techniques derive from the general model as special cases associated with a particular linear operator. Some possible
Kim, Y J; Bae, H; Ko, J H; Poo, K M; Kim, S; Kim, C W; Woo, H J
2006-01-01
A fuzzy inference system using sensor measurements was developed to estimate the influent COD/N ratio and ammonia load. The sensors measured ORP, DO and pH. The sensor profiles had a close relationship with the influent COD/N ratio and ammonia load. To confirm this operational knowledge for constructing a rule set, a correlation analysis was conducted. The results showed that a rule generation method based only on operational knowledge did not generate a sufficiently accurate relationship between sensor measurements and target variables. To compensate for this defect, a decision tree algorithm was used as a standardized method for rule generation. Given a set of inputs, this algorithm was used to determine the output variables. However, the generated rules could not estimate the continuous influent COD/N ratio and ammonia load. Fuzzified rules and the fuzzy inference system were developed to overcome this problem. The fuzzy inference system estimated the influent COD/N ratio and ammonia load quite well. When these results were compared to the results from a predictive polynomial neural network model, the fuzzy inference system was more stable.
Zou, Jinte; Li, Yongmei; Zhang, Lili; Wang, Ruyi; Sun, Jing
2015-02-01
To better understand the effect of influent nitrogen concentration on granule size and microbial community in a granule-based enhanced biological phosphorus removal system, three influent nitrogen concentrations were tested while carbon concentration was an unlimited factor. The results show that although ammonium and phosphate were well removed in the tested nitrogen concentration range (20-50 mg L(-1)), granule size, the amount of phosphate accumulating organisms (PAOs) and microbial activity were affected significantly. A possible mechanism for the effect of influent nitrogen concentration on granule size is proposed based on the experimental results. The increase in proteins/polysaccharides ratio caused by high influent nitrogen concentration plays a crucial role in granule breakage. The small granule size then weakens simultaneous nitrification-denitrification, which further causes higher nitrate concentration in the effluent and lower amount of PAOs in sludge. Consequently, phosphate concentration in the anaerobic phase decreases, which plays the secondary role in granule breakage. Copyright © 2014 Elsevier Ltd. All rights reserved.
To investigate the potential for contaminants in Las Vegas Wash (LW) influent to produce effects indicative of endocrine disruption in vivo, adult male and female common carp were exposed in cages for 42-48 d at four sites and two reference locations in Lake Mead.
To investigate the potential for contaminants in Las Vegas Wash (LW) influent to produce effects indicative of endocrine disruption in vivo, adult male and female common carp were exposed in cages for 42-48 d at four sites and two reference locations in Lake Mead.
Machado, Vinicius Cunha; Lafuente, Javier; Baeza, Juan Antonio
2014-07-01
The present work developed a model for the description of a full-scale wastewater treatment plant (WWTP) (Manresa, Catalonia, Spain) for further plant upgrades based on the systematic parameter calibration of the activated sludge model 2d (ASM2d) using a methodology based on the Fisher information matrix. The influent was characterized for the application of the ASM2d and the confidence interval of the calibrated parameters was also assessed. No expert knowledge was necessary for model calibration and a huge available plant database was converted into more useful information. The effect of the influent and operating variables on the model fit was also studied using these variables as calibrating parameters and keeping the ASM2d kinetic and stoichiometric parameters, which traditionally are the calibration parameters, at their default values. Such an "inversion" of the traditional way of model fitting allowed evaluating the sensitivity of the main model outputs regarding the influent and the operating variables changes. This new approach is able to evaluate the capacity of the operational variables used by the WWTP feedback control loops to overcome external disturbances in the influent and kinetic/stoichiometric model parameters uncertainties. In addition, the study of the influence of operating variables on the model outputs provides useful information to select input and output variables in decentralized control structures.
Monitoring of Harmful Algal Blooms in Influent and Through Drinking Water Treatment Facilities Located on Lake Erie in the 2013 and 2014 Bloom SeasonsToby Sanan, Nicholas Dugan, Darren Lytle, Heath MashHarmful algal blooms (HABs) and their associated toxins are emerging as signif...
Monitoring of Harmful Algal Blooms in Influent and Through Drinking Water Treatment Facilities Located on Lake Erie in the 2013 and 2014 Bloom SeasonsToby Sanan, Nicholas Dugan, Darren Lytle, Heath MashHarmful algal blooms (HABs) and their associated toxins are emerging as signif...
Boles, Tammy H; Wells, Martha J M
2016-12-01
Amphetamine and methamphetamine are emerging contaminants-those for which no regulations currently require monitoring or public reporting of their presence in our water supply. In this research, a protocol for weak cation-exchange (WCX) SPE coupled with LC-MS/MS was developed for determination of emerging contaminants amphetamine and methamphetamine in a complex wastewater matrix. Gradient LC parameters were adjusted to yield baseline separation of methamphetamine from other contaminants. Methamphetamine-D5 was used as the internal standard (IS) to compensate for sample loss during SPE and for signal loss during MS (matrix effects). Recoveries were 102.1 ± 7.9% and 99.4 ± 4.0% for amphetamine and methamphetamine, respectively, using WCX sorbent. Notably, methamphetamine was determined to be present in wastewater influent at each sampling date tested. Amphetamine was present in wastewater influent on two of four sampling dates. Amphetamine concentrations ranged from undetectable to 86.4 ng/L in influent, but it was undetectable in wastewater effluent. Methamphetamine was detected in influent at concentrations ranging from 27.0-60.3 ng/L. Methamphetamine concentration was reduced but incompletely removed at this facility. Although absent in one post-UV effluent sample, concentrations of methamphetamine ranged from 10.8-14.8 ng/L. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Parametric Model Checking with VerICS
NASA Astrophysics Data System (ADS)
Knapik, Michał; Niewiadomski, Artur; Penczek, Wojciech; Półrola, Agata; Szreter, Maciej; Zbrzezny, Andrzej
The paper presents the verification system verICS, extended with the three new modules aimed at parametric verification of Elementary Net Systems, Distributed Time Petri Nets, and a subset of UML. All the modules exploit Bounded Model Checking for verifying parametric reachability and the properties specified in the logic PRTECTL - the parametric extension of the existential fragment of CTL.
Direct emissions of N2O, CO 2, and CH 4 from A/A/O bioreactor systems: impact of influent C/N ratio.
Ren, Yangang; Wang, Jinhe; Xu, Li; Liu, Cui; Zong, Ruiqiang; Yu, Jianlin; Liang, Shuang
2015-06-01
Direct emissions of N2O, CO2, and CH4, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26-39 to 112-173 g CO2-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N2O, CO2, and CH4) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO2-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems.
NASA Astrophysics Data System (ADS)
Maeda, Shigeya; Kawachi, Toshihiko; Unami, Koichi; Takeuchi, Junichiro
Lake water quality management is an extremely complicated problem due to a variety of land use and existence of multiple stakeholders in the watershed. A decision support tool is thus necessary for examining physical, economical and social constraints associated with the management and for coordinating conflicting goals of the stakeholders. In this study, a multiobjective linear programming model is developed for supporting strategic management of lake water quality. Optimal allocation of river-genetic pollutant load is determined to maximize total allowable load into the lake with in-lake water quality standard. The shallow water equations and two-dimensional COD (chemical oxygen demand) transport equation are employed as basic equations to represent physical constraints on COD concentration. In order to consider an economical requirement on equity, the model proactively controls the difference in share of the total allowable load among influent rivers. An optimization example demonstrates that the methodology developed can produce several noninferior solutions (i.e., load allocations) useful for decision-making in lake water quality management.
Kim, J R; Ko, J H; Im, J H; Lee, S H; Kim, S H; Kim, C W; Park, T J
2006-01-01
The information on the incoming load to wastewater treatment plants is not often available to apply modelling for evaluating the effect of control actions on a full-scale plant. In this paper, a time series model was developed to forecast flow rate, COD, NH4(+)-N and PO4(3-)-P in influent by using 250 days data of field plant operation data. The data for 150 days and 100 days were used for model development and model validation, respectively. The missing data were interpolated by the spline method and the time series model. Three different methods were proposed for model development: one model and one-step to seven-step ahead forecasting (Method 1); seven models and one-step-ahead forecasting (Method 2); and one model and one-step-ahead forecasting (Method 3). Method 3 featured only one-step-ahead forecasting that could avoid the accumulated error and give simple estimation of coefficients. Therefore, Method 3 was the reliable approach to developing the time series model for the purpose of this research.
Liu, Hongbo; Leng, Feng; Chen, Piao; Kueppers, Stephan
2016-11-01
This paper studied denitrifying phosphorus removal of a novel two-line biological nutrient removal process treating low strength domestic wastewater under different sludge recycling ratios. Mass balance of intracellular compounds including polyhydroxyvalerate, polyhydroxybutyrate and glycogen was investigated together with total nitrogen (TN) and total phosphorus (TP). Results showed that sludge recycling ratios had a significant influence on the use of organics along bioreactors and 73.6% of the average removal efficiency was obtained when the influent chemical oxygen demand (COD) ranged from 175.9 mgL(-1) to 189.9 mgL(-1). The process performed better under a sludge recycling ratio of 100% compared to 25% and 50% in terms of ammonia and COD removal rates. Overall, TN removal efficiency for 50% and 100% sludge recycling ratios were 56.4% and 61.9%, respectively, unlike the big gap for carbon utilization and the TP removal rates, indicating that the effect of sludge recycling ratio on the anaerobic compartments had been counteracted by change in the efficiency of other compartments. The higher ratio of sludge recycling was conducive to the removal of TN, not in favor of TP, and less influence on COD. Thus, 25% was considered to be the optimal sludge recycling ratio.
Cierkens, Katrijn; Plano, Salvatore; Benedetti, Lorenzo; Weijers, Stefan; de Jonge, Jarno; Nopens, Ingmar
2012-01-01
Application of activated sludge models (ASMs) to full-scale wastewater treatment plants (WWTPs) is still hampered by the problem of model calibration of these over-parameterised models. This either requires expert knowledge or global methods that explore a large parameter space. However, a better balance in structure between the submodels (ASM, hydraulic, aeration, etc.) and improved quality of influent data result in much smaller calibration efforts. In this contribution, a methodology is proposed that links data frequency and model structure to calibration quality and output uncertainty. It is composed of defining the model structure, the input data, an automated calibration, confidence interval computation and uncertainty propagation to the model output. Apart from the last step, the methodology is applied to an existing WWTP using three models differing only in the aeration submodel. A sensitivity analysis was performed on all models, allowing the ranking of the most important parameters to select in the subsequent calibration step. The aeration submodel proved very important to get good NH(4) predictions. Finally, the impact of data frequency was explored. Lowering the frequency resulted in larger deviations of parameter estimates from their default values and larger confidence intervals. Autocorrelation due to high frequency calibration data has an opposite effect on the confidence intervals. The proposed methodology opens doors to facilitate and improve calibration efforts and to design measurement campaigns.
Wang, Wei; Ding, Yi; Ullman, Jeffrey L; Ambrose, Richard F; Wang, Yuhui; Song, Xinshan; Zhao, Zhimiao
2016-05-01
Microcosm horizontal subsurface flow constructed wetlands (HSSFCWs) were used to examine the impacts of vegetation on nitrogen dynamics treating different influent COD/N ratios (1:1, 4:1, and 8:1). An increase in the COD/N ratio led to increased reductions in NO3 and total inorganic nitrogen (TIN) in planted and unplanted wetlands, but diminished removal of NH4. The HSSFCW planted with Canna indica L. exhibited a significant reduction in NH4 compared to the unplanted system, particularly in the active root zone where NH4 removal performance increased by up to 26 % at the COD/N ratio of 8:1. There was no significant difference in NO3 removal between the planted and unplanted wetlands. TIN removal efficiency in the planted wetland increased with COD/N ratios, which was likely influenced by plant uptake. NH4 reductions were greater in planted wetland at the 20- and 40-cm depths while NO3 reductions were uniformly greater with depth in all cases, but no statistical difference was impacted by depth on TIN removal. These findings show that planting a HSSFCW can provide some benefit in reducing nitrogen loads in effluents, but only when a sufficient carbon source is present.
Hashimoto, A.G.
1982-09-01
The effects of temperature (35 and 55 degrees C), influent volatile solids (VS) concentration (So equal to 43, 64, 82, 100, 128 kg VS/cu.m) and hydraulic retention time (HRT equal to 4, 5, 8, 10, 15, and 25 days) on methane (CH/sub 4/) production from cattle waste were evaluated using 3-d cu.m laboratory scale fermentors. The highest CH/sub 4/ production rate achieved was 6.11 cu.m CH/sub 4//cu.m fermentor/day at 55 degrees C, four days HRT, and So equal to 100 kg VS/cu.m. Batch fermentations showed an ultimate CH/sub 4/ yield (Bo) of 0.42 cu.m CH/sub 4//kg VS fed. The maximum loading rates for unstressed fermentation were 7 kg VS/cu.m/day at 35 degrees C and 20 kg VS/cu.m/day at 55 degrees C. The kinetic parameter (K, an increasing K indicates inhibition of fermentation) increased exponentially as So increased, and was described by : K equal to 0.8 plus 0.0016e 0.06So. Temperature had no significant effect on K for So between 40 and 100 kg VS/cu.m. The above equation predicted published K values for cattle waste within a mean standard error of 7%. (Refs. 11).
Zhang, Yaobin; Liu, Yiwen; Jing, Yanwen; Zhao, Zhiqiang; Quan, Xie
2012-01-01
Zero valent iron (ZVI) is expected to help create an enhanced anaerobic environment that might improve the performance of anaerobic treatment. Based on this idea, a novel ZVI packed upflow anaerobic sludge blanket (ZVI-UASB) reactor was developed to treat azo dye wastewater with variable influent quality. The results showed that the reactor was less influenced by increases of Reactive Brilliant Red X-3B concentration from 50 to 1000 mg/L and chemical oxygen demand (COD) from 1000 to 7000 mg/L in the feed than a reference UASB reactor without the ZVI. The ZVI decreased oxidation-reduction potential in the reactor by about 80 mV. Iron ion dissolution from the ZVI could buffer acidity in the reactor, the amount of which was related to the COD concentration. Fluorescence in situ hybridization test showed the abundance of methanogens in the sludge of the ZVI-UASB reactor was significantly greater than that of the reference one. Denaturing gradient gel electrophoresis showed that the ZVI increased the diversity of microbial strains responsible for high efficiency.
Zinatizadeh, A A L; Pirsaheb, M; Bonakdari, H; Younesi, H
2010-10-01
The interactive effects of hydraulic retention time (HRT) and influent chemical oxygen demand (COD(in)) on the performance of an up-flow anaerobic sludge fixed film (UASFF) bioreactor treating palm oil mill effluent (POME) was studied. Anaerobic digestion of POME was modeled and analyzed with two variables i.e. HRT and COD(in). Experiments were conducted based on a general factorial design and analyzed using response surface methodology (RSM). The region of exploration for digestion of POME was taken as the area enclosed by HRT (1-6 days) and COD(in) (5260-34,725 mg/l) boundaries. Eight dependent parameters were either directly measured or calculated as response. Increase in the variables resulted in decrease in COD removal efficiency, solid retention time (SRT) and sludge retention factor (SRF) and increase of COD removal rate, volatile fatty acid to alkalinity ratio (VFA/Alk), CO(2) percentage in biogas and methane production rate. The value of the maximum specific microbial growth rate (micro(m)) determined through the equation that correlated organic loading rate (OLR) and mu (calculated by quadratic model for SRF) was found to be 0.153 d(-1). This value was close to that obtained using Chen and Hashimoto kinetic equation (0.207 d(-1)) in a previous study. The present study provides valuable information about interrelations of quality and process parameters in POME digestion using a UASFF bioreactor. (c) 2010 Elsevier Ltd. All rights reserved.
Parametric sonars for seafloor characterization
NASA Astrophysics Data System (ADS)
Caiti, Andrea; Bergem, Oddbjorn; Dybedal, Johnny
1999-12-01
Parametric sonars are instruments capable of transmitting acoustic signals in the water with a very narrow beam and almost no sidelobes. These features are exploited in this paper to define a methodology for quantitative estimation of the geo-acoustic and morphological properties of the uppermost seafloor sediment layer. The three major components of the approach are the parametric instrument itself; the modelling of the forward-propagation problem, with the use of the Kirchhoff approximation for surface scattering and of the small-perturbation theory for the volume scattering; and the definition of a criterion for comparison between data and model predictions, which is accomplished by a generalized time-frequency analysis. In this way the estimation becomes one of a model-based identification, or a model-based inverse problem. Results from a field trial in a shallow water area of the Mediterranean are shown, and compared with independently gathered ground truth.
Frequency domain optical parametric amplification
Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François
2014-01-01
Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength. PMID:24805968
Experience with parametric binary dissection
NASA Technical Reports Server (NTRS)
Bokhari, Shahid H.
1993-01-01
Parametric Binary Dissection (PBD) is a new algorithm that can be used for partitioning graphs embedded in 2- or 3-dimensional space. It partitions explicitly on the basis of nodes + (lambda)x(edges cut), where lambda is the ratio of time to communicate over an edge to the time to compute at a node. The new algorithm is faster than the original binary dissection algorithm and attempts to obtain better partitions than the older algorithm, which only takes nodes into account. The performance of parametric dissection with plain binary dissection on 3 large unstructured 3-d meshes obtained from computational fluid dynamics and on 2 random graphs were compared. It was showm that the new algorithm can usually yield partitions that are substantially superior, but that its performance is heavily dependent on the input data.
PHAZE. Parametric Hazard Function Estimation
Atwood, C.L.
1990-09-01
Phaze performs statistical inference calculations on a hazard function ( also called a failure rate or intensity function) based on reported failure times of components that are repaired and restored to service. Three parametric models are allowed: the exponential, linear, and Weibull hazard models. The inference includes estimation (maximum likelihood estimators and confidence regions) of the parameters and of the hazard function itself, testing of hypotheses such as increasing failure rate, and checking of the model assumptions.
Song, Dong; Wang, Zhuo; Marmarelis, Vasilis Z; Berger, Theodore W
2009-02-01
This paper presents a synergistic parametric and non-parametric modeling study of short-term plasticity (STP) in the Schaffer collateral to hippocampal CA1 pyramidal neuron (SC) synapse. Parametric models in the form of sets of differential and algebraic equations have been proposed on the basis of the current understanding of biological mechanisms active within the system. Non-parametric Poisson-Volterra models are obtained herein from broadband experimental input-output data. The non-parametric model is shown to provide better prediction of the experimental output than a parametric model with a single set of facilitation/depression (FD) process. The parametric model is then validated in terms of its input-output transformational properties using the non-parametric model since the latter constitutes a canonical and more complete representation of the synaptic nonlinear dynamics. Furthermore, discrepancies between the experimentally-derived non-parametric model and the equivalent non-parametric model of the parametric model suggest the presence of multiple FD processes in the SC synapses. Inclusion of an additional set of FD process in the parametric model makes it replicate better the characteristics of the experimentally-derived non-parametric model. This improved parametric model in turn provides the requisite biological interpretability that the non-parametric model lacks.
Parametric Modeling for Fluid Systems
NASA Technical Reports Server (NTRS)
Pizarro, Yaritzmar Rosario; Martinez, Jonathan
2013-01-01
Fluid Systems involves different projects that require parametric modeling, which is a model that maintains consistent relationships between elements as is manipulated. One of these projects is the Neo Liquid Propellant Testbed, which is part of Rocket U. As part of Rocket U (Rocket University), engineers at NASA's Kennedy Space Center in Florida have the opportunity to develop critical flight skills as they design, build and launch high-powered rockets. To build the Neo testbed; hardware from the Space Shuttle Program was repurposed. Modeling for Neo, included: fittings, valves, frames and tubing, between others. These models help in the review process, to make sure regulations are being followed. Another fluid systems project that required modeling is Plant Habitat's TCUI test project. Plant Habitat is a plan to develop a large growth chamber to learn the effects of long-duration microgravity exposure to plants in space. Work for this project included the design and modeling of a duct vent for flow test. Parametric Modeling for these projects was done using Creo Parametric 2.0.
Hu, Yong; Jing, Zhaoqian; Sudo, Yuta; Niu, Qigui; Du, Jingru; Wu, Jiang; Li, Yu-You
2015-07-01
The effect of the chemical oxygen demand/sulfate (COD/SO4(2-)) ratio on the anaerobic treatment of synthetic chemical wastewater containing acetate, ethanol, and sulfate, was investigated using a UASB reactor. The experimental results show that at a COD/SO4(2-) ratio of 20 and a COD loading rate of 25.2gCODL(-1)d(-1), a COD removal of as high as 87.8% was maintained. At a COD/SO4(2-) ratio of 0.5 (sulfate concentration 6000mgL(-1)), however, the COD removal was 79.2% and the methane yield was 0.20LCH4gCOD(-1). The conversion of influent COD to methane dropped from 80.5% to 54.4% as the COD/SO4(2-) ratio decreased from 20 to 0.5. At all the COD/SO4(2-) ratios applied, over 79.4% of the total electron flow was utilized by methane-producing archaea (MPA), indicating that methane fermentation was the predominant reaction. The majority of the methane was produced by acetoclastic MPA at high COD/SO4(2-) ratios and both acetoclastic and hydrogenthrophic MPA at low COD/SO4(2-) ratios. Only at low COD/SO4(2-) ratios were SRB species such as Desulfovibrio found to play a key role in ethanol degradation, whereas all the SRB species were found to be incomplete oxidizers at both high and low COD/SO4(2-) ratios.
Oliveira, Tiago S; Murphy, Mark; Mendola, Nicholas; Wong, Virginia; Carlson, Doreen; Waring, Linda
2015-06-15
Two USEPA Regional Laboratories developed direct-injection LC/MS/MS methods to measure Pharmaceuticals and Personal Care Products (PPCPs) in water matrices. Combined, the laboratories were prepared to analyze 185 PPCPs (with 74 overlapping) belonging to more than 20 therapeutical categories with reporting limits at low part-per-trillion. In partnership with Suffolk County in NY, the laboratories conducted PPCP analysis on 72 samples belonging to 4 Water Systems (WS). Samples were collected at different stages of the WS (hospital effluents, WWTP influents/effluents) to assess PPCP relevance in hospital discharges, impact on WWTP performance and potential ecological risk posed by analytes not eliminated during treatment. Major findings include: a) acceptable accuracy between the two laboratories for most overlapping PPCPs with better agreement for higher concentrations; b) the measurement of PPCPs throughout all investigated WS with total PPCP concentrations ranging between 324 and 965 μg L(-1) for hospital effluent, 259 and 573 μg L(-1) for WWTP influent and 19 and 118 μg L(-1) for WWTP effluent; c) the variable contribution of hospital effluents to the PPCP loads into the WWTP influents (contribution ranging between 1% (WS-2) and 59% (WS-3); d) the PPCP load reduction after treatment for all WS reaching more than 95% for WS using activated sludge processes (WS-2 and WS-4), with inflow above 6500 m(3) d(-1), and having a lower percentage of hospital effluent in the WWTP influent; e) the relevance of four therapeutical categories for the PPCP load in WWTP effluents (analgesics, antidiabetics, antiepileptics and psychoanaleptics); and f) the risk quotients calculated using screening-level Predicted Non Effect Concentration indicate that WWTP effluents contain 33 PPCPs with potential medium to high ecological risk. To our knowledge no other monitoring investigation published in the scientific literature uses direct-injection methods to cover as many PPCPs and
Stimulated Parametric Emission Microscope Systems
NASA Astrophysics Data System (ADS)
Itoh, Kazuyoshi; Isobe, Keisuke
2006-10-01
We present a novel microscopy technique based on the fourwave mixing (FWM) process that is enhanced by two-photon electronic resonance induced by a pump pulse along with stimulated emission induced by a dump pulse. A Ti:sapphire laser and an optical parametric oscillator are used as light sources for the pump and dump pulses, respectively. We demonstrate that our FWM technique can be used to obtain two-dimensional microscopic images of an unstained leaf of Camellia sinensis and an unlabeled tobacco BY2 Cell.
Whispering gallery optical parametric oscillators
NASA Astrophysics Data System (ADS)
Breunig, Ingo; Buse, Karsten
2013-12-01
Whispering gallery optical parametric oscillators (WGR OPOs) are monolithic sources for tunable coherent and non-classical light. They are based on total internal reflection. Since reflection losses are negligible, their oscillation threshold can be far below one milliwatt. With sub-millimeter diameters, they are the most compact OPOs demonstrated so far. Recent experimental results demonstrate that WGR OPOs emit coherent light tunable over hundreds of nanometers. Operation in the visible as well as in the near-infrared has been demonstrated with up to 30 % conversion efficiency. These results indicate a great potential of WGR OPOs for spectroscopic and sensing applications.
Wang, Zhen; Meng, Yuan; Fan, Ting; Du, Yuneng; Tang, Jie; Fan, Shisuo
2015-03-01
This study was conducted to investigate the long-term impact of influent phosphorus concentration on denitrifying phosphorus removal and N2O production during denitrifying phosphorous removal process. The results showed that, denitrifying phosphate accumulating organisms (DPAOs) could become dominant populations quickly in anaerobic/anoxic SBR by providing optimum cultivating conditions, and the reactor performed well for denitrifying phosphorus removal. The influent phosphorus concentration significantly affected anaerobic poly-β-hydroxyalkanoates (PHA) synthesis, denitrifying phosphorus removal, and N2O production during the denitrifying phosphorus removal process. As the influent phosphorus concentration was more than 20 mg L(-1), the activity of DPAOs began to be inhibited due to the transformation of the available carbon source type. Meanwhile, N2O production was inhibited with the mitigation of anoxic NO2(-)-N accumulation. Adoption of a modified feeding could enhance denitrifying phosphorus removal and inhibit N2O production during denitrifying phosphorous removal processes. Copyright © 2014 Elsevier Ltd. All rights reserved.
Wang, Yayi; Peng, Yongzhen; Stephenson, Tom
2009-07-01
A laboratory-scale anaerobic-anoxic/nitrification sequencing batch reactor (A(2)N-SBR) fed with domestic wastewater was operated to examine the effect of varying ratios of influent COD/P, COD/TN and TN/P on the nutrient removal. With the increased COD/P, the phosphorus removals exhibited an upward trend. The influent TN/P ratios had a positive linear correlation with the phosphorus removal efficiencies, mainly because nitrates act as electron acceptors for the phosphorus uptake in the A(2)N-SBR. Moreover, it was found that lower COD/TN ratio, e.g. 3.5, did not significantly weaken the phosphorus removal, though the nitrogen removal first decreased greatly. The optimal phosphorus and nitrogen removals of 94% and 91%, respectively were achieved with influent COD/P and COD/TN ratios of 19.9 and 9.9, respectively. Additionally, a real-time control strategy for A(2)N-SBR can be undertaken based on some characteristic points of pH, redox potential (ORP) and dissolved oxygen (DO) profiles in order to obtain the optimum hydraulic retention time (HRT) and improve the operating reliability.
Parametric nanomechanical amplification at very high frequency.
Karabalin, R B; Feng, X L; Roukes, M L
2009-09-01
Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.
Rosetta stone for parametrized tests of gravity
NASA Astrophysics Data System (ADS)
Sampson, Laura; Yunes, Nicolás; Cornish, Neil
2013-09-01
Several model-independent parametrizations of deviations from general relativity have been developed to test Einstein’s theory. Although these different parametrizations were developed for different gravitational observables, they ultimately all test the same underlying physics. In this paper, we develop connections between the parametrized post-Newtonian, parametrized post-Keplerian, and the parametrized post-Einsteinian frameworks, developed to carry out tests of general relativity with Solar System, binary pulsar, and gravitational wave observations, respectively. These connections, although only valid under certain assumptions such as energy/momentum conservation, allow us to use knowledge gained from one framework to inform and guide tests using the others. Relating these parametrizations and combining the results from each approach strengthens our tests of general relativity.
A THEORY FOR BROADBAND VARACTOR PARAMETRIC AMPLIFIERS
This thesis is concerned with the development of a general and rigorous broadbanding theory for varactor parametric amplifiers . Fundamental gain...bandwidth limitations of a varactor parametric amplifier are obtained which are independent of the equalizer. Results obtained in this theory lead to the...design and synthesis of broadband varactor parametric amplifiers . The circuit considered in this thesis is that of linear variable capacitors embedded
Software for Managing Parametric Studies
NASA Technical Reports Server (NTRS)
Yarrow, Maurice; McCann, Karen M.; DeVivo, Adrian
2003-01-01
The Information Power Grid Virtual Laboratory (ILab) is a Practical Extraction and Reporting Language (PERL) graphical-user-interface computer program that generates shell scripts to facilitate parametric studies performed on the Grid. (The Grid denotes a worldwide network of supercomputers used for scientific and engineering computations involving data sets too large to fit on desktop computers.) Heretofore, parametric studies on the Grid have been impeded by the need to create control language scripts and edit input data files painstaking tasks that are necessary for managing multiple jobs on multiple computers. ILab reflects an object-oriented approach to automation of these tasks: All data and operations are organized into packages in order to accelerate development and debugging. A container or document object in ILab, called an experiment, contains all the information (data and file paths) necessary to define a complex series of repeated, sequenced, and/or branching processes. For convenience and to enable reuse, this object is serialized to and from disk storage. At run time, the current ILab experiment is used to generate required input files and shell scripts, create directories, copy data files, and then both initiate and monitor the execution of all computational processes.
Yan, Xu; Zheng, Jiaxi; Han, Yunping; Liu, Jianwei; Sun, Jianhui
2017-09-01
The problem of producing strong greenhouse gas of nitrous oxide (N2O) from biological nitrogen removal (BNR) process in wastewater treatment plants (WWTP) has elicited great concern from various sectors. In this study, three laboratory-scale wastewater treatment systems, with influent C/N ratios of 3.4, 5.4, and 7.5, were set up to study the effect of influent C/N ratio on N2O generation in anaerobic/anoxic/oxic (A(2)O) process. Results showed, with the increased influent C/N ratio, N2O generation from both nitrification and denitrification process was decreased, and the N2O-N conversion ratio of the process was obviously reduced from 2.23 to 0.05%. Nitrification rate in oxic section was reduced, while denitrification rate in anaerobic and anoxic section was elevated and the removal efficiency of COD, NH4(+)-N, TN, and TP was enhanced in different extent. As the C/N ratio increased from 3.4 to 7.5, activities of three key denitrifying enzymes of nitrate reductase, nitrite reductase, and nitrous oxide reductase were increased. Moreover, microorganism analysis indicated that the relative abundance of ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were positively correlated with N2O generation, which was reduced from (8.42 ± 3.65) to (3.61 ± 1.66)% and (10.38 ± 4.12) to (4.67 ± 1.62)%, respectively. NosZ gene copy numbers of the A(2)O system were increased from (1.19 ± 0.49) × 10(7) to (2.84 ± 0.54) × 10(8) copies/g MLSS with the influent C/N ratio elevated from 3.4 to 7.5. Hence, appropriate influent C/N condition of A(2)O process could optimize the microbial community structure that simultaneously improve treatment efficiency and decrease the N2O generation.
Observation of Parametric Instability in Advanced LIGO
NASA Astrophysics Data System (ADS)
Evans, Matthew; Gras, Slawek; Fritschel, Peter; Miller, John; Barsotti, Lisa; Martynov, Denis; Brooks, Aidan; Coyne, Dennis; Abbott, Rich; Adhikari, Rana X.; Arai, Koji; Bork, Rolf; Kells, Bill; Rollins, Jameson; Smith-Lefebvre, Nicolas; Vajente, Gabriele; Yamamoto, Hiroaki; Adams, Carl; Aston, Stuart; Betzweiser, Joseph; Frolov, Valera; Mullavey, Adam; Pele, Arnaud; Romie, Janeen; Thomas, Michael; Thorne, Keith; Dwyer, Sheila; Izumi, Kiwamu; Kawabe, Keita; Sigg, Daniel; Derosa, Ryan; Effler, Anamaria; Kokeyama, Keiko; Ballmer, Stefan; Massinger, Thomas J.; Staley, Alexa; Heinze, Matthew; Mueller, Chris; Grote, Hartmut; Ward, Robert; King, Eleanor; Blair, David; Ju, Li; Zhao, Chunnong
2015-04-01
Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been observed in a kilometer-scale interferometer. In this Letter, we describe the first observation of parametric instability in a gravitational wave detector, and the means by which it has been removed as a barrier to progress.
A Comparison of Parametric versus Nonparametric Statistics.
ERIC Educational Resources Information Center
Royeen, Charlotte Brasic
In order to examine the possible effects of violation of assumptions using parametric procedures, this study is an exploratory investigation into the use of parametric versus nonparametric procedures using a multiple case study design. The case study investigation guidelines outlined by Yin served as the methodology. The following univariate…
Why preferring parametric forecasting to nonparametric methods?
Jabot, Franck
2015-05-07
A recent series of papers by Charles T. Perretti and collaborators have shown that nonparametric forecasting methods can outperform parametric methods in noisy nonlinear systems. Such a situation can arise because of two main reasons: the instability of parametric inference procedures in chaotic systems which can lead to biased parameter estimates, and the discrepancy between the real system dynamics and the modeled one, a problem that Perretti and collaborators call "the true model myth". Should ecologists go on using the demanding parametric machinery when trying to forecast the dynamics of complex ecosystems? Or should they rely on the elegant nonparametric approach that appears so promising? It will be here argued that ecological forecasting based on parametric models presents two key comparative advantages over nonparametric approaches. First, the likelihood of parametric forecasting failure can be diagnosed thanks to simple Bayesian model checking procedures. Second, when parametric forecasting is diagnosed to be reliable, forecasting uncertainty can be estimated on virtual data generated with the fitted to data parametric model. In contrast, nonparametric techniques provide forecasts with unknown reliability. This argumentation is illustrated with the simple theta-logistic model that was previously used by Perretti and collaborators to make their point. It should convince ecologists to stick to standard parametric approaches, until methods have been developed to assess the reliability of nonparametric forecasting.
Pump noise cancellation in parametric wavelength converters.
Ataie, Vahid; Myslivets, Evgeny; Wiberg, Andereas O J; Alic, Nikola; Radic, Stojan
2012-12-10
A novel technique for pump noise effect mitigation in parametric wavelength converters is introduced. The method relies on digital signal processing and effectively takes advantage of the correlation property between the pump and idler, imposed by the parametric interaction. A 4 dB improvement in receiver performance is demonstrated experimentally for the conventional 10 Gbps OOK signal converted over 20 nm.
Parametric Cost Models for Space Telescopes
NASA Technical Reports Server (NTRS)
Stahl, H. Philip
2010-01-01
A study is in-process to develop a multivariable parametric cost model for space telescopes. Cost and engineering parametric data has been collected on 30 different space telescopes. Statistical correlations have been developed between 19 variables of 59 variables sampled. Single Variable and Multi-Variable Cost Estimating Relationships have been developed. Results are being published.
Calculations of superconducting parametric amplifiers performances
NASA Astrophysics Data System (ADS)
Goto, T.; Takeda, M.; Saito, S.; Shimakage, H.
2017-07-01
A superconducting parametric amplifier is an electromagnetic wave amplifier with high-quality characteristics such as a wide bandwidth, an extremely low noise, and a high dynamic range. In this paper, we report on the estimations of a YBCO superconducting parametric amplifier characteristic. The YBCO thin films were deposited on an MgO substrate by a pulsed laser deposition method. Based on the measured YBCO thin film parameters, theoretical calculations were implemented for evaluations of kinetic inductance nonlinearities and parametric gains. The nonlinearity of the YBCO thin film was estimated to be stronger than a single crystal NbTiN thin film. It is indicated that the YBCO parametric amplifier has a potential to be realized the amplifier with the high parametric gain. It is also expected that it could be operated in the range of the high frequency band, at the high temperature, and low applied current.
Marmarelis, Vasilis Z.; Berger, Theodore W.
2009-01-01
Parametric and non-parametric modeling methods are combined to study the short-term plasticity (STP) of synapses in the central nervous system (CNS). The nonlinear dynamics of STP are modeled by means: (1) previously proposed parametric models based on mechanistic hypotheses and/or specific dynamical processes, and (2) non-parametric models (in the form of Volterra kernels) that transforms the presynaptic signals into postsynaptic signals. In order to synergistically use the two approaches, we estimate the Volterra kernels of the parametric models of STP for four types of synapses using synthetic broadband input–output data. Results show that the non-parametric models accurately and efficiently replicate the input–output transformations of the parametric models. Volterra kernels provide a general and quantitative representation of the STP. PMID:18506609
Characteristics of stereo reproduction with parametric loudspeakers
NASA Astrophysics Data System (ADS)
Aoki, Shigeaki; Toba, Masayoshi; Tsujita, Norihisa
2012-05-01
A parametric loudspeaker utilizes nonlinearity of a medium and is known as a super-directivity loudspeaker. The parametric loudspeaker is one of the prominent applications of nonlinear ultrasonics. So far, the applications have been limited monaural reproduction sound system for public address in museum, station and street etc. In this paper, we discussed characteristics of stereo reproduction with two parametric loudspeakers by comparing with those with two ordinary dynamic loudspeakers. In subjective tests, three typical listening positions were selected to investigate the possibility of correct sound localization in a wide listening area. The binaural information was ILD (Interaural Level Difference) or ITD (Interaural Time Delay). The parametric loudspeaker was an equilateral hexagon. The inner and outer diameters were 99 and 112 mm, respectively. Signals were 500 Hz, 1 kHz, 2 kHz and 4 kHz pure tones and pink noise. Three young males listened to test signals 10 times in each listening condition. Subjective test results showed that listeners at the three typical listening positions perceived correct sound localization of all signals using the parametric loudspeakers. It was almost similar to those using the ordinary dynamic loudspeakers, however, except for the case of sinusoidal waves with ITD. It was determined the parametric loudspeaker could exclude the contradiction between the binaural information ILD and ITD that occurred in stereo reproduction with ordinary dynamic loudspeakers because the super directivity of parametric loudspeaker suppressed the cross talk components.
Ionization Cooling using Parametric Resonances
Johnson, Rolland P.
2008-06-07
Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been
Self-seeding ring optical parametric oscillator
Smith, Arlee V.; Armstrong, Darrell J.
2005-12-27
An optical parametric oscillator apparatus utilizing self-seeding with an external nanosecond-duration pump source to generate a seed pulse resulting in increased conversion efficiency. An optical parametric oscillator with a ring configuration are combined with a pump that injection seeds the optical parametric oscillator with a nanosecond duration, mJ pulse in the reverse direction as the main pulse. A retroreflecting means outside the cavity injects the seed pulse back into the cavity in the direction of the main pulse to seed the main pulse, resulting in higher conversion efficiency.
Airy beam optical parametric oscillator
NASA Astrophysics Data System (ADS)
Aadhi, A.; Chaitanya, N. Apurv; Jabir, M. V.; Vaity, Pravin; Singh, R. P.; Samanta, G. K.
2016-05-01
Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51–1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond).
Airy beam optical parametric oscillator
Aadhi, A.; Chaitanya, N. Apurv; Jabir, M. V.; Vaity, Pravin; Singh, R. P.; Samanta, G. K.
2016-01-01
Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51–1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond). PMID:27143582
Airy beam optical parametric oscillator.
Aadhi, A; Chaitanya, N Apurv; Jabir, M V; Vaity, Pravin; Singh, R P; Samanta, G K
2016-05-04
Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51-1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond).
Parametric display of myocardial function.
Eusemann, C D; Ritman, E L; Bellemann, M E; Robb, R A
2001-01-01
Quantitative assessment of regional heart motion has significant potential to provide more specific diagnosis of cardiac disease and cardiac malfunction than currently possible. Local heart motion may be captured from various medical imaging scanners. In this study, 3-D reconstructions of pre-infarct and post-infarct hearts were obtained from the Dynamic Spatial Reconstructor (DSR)[Ritman EL, Robb RA, Harris LD. Imaging physiological functions: experience with DSR. Philadelphia: Praeger, 1985; Robb RA, Lent AH, Gilbert BK, Chu A. The dynamic spatial reconstructor: a computed tomography system for high-speed simultaneous scanning of multiple cross sections of the heart. J Med Syst 1980;4(2):253-88; Jorgensen SM, Whitlock SV, Thomas PJ, Roessler RW, Ritman EL. The dynamic spatial reconstructor: a high speed, stop action, 3-D, digital radiographic imager of moving internal organs and blood. Proceedings of SPIE, Ultrahigh- and High-speed Photography, Videography, Photonics, and Velocimetry 1990;1346:180-91.] (DSR). Using functional parametric mapping of disturbances in regional contractility and relaxation, regional myocardial motion during a cardiac cycle is color mapped onto a deformable heart model to facilitate appreciation of the structure-to-function relationships in the myocardium, such as occurs in regional patterns of akinesis or dyskinesis associated with myocardial ischemia or infarction resulting from coronary artery occlusion.
Parametrically enhanced hidden photon search
NASA Astrophysics Data System (ADS)
Graham, Peter W.; Mardon, Jeremy; Rajendran, Surjeet; Zhao, Yue
2014-10-01
Many theories beyond the Standard Model contain hidden photons. A light hidden photon will generically couple to the Standard Model through a kinetic mixing term, giving a powerful avenue for detection using "light-shining-through-a-wall"-type transmission experiments with resonant cavities. We demonstrate a parametric enhancement of the signal in such experiments, resulting from transmission of the longitudinal mode of the hidden photon. While previous literature has focused on the production and detection of transverse modes, the longitudinal mode allows a significant improvement in experimental sensitivity. Although optical experiments such as ALPS are unable to take useful advantage of this enhancement, the reach of existing microwave cavity experiments such as CROWS is significantly enhanced beyond their published results. Future microwave cavity experiments, designed with appropriate geometry to take full advantage of the longitudinal mode, will provide a powerful probe of hidden-photon parameter space extending many orders of magnitude beyond current limits, including significant regions where the hidden photon can be dark matter.
Solon, Kimberly; Flores-Alsina, Xavier; Gernaey, Krist V; Jeppsson, Ulf
2015-01-01
This paper examines the importance of influent fractionation, kinetic, stoichiometric and mass transfer parameter uncertainties when modeling biogas production in wastewater treatment plants. The anaerobic digestion model no. 1 implemented in the plant-wide context provided by the benchmark simulation model no. 2 is used to quantify the generation of CH₄, H₂and CO₂. A comprehensive global sensitivity analysis based on (i) standardized regression coefficients (SRC) and (ii) Morris' screening's (MS's) elementary effects reveals the set of parameters that influence the biogas production uncertainty the most. This analysis is repeated for (i) different temperature regimes and (ii) different solids retention times (SRTs) in the anaerobic digester. Results show that both SRC and MS are good measures of sensitivity unless the anaerobic digester is operating at low SRT and mesophilic conditions. In the latter situation, and due to the intrinsic nonlinearities of the system, SRC fails in decomposing the variance of the model predictions (R² < 0.7) making MS a more reliable method. At high SRT, influent fractionations are the most influential parameters for predictions of CH₄and CO₂emissions. Nevertheless, when the anaerobic digester volume is decreased (for the same load), the role of acetate degraders gains more importance under mesophilic conditions, while lipids and fatty acid metabolism is more influential under thermophilic conditions. The paper ends with a critical discussion of the results and their implications during model calibration and validation exercises.
Zhao, Yong Jun; Liu, Bo; Zhang, Wen Guang; Ouyang, Yan; An, Shu Qing
2010-03-01
The performance response of planted and the unplanted wetlands to simulated wastewater with different ratios of carbon to nitrogen (C/N) was studied during a 9-month period in greenhouse conditions. With different C/N ratios for influent water (C/N ratios 2.5:1, 5:1 and 10:1), average removal efficiencies for the unplanted and the planted wetlands were as follows: COD (41-52% and 59-68%), TN (24-48% and 25-62%), TP (35-64% and 59-71%) and TOC (22-37% and 16-33%). At C/N 5:1, both systems performed most efficiently for removal of COD and TP. However, high N removal efficiency only occurred when C/N ratio ranged 2.5-5. Both wetlands exhibited good capabilities of total organic carbon removal at C/N 10:1. Maybe, appropriate control of the carbon or nitrogen source concentration and C/N ratio in the influent can achieve the optimal effect of nutrients removal.
Azuma, Takashi; Arima, Natsumi; Tsukada, Ai; Hirami, Satoru; Matsuoka, Rie; Moriwake, Ryogo; Ishiuchi, Hirotaka; Inoyama, Tomomi; Teranishi, Yusuke; Yamaoka, Misato; Mino, Yoshiki; Hayashi, Tetsuya; Fujita, Yoshikazu; Masada, Mikio
2016-04-01
The occurrence of 41 pharmaceuticals and phytochemicals (PPs) including their metabolites was surveyed in hospital effluent in an urban area of Japan. A detailed survey of sewage treatment plant (STP) influent and effluent, and river water was also conducted. Finally, mass balances with mass fluxes of the target PPs through the water flow were evaluated and the degree of contribution of hospital effluent to the environmental discharge was estimated. The results indicate that 38 compounds were detectable in hospital effluent over a wide concentration range from ng/L to μg/L, with a maximum of 92μg/L. The contributions of PPs in the hospital effluent to STP influent varied widely from <0.1% to 14.8%. Although almost all of the remaining components could be removed below 1.0ng/L at STPs by the addition of ozone treatment, a number of PPs still remained above 10ng/L in STP effluent. These findings suggest the importance of applying highly developed treatments to hospital effluents and at STPs in the future to reduce the environmental risks posed by PPs. To our knowledge, this is the first demonstration of the presence of two conjugated metabolites of acetaminophen, acetaminophen glucuronide and acetaminophen sulfate, as well as of loxoprofen and loxoprofen alcohol, in hospital effluent, STP, and river waters. Copyright © 2016 Elsevier B.V. All rights reserved.
Ren, Shijin; Frymier, Paul D
2003-01-01
Heavy metals are known to be inhibitory and toxic to the activated-sludge microbial community in biological wastewater treatment plants. Toxicity screening of aqueous mixtures of these heavy metal ions in plant influent could use both chemical and biological methods. As a biological method, luminescent bacterial bioreporters offer the advantages of a simple test procedure and rapid response. Current biologically based methods for screening aqueous streams for toxicity are labor-intensive, inaccurate, or difficult to use in continuous monitoring applications. In the present study, a system was developed that is simple and easily automated. This system is based on the bacterium Shk1, a genetically engineered bioluminescent Pseudomonad whose parent strain was originally isolated from activated sludge. Compared with other bioluminescence-based systems (specifically, the Microtox assay), the system of the present study more accurately reflects the effects of the toxicity of common metal ions on activated-sludge respirometry without being overly sensitive to typical constituents of wastewater. The use of Shk1 as a bioluminescent reporter for heavy metal toxicity testing for the application of wastewater treatment influent toxicity screening is presented in this study.
Generating Entangled State with Parametric Amplifier
NASA Astrophysics Data System (ADS)
Huang, Jian
2017-04-01
We present a scheme for generating entangled state with parametric amplifier with different initial states. Its shown that the entangled state is always generated except some special cases by adjusting the coupling strength and the total number of photons.
Ranking Forestry Investments With Parametric Linear Programming
Paul A. Murphy
1976-01-01
Parametric linear programming is introduced as a technique for ranking forestry investments under multiple constraints; it combines the advantages of simple tanking and linear programming as capital budgeting tools.
Conformally covariant parametrizations for relativistic initial data
NASA Astrophysics Data System (ADS)
Delay, Erwann
2017-01-01
We revisit the Lichnerowicz-York method, and an alternative method of York, in order to obtain some conformally covariant systems. This type of parametrization is certainly more natural for non constant mean curvature initial data.
Parametrically disciplined operation of a vibratory gyroscope
NASA Technical Reports Server (NTRS)
Shcheglov, Kirill V. (Inventor); Hayworth, Ken J. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)
2008-01-01
Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.
A Parametric k-Means Algorithm
Tarpey, Thaddeus
2007-01-01
Summary The k points that optimally represent a distribution (usually in terms of a squared error loss) are called the k principal points. This paper presents a computationally intensive method that automatically determines the principal points of a parametric distribution. Cluster means from the k-means algorithm are nonparametric estimators of principal points. A parametric k-means approach is introduced for estimating principal points by running the k-means algorithm on a very large simulated data set from a distribution whose parameters are estimated using maximum likelihood. Theoretical and simulation results are presented comparing the parametric k-means algorithm to the usual k-means algorithm and an example on determining sizes of gas masks is used to illustrate the parametric k-means algorithm. PMID:17917692
A Parametric k-Means Algorithm.
Tarpey, Thaddeus
2007-04-01
The k points that optimally represent a distribution (usually in terms of a squared error loss) are called the k principal points. This paper presents a computationally intensive method that automatically determines the principal points of a parametric distribution. Cluster means from the k-means algorithm are nonparametric estimators of principal points. A parametric k-means approach is introduced for estimating principal points by running the k-means algorithm on a very large simulated data set from a distribution whose parameters are estimated using maximum likelihood. Theoretical and simulation results are presented comparing the parametric k-means algorithm to the usual k-means algorithm and an example on determining sizes of gas masks is used to illustrate the parametric k-means algorithm.
The Quantum Theory of Optical Parametric Amplification
NASA Astrophysics Data System (ADS)
Hussain, N. A.
Available from UMI in association with The British Library. Requires signed TDF. The aim of this thesis is to investigate the effect of parametric amplification on various forms of light. In particular we shall consider number and coherent states, but many of the calculations hold for those states whose operators satisfy the properties, < {a}^+{a}^+ >=<{a}{a }> = < {a}^+>=<{a }>=0 e.g. chaotic light. The first chapter lays down the fundamental preliminaries necessary for our calculations and reviews linear amplifier theory. We consider the phase sensitive and insensitive forms of amplifiers modelling the former on the degenerate parametric amplifier and the latter on the non-degenerate and inverted population amplifiers. Chapter 2 deals with balanced homodyne detection of a narrow band coherent state before and after degenerate parametric amplification. In chapter 3 we consider a continuous mode number state produced by atomic emission and parametrically amplified using the formalism of Collett and Gardiner. We give general results for the output flux intensity and also consider the simpler case where the atomic decay rate is much smaller than the parametric cavity decay rate. Also we consider the degree of second order coherence using this simplified theory. Chapters 4 and 5 consider the double amplifier interferometer, using single and continuous mode theories, and enable us to determine the form of amplifier which produces the best visibility and hence lowest noise figures. The travelling-wave parametric amplifier is discussed in chapter 6 and is contrasted with the cavity parametric amplifier discussed in chapters 1 and 2. Finally we consider the much contemplated idea of using amplifiers to boost signals in fibre optic transmission lines using our model of the parametric amplifier and examining the degradation of the signal-to-noise ratio. We consider both coherent and squeezed inputs and our results hold for both cavity and travelling -wave amplifiers.
Chaos control of parametric driven Duffing oscillators
Jin, Leisheng; Mei, Jie; Li, Lijie
2014-03-31
Duffing resonators are typical dynamic systems, which can exhibit chaotic oscillations, subject to certain driving conditions. Chaotic oscillations of resonating systems with negative and positive spring constants are identified to investigate in this paper. Parametric driver imposed on these two systems affects nonlinear behaviours, which has been theoretically analyzed with regard to variation of driving parameters (frequency, amplitude). Systematic calculations have been performed for these two systems driven by parametric pumps to unveil the controllability of chaos.
Chaos control of parametric driven Duffing oscillators
NASA Astrophysics Data System (ADS)
Jin, Leisheng; Mei, Jie; Li, Lijie
2014-03-01
Duffing resonators are typical dynamic systems, which can exhibit chaotic oscillations, subject to certain driving conditions. Chaotic oscillations of resonating systems with negative and positive spring constants are identified to investigate in this paper. Parametric driver imposed on these two systems affects nonlinear behaviours, which has been theoretically analyzed with regard to variation of driving parameters (frequency, amplitude). Systematic calculations have been performed for these two systems driven by parametric pumps to unveil the controllability of chaos.
NON-PARAMETRIC ESTIMATION UNDER STRONG DEPENDENCE
Zhao, Zhibiao; Zhang, Yiyun; Li, Runze
2014-01-01
We study non-parametric regression function estimation for models with strong dependence. Compared with short-range dependent models, long-range dependent models often result in slower convergence rates. We propose a simple differencing-sequence based non-parametric estimator that achieves the same convergence rate as if the data were independent. Simulation studies show that the proposed method has good finite sample performance. PMID:25018572
Theory of Parametric Amplification in Superlattices
NASA Astrophysics Data System (ADS)
Hyart, Timo; Shorokhov, Alexey V.; Alekseev, Kirill N.
2007-06-01
We consider a high-frequency response of electrons in a single miniband of superlattice subject to dc and ac electric fields. We show that Bragg reflections in miniband result in a parametric resonance which is detectable using ac probe field. We establish theoretical feasibility of phase-sensitive THz amplification at the resonance. The parametric amplification does not require operation in conditions of negative differential conductance. This prevents a formation of destructive domains of high electric field inside the superlattice.
NON-PARAMETRIC ESTIMATION UNDER STRONG DEPENDENCE.
Zhao, Zhibiao; Zhang, Yiyun; Li, Runze
2014-01-01
We study non-parametric regression function estimation for models with strong dependence. Compared with short-range dependent models, long-range dependent models often result in slower convergence rates. We propose a simple differencing-sequence based non-parametric estimator that achieves the same convergence rate as if the data were independent. Simulation studies show that the proposed method has good finite sample performance.
On Topological Structures of Fuzzy Parametrized Soft Sets
Zorlutuna, İdris
2014-01-01
We introduce the topological structure of fuzzy parametrized soft sets and fuzzy parametrized soft mappings. We define the notion of quasi-coincidence for fuzzy parametrized soft sets and investigated its basic properties. We study the closure, interior, base, continuity, and compactness and properties of these concepts in fuzzy parametrized soft topological spaces. PMID:24955386
Parametrizing arbitrary galaxy morphologies: potentials and pitfalls
NASA Astrophysics Data System (ADS)
Andrae, René; Jahnke, Knud; Melchior, Peter
2011-02-01
Given the enormous galaxy data bases of modern sky surveys, parametrizing galaxy morphologies is a very challenging task due to the huge number and variety of objects. We assess the different problems faced by existing parametrization schemes (CAS, Gini, M20, Sérsic profile, shapelets) in an attempt to understand why parametrization is so difficult and in order to suggest improvements for future parametrization schemes. We demonstrate that morphological observables (e.g. steepness of the radial light profile, ellipticity, asymmetry) are intertwined and cannot be measured independently of each other. We present strong arguments in favour of model-based parametrization schemes, namely reliability assessment, disentanglement of morphological observables and point spread function modelling. Furthermore, we demonstrate that estimates of the concentration and Sérsic index obtained from the Zurich Structure & Morphology catalogue are in excellent agreement with theoretical predictions. We also demonstrate that the incautious use of the concentration index for classification purposes can cause a severe loss of the discriminative information contained in a given data sample. Moreover, we show that, for poorly resolved galaxies, concentration index and M20 suffer from strong discontinuities, i.e. similar morphologies are not necessarily mapped to neighbouring points in the parameter space. This limits the reliability of these parameters for classification purposes. Two-dimensional Sérsic profiles accounting for centroid and ellipticity are identified as the currently most reliable parametrization scheme in the regime of intermediate signal-to-noise ratios and resolutions, where asymmetries and substructures do not play an important role. We argue that basis functions provide good parametrization schemes in the regimes of high signal-to-noise ratios and resolutions. Concerning Sérsic profiles, we show that scale radii cannot be compared directly for profiles of different
Manssouri, M; Rodrigues, J A D; Ratusznei, S M; Zaiat, M
2013-12-01
An anaerobic sequencing batch biofilm reactor (AnSBBR-total volume 7.5 L; liquid volume 3.6 L; treated volume per cycle 1.5 L) treated sucrose-based wastewater to produce biohydrogen (at 30 °C). Different applied volumetric organic loads (AVOL of 9.0, 12.0, 13.5, 18.0, and 27.0 kg COD m(-3) day(-1)), which were varied according to the influent concentration (3,600 and 5,400 mg COD L(-1)) and cycle length (4, 3, and 2 h), have been used to assess the following parameters: productivity and yield of biohydrogen per applied and removed load, reactor stability, and efficiency. The removed organic matter (COD) remained stable and close to 18 % and carbohydrates (sucrose) uptake rate remained between 83 and 97 % during operation. The decrease in removal performance of the reactor with increasing AVOL, by increasing the influent concentration (at constant cycle length) and decreasing the cycle lengths (at constant influent concentrations), resulted in lower conversion efficiencies. Under all conditions, when organic load increased there was a predominance of acetic, propionic, and butyric acid as well as ethanol. The highest concentration of biohydrogen in the biogas (24-25 %) was achieved at conditions with AVOL of 12.0 and 13.5 kg COD m(-3) day(-1), the highest daily production rate (0.139 mol H2 day(-1)) was achieved at AVOL of 18.0 kg COD m(-3) day(-1), and the highest production yields per removed and applied load were 2.83 and 3.04 mol H2 kg SUC(-1), respectively, at AVOL of 13.5 kg COD m(-3) day(-1). The results indicated that the best productivity tends to occur at higher organic loads, as this parameter involves the "biochemical generation" of biogas, and the best yield tends to occur at lower and/or intermediate organic loads, as this parameter involves "biochemical consumption" of the substrate.
Fiber-optic parametric amplifier and oscillator based on intracavity parametric pump technique.
Luo, Zhengqian; Zhong, Wen-De; Tang, Ming; Cai, Zhiping; Ye, Chenchun; Xiao, Xiaosheng
2009-01-15
A cost-effective fiber optical parametric amplifier (FOPA) based on the laser intracavity pump technique has been proposed and demonstrated experimentally. The parametric process is realized by inserting a 1 km highly nonlinear dispersion-shifted fiber (HNL-DSF) into a fiber ring-laser cavity that consists of a high-power erbium-doped fiber (EDF) amplifier and two highly reflective fiber Bragg gratings. Compared with the conventional parametric pump schemes, the proposed pumping technique is free from a tunable semiconductor laser as the pump source and also the pump phase modulation. When the oscillating power of 530 mW in the EDF laser cavity is achieved to pump the HNL-DSF, a peak parametric gain of 27.5 dB and a net gain over 45 nm are obtained. Moreover, a widely tunable fiber-optic parametric oscillator is further developed using the FOPA as a gain medium.
Parametric instability of pressurized propellant tanks
NASA Astrophysics Data System (ADS)
Albus, Jochen; Dieker, Stefan; Őry, Huba; Rittweger, Andreas
2008-01-01
Pressurized propellant tanks might become dynamically unstable with detrimental dynamic responses if a dynamic excitation leads to a coupling of pressure oscillations (especially due to the response of axisymmetric modes) with very low damped ovalizing modes. This phenomenon can be described and identified as the so-called parametric instability. During the dynamic qualification test campaign of the new Ariane 5 Cryogenic Upper Stage ESC-A, a parametric instability was observed for sinusoidal tests under certain test conditions with low static pressure in the propellant tank. The parametric instability was identified and an analytical simulation was performed that confirmed the instability. During flight, harmonic excitations might occur due to pressure oscillations within the solid rocket booster. However, the application of the analytical model on flight conditions indicates that the flight behaviour will be stable. This was confirmed by results from additional tests. This paper describes the phenomenon of the parametric instability of pressurized propellant tanks and presents an analytical methodology to assess the risk of the occurrence of a parametric instability.
Optimization of noncollinear optical parametric amplification
NASA Astrophysics Data System (ADS)
Schimpf, D. N.; Rothardt, J.; Limpert, J.; Tünnermann, A.
2007-02-01
Noncollinearly phase-matched optical parametric amplifiers (NOPAs) - pumped with the green light of a frequency doubled Yb-doped fiber-amplifier system 1, 2 - permit convenient generation of ultrashort pulses in the visible (VIS) and near infrared (NIR) 3. The broad bandwidth of the parametric gain via the noncollinear pump configuration allows amplification of few-cycle optical pulses when seeded with a spectrally flat, re-compressible signal. The short pulses tunable over a wide region in the visible permit transcend of frontiers in physics and lifescience. For instance, the resulting high temporal resolution is of significance for many spectroscopic techniques. Furthermore, the high magnitudes of the peak-powers of the produced pulses allow research in high-field physics. To understand the demands of noncollinear optical parametric amplification using a fiber pump source, it is important to investigate this configuration in detail 4. An analysis provides not only insight into the parametric process but also determines an optimal choice of experimental parameters for the objective. Here, the intention is to design a configuration which yields the shortest possible temporal pulse. As a consequence of this analysis, the experimental setup could be optimized. A number of aspects of optical parametric amplifier performance have been treated analytically and computationally 5, but these do not fully cover the situation under consideration here.
Grating lobe elimination in steerable parametric loudspeaker.
Shi, Chuang; Gan, Woon-Seng
2011-02-01
In the past two decades, the majority of research on the parametric loudspeaker has concentrated on the nonlinear modeling of acoustic propagation and pre-processing techniques to reduce nonlinear distortion in sound reproduction. There are, however, very few studies on directivity control of the parametric loudspeaker. In this paper, we propose an equivalent circular Gaussian source array that approximates the directivity characteristics of the linear ultrasonic transducer array. By using this approximation, the directivity of the sound beam from the parametric loudspeaker can be predicted by the product directivity principle. New theoretical results, which are verified through measurements, are presented to show the effectiveness of the delay-and-sum beamsteering structure for the parametric loudspeaker. Unlike the conventional loudspeaker array, where the spacing between array elements must be less than half the wavelength to avoid spatial aliasing, the parametric loudspeaker can take advantage of grating lobe elimination to extend the spacing of ultrasonic transducer array to more than 1.5 wavelengths in a typical application.
Parametric wavelength conversion in photonic crystal fibers
NASA Astrophysics Data System (ADS)
Yang, Sigang; Wu, Zhaohui; Yang, Yi; Chen, Minghua; Xie, Shizhong
2016-11-01
Nonlinear wavelength conversion provides flexible solutions for generating wideband tunable radiation in novel wavelength band. Parametric process in photonic crystal fibers (PCFs) has attracted comprehensive interests since it can act as broadband tunable light sources in non-conventional wavelength bands. The current state-of-the-art photonic crystal fibers can provide more freedom for customizing the dispersion and nonlinearity which is critical to the nonlinear process, such as four wave mixing (FWM), compared with the traditional fibers fabricated with doping techniques. Here we demonstrate broadband parametric wavelength conversion in our homemade photonic crystal fibers. The zero dispersion wavelength (ZDW) of PCFs is critical for the requirement of phase matching condition in the parametric four wave mixing process. Firstly a procedure of the theoretical design of PCF with the ZDW at 1060 nm is proposed through our homemade simulation software. A group of PCF samples with gradually variable parameters are fabricated according to the theoretical design. The broadband parametric gain around 1060 nm band is demonstrated pumped with our homemade mode locked fiber laser in the anomalous dispersion region. Also a narrow gain band with very large wavelength detune with the pump wavelength in the normal dispersion region is realized. Wavelength conversion with a span of 194 nm is realized. Furthermore a fiber optical parametric oscillator based on the fabricated PCF is built up. A wavelength tunable range as high as 340 nm is obtained. This report demonstrates a systematic procedure to realize wide band wavelength conversion based on PCFs.
Phase noise suppression through parametric filtering
NASA Astrophysics Data System (ADS)
Cassella, Cristian; Strachan, Scott; Shaw, Steven W.; Piazza, Gianluca
2017-02-01
In this work, we introduce and experimentally demonstrate a parametric phase noise suppression technique, which we call "parametric phase noise filtering." This technique is based on the use of a solid-state parametric amplifier operating in its instability region and included in a non-autonomous feedback loop connected at the output of a noisy oscillator. We demonstrate that such a system behaves as a parametrically driven Duffing resonator and can operate at special points where it becomes largely immune to the phase fluctuations that affect the oscillator output signal. A prototype of a parametric phase noise filter (PFIL) was designed and fabricated to operate in the very-high-frequency range. The PFIL prototype allowed us to significantly reduce the phase noise at the output of a commercial signal generator operating around 220 MHz. Noise reduction of 16 dB (40×) and 13 dB (20×) were obtained, respectively, at 1 and 10 kHz offsets from the carrier frequency. The demonstration of this phase noise suppression technique opens up scenarios in the development of passive and low-cost phase noise cancellation circuits for any application demanding high quality frequency generation.
Parametric resonance in tunable superconducting cavities
NASA Astrophysics Data System (ADS)
Wustmann, Waltraut; Shumeiko, Vitaly
2013-05-01
We develop a theory of parametric resonance in tunable superconducting cavities. The nonlinearity introduced by the superconducting quantum interference device (SQUID) attached to the cavity and damping due to connection of the cavity to a transmission line are taken into consideration. We study in detail the nonlinear classical dynamics of the cavity field below and above the parametric threshold for the degenerate parametric resonance, featuring regimes of multistability and parametric radiation. We investigate the phase-sensitive amplification of external signals on resonance, as well as amplification of detuned signals, and relate the amplifier performance to that of linear parametric amplifiers. We also discuss applications of the device for dispersive qubit readout. Beyond the classical response of the cavity, we investigate small quantum fluctuations around the amplified classical signals. We evaluate the noise power spectrum both for the internal field in the cavity and the output field. Other quantum-statistical properties of the noise are addressed such as squeezing spectra, second-order coherence, and two-mode entanglement.
Hu, Zhen; Zhang, Jian; Xie, Huijun; Liang, Shuang; Li, Shanping
2013-03-01
Nitrous oxide (N(2)O) is an important greenhouse gas and biological nitrogen removal process of wastewater treatment plant is one of its sources. Mechanisms of N(2)O emissions from anoxic-oxic biological nitrogen removal process were investigated and minimizations of N(2)O emissions were carried out from the aspect of organic carbon supplement, i.e., influent COD/NH4+ ratio (C/N ratio) and feeding strategy. Results showed that during anoxic-oxic biological nitrogen removal process, most of the N(2)O emissions occurred during the oxic phase, and both nitrifier denitrification and aerobic hydroxylamine oxidation pathways were possible mechanisms responsible for N(2)O emissions. N(2)O conversion rate decreased from 6.0% to 1.3% when the influent C/N ratio was increased from 7.5 to 14.5. This was mainly because of decrease in the abundance of Nitrosomonas-like ammonia oxidizing bacteria. Step feeding and external carbon source addition could reduce N(2)O conversion rate by 66.6% and 12.0%, respectively. Both of them were feasible methods for minimizing N(2)O emission from wastewater treatment process. The low N(2)O emission of step feeding was because of its high dissolved oxygen (DO) and low ammonium concentrations during the oxic phase, while the minimization effect of external carbon source addition was ascribed to its high nitrogen removal efficiency. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Reid, Antoinette M.; Brougham, Concepta A.; Fogarty, Andrew M.; Roche, James J.
2009-01-01
The application of an acid digestion and subsequent solid-phase extraction (SPE) procedure were implemented as preliminary treatments prior to quantifying the levels of potentially endocrine disrupting metals (EDMs) in a variety of solid and liquid matrices. These included (solid) river sediment, leachate sediment and sewage sludge and also (liquid) river water, landfill leachate, concentrated leachate, sewage influent, and sewage effluent, sampled in the Irish Midlands. The total concentrations of cobalt (Co), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and manganese (Mn), after extraction and preconcentration, were determined by atomic absorption spectroscopy (AAS). Mercury (Hg) in sediment and sludge was determined using cold-vapour atomic fluorescence spectroscopy (AFS). For sewage sludge maximum values (mg/kgdw) of 4700 Ni, 1642 Mn, 100.0 Cd, 3400 Zn, 36.70 Co, 750.0 Pb, 485.8 Cr, and 1003 Cu were determined whilst in leachate sediment, maximum values (mg/kgdw) of 32.10 Ni, 815.0 Mn, 32.78 Cd, 230.3 Zn, 26.73 Co, 3525 Pb, 124.9 Cr, and 50.13 Cu were found. Over several months, the data showed elevated levels in sewage influents, effluents, and sludges compared to a battery of adjacent river water samples and corresponding sediments. There was a definite trend for target values for sediments to be exceeded, while intervention values were only exceeded for cadmium. Overall the pattern in terms of concentration was sewage > leachate > river matrices. A nonparametric assessment of the effect of sewage treatment method on median metal levels in sludge revealed statistically significant differences at the 95% level of confidence for Co, Cr, and Hg and at the 90% level of confidence for Cd. PMID:20150974
Nefau, Thomas; Karolak, Sara; Castillo, Luis; Boireau, Véronique; Levi, Yves
2013-09-01
Consumption of illicit drugs is a new concern for water management that must be considered not only because of the social and public health aspects but also in an environmental context in relation with the contamination of surface waters. Indeed, sewage treatment plant (STP) effluents contain drug residues that have not been eliminated since STP treatments are not completely efficient in their removal. We developed and validated an HPLC-MS/MS analytical method to assess the concentrations of 17 illicit drugs and metabolites in raw urban wastewaters: cocaine and its metabolites, amphetamine and amphetamine-likes (methamphetamine, MDMA, MDEA, MDA), opiates and opiate substitutes (methadone and buprenorphine), and THC-COOH cannabis metabolite. This method has been applied to the analysis of influent and effluent samples from 25 STPs located in France all over the country. The results allowed evaluating the drug consumption in the areas connected to the STPs and the efficiency of the treatment technology implied. We selected STPs according to their volume capacity, their treatment technologies (biofilters, activated sludges, MBR) and their geographical location. In influents, the concentrations varied between 6 ng/L for EDDP (main metabolite of methadone) and 3050 ng/L for benzoylecgonine (cocaine metabolite). Consumption maps were drawn for cocaine, MDMA, opiates, cannabis and amphetamine-like compounds. Geographical significant differences were observed and highlighted the fact that drug consumption inside a country is not homogeneous. In parallel, comparisons between STP technology processes showed differences of efficiency. More, some compounds appear very resistant to STP processes leading to the contamination of receiving water. Copyright © 2013 Elsevier B.V. All rights reserved.
Bravo, I S Moncayo; Lovato, G; Rodrigues, J A D; Ratusznei, S M; Zaiat, M
2015-02-01
This study evaluated the influence of the applied volumetric organic load on biohydrogen production in an anaerobic sequencing batch biofilm reactor (AnSBBR) with 3.5 L of liquid medium and treating 1.5 L of glycerin-based wastewater per cycle at 30 °C. Six applied volumetric organic loads (AVOLCT) were generated from the combination of cycle periods (3 and 4 h) and influent concentrations (3000, 4000, and 5000 mg chemical oxygen demand (COD) L(-1)), with values ranging from 7565 to 16,216 mg COD L(-1) day(-1). No clear relationship was found between the applied volumetric organic load and the hydrogen production. However, the highest hydrogen molar production (MPr 67.5 mol H2 m(-3) day(-1)) was reached when the reactor was operated with a cycle period of 4 h and an influent concentration of 5000 mg COD L(-1) (AVOLCT 12,911 mg COD L(-1) day(-1)). This condition also reached the highest molar yield per applied load based on the organic matter (MYALC,m 21.1 mol H2 kg COD(-1)). In addition, the pretreatment of the sludge/inoculum was found to not influence the productivity/yield of the process, and the use of crude glycerol as a sole source of carbon exhibited a clear disadvantage for hydrogen production compared to pure glycerol. The AnSBBR used for the hydrogen production experiments operated with pure glycerol as a sole carbon source exhibited important practical potential.
Movassaghi, Karim; Hemmatian, Zahra; Akbari-Adergani, Behrouz; Palmisano, Giovanni
2006-01-01
In this work a series of total organic carbon (TOC) analyses were carried out to analyse the influent and the effluent of a water treatment plant providing Isfahan city in Iran. Other analyses were focused on the determination of TOC in the urban network and Fellman wells (in Isfahan and Dehaghan cities), in order to compare the water quality soon after the treatment with that of circulating water in the city network. Since it supplies water treatment plant, TOC content of Zayandehrood River was also compared with the treated water. The obtained results revealed that there were significant differences between TOC content of effluent of water treatment plant and that of the urban network (made with eight different points). In this project all the samples were withdrawn during 2005. It is worth noting that the analyses were carried out with a high precision combustion-infrared method with a confidence limit lower than 0.05. The mean of TOC in Isfahan and Dehaghan Fellman wells were 0.7 and 2.6 mg.l(-1), respectively. The mean of TOC in influent of water treatment plant during June, July and September were 0.703, 1.148, 1.513 mg.l(-1) respectively which after treatment process reduced to about 0.7 mg.l(-1). In conclusion it can be said that during the summer with higher consumption of water and increase in vaporizing surface waters, we have accumulation of organic compounds and therefore we have increase in TOC content of various waters.
Ku band low noise parametric amplifier
NASA Technical Reports Server (NTRS)
1976-01-01
A low noise, K sub u-band, parametric amplifier (paramp) was developed. The unit is a spacecraft-qualifiable, prototype, parametric amplifier for eventual application in the shuttle orbiter. The amplifier was required to have a noise temperature of less than 150 K. A noise temperature of less than 120 K at a gain level of 17 db was achieved. A 3-db bandwidth in excess of 350 MHz was attained, while deviation from phase linearity of about + or - 1 degree over 50 MHz was achieved. The paramp operates within specification over an ambient temperature range of -5 C to +50 C. The performance requirements and the operation of the K sub u-band parametric amplifier system are described. The final test results are also given.
Parametric modelling of a knee joint prosthesis.
Khoo, L P; Goh, J C; Chow, S L
1993-01-01
This paper presents an approach for the establishment of a parametric model of knee joint prosthesis. Four different sizes of a commercial prosthesis are used as an example in the study. A reverse engineering technique was employed to reconstruct the prosthesis on CATIA, a CAD (computer aided design) system. Parametric models were established as a result of the analysis. Using the parametric model established and the knee data obtained from a clinical study on 21 pairs of cadaveric Asian knees, the development of a prototype prosthesis that suits a patient with a very small knee joint is presented. However, it was found that modification to certain parameters may be inevitable due to the uniqueness of the Asian knee. An avenue for rapid modelling and eventually economical production of a customized knee joint prosthesis for patients is proposed and discussed.
Modeling personnel turnover in the parametric organization
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1991-01-01
A model is developed for simulating the dynamics of a newly formed organization, credible during all phases of organizational development. The model development process is broken down into the activities of determining the tasks required for parametric cost analysis (PCA), determining the skills required for each PCA task, determining the skills available in the applicant marketplace, determining the structure of the model, implementing the model, and testing it. The model, parameterized by the likelihood of job function transition, has demonstrated by the capability to represent the transition of personnel across functional boundaries within a parametric organization using a linear dynamical system, and the ability to predict required staffing profiles to meet functional needs at the desired time. The model can be extended by revisions of the state and transition structure to provide refinements in functional definition for the parametric and extended organization.
Modeling personnel turnover in the parametric organization
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1991-01-01
A model is developed for simulating the dynamics of a newly formed organization, credible during all phases of organizational development. The model development process is broken down into the activities of determining the tasks required for parametric cost analysis (PCA), determining the skills required for each PCA task, determining the skills available in the applicant marketplace, determining the structure of the model, implementing the model, and testing it. The model, parameterized by the likelihood of job function transition, has demonstrated by the capability to represent the transition of personnel across functional boundaries within a parametric organization using a linear dynamical system, and the ability to predict required staffing profiles to meet functional needs at the desired time. The model can be extended by revisions of the state and transition structure to provide refinements in functional definition for the parametric and extended organization.
Use of robust estimators in parametric classifiers
NASA Technical Reports Server (NTRS)
Safavian, S. Rasoul; Landgrebe, David A.
1989-01-01
The parametric approach to density estimation and classifier design is a well studied subject. The parametric approach is desirable because basically it reduces the problem of classifier design to that of estimating a few parameters for each of the pattern classes. The class parameters are usually estimated using maximum-likelihood (ML) estimators. ML estimators are, however, very sensitive to the presence of outliers. Several robust estimators of mean and covariance matrix and their effect on the probability of error in classification are examined. Comments are made about alpha-ranked (alpha-trimmed) estimators.
Parametric number covariance in quantum chaotic spectra.
Vinayak; Kumar, Sandeep; Pandey, Akhilesh
2016-03-01
We study spectral parametric correlations in quantum chaotic systems and introduce the number covariance as a measure of such correlations. We derive analytic results for the classical random matrix ensembles using the binary correlation method and obtain compact expressions for the covariance. We illustrate the universality of this measure by presenting the spectral analysis of the quantum kicked rotors for the time-reversal invariant and time-reversal noninvariant cases. A local version of the parametric number variance introduced earlier is also investigated.
Use of robust estimators in parametric classifiers
NASA Technical Reports Server (NTRS)
Safavian, S. Rasoul; Landgrebe, David A.
1989-01-01
The parametric approach to density estimation and classifier design is a well studied subject. The parametric approach is desirable because basically it reduces the problem of classifier design to that of estimating a few parameters for each of the pattern classes. The class parameters are usually estimated using maximum-likelihood (ML) estimators. ML estimators are, however, very sensitive to the presence of outliers. Several robust estimators of mean and covariance matrix and their effect on the probability of error in classification are examined. Comments are made about alpha-ranked (alpha-trimmed) estimators.
A Comparison of Parametric and Non-Parametric Methods Applied to a Likert Scale.
Mircioiu, Constantin; Atkinson, Jeffrey
2017-05-10
A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple "yes" or "no" but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies for practice. Results obtained show that with "large" (>15) numbers of responses and similar (but clearly not normal) distributions from different subgroups, parametric and non-parametric analyses give in almost all cases the same significant or non-significant results for inter-subgroup comparisons. Parametric methods were more discriminant in the cases of non-similar conclusions. Considering that the largest differences in opinions occurred in the upper part of the 4-point Likert scale (ranks 3 "very important" and 4 "essential"), a "score analysis" based on this part of the data was undertaken. This transformation of the ordinal Likert data into binary scores produced a graphical representation that was visually easier to understand as differences were accentuated. In conclusion, in this case of Likert ordinal data with high response rates, restraining the analysis to non-parametric methods leads to a loss of information. The addition of parametric methods, graphical analysis, analysis of subsets, and transformation of data leads to more in-depth analyses.
NASA Astrophysics Data System (ADS)
Prakash, Gyan; Raman, Arvind; Rhoads, Jeffrey; Reifenberger, Ronald G.
2012-06-01
In this work, parametric noise squeezing and parametric resonance are realized through the use of an electronic feedback circuit to excite a microcantilever with a signal proportional to the product of the microcantilever's displacement and a harmonic signal. The cantilever's displacement is monitored using an optical lever technique. By adjusting the gain of an amplifier in the feedback circuit, regimes of parametric noise squeezing/amplification and the principal and secondary parametric resonances of fundamental and higher order eigenmodes can be easily accessed. The exceptionally symmetric amplitude response of the microcantilever in the narrow frequency bandwidth is traced to a nonlinear parametric excitation term that arises due to the cubic nonlinearity in the output of the position-sensitive photodiode. The feedback circuit, working in both the regimes of parametric resonance and noise squeezing, allows an enhancement of the microcantilever's effective quality-factor (Q-factor) by two orders of magnitude under ambient conditions, extending the mass sensing capabilities of a conventional microcantilever into the sub-picogram regime. Likewise, experiments designed to parametrically oscillate a microcantilever in water using electronic feedback also show an increase in the microcantilever's effective Q-factor by two orders of magnitude, opening the field to high-sensitivity mass sensing in liquid environments.
Prakash, Gyan; Raman, Arvind; Rhoads, Jeffrey; Reifenberger, Ronald G
2012-06-01
In this work, parametric noise squeezing and parametric resonance are realized through the use of an electronic feedback circuit to excite a microcantilever with a signal proportional to the product of the microcantilever's displacement and a harmonic signal. The cantilever's displacement is monitored using an optical lever technique. By adjusting the gain of an amplifier in the feedback circuit, regimes of parametric noise squeezing/amplification and the principal and secondary parametric resonances of fundamental and higher order eigenmodes can be easily accessed. The exceptionally symmetric amplitude response of the microcantilever in the narrow frequency bandwidth is traced to a nonlinear parametric excitation term that arises due to the cubic nonlinearity in the output of the position-sensitive photodiode. The feedback circuit, working in both the regimes of parametric resonance and noise squeezing, allows an enhancement of the microcantilever's effective quality-factor (Q-factor) by two orders of magnitude under ambient conditions, extending the mass sensing capabilities of a conventional microcantilever into the sub-picogram regime. Likewise, experiments designed to parametrically oscillate a microcantilever in water using electronic feedback also show an increase in the microcantilever's effective Q-factor by two orders of magnitude, opening the field to high-sensitivity mass sensing in liquid environments.
Quantifying parametric uncertainty in the Rothermel model
S. Goodrick
2008-01-01
The purpose of the present work is to quantify parametric uncertainty in the Rothermel wildland fire spreadmodel (implemented in software such as fire spread models in the United States. This model consists of a non-linear system of equations that relates environmentalvariables (input parameter groups...
Noise figure of hybrid optical parametric amplifiers.
Marhic, Michel E
2012-12-17
Following a fiber optical parametric amplifier, used as a wavelength converter or in the phase-sensitive mode, by a phase-insensitive amplifier (PIA) can significantly reduce four-wave mixing between signals in broadband systems. We derive the quantum mechanical noise figures (NF) for these two hybrid configurations, and show that adding the PIA only leads to a moderate increase in NF.
New Logic Circuit with DC Parametric Excitation
NASA Astrophysics Data System (ADS)
Sugahara, Masanori; Kaneda, Hisayoshi
1982-12-01
It is shown that dc parametric excitation is possible in a circuit named JUDO, which is composed of two resistively-connected Josephson junctions. Simulation study proves that the circuit has large gain and properties suitable for the construction of small, high-speed logic circuits.
Measurement selection for parametric IC fault diagnosis
NASA Technical Reports Server (NTRS)
Wu, A.; Meador, J.
1991-01-01
Experimental results obtained with the use of measurement reduction for statistical IC fault diagnosis are described. The reduction method used involves data pre-processing in a fashion consistent with a specific definition of parametric faults. The effects of this preprocessing are examined.
Holographic Dark Energy Density and JBP Parametrization
NASA Astrophysics Data System (ADS)
Saadat, Hassan; Mousavi, S. N.; Saadat, A. M.
2011-09-01
In this article we consider the holographic dark energy density. We study dark energy density in Universe with arbitrary spatially curvature described by the Friedmann-Robertson-Walker metric. We use Jassal-Bagla-Padmanabhan parametrization to specify dark energy density.
Parametric Oscillations in High Power Microwave Amplifiers.
1979-01-01
report. I j I 1 1) G. Dohler, Parametric Oscillations in High Power Microwave Amplifiers, L Contract No. F49620-77-C-O0 (1979). 2) O. Doehler B. Dohler...IEEE Transactions on Electron Devices, ED 26(10),[ 1602 (19795. 3) 0. Doehler , G. Dohler, International Electron Devices Meeting, I Washington, D.C
A parametric reconstruction of the deceleration parameter
NASA Astrophysics Data System (ADS)
Mamon, Abdulla Al; Das, Sudipta
2017-07-01
The present work is based on a parametric reconstruction of the deceleration parameter q( z) in a model for the spatially flat FRW universe filled with dark energy and non-relativistic matter. In cosmology, the parametric reconstruction technique deals with an attempt to build up a model by choosing some specific evolution scenario for a cosmological parameter and then estimate the values of the parameters with the help of different observational datasets. In this paper, we have proposed a logarithmic parametrization of q( z) to probe the evolution history of the universe. Using the type Ia supernova, baryon acoustic oscillation and the cosmic microwave background datasets, the constraints on the arbitrary model parameters q0 and q1 are obtained (within 1σ and 2σ confidence limits) by χ 2-minimization technique. We have then reconstructed the deceleration parameter, the total EoS parameter ω _tot, the jerk parameter and have compared the reconstructed results of q( z) with other well-known parametrizations of q( z). We have also shown that two model selection criteria (namely, the Akaike information criterion and Bayesian information criterion) provide a clear indication that our reconstructed model is well consistent with other popular models.
The fast parametric slantlet transform with applications
NASA Astrophysics Data System (ADS)
Agaian, Sos S.; Tourshan, Khaled; Noonan, Joseph P.
2004-05-01
Transform methods have played an important role in signal and image processing applications. Recently, Selesnick has constructed the new orthogonal discrete wavelet transform, called the slantlet wavelet, with two zero moments and with improved time localization. The discrete slantlet wavelet transform is carried out by an existing filterbank which lacks a tree structure and has a complexity problem. The slantlet wavelet has been successfully applied in compression and denoising. In this paper, we present a new class of orthogonal parametric fast Haar slantlet transform system where the slantlet wavelet and Haar transforms are special cases of it. We propose designing the slantlet wavelet transform using Haar slantlet transform matrix. A new class of parametric filterbanks is developed. The behavior of the parametric Haar slantlet transforms in signal and image denoising is presented. We show that the new technique performs better than the slantlet wavelet transform in denoising for piecewise constant signals. We also show that the parametric Haar slantlet transform performs better than the cosine and Fourier transforms for grey level images.
A general framework for parametric survival analysis.
Crowther, Michael J; Lambert, Paul C
2014-12-30
Parametric survival models are being increasingly used as an alternative to the Cox model in biomedical research. Through direct modelling of the baseline hazard function, we can gain greater understanding of the risk profile of patients over time, obtaining absolute measures of risk. Commonly used parametric survival models, such as the Weibull, make restrictive assumptions of the baseline hazard function, such as monotonicity, which is often violated in clinical datasets. In this article, we extend the general framework of parametric survival models proposed by Crowther and Lambert (Journal of Statistical Software 53:12, 2013), to incorporate relative survival, and robust and cluster robust standard errors. We describe the general framework through three applications to clinical datasets, in particular, illustrating the use of restricted cubic splines, modelled on the log hazard scale, to provide a highly flexible survival modelling framework. Through the use of restricted cubic splines, we can derive the cumulative hazard function analytically beyond the boundary knots, resulting in a combined analytic/numerical approach, which substantially improves the estimation process compared with only using numerical integration. User-friendly Stata software is provided, which significantly extends parametric survival models available in standard software. Copyright © 2014 John Wiley & Sons, Ltd.
Robustness analysis for real parametric uncertainty
NASA Technical Reports Server (NTRS)
Sideris, Athanasios
1989-01-01
Some key results in the literature in the area of robustness analysis for linear feedback systems with structured model uncertainty are reviewed. Some new results are given. Model uncertainty is described as a combination of real uncertain parameters and norm bounded unmodeled dynamics. Here the focus is on the case of parametric uncertainty. An elementary and unified derivation of the celebrated theorem of Kharitonov and the Edge Theorem is presented. Next, an algorithmic approach for robustness analysis in the cases of multilinear and polynomic parametric uncertainty (i.e., the closed loop characteristic polynomial depends multilinearly and polynomially respectively on the parameters) is given. The latter cases are most important from practical considerations. Some novel modifications in this algorithm which result in a procedure of polynomial time behavior in the number of uncertain parameters is outlined. Finally, it is shown how the more general problem of robustness analysis for combined parametric and dynamic (i.e., unmodeled dynamics) uncertainty can be reduced to the case of polynomic parametric uncertainty, and thus be solved by means of the algorithm.
Parametric acoustic arrays: A state of the art review
NASA Technical Reports Server (NTRS)
Fenlon, F. H.
1976-01-01
Following a brief introduction to the concept of parametric acoustic interactions, the basic properties of parametric transmitting and receiving arrays are considered in the light of conceptual advances resulting from experimental and theoretical investigations that have taken place since 1963.
Parametric Acoustic Receiving Array (Parray) Research and Experiments.
1980-02-06
AD-AC83 704 TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS FIG 17/1 PARAMETRIC ACOUSTIC RECEIVING ARRAY ( PARRAY ) RESEARCH AND EXPER-CTC(U) FEB 80 T G...TITLE anld Subtitle) ,__t, I -1rilUl tT :. 40441" ,APT19* .... ,. L PARAMETRIC ACOUSTIC RECEIVING ARRAY ( PARRAY ) inal technical re. m , LIESEARCH AND...WORDS (Continue on reverse side it necaesary and Identify by block number) PARRAY parametric acoustic receiver nonlinear acoustics parametric acoustic
Hyperbolic and semi-parametric models in finance
NASA Astrophysics Data System (ADS)
Bingham, N. H.; Kiesel, Rüdiger
2001-02-01
The benchmark Black-Scholes-Merton model of mathematical finance is parametric, based on the normal/Gaussian distribution. Its principal parametric competitor, the hyperbolic model of Barndorff-Nielsen, Eberlein and others, is briefly discussed. Our main theme is the use of semi-parametric models, incorporating the mean vector and covariance matrix as in the Markowitz approach, plus a non-parametric part, a scalar function incorporating features such as tail-decay. Implementation is also briefly discussed.
Unifying framework for decomposition models of parametric and non-parametric image registration
NASA Astrophysics Data System (ADS)
Ibrahim, Mazlinda; Chen, Ke
2017-08-01
Image registration aims to find spatial transformations such that the so-called given template image becomes similar in some sense to the reference image. Methods in image registration can be divided into two classes (parametric or non-parametric) based on the degree of freedom of the given method. In parametric image registration, the transformation is governed by a finite set of image features or by expanding the transformation in terms of basis functions. Meanwhile, in non-parametric image registration, the problem is modelled as a functional minimisation problem via the calculus of variations. In this paper, we provide a unifying framework for decomposition models for image registration which combine parametric and non-parametric models. Several variants of the models are presented with focus on the affine, diffusion and linear curvature models. An effective numerical solver is provided for the models as well as experimental results to show the effectiveness, robustness and accuracy of the models. The decomposition model of affine and linear curvature outperforms the competing models based on tested images.
Wang, De-Gao; Steer, Helena; Tait, Tara; Williams, Zackery; Pacepavicius, Grazina; Young, Teresa; Ng, Timothy; Smyth, Shirley Anne; Kinsman, Laura; Alaee, Mehran
2013-10-01
A comprehensive surveillance program was conducted to determine the occurrence of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in environmental compartments impacted by wastewater effluent discharges. Eleven wastewater treatment plants (WWTPs), representative of those found in Southern Ontario and Southern Quebec, Canada, were investigated to determine levels of cVMS in their influents and effluents. In addition, receiving water and sediment impacted by WWTP effluents, and biosolid-amended soil from agricultural fields were also analyzed for a preliminary evaluation of the environmental exposure of cVMS in media impacted by wastewater effluent and solids. A newly-developed large volume injection (septumless head adapter and cooled injection system) gas chromatography - mass spectrometry method was used to avoid contamination originating from instrumental analysis. Concentrations of D4, D5, and D6 in influents to the 11 WWTPs were in the range 0.282-6.69μgL(-1), 7.75-135μgL(-1), and 1.53-26.9μgL(-1), respectively. In general, wastewater treatment showed cVMS removal rates of greater than 92%, regardless of treatment type. The D4, D5, and D6 concentration ranges in effluent were <0.009-0.045μgL(-1), <0.027-1.56μgL(-1), and <0.022-0.093μgL(-1), respectively. The concentrations in receiving water influenced by effluent, were lower compared to those in effluent in most cases, with the ranges <0.009-0.023μgL(-1), <0.027-1.48μgL(-1), and <0.022-0.151μgL(-1) for D4, D5, and D6, respectively. Sediment concentrations ranged from <0.003-0.049μgg(-1)dw, 0.011-5.84μgg(-1)dw, and 0.004-0.371μgg(-1)dw for D4, D5, and D6, respectively. The concentrations in biosolid-amended soil, having values of <0.008-0.017μgg(-1)dw, <0.007-0.221μgg(-1)dw, and <0.009-0.711μgg(-1)dw for D4, D5, and D6, respectively, were lower than those in sediment impacted by wastewater
Parametric vs. non-parametric statistics of low resolution electromagnetic tomography (LORETA).
Thatcher, R W; North, D; Biver, C
2005-01-01
This study compared the relative statistical sensitivity of non-parametric and parametric statistics of 3-dimensional current sources as estimated by the EEG inverse solution Low Resolution Electromagnetic Tomography (LORETA). One would expect approximately 5% false positives (classification of a normal as abnormal) at the P < .025 level of probability (two tailed test) and approximately 1% false positives at the P < .005 level. EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) from 43 normal adult subjects were imported into the Key Institute's LORETA program. We then used the Key Institute's cross-spectrum and the Key Institute's LORETA output files (*.lor) as the 2,394 gray matter pixel representation of 3-dimensional currents at different frequencies. The mean and standard deviation *.lor files were computed for each of the 2,394 gray matter pixels for each of the 43 subjects. Tests of Gaussianity and different transforms were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of parametric vs. non-parametric statistics were compared using a "leave-one-out" cross validation method in which individual normal subjects were withdrawn and then statistically classified as being either normal or abnormal based on the remaining subjects. Log10 transforms approximated Gaussian distribution in the range of 95% to 99% accuracy. Parametric Z score tests at P < .05 cross-validation demonstrated an average misclassification rate of approximately 4.25%, and range over the 2,394 gray matter pixels was 27.66% to 0.11%. At P < .01 parametric Z score cross-validation false positives were 0.26% and ranged from 6.65% to 0% false positives. The non-parametric Key Institute's t-max statistic at P < .05 had an average misclassification error rate of 7.64% and ranged from 43.37% to 0.04% false positives. The nonparametric t-max at P < .01 had an average misclassification rate
Ma, Lili; Mao, Guannan; Liu, Jie; Yu, Hui; Gao, Guanghai; Wang, Yingying
2013-01-01
As microbiological parameters are important in monitoring the correct operation of wastewater treatment plants and controlling the microbiological quality of wastewater, the abundances of total bacteria (including intact and damaged bacterial cells) and total viruses in wastewater were investigated using a combination of ultrasonication and flow cytometry. The comparisons between flow cytometry (FCM) and other cultivation-independent methods (adenosine tri-phosphate (ATP) analysis for bacteria enumeration and epifluorescence microscopy (EFM) for virus enumeration) gave very similar patterns of microbial abundance changes, suggesting that FCM is suitable for targeting and obtaining reliable counts for bacteria and viruses in wastewater samples. The main experimental results obtained were: (1) effective removal of total bacteria in wastewater, with a decrease from an average concentration of 1.74 × 10(8)counts ml(-1) in raw wastewater to 3.91 × 10(6)counts ml(-1) in the effluent, (2) compared to influent raw wastewater, the average concentration of total viruses in the treated effluent (3.94 × 10(8)counts ml(-1)) exhibited no obvious changes, (3) the applied FCM approach is a rapid, easy, and convenient tool for understanding the microbial dynamics and monitoring microbiological quality in wastewater treatment processes.
A Comparison of Parametric and Non-Parametric Methods Applied to a Likert Scale
Mircioiu, Constantin; Atkinson, Jeffrey
2017-01-01
A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple “yes” or “no” but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies for practice. Results obtained show that with “large” (>15) numbers of responses and similar (but clearly not normal) distributions from different subgroups, parametric and non-parametric analyses give in almost all cases the same significant or non-significant results for inter-subgroup comparisons. Parametric methods were more discriminant in the cases of non-similar conclusions. Considering that the largest differences in opinions occurred in the upper part of the 4-point Likert scale (ranks 3 “very important” and 4 “essential”), a “score analysis” based on this part of the data was undertaken. This transformation of the ordinal Likert data into binary scores produced a graphical representation that was visually easier to understand as differences were accentuated. In conclusion, in this case of Likert ordinal data with high response rates, restraining the analysis to non-parametric methods leads to a loss of information. The addition of parametric methods, graphical analysis, analysis of subsets, and transformation of data leads to more in-depth analyses. PMID:28970438
Revisiting Parametric Types and Virtual Classes
NASA Astrophysics Data System (ADS)
Madsen, Anders Bach; Ernst, Erik
This paper presents a conceptually oriented updated view on the relationship between parametric types and virtual classes. The traditional view is that parametric types excel at structurally oriented composition and decomposition, and virtual classes excel at specifying mutually recursive families of classes whose relationships are preserved in derived families. Conversely, while class families can be specified using a large number of F-bounded type parameters, this approach is complex and fragile; and it is difficult to use traditional virtual classes to specify object composition in a structural manner, because virtual classes are closely tied to nominal typing. This paper adds new insight about the dichotomy between these two approaches; it illustrates how virtual constraints and type refinements, as recently introduced in gbeta and Scala, enable structural treatment of virtual types; finally, it shows how a novel kind of dynamic type check can detect compatibility among entire families of classes.
Parametric amplification of a superconducting plasma wave
NASA Astrophysics Data System (ADS)
Rajasekaran, S.; Casandruc, E.; Laplace, Y.; Nicoletti, D.; Gu, G. D.; Clark, S. R.; Jaksch, D.; Cavalleri, A.
2016-11-01
Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor-metal oscillations and soliton formation. Here, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Parametric amplification is sensitive to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.
Parametric structural modeling of insect wings.
Mengesha, T E; Vallance, R R; Barraja, M; Mittal, R
2009-09-01
Insects produce thrust and lift forces via coupled fluid-structure interactions that bend and twist their compliant wings during flapping cycles. Insight into this fluid-structure interaction is achieved with numerical modeling techniques such as coupled finite element analysis and computational fluid dynamics, but these methods require accurate and validated structural models of insect wings. Structural models of insect wings depend principally on the shape, dimensions and material properties of the veins and membrane cells. This paper describes a method for parametric modeling of wing geometry using digital images and demonstrates the use of the geometric models in constructing three-dimensional finite element (FE) models and simple reduced-order models. The FE models are more complete and accurate than previously reported models since they accurately represent the topology of the vein network, as well as the shape and dimensions of the veins and membrane cells. The methods are demonstrated by developing a parametric structural model of a cicada forewing.
Rayleigh-type parametric chemical oscillation.
Ghosh, Shyamolina; Ray, Deb Shankar
2015-09-28
We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.
A multimode electromechanical parametric resonator array
Mahboob, I.; Mounaix, M.; Nishiguchi, K.; Fujiwara, A.; Yamaguchi, H.
2014-01-01
Electromechanical resonators have emerged as a versatile platform in which detectors with unprecedented sensitivities and quantum mechanics in a macroscopic context can be developed. These schemes invariably utilise a single resonator but increasingly the concept of an array of electromechanical resonators is promising a wealth of new possibilities. In spite of this, experimental realisations of such arrays have remained scarce due to the formidable challenges involved in their fabrication. In a variation to this approach, we identify 75 harmonic vibration modes in a single electromechanical resonator of which 7 can also be parametrically excited. The parametrically resonating modes exhibit vibrations with only 2 oscillation phases which are used to build a binary information array. We exploit this array to execute a mechanical byte memory, a shift-register and a controlled-NOT gate thus vividly illustrating the availability and functionality of an electromechanical resonator array by simply utilising higher order vibration modes. PMID:24658349
Parametric amplification by coupled flux qubits
Rehák, M.; Neilinger, P.; Grajcar, M.; Oelsner, G.; Hübner, U.; Meyer, H.-G.; Il'ichev, E.
2014-04-21
We report parametric amplification of a microwave signal in a Kerr medium formed from superconducting qubits. Two mutually coupled flux qubits, embedded in the current antinode of a superconducting coplanar waveguide resonator, are used as a nonlinear element. Shared Josephson junctions provide the qubit-resonator coupling, resulting in a device with a tunable Kerr constant (up to 3 × 10{sup −3}) and a measured gain of about 20 dB. This arrangement represents a unit cell which can be straightforwardly extended to a quasi one-dimensional quantum metamaterial with large tunable Kerr nonlinearity, providing a basis for implementation of wide-band travelling wave parametric amplifiers.
Parametric amplification of a superconducting plasma wave
Rajasekaran, S.; Casandruc, E.; Laplace, Y.; ...
2016-07-11
Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor–metal oscillations and soliton formation. In this paper, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Finally, parametric amplification is sensitivemore » to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.« less
Nondegenerate optical parametric chirped pulse amplifier
Jovanovic, Igor; Ebbers, Christopher A.
2005-03-22
A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energy from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.
Phase shielding soliton in parametrically driven systems.
Clerc, Marcel G; Garcia-Ñustes, Mónica A; Zárate, Yair; Coulibaly, Saliya
2013-05-01
Parametrically driven extended systems exhibit dissipative localized states. Analytical solutions of these states are characterized by a uniform phase and a bell-shaped modulus. Recently, a type of dissipative localized state with a nonuniform phase structure has been reported: the phase shielding solitons. Using the parametrically driven and damped nonlinear Schrödinger equation, we investigate the main properties of this kind of solution in one and two dimensions and develop an analytical description for its structure and dynamics. Numerical simulations are consistent with our analytical results, showing good agreement. A numerical exploration conducted in an anisotropic ferromagnetic system in one and two dimensions indicates the presence of phase shielding solitons. The structure of these dissipative solitons is well described also by our analytical results. The presence of corrective higher-order terms is relevant in the description of the observed phase dynamical behavior.
Parametric amplification of a superconducting plasma wave
Rajasekaran, S.; Casandruc, E.; Laplace, Y.; Nicoletti, D.; Gu, G. D.; Clark, S. R.; Jaksch, D.; Cavalleri, A.
2016-07-11
Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor–metal oscillations and soliton formation. In this paper, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Finally, parametric amplification is sensitive to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.
Diode-pumped optical parametric oscillator
Geiger, A.R.; Hemmati, H.; Farr, W.H.
1996-02-01
Diode-pumped optical parametric oscillation has been demonstrated for the first time to our knowledge in a single Nd:MgO:LiNbO{sub 3} nonlinear crystal. The crystal is pumped by a semiconductor diode laser array at 812 nm. The Nd{sup 3+} ions absorb the 812-nm radiation to generate 1084-nm laser oscillation. On internal {ital Q} switching the 1084-nm radiation pumps the LiNbO{sub 3} host crystal that is angle cut at 46.5{degree} and generates optical parametric oscillation. The oscillation threshold that is due to the 1084-nm laser pump with a pulse length of 80 ns in a 1-mm-diameter beam was measured to be {approx_equal}1 mJ and produced 0.5-mJ output at 3400-nm signal wavelength. {copyright} {ital 1996 Optical Society of America.}
Rayleigh-type parametric chemical oscillation
Ghosh, Shyamolina; Ray, Deb Shankar
2015-09-28
We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.
Rayleigh-type parametric chemical oscillation
NASA Astrophysics Data System (ADS)
Ghosh, Shyamolina; Ray, Deb Shankar
2015-09-01
We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.
Pattern Generation by Dissipative Parametric Instability.
Perego, A M; Tarasov, N; Churkin, D V; Turitsyn, S K; Staliunas, K
2016-01-15
Nonlinear instabilities are responsible for spontaneous pattern formation in a vast number of natural and engineered systems, ranging from biology to galaxy buildup. We propose a new instability mechanism leading to pattern formation in spatially extended nonlinear systems, which is based on a periodic antiphase modulation of spectrally dependent losses arranged in a zigzag way: an effective filtering is imposed at symmetrically located wave numbers k and -k in alternating order. The properties of the dissipative parametric instability differ from the features of both key classical concepts of modulation instabilities, i.e., the Benjamin-Feir instability and the Faraday instabiltyity. We demonstrate how the dissipative parametric instability can lead to the formation of stable patterns in one- and two-dimensional systems. The proposed instability mechanism is generic and can naturally occur or can be implemented in various physical systems.
Parametrizing modified gravity for cosmological surveys
NASA Astrophysics Data System (ADS)
Gleyzes, Jérôme
2017-09-01
One of the challenges in testing gravity with cosmology is the vast freedom opened when extending General Relativity. For linear perturbations, one solution consists in using the effective field theory of dark energy. Even then, the theory space is described in terms of a handful of free functions of time. This needs to be reduced to a finite number of parameters to be practical for cosmological surveys. We explore in this article how well simple parametrizations, with a small number of parameters, can fit observables computed from complex theories. Imposing the stability of linear perturbations appreciably reduces the theory space we explore. We find that observables are not extremely sensitive to short time-scale variations and that simple, smooth parametrizations are usually sufficient to describe this theory space. Using the Bayesian information criterion, we find that using two parameters for each function (an amplitude and a power-law index) is preferred over complex models for 86% of our theory space.
Parametric Amplification of a Superconducting Plasma Wave.
Rajasekaran, S; Casandruc, E; Laplace, Y; Nicoletti, D; Gu, G D; Clark, S R; Jaksch, D; Cavalleri, A
2016-11-01
Many applications in photonics require all-optical manipulation of plasma waves1, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves (JPWs)2,3, involving oscillatory tunneling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear4, and exhibit striking phenomena like cooperative emission of coherent terahertz radiation5,6, superconductor-metal oscillations7 and soliton formation8. We show here that terahertz JPWs can be parametrically amplified through the cubic tunneling nonlinearity in a cuprate superconductor. Parametric amplification is sensitive to the relative phase between pump and seed waves and may be optimized to achieve squeezing of the order parameter phase fluctuations9 or single terahertz-photon devices.
Parametric Amplification of a Superconducting Plasma Wave
Rajasekaran, S.; Casandruc, E.; Laplace, Y.; Nicoletti, D.; Gu, G. D.; Clark, S. R.; Jaksch, D.; Cavalleri, A.
2016-01-01
Many applications in photonics require all-optical manipulation of plasma waves1, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves (JPWs)2,3, involving oscillatory tunneling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear4, and exhibit striking phenomena like cooperative emission of coherent terahertz radiation5,6, superconductor-metal oscillations7 and soliton formation8. We show here that terahertz JPWs can be parametrically amplified through the cubic tunneling nonlinearity in a cuprate superconductor. Parametric amplification is sensitive to the relative phase between pump and seed waves and may be optimized to achieve squeezing of the order parameter phase fluctuations9 or single terahertz-photon devices. PMID:27833647
Pattern Generation by Dissipative Parametric Instability
NASA Astrophysics Data System (ADS)
Perego, A. M.; Tarasov, N.; Churkin, D. V.; Turitsyn, S. K.; Staliunas, K.
2016-01-01
Nonlinear instabilities are responsible for spontaneous pattern formation in a vast number of natural and engineered systems, ranging from biology to galaxy buildup. We propose a new instability mechanism leading to pattern formation in spatially extended nonlinear systems, which is based on a periodic antiphase modulation of spectrally dependent losses arranged in a zigzag way: an effective filtering is imposed at symmetrically located wave numbers k and -k in alternating order. The properties of the dissipative parametric instability differ from the features of both key classical concepts of modulation instabilities, i.e., the Benjamin-Feir instability and the Faraday instabiltyity. We demonstrate how the dissipative parametric instability can lead to the formation of stable patterns in one- and two-dimensional systems. The proposed instability mechanism is generic and can naturally occur or can be implemented in various physical systems.
Parametric amplification of a superconducting plasma wave
Rajasekaran, S.; Casandruc, E.; Laplace, Y.; Nicoletti, D.; Gu, G. D.; Clark, S. R.; Jaksch, D.; Cavalleri, A.
2016-07-11
Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor–metal oscillations and soliton formation. In this paper, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Finally, parametric amplification is sensitive to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.
Intersection of parametric surfaces using lookup tables
NASA Technical Reports Server (NTRS)
Hanna, S. L.; Abel, J. F.; Greenberg, D. P.
1984-01-01
When primitive structures in the form of parametric surfaces are combined and modified interactively to form complex intersecting surfaces, it becomes important to find the curves of intersection. One must distinguish between finding the shape of the intersection curve, which may only be useful for display purposes, and finding an accurate mathematical representation of the curve, which is important for any meaningful geometric modeling, analysis, design, or manufacturing involving the intersection. The intersection curve between two or more parametric surfaces is important in a variety of computer-aided design and manufacture areas. A few examples are shape design, analysis of groins, design of fillets, and computation of numerically controlled tooling paths. The algorithm presented here provides a mathematical representation of the intersection curve to a specified accuracy. It also provides the database that can simplify operations such as hidden-surface removal, surface rendering, profile identification, and interference or clearance computations.
Dynamics of weakly coupled parametrically forced oscillators.
Salgado Sánchez, P; Porter, J; Tinao, I; Laverón-Simavilla, A
2016-08-01
The dynamics of two weakly coupled parametric oscillators are studied in the neighborhood of the primary subharmonic instability. The nature of both primary and secondary instabilities depends in a critical way on the permutation symmetries, if any, that remain after coupling is considered, and this depends on the relative phases of the parametric forcing terms. Detailed bifurcation sets, revealing a complex series of transitions organized in part by Bogdanov-Takens points, are calculated for representative sets of parameters. In the particular case of out-of-phase forcing the predictions of the coupled oscillator model are compared with direct numerical simulations and with recent experiments on modulated cross waves. Both the initial Hopf bifurcation and the subsequent saddle-node heteroclinic bifurcation are confirmed.
Parametric Model of an Aerospike Rocket Engine
NASA Technical Reports Server (NTRS)
Korte, J. J.
2000-01-01
A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHTI multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.
Parametric Model of an Aerospike Rocket Engine
NASA Technical Reports Server (NTRS)
Korte, J. J.
2000-01-01
A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHT multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.
SEC sensor parametric test and evaluation system
NASA Technical Reports Server (NTRS)
1978-01-01
This system provides the necessary automated hardware required to carry out, in conjunction with the existing 70 mm SEC television camera, the sensor evaluation tests which are described in detail. The Parametric Test Set (PTS) was completed and is used in a semiautomatic data acquisition and control mode to test the development of the 70 mm SEC sensor, WX 32193. Data analysis of raw data is performed on the Princeton IBM 360-91 computer.
Parametric instabilities in large nonuniform laser plasmas
Baldis, H.A.; Montgomery, D.S.; Moody, J.D.; Estabrook, K.G.; Berger, R.L.; Kruer, W.L.; Labaune, C.; Batha, S.H.
1992-09-01
The study of parametric instabilities in laser plasmas is of vital importance for inertial confinement fusion (ICF). The long scale-length plasma encountered in the corona of an ICF target provides ideal conditions for the growth of instabilities such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and filamentation. These instabilities can have detrimental effects in ICF and their characterization and understanding is of importance. Scattering instabilities are driven through a feedback loop by which the beating between the electromagnetic EM fields of the laser and the scattered light matches the frequency of a local longitudinal mode of the plasma. Any process which interferes with the coherence of this mechanism can substantially alter the behavior of the instability. Of particular interest is the study of laser beam smoothing techniques on parametric instabilities. These techniques are used to improve irradiation uniformity which can suppress hydrodynamic instabilities. Laser beam smoothing techniques have the potential to control the scattering level from parametric instabilities since they provide not only a smoother laser intensity distribution, but also reduced coherence. Beam smoothing techniques that affect the growth of parametric instabilities include spatial smoothing and temporal smoothing by laser bandwidth. Spatial smoothing modifies the phase fronts and temporal distribution of intensities in the focal volume. The transverse intensity spectrum is shifted towards higher spatial wavenumber and can significantly limit the growth of filamentation. Temporal smoothing reduces the coherence time and consequently limits the growth time. Laser bandwidth is required for most smoothing techniques, and can have an independent effect on the instabilities as well.
Wavelength-doubling optical parametric oscillator
Armstrong, Darrell J.; Smith, Arlee V.
2007-07-24
A wavelength-doubling optical parametric oscillator (OPO) comprising a type II nonlinear optical medium for generating a pair of degenerate waves at twice a pump wavelength and a plurality of mirrors for rotating the polarization of one wave by 90 degrees to produce a wavelength-doubled beam with an increased output energy by coupling both of the degenerate waves out of the OPO cavity through the same output coupler following polarization rotation of one of the degenerate waves.
Parametric study of laser photovoltaic energy converters
NASA Technical Reports Server (NTRS)
Walker, G. H.; Heinbockel, J. H.
1987-01-01
Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.
Semi-Parametric Generalized Linear Models.
1985-08-01
is nonsingular, upper triangular, and of full rank r. It is known (Dongarra et al., 1979) that G-1 FT is the Moore - Penrose inverse of L . Therefore... GENERALIZED LINEAR pq Mathematics Research Center University of Wisconsin-Madison 610 Walnut Street Madison, Wisconsin 53705 TI C August 1985 E T NOV 7 8...North Carolina 27709 -. -.. . - -.-. g / 6 O5’o UNIVERSITY OF WISCONSIN-MADISON MATHD4ATICS RESEARCH CENTER SD4I-PARAMETRIC GENERALIZED LINEAR MODELS
Beam splitter coupled CDSE optical parametric oscillator
Levinos, Nicholas J.; Arnold, George P.
1980-01-01
An optical parametric oscillator is disclosed in which the resonant radiation is separated from the pump and output radiation so that it can be manipulated without interfering with them. Thus, for example, very narrow band output may readily be achieved by passing the resonant radiation through a line narrowing device which does not in itself interfere with either the pump radiation or the output radiation.
Energy and momentum entanglement in parametric downconversion
NASA Astrophysics Data System (ADS)
Saldanha, Pablo L.; Monken, C. H.
2013-01-01
We present a simple treatment of the phenomenon of spontaneous parametric downconversion consisting of the coherent scattering of a single pump photon into an entangled photon pair inside a nonlinear crystal. The energy and momentum entanglement of the quantum state of the generated twin photons are seen as a consequence of the fundamental indistinguishability of the time and the position in which the photon pair is created inside the crystal. We also discuss some consequences of photon entanglement.
Degeneracies in parametrized modified gravity models
Hojjati, Alireza
2013-01-01
We study degeneracies between parameters in some of the widely used parametrized modified gravity models. We investigate how different observables from a future photometric weak lensing survey such as LSST, correlate the effects of these parameters and to what extent the degeneracies are broken. We also study the impact of other degenerate effects, namely massive neutrinos and some of the weak lensing systematics, on the correlations.
Parametric identification of human operator models
NASA Technical Reports Server (NTRS)
Ninz, N. R.
1982-01-01
The accurate and efficient identification of the human operator is still a need in human factors engineering especially concerning multivariable control. Control theoretic identification methods need to be tested with human operator models under realistic boundary conditons. The requirements and criteria for the use of parametric methods, selected models as well as the Maximum Likelihood Method and the Extended Kalman Filter are displayed. The experiments and results are comparatively discussed from the point of practical engineering.
Sen, Tanaji
2016-06-01
We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.
Parametrized relativistic dynamical framework for neutrino oscillations
NASA Astrophysics Data System (ADS)
Fanchi, John R.
2017-05-01
Mass state transitions are a key feature of parametrized relativistic dynamics (PRD). PRD is a manifestly covariant quantum theory with invariant evolution parameter. The theory has been applied to neutrino flavor oscillations between two mass states. It is generalized to transitions between three mass states and applied to the survival of electron neutrinos. The analysis shows that significant differences exist between theoretical results of the conventional model and the PRD model.
Parametric Cost Models for Space Telescopes
NASA Technical Reports Server (NTRS)
Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtney
2010-01-01
Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.
Parametric energy conversion of thermoacoustic vibrations
NASA Astrophysics Data System (ADS)
Guthy, C.; Van Neste, C. W.; Mitra, S.; Bhattacharjee, S.; Thundat, T.
2012-05-01
We demonstrate a parametric energy conversion method of thermoacoustic (TA) vibrations into electrical oscillations of a LC circuit. The inductance modulation necessary to excite the parametric oscillations is achieved by varying the air gap between two halves of a ferrite E-core coil. As a proof-of-concept, the parametric converter was attached to a Sondhauss tube that converts the heat into acoustic vibrations. The maximum total acoustic power output of this thermoacoustic engine was ˜5.3 mW. A flexible metallic membrane capping the Sondhauss tube connected to the moving half E-core served as a mechanical oscillator. The resonance frequency of the membrane was matched with the operating frequency (130 Hz) of the Sondhauss tube for resonant energy extraction. We have characterized the power output of the complete system as a function of electrical load. The maximum electrical power of 2.3 mW produced by the system corresponds to an acoustic-to-electric conversion efficiency of 44%.
A variable parameter parametric snake method
NASA Astrophysics Data System (ADS)
Marouf, A.; Houacine, A.
2015-12-01
In this paper, we introduce a new approach to parametric snake method by using variable snake parameters. Adopting fixed parameter values for all points of the snake, as usual, constitutes by itself a limitation that leads to poor performances in terms of convergence and tracking properties. A more adapted choice should be the one that allows selection depending on the image region properties as on the contour shape and position. However, such variability is not an easy task in general and a precise method need to be defined to assure contour point dependent tuning at iterations. We were particularly interested in applying this idea to the recently presented parametric method [1]. In the work mentioned, an attraction term is used to improve the convergence of the standard parametric snake without a significant increase in computational load. We show here, that improved performances can ensue from applying variable parameter concepts. For this purpose, the method is first analyzed and then a procedure is developed to assure an automatic variable parameter tuning. The interest of our approach is illustrated through object segmentation results.
Free response approach in a parametric system
NASA Astrophysics Data System (ADS)
Huang, Dishan; Zhang, Yueyue; Shao, Hexi
2017-07-01
In this study, a new approach to predict the free response in a parametric system is investigated. It is proposed in the special form of a trigonometric series with an exponentially decaying function of time, based on the concept of frequency splitting. By applying harmonic balance, the parametric vibration equation is transformed into an infinite set of homogeneous linear equations, from which the principal oscillation frequency can be computed, and all coefficients of harmonic components can be obtained. With initial conditions, arbitrary constants in a general solution can be determined. To analyze the computational accuracy and consistency, an approach error function is defined, which is used to assess the computational error in the proposed approach and in the standard numerical approach based on the Runge-Kutta algorithm. Furthermore, an example of a dynamic model of airplane wing flutter on a turbine engine is given to illustrate the applicability of the proposed approach. Numerical solutions show that the proposed approach exhibits high accuracy in mathematical expression, and it is valuable for theoretical research and engineering applications of parametric systems.
A probabilistic strategy for parametric catastrophe insurance
NASA Astrophysics Data System (ADS)
Figueiredo, Rui; Martina, Mario; Stephenson, David; Youngman, Benjamin
2017-04-01
Economic losses due to natural hazards have shown an upward trend since 1980, which is expected to continue. Recent years have seen a growing worldwide commitment towards the reduction of disaster losses. This requires effective management of disaster risk at all levels, a part of which involves reducing financial vulnerability to disasters ex-ante, ensuring that necessary resources will be available following such events. One way to achieve this is through risk transfer instruments. These can be based on different types of triggers, which determine the conditions under which payouts are made after an event. This study focuses on parametric triggers, where payouts are determined by the occurrence of an event exceeding specified physical parameters at a given location, or at multiple locations, or over a region. This type of product offers a number of important advantages, and its adoption is increasing. The main drawback of parametric triggers is their susceptibility to basis risk, which arises when there is a mismatch between triggered payouts and the occurrence of loss events. This is unavoidable in said programmes, as their calibration is based on models containing a number of different sources of uncertainty. Thus, a deterministic definition of the loss event triggering parameters appears flawed. However, often for simplicity, this is the way in which most parametric models tend to be developed. This study therefore presents an innovative probabilistic strategy for parametric catastrophe insurance. It is advantageous as it recognizes uncertainties and minimizes basis risk while maintaining a simple and transparent procedure. A logistic regression model is constructed here to represent the occurrence of loss events based on certain loss index variables, obtained through the transformation of input environmental variables. Flood-related losses due to rainfall are studied. The resulting model is able, for any given day, to issue probabilities of occurrence of loss
Parametric and non-parametric estimation of speech formants: application to infant cry.
Fort, A; Ismaelli, A; Manfredi, C; Bruscaglioni, P
1996-12-01
The present paper addresses the issue of correctly estimating the peaks in the speech envelope (formants) occurring in newborn infant cry. Clinical studies have shown that the analysis of such spectral characteristics is a helpful noninvasive diagnostic tool. In fact it can be applied to explore brain function at very early stage of child development, for a timely diagnosis of neonatal disease and malformation. The paper focuses on the performance comparison between some classical parametric and non-parametric estimation techniques particularly well suited for the present application, specifically the LP, ARX and cepstrum approaches. It is shown that, if the model order is correctly chosen, parametric methods are in general more reliable and robust against noise, but exhibit a less uniform behaviour than cepstrum. The methods are compared also in terms of tracking capability, since the signals under study are nonstationary. Both simulated and real signals are used in order to outline the relevant features of the proposed approaches.
Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H.; Maurits, Natasha M.
2016-01-01
In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a better insight into tremor. Typically, routine clinical assessment of accelerometry and electromyography data involves visual inspection by clinicians and occasionally computational analysis to obtain objective characteristics of tremor. However, for some tremor disorders these characteristics may be different during daily activity. This variability in presentation between the clinic and daily life makes a differential diagnosis more difficult. A long-term recording of tremor by accelerometry and/or electromyography in the home environment could help to give a better insight into the tremor disorder. However, an evaluation of such recordings using routine clinical standards would take too much time. We evaluated a range of techniques that automatically detect tremor segments in accelerometer data, as accelerometer data is more easily obtained in the home environment than electromyography data. Time can be saved if clinicians only have to evaluate the tremor characteristics of segments that have been automatically detected in longer daily activity recordings. We tested four non-parametric methods and five parametric methods on clinical accelerometer data from 14 patients with different tremor disorders. The consensus between two clinicians regarding the presence or absence of tremor on 3943 segments of accelerometer data was employed as reference. The nine methods were tested against this reference to identify their optimal parameters. Non-parametric methods generally performed better than parametric methods on our dataset when optimal parameters were used. However, one parametric method, employing the high frequency content of the tremor bandwidth under consideration
NASA Astrophysics Data System (ADS)
Cao, Jiashun; Oleyiblo, Oloche James; Xue, Zhaoxia; Otache, Y. Martins; Feng, Qian
2015-07-01
Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A2/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification , the maximum growth rate of heterotrophs (µH), the rate constant for stored polyphosphates in PAOs ( q pp), and the hydrolysis rate constant ( k h)) were adjusted. Whereas three BioWin parameters (aerobic decay rate ( b H), heterotrophic dissolved oxygen (DO) half saturation ( K OA), and Y P/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO3), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.
Mutiyar, Pravin K; Mittal, Atul K
2014-01-01
Antibiotics consumption has increased worldwide, and their residues are frequently reported in aquatic environments. It is believed that antibiotics reach aquatic water bodies through sewage. Medicine consumed for healthcare practices are often released into sewage, and after sewage treatment plant, it reaches the receiving water bodies of lakes or rivers. In the present study, we determined the fate of some commonly used antibiotics in a sewage treatment plant (STP) located in Delhi and the environmental concentration of these antibiotics in the Yamuna River, which receives the sewage and industrial effluent of Delhi. There are many reports on antibiotics occurrences in STP and river water worldwide, but monitoring data from the Indian subcontinent is sparse. Samples were taken from a STP and from six sampling sites on the Yamuna River. Several antibiotics were tested for using offline solid-phase extraction followed by high-performance liquid chromatography equipped with photodiode array analysis. Recoveries varied from 25.5-108.8 %. Ampicillin had the maximum concentration in wastewater influents (104.2 ± 98.11 μg l(-1)) and effluents (12.68 ± 8.38 μg l(-1)). The fluoroquinolones and cephalosporins had the lower concentrations. Treatment efficiencies varied between 55 and 99 %. Significant amounts of antibiotics were discharged in effluents and were detected in the receiving water body. The concentration of antibiotics in the Yamuna River varied from not detected to 13.75 μg l(-1) (ampicillin) for the compounds investigated.
Markovian Dynamics of Josephson Parametric Amplification
NASA Astrophysics Data System (ADS)
Kaiser, Waldemar; Haider, Michael; Russer, Johannes A.; Russer, Peter; Jirauschek, Christian
2017-09-01
In this work, we derive the dynamics of the lossy DC pumped non-degenerate Josephson parametric amplifier (DCPJPA). The main element in a DCPJPA is the superconducting Josephson junction. The DC bias generates the AC Josephson current varying the nonlinear inductance of the junction. By this way the Josephson junction acts as the pump oscillator as well as the time varying reactance of the parametric amplifier. In quantum-limited amplification, losses and noise have an increased impact on the characteristics of an amplifier. We outline the classical model of the lossy DCPJPA and derive the available noise power spectral densities. A classical treatment is not capable of including properties like spontaneous emission which is mandatory in case of amplification at the quantum limit. Thus, we derive a quantum mechanical model of the lossy DCPJPA. Thermal losses are modeled by the quantum Langevin approach, by coupling the quantized system to a photon heat bath in thermodynamic equilibrium. The mode occupation in the bath follows the Bose-Einstein statistics. Based on the second quantization formalism, we derive the Heisenberg equations of motion of both resonator modes. We assume the dynamics of the system to follow the Markovian approximation, i.e. the system only depends on its actual state and is memory-free. We explicitly compute the time evolution of the contributions to the signal mode energy and give numeric examples based on different damping and coupling constants. Our analytic results show, that this model is capable of including thermal noise into the description of the DC pumped non-degenerate Josephson parametric amplifier.
Parametric modulation of an atomic magnetometer
Li, Zhimin; Wakai, Ronald T.; Walker, Thad G.
2012-01-01
The authors report on a rubidium atomic magnetometer designed for use in a shielded environment. Operating in the spin-exchange relaxation-free regime, the magnetometer utilizes parametric modulation of the z-magnetic field to suppress noise associated with airflow through the oven and to simultaneously detect x- and y-field components, using a single probe beam, with minimal loss of sensitivity and bandwidth. A white noise level of 60 fT/(Hz)1/2 was achieved. PMID:22942436
White-light parametric instabilities in plasmas.
Santos, J E; Silva, L O; Bingham, R
2007-06-08
Parametric instabilities driven by partially coherent radiation in plasmas are described by a generalized statistical Wigner-Moyal set of equations, formally equivalent to the full wave equation, coupled to the plasma fluid equations. A generalized dispersion relation for stimulated Raman scattering driven by a partially coherent pump field is derived, revealing a growth rate dependence, with the coherence width sigma of the radiation field, scaling with 1/sigma for backscattering (three-wave process), and with 1/sigma1/2 for direct forward scattering (four-wave process). Our results demonstrate the possibility to control the growth rates of these instabilities by properly using broadband pump radiation fields.
Automatic Parametric Testing Of Integrated Circuits
NASA Technical Reports Server (NTRS)
Jennings, Glenn A.; Pina, Cesar A.
1989-01-01
Computer program for parametric testing saves time and effort in research and development of integrated circuits. Software system automatically assembles various types of test structures and lays them out on silicon chip, generates sequency of test instructions, and interprets test data. Employs self-programming software; needs minimum of human intervention. Adapted to needs of different laboratories and readily accommodates new test structures. Program codes designed to be adaptable to most computers and test equipment now in use. Written in high-level languages to enhance transportability.
Parametric uncertain identification of a robotic system
NASA Astrophysics Data System (ADS)
Angel, L.; Viola, J.; Hernández, C.
2016-07-01
This paper presents the parametric uncertainties identification of a robotic system of one degree of freedom. A MSC-ADAMS / MATLAB co-simulation model was built to simulate the uncertainties that affect the robotic system. For a desired trajectory, a set of dynamic models of the system was identified in presence of variations in the mass, length and friction of the system employing least squares method. Using the input-output linearization technique a linearized model plant was defined. Finally, the maximum multiplicative uncertainty of the system was modelled giving the controller desired design conditions to achieve a robust stability and performance of the closed loop system.
A computer application for parametric aircraft design
NASA Astrophysics Data System (ADS)
Fraqueiro, Filipe R.; Albuquerque, Pedro F.; Gamboa, Pedro V.
2016-11-01
The present work describes the development and final result of a graphical user interface tailored for a mission-based parametric aircraft design optimization code which targets the preliminary design phase of unmanned aerial vehicles. This development was built from the XFLR5 open source platform and further benefits from two-dimensional aerodynamic data obtained from XFOIL. For a better understanding, the most important graphical windows are shown. In order to demonstrate the graphical user interface interaction with the aircraft designer, the results of a case study which maximizes payload are presented.
Parametric study of modern airship productivity
NASA Technical Reports Server (NTRS)
Ardema, M. D.; Flaig, K.
1980-01-01
A method for estimating the specific productivity of both hybrid and fully buoyant airships is developed. Various methods of estimating structural weight of deltoid hybrids are discussed and a derived weight estimating relationship is presented. Specific productivity is used as a figure of merit in a parametric study of fully buoyant ellipsoidal and deltoid hybrid semi-buoyant vehicles. The sensitivity of results as a function of assumptions is also determined. No airship configurations were found to have superior specific productivity to transport airplanes.
Bayesian inference and the parametric bootstrap
Efron, Bradley
2013-01-01
The parametric bootstrap can be used for the efficient computation of Bayes posterior distributions. Importance sampling formulas take on an easy form relating to the deviance in exponential families, and are particularly simple starting from Jeffreys invariant prior. Because of the i.i.d. nature of bootstrap sampling, familiar formulas describe the computational accuracy of the Bayes estimates. Besides computational methods, the theory provides a connection between Bayesian and frequentist analysis. Efficient algorithms for the frequentist accuracy of Bayesian inferences are developed and demonstrated in a model selection example. PMID:23843930
Multicutter machining of compound parametric surfaces
NASA Astrophysics Data System (ADS)
Hatna, Abdelmadjid; Grieve, R. J.; Broomhead, P.
2000-10-01
Parametric free forms are used in industries as disparate as footwear, toys, sporting goods, ceramics, digital content creation, and conceptual design. Optimizing tool path patterns and minimizing the total machining time is a primordial issue in numerically controlled (NC) machining of free form surfaces. We demonstrate in the present work that multi-cutter machining can achieve as much as 60% reduction in total machining time for compound sculptured surfaces. The given approach is based upon the pre-processing as opposed to the usual post-processing of surfaces for the detection and removal of interference followed by precise tracking of unmachined areas.
The Parametrized Post-Newtonian Gravitational Redshift
NASA Technical Reports Server (NTRS)
Krisher, T. P.
1993-01-01
A derivation of the gravitational redshift effect to order c ^(-4) is presented. The calculation isperformed within the framework of the parametrized post-Newtonian formalism for analyzing metrictheories of gravity, which includes corrections to second- order in the Newtonian potential,gravitomagnetic contributions, and preferred-frame terms. We briefly discuss how to generalize ourresults to include possible violations of local Lorentz invariance or local position invariance which canarise in nonmetric theories. Our results are useful for analyzing possible new redshift experimentswhich may be sensitive to second-order effects, such as a close solar flyby mission.
Lottery spending: a non-parametric analysis.
Garibaldi, Skip; Frisoli, Kayla; Ke, Li; Lim, Melody
2015-01-01
We analyze the spending of individuals in the United States on lottery tickets in an average month, as reported in surveys. We view these surveys as sampling from an unknown distribution, and we use non-parametric methods to compare properties of this distribution for various demographic groups, as well as claims that some properties of this distribution are constant across surveys. We find that the observed higher spending by Hispanic lottery players can be attributed to differences in education levels, and we dispute previous claims that the top 10% of lottery players consistently account for 50% of lottery sales.
Ground-Based Telescope Parametric Cost Model
NASA Technical Reports Server (NTRS)
Stahl, H. Philip; Rowell, Ginger Holmes
2004-01-01
A parametric cost model for ground-based telescopes is developed using multi-variable statistical analysis, The model includes both engineering and performance parameters. While diameter continues to be the dominant cost driver, other significant factors include primary mirror radius of curvature and diffraction limited wavelength. The model includes an explicit factor for primary mirror segmentation and/or duplication (i.e.. multi-telescope phased-array systems). Additionally, single variable models based on aperture diameter are derived. This analysis indicates that recent mirror technology advances have indeed reduced the historical telescope cost curve.
Observation of ultrabroadband, beamlike parametric downconversion.
O'Donnell, Kevin A; U'Ren, Alfred B
2007-04-01
We report spontaneous parametric downconversion having an unusually wide spectral bandwidth. A collinear type 1 phase-matching configuration is employed with degeneracy near the zero group-velocity dispersion frequency. With a spectral width of 1080 nm and degenerate wavelength of 1885 nm, the source also emits a high flux of 3.4 x 10(11) s(-1)W(-1) photon pairs constrained to a cone of only approximately 2 degrees half-angle. A rigorous theoretical approach is developed that confirms the experimental observations. The source properties are consistent with an ultrashort photon-pair correlation time and, for a narrowband pump, extremely high-dimensional spectral entanglement.
SIMULATIONS OF PARAMETRIC-RESONANCE IONIZATION COOLING
David Newsham; Richard Sah; Alex Bogacz; Yu-Chiu Chao; Yaroslav Derbenev
2007-06-01
Parametric-resonance ionization cooling (PIC) is a muon-cooling technique that is useful for low-emittance muon colliders. This method requires a well-tuned focusing channel that is free of chromatic and spherical aberrations. In order to be of practical use in a muon collider, it also necessary that the focusing channel be as short as possible to minimize muon loss due to decay. G4Beamline numerical simulations are presented of a compact PIC focusing channel in which spherical aberrations are minimized by using design symmetry.
Parametric Uncertainty Reduction in Robust Multivariable Control
1993-09-01
presents a method for reducing the Dumber of parametric un- certainties used in the design of a robust Ho, controller. The resulting controller is shown...determining robust stability can be de- duced from Figure 2.9. Stability in the loop containing the perturbation requires that for all frequencies det {I... det (I + MA) = 01 {minAEA(a(A) I det (J + MA) = 0)1’ otherwise 15 It can be shown that the SSV has the following properties (Doyle, 1982): 1. F(oM) =1
Detecting Atlantic herring by parametric sonar.
Godo, Olav Rune; Foote, Kenneth G; Dybedal, Johnny; Tenningen, Eirik; Patel, Ruben
2010-04-01
The difference-frequency band of the Kongsberg TOPAS PS18 parametric sub-bottom profiling sonar, nominally 1-6 kHz, is being used to observe Atlantic herring. Representative TOPAS echograms of herring layers and schools observed in situ in December 2008 and November 2009 are presented. These agree well with echograms of volume backscattering strength derived simultaneously with the narrowband Simrad EK60/18- and 38-kHz scientific echo sounder, also giving insight into herring avoidance behavior in relation to survey vessel passage. Progress in rendering the TOPAS echograms quantitative is described.
Lottery Spending: A Non-Parametric Analysis
Garibaldi, Skip; Frisoli, Kayla; Ke, Li; Lim, Melody
2015-01-01
We analyze the spending of individuals in the United States on lottery tickets in an average month, as reported in surveys. We view these surveys as sampling from an unknown distribution, and we use non-parametric methods to compare properties of this distribution for various demographic groups, as well as claims that some properties of this distribution are constant across surveys. We find that the observed higher spending by Hispanic lottery players can be attributed to differences in education levels, and we dispute previous claims that the top 10% of lottery players consistently account for 50% of lottery sales. PMID:25642699
A Cartesian parametrization for the numerical analysis of material instability
Mota, Alejandro; Chen, Qiushi; Foulk, III, James W.; ...
2016-02-25
We examine four parametrizations of the unit sphere in the context of material stability analysis by means of the singularity of the acoustic tensor. We then propose a Cartesian parametrization for vectors that lie a cube of side length two and use these vectors in lieu of unit normals to test for the loss of the ellipticity condition. This parametrization is then used to construct a tensor akin to the acoustic tensor. It is shown that both of these tensors become singular at the same time and in the same planes in the presence of a material instability. Furthermore, themore » performance of the Cartesian parametrization is compared against the other parametrizations, with the results of these comparisons showing that in general, the Cartesian parametrization is more robust and more numerically efficient than the others.« less
A Cartesian parametrization for the numerical analysis of material instability
Mota, Alejandro; Chen, Qiushi; Foulk, III, James W.; Ostien, Jakob T.; Lai, Zhengshou
2016-02-25
We examine four parametrizations of the unit sphere in the context of material stability analysis by means of the singularity of the acoustic tensor. We then propose a Cartesian parametrization for vectors that lie a cube of side length two and use these vectors in lieu of unit normals to test for the loss of the ellipticity condition. This parametrization is then used to construct a tensor akin to the acoustic tensor. It is shown that both of these tensors become singular at the same time and in the same planes in the presence of a material instability. Furthermore, the performance of the Cartesian parametrization is compared against the other parametrizations, with the results of these comparisons showing that in general, the Cartesian parametrization is more robust and more numerically efficient than the others.
Sedmak, Gerald; Bina, David; Macdonald, Jeffrey; Couillard, Lon
2005-02-01
Reoviruses, enteroviruses, and adenoviruses were quantified by culture for various ambient waters in the Milwaukee area. From August 1994 through July 2003, the influent and effluent of a local wastewater treatment plant (WWTP) were tested monthly by a modified U.S. Environmental Protection Agency Information Collection Rule (ICR) organic flocculation cell culture procedure for the detection of culturable viruses. Modification of the ICR procedure included using Caco-2, RD, and HEp-2 cells in addition to BGM cells. Lake Michigan source water for two local drinking water treatment plants (DWTPs) was also tested monthly for culturable viruses by passing 200 liters of source water through a filter and culturing a concentrate representing 100 liters of source water. Reoviruses, enteroviruses, and adenoviruses were detected frequently (105 of 107 samples) and, at times, in high concentration in WWTP influent but were detected less frequently (32 of 107 samples) in plant effluent and at much lower concentrations. Eighteen of 204 samples (8.8%) of source waters for the two DWTPs were positive for virus and exclusively positive for reoviruses at relatively low titers. Both enteroviruses and reoviruses were detected in WWTP influent, most frequently during the second half of the year.
Sedmak, Gerald; Bina, David; MacDonald, Jeffrey; Couillard, Lon
2005-01-01
Reoviruses, enteroviruses, and adenoviruses were quantified by culture for various ambient waters in the Milwaukee area. From August 1994 through July 2003, the influent and effluent of a local wastewater treatment plant (WWTP) were tested monthly by a modified U.S. Environmental Protection Agency Information Collection Rule (ICR) organic flocculation cell culture procedure for the detection of culturable viruses. Modification of the ICR procedure included using Caco-2, RD, and HEp-2 cells in addition to BGM cells. Lake Michigan source water for two local drinking water treatment plants (DWTPs) was also tested monthly for culturable viruses by passing 200 liters of source water through a filter and culturing a concentrate representing 100 liters of source water. Reoviruses, enteroviruses, and adenoviruses were detected frequently (105 of 107 samples) and, at times, in high concentration in WWTP influent but were detected less frequently (32 of 107 samples) in plant effluent and at much lower concentrations. Eighteen of 204 samples (8.8%) of source waters for the two DWTPs were positive for virus and exclusively positive for reoviruses at relatively low titers. Both enteroviruses and reoviruses were detected in WWTP influent, most frequently during the second half of the year. PMID:15691964
Quantiles, Parametric-Select Density Estimations, and Bi-Information Parameter Estimators.
1982-06-01
A non- parametric estimation method forms estimators which are not based on parametric models. Important examples of non-parametric estimators of a...raw descriptive functions F, f, Q, q, fQ. One distinguishes between parametric and non-parametric methods of estimating smooth functions. A parametric ... estimation method : (1) assumes a family F8, fo’ Q0, qo’ foQ8 of functions, called parametric models, which are indexed by a parameter 6 = ( l
Characterization of a multimode coplanar waveguide parametric amplifier
Simoen, M. Krantz, P.; Bylander, Jonas; Shumeiko, V.; Delsing, P.; Chang, C. W. S.; Wilson, C. M.; Wustmann, W.
2015-10-21
We characterize a Josephson parametric amplifier based on a flux-tunable quarter-wavelength resonator. The fundamental resonance frequency is ∼1 GHz, but we use higher modes of the resonator for our measurements. An on-chip tuning line allows for magnetic flux pumping of the amplifier. We investigate and compare degenerate parametric amplification, involving a single mode, and nondegenerate parametric amplification, using a pair of modes. We show that we reach quantum-limited noise performance in both cases.
Cascade frequency generation regime in an optical parametric oscillator
Kolker, D B; Dmitriev, Aleksandr K; Gorelik, P; Vong, Franko; Zondy, J J
2009-05-31
In a parametric oscillator of a special two-sectional design based on a lithium niobate periodic structure, a cascade frequency generation regime was observed in which a signal wave pumped a secondary parametric oscillator, producing secondary signal and idler waves. The secondary parametric oscillator can be tuned in a broad range of {approx}200 nm with respect to a fixed wavelength of the primary idler wave. (nonlinear optical phenomena)
Second order parametric processes in nonlinear silica microspheres.
Xu, Yong; Han, Ming; Wang, Anbo; Liu, Zhiwen; Heflin, James R
2008-04-25
We analyze second order parametric processes in a silica microsphere coated with radially aligned nonlinear optical molecules. In a high-Q nonlinear microsphere, we discover that it is possible to achieve ultralow threshold parametric oscillation that obeys the rule of angular momentum conservation. Based on symmetry considerations, one can also implement parametric processes that naturally generate quantum entangled photon pairs. Practical issues regarding implementation of the nonlinear microsphere are also discussed.
Approximately Integrable Linear Statistical Models in Non-Parametric Estimation
1990-08-01
OTIC I EL COPY Lfl 0n Cf) NAPPROXIMATELY INTEGRABLE LINEAR STATISTICAL MODELS IN NON- PARAMETRIC ESTIMATION by B. Ya. Levit University of Maryland...Integrable Linear Statistical Models in Non- Parametric Estimation B. Ya. Levit Sumnmary / The notion of approximately integrable linear statistical models...models related to the study of the "next" order optimality in non- parametric estimation . It appears consistent to keep the exposition at present at the
Study of Vertical Sound Image Control Using Parametric Loudspeakers
NASA Astrophysics Data System (ADS)
Shimizu, Kazuhiro; Itou, Kouki; Aoki, Shigeaki
A parametric loudspeaker is known as a super-directivity loudspeaker. So far, the applications have been limited monaural reproduction sound system. We had discussed characteristics of stereo reproduction with two parametric loudspeakers. In this paper, the sound localization in the vertical direction using the parametric loudspeakers was confirmed. The direction of sound localization was able to be controlled. The results were similar as in using ordinary loudspeakers. However, by setting the parametric loudspeaker 5 degrees rightward, the direction of sound localization moved about 20 degrees rightward. The measured ILD (Interaural Level Difference) using a dummy head were analyzed.
Parametric robust control and system identification: Unified approach
NASA Technical Reports Server (NTRS)
Keel, Leehyun
1994-01-01
Despite significant advancement in the area of robust parametric control, the problem of synthesizing such a controller is still a wide open problem. Thus, we attempt to give a solution to this important problem. Our approach captures the parametric uncertainty as an H(sub infinity) unstructured uncertainty so that H(sub infinity) synthesis techniques are applicable. Although the techniques cannot cope with the exact parametric uncertainty, they give a reasonable guideline to model the unstructured uncertainty that contains the parametric uncertainty. An additional loop shaping technique is also introduced to relax its conservatism.
Effects of dispersion on mode locking in optical parametric oscillators
NASA Astrophysics Data System (ADS)
Longhi, S.
1995-08-01
We discuss the role that group-velocity dispersion and cavity detuning play in the onset of mode locking in synchronously pumped optical parametric oscillators. Because of the phase-sensitive character of the parametric gain, it is shown for the degenerate case that dispersion effects associated with off-resonance operation can lead to subpulse structures and spectral splitting of the parametric pulses. This behavior is interpreted on the basis of a dispersion-induced interference phenomenon between the two nearly degenerate parametric photons produced by the conversion of one pump photon in the nonlinear medium.
Optical parametrically gated microscopy in scattering media.
Zhao, Youbo; Adie, Steven G; Tu, Haohua; Liu, Yuan; Graf, Benedikt W; Chaney, Eric J; Marjanovic, Marina; Boppart, Stephen A
2014-09-22
High-resolution imaging in turbid media has been limited by the intrinsic compromise between the gating efficiency (removal of multiply-scattered light background) and signal strength in the existing optical gating techniques. This leads to shallow depths due to the weak ballistic signal, and/or degraded resolution due to the strong multiply-scattering background--the well-known trade-off between resolution and imaging depth in scattering samples. In this work, we employ a nonlinear optics based optical parametric amplifier (OPA) to address this challenge. We demonstrate that both the imaging depth and the spatial resolution in turbid media can be enhanced simultaneously by the OPA, which provides a high level of signal gain as well as an inherent nonlinear optical gate. This technology shifts the nonlinear interaction to an optical crystal placed in the detection arm (image plane), rather than in the sample, which can be used to exploit the benefits given by the high-order parametric process and the use of an intense laser field. The coherent process makes the OPA potentially useful as a general-purpose optical amplifier applicable to a wide range of optical imaging techniques.
Supramodal parametric working memory processing in humans.
Spitzer, Bernhard; Blankenburg, Felix
2012-03-07
Previous studies of delayed-match-to-sample (DMTS) frequency discrimination in animals and humans have succeeded in delineating the neural signature of frequency processing in somatosensory working memory (WM). During retention of vibrotactile frequencies, stimulus-dependent single-cell and population activity in prefrontal cortex was found to reflect the task-relevant memory content, whereas increases in occipital alpha activity signaled the disengagement of areas not relevant for the tactile task. Here, we recorded EEG from human participants to determine the extent to which these mechanisms can be generalized to frequency retention in the visual and auditory domains. Subjects performed analogous variants of a DMTS frequency discrimination task, with the frequency information presented either visually, auditorily, or by vibrotactile stimulation. Examining oscillatory EEG activity during frequency retention, we found characteristic topographical distributions of alpha power over visual, auditory, and somatosensory cortices, indicating systematic patterns of inhibition and engagement of early sensory areas, depending on stimulus modality. The task-relevant frequency information, in contrast, was found to be represented in right prefrontal cortex, independent of presentation mode. In each of the three modality conditions, parametric modulations of prefrontal upper beta activity (20-30 Hz) emerged, in a very similar manner as recently found in vibrotactile tasks. Together, the findings corroborate a view of parametric WM as supramodal internal scaling of abstract quantity information and suggest strong relevance of previous evidence from vibrotactile work for a more general framework of quantity processing in human working memory.
Quantum dynamics of the parametric oscillator
NASA Astrophysics Data System (ADS)
Kinsler, P.; Drummond, P. D.
1991-06-01
We present dynamical calculations for the quantum parametric oscillator using both number-state and coherent-state bases. The coherent-state methods use the positive-P representation, which has a nonclassical phase space-an essential requirement in obtaining an exact stochastic representation of this nonlinear problem. This also provides a way to directly simulate quantum tunneling between the two above-threshold stable states of the oscillator. The coherent-state methods provide both analytic results at large photon numbers, and numerical results for any photon number, while our number-state calculations are restricted to numerical results in the low-photon-number regime. The number-state and coherent-state methods give precise agreement within the accuracy of the numerical calculations. We also compare our results with methods based on a truncated Wigner representation equivalent to stochastic electrodynamics, and find that these are unable to correctly predict the tunneling rate given by the other methods. An interesting feature of the results is the much faster tunneling predicted by the exact quantum-theory methods compared with earlier semiclassical calculations using an approximate potential barrier. This is similar to the faster tunneling found when comparing quantum penetration of a barrier to classical thermal activation. The quantum parametric oscillator, which has an exact steady-state solution, therefore provides a useful and accessible system in which nonlinear quantum effects can be studied far from thermal equilibrium.
Modeling Personnel Turnover in the Parametric Organization
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1991-01-01
A primary issue in organizing a new parametric cost analysis function is to determine the skill mix and number of personnel required. The skill mix can be obtained by a functional decomposition of the tasks required within the organization and a matrixed correlation with educational or experience backgrounds. The number of personnel is a function of the skills required to cover all tasks, personnel skill background and cross training, the intensity of the workload for each task, migration through various tasks by personnel along a career path, personnel hiring limitations imposed by management and the applicant marketplace, personnel training limitations imposed by management and personnel capability, and the rate at which personnel leave the organization for whatever reason. Faced with the task of relating all of these organizational facets in order to grow a parametric cost analysis (PCA) organization from scratch, it was decided that a dynamic model was required in order to account for the obvious dynamics of the forming organization. The challenge was to create such a simple model which would be credible during all phases of organizational development. The model development process was broken down into the activities of determining the tasks required for PCA, determining the skills required for each PCA task, determining the skills available in the applicant marketplace, determining the structure of the dynamic model, implementing the dynamic model, and testing the dynamic model.
Quantum metrology with unitary parametrization processes.
Liu, Jing; Jing, Xiao-Xing; Wang, Xiaoguang
2015-02-24
Quantum Fisher information is a central quantity in quantum metrology. We discuss an alternative representation of quantum Fisher information for unitary parametrization processes. In this representation, all information of parametrization transformation, i.e., the entire dynamical information, is totally involved in a Hermitian operator H. Utilizing this representation, quantum Fisher information is only determined by H and the initial state. Furthermore, H can be expressed in an expanded form. The highlights of this form is that it can bring great convenience during the calculation for the Hamiltonians owning recursive commutations with their partial derivative. We apply this representation in a collective spin system and show the specific expression of H. For a simple case, a spin-half system, the quantum Fisher information is given and the optimal states to access maximum quantum Fisher information are found. Moreover, for an exponential form initial state, an analytical expression of quantum Fisher information by H operator is provided. The multiparameter quantum metrology is also considered and discussed utilizing this representation.
Degenerate parametric oscillation in quantum membrane optomechanics
NASA Astrophysics Data System (ADS)
Benito, Mónica; Sánchez Muñoz, Carlos; Navarrete-Benlloch, Carlos
2016-02-01
The promise of innovative applications has triggered the development of many modern technologies capable of exploiting quantum effects. But in addition to future applications, such quantum technologies have already provided us with the possibility of accessing quantum-mechanical scenarios that seemed unreachable just a few decades ago. With this spirit, in this work we show that modern optomechanical setups are mature enough to implement one of the most elusive models in the field of open system dynamics: degenerate parametric oscillation. Introduced in the eighties and motivated by its alleged implementability in nonlinear optical resonators, it rapidly became a paradigm for the study of dissipative phase transitions whose corresponding spontaneously broken symmetry is discrete. However, it was found that the intrinsic multimode nature of optical cavities makes it impossible to experimentally study the model all the way through its phase transition. In contrast, here we show that this long-awaited model can be implemented in the motion of a mechanical object dispersively coupled to the light contained in a cavity, when the latter is properly driven with multichromatic laser light. We focus on membranes as the mechanical element, showing that the main signatures of the degenerate parametric oscillation model can be studied in state-of-the-art setups, thus opening the possibility of analyzing spontaneous symmetry breaking and enhanced metrology in one of the cleanest dissipative phase transitions. In addition, the ideas put forward in this work would allow for the dissipative preparation of squeezed mechanical states.
Parametric uncertainty in nanoscale optical dimensional measurements.
Potzick, James; Marx, Egon
2012-06-10
Image modeling establishes the relation between an object and its image when an optical microscope is used to measure the dimensions of an object of size comparable to the illumination wavelength. It accounts for the influence of all of the parameters that can affect the image and relates the apparent feature width (FW) in the image to the true FW of the object. The values of these parameters, however, have uncertainties, and these uncertainties propagate through the model and lead to parametric uncertainty in the FW measurement, a key component of the combined measurement uncertainty. The combined uncertainty is required in order to decide if the result is adequate for its intended purpose and to ascertain if it is consistent with other results. The parametric uncertainty for optical photomask measurements derived using an edge intensity threshold approach has been described previously; this paper describes an image library approach to this issue and shows results for optical photomask metrology over a FW range of 10 nm to 8 µm using light of wavelength 365 nm. The principles will be described; a one-dimensional image library will be used; the method of comparing images, along with a simple interpolation method, will be explained; and results will be presented. This method is easily extended to any kind of imaging microscope and to more dimensions in parameter space. It is more general than the edge threshold method and leads to markedly different uncertainties for features smaller than the wavelength.
Ab initio based polarizable force field parametrization
NASA Astrophysics Data System (ADS)
Masia, Marco
2008-05-01
Experimental and simulation studies of anion-water systems have pointed out the importance of molecular polarization for many phenomena ranging from hydrogen-bond dynamics to water interfaces structure. The study of such systems at molecular level is usually made with classical molecular dynamics simulations. Structural and dynamical features are deeply influenced by molecular and ionic polarizability, which parametrization in classical force field has been an object of long-standing efforts. Although when classical models are compared to ab initio calculations at condensed phase, it is found that the water dipole moments are underestimated by ˜30%, while the anion shows an overpolarization at short distances. A model for chloride-water polarizable interaction is parametrized here, making use of Car-Parrinello simulations at condensed phase. The results hint to an innovative approach in polarizable force fields development, based on ab initio simulations, which do not suffer for the mentioned drawbacks. The method is general and can be applied to the modeling of different systems ranging from biomolecular to solid state simulations.
Quantum metrology with unitary parametrization processes
Liu, Jing; Jing, Xiao-Xing; Wang, Xiaoguang
2015-01-01
Quantum Fisher information is a central quantity in quantum metrology. We discuss an alternative representation of quantum Fisher information for unitary parametrization processes. In this representation, all information of parametrization transformation, i.e., the entire dynamical information, is totally involved in a Hermitian operator . Utilizing this representation, quantum Fisher information is only determined by and the initial state. Furthermore, can be expressed in an expanded form. The highlights of this form is that it can bring great convenience during the calculation for the Hamiltonians owning recursive commutations with their partial derivative. We apply this representation in a collective spin system and show the specific expression of . For a simple case, a spin-half system, the quantum Fisher information is given and the optimal states to access maximum quantum Fisher information are found. Moreover, for an exponential form initial state, an analytical expression of quantum Fisher information by operator is provided. The multiparameter quantum metrology is also considered and discussed utilizing this representation. PMID:25708678
Parametric Symmetry Breaking in a Nonlinear Resonator
NASA Astrophysics Data System (ADS)
Leuch, Anina; Papariello, Luca; Zilberberg, Oded; Degen, Christian L.; Chitra, R.; Eichler, Alexander
2016-11-01
Much of the physical world around us can be described in terms of harmonic oscillators in thermodynamic equilibrium. At the same time, the far-from-equilibrium behavior of oscillators is important in many aspects of modern physics. Here, we investigate a resonating system subject to a fundamental interplay between intrinsic nonlinearities and a combination of several driving forces. We have constructed a controllable and robust realization of such a system using a macroscopic doubly clamped string. We experimentally observe a hitherto unseen double hysteresis in both the amplitude and the phase of the resonator's response function and present a theoretical model that is in excellent agreement with the experiment. Our work unveils that the double hysteresis is a manifestation of an out-of-equilibrium symmetry breaking between parametric phase states. Such a fundamental phenomenon, in the most ubiquitous building block of nature, paves the way for the investigation of new dynamical phases of matter in parametrically driven many-body systems and motivates applications ranging from ultrasensitive force detection to low-energy computing memory units.
Quantum transformation limits in multiwave parametric interactions
NASA Astrophysics Data System (ADS)
Saygin, M. Yu
2016-10-01
The possibility to realize multiple nonlinear optical processes in a single crystal as means to produce multicolor quantum states favours stability and compactness of optical settings. Hence, this approach can be advantageous compared to the traditional one based on cascaded arrangement of optical elements. However, it comes with an obstacle—the class of accessible quantum states is narrower than that of the cascade counterpart. In this letter, we study this task using an example of three coupled nonlinear optical processes, namely, one parametric down-conversion and two of sum-frequency generation. To this end, the singular value decomposition has been applied to find the cascade representation of the compound field evolution. We have found the link between the parameters of the multiwave processes and the relevant cascade parameters—beam-splitting and squeezing parameters, by means of which the generated quantum states have been characterized. The relation between the squeezing parameters that has been found in the course of this work shows that the squeezing resource, produced in the parametric down-conversion, is shared among the modes involved in the compound interactions. Moreover, we have shown that the degree of two-mode entanglement carried by the up-converted frequencies cannot exceed that of the down-converted frequencies.
Bifurcations and sensitivity in parametric nonlinear programming
NASA Technical Reports Server (NTRS)
Lundberg, Bruce N.; Poore, Aubrey B.
1990-01-01
The parametric nonlinear programming problem is that of determining the behavior of solution(s) as a parameter or vector of parameters alpha belonging to R(sup r) varies over a region of interest for the problem: Minimize over x the set f(x, alpha):h(x, alpha) = 0, g(x, alpha) is greater than or equal to 0, where f:R(sup (n+r)) approaches R, h:R(sup (n+r)) approaches R(sup q) and g:R(sup (n+r)) approaches R(sup p) are assumed to be at least twice continuously differentiable. Some of these parameters may be fixed but not known precisely and others may be varied to enhance the performance of the system. In both cases a fundamentally important problem in the investigation of global sensitivity of the system is to determine the stability boundaries of the regions in parameter space which define regions of qualitatively similar solutions. The objective is to explain how numerical continuation and bifurcation techniques can be used to investigate the parametric nonlinear programming problem in a global sense. Thus, first the problem is converted to a closed system of parameterized nonlinear equations whose solution set contains all local minimizers of the original problem. This system, which will be represented as F(z,alpha) = O, will include all Karush-Kuhn-Tucker and Fritz John points, both feasible and infeasible solutions, and relative minima, maxima, and saddle points of the problem. The local existence and uniqueness of a solution path (z(alpha), alpha) of this system as well as the solution type persist as long as a singularity in the Jacobian D(sub z)F(z,alpha) is not encountered. Thus the nonsingularity of this Jacobian is characterized in terms of conditions on the problem itself. Then, a class of efficient predictor-corrector continuation procedures for tracing solution paths of the system F(z,alpha) = O which are tailored specifically to the parametric programming problem are described. Finally, these procedures and the obtained information are illustrated
Bifurcations and sensitivity in parametric nonlinear programming
NASA Technical Reports Server (NTRS)
Lundberg, Bruce N.; Poore, Aubrey B.
1990-01-01
The parametric nonlinear programming problem is that of determining the behavior of solution(s) as a parameter or vector of parameters alpha belonging to R(sup r) varies over a region of interest for the problem: Minimize over x the set f(x, alpha):h(x, alpha) = 0, g(x, alpha) is greater than or equal to 0, where f:R(sup (n+r)) approaches R, h:R(sup (n+r)) approaches R(sup q) and g:R(sup (n+r)) approaches R(sup p) are assumed to be at least twice continuously differentiable. Some of these parameters may be fixed but not known precisely and others may be varied to enhance the performance of the system. In both cases a fundamentally important problem in the investigation of global sensitivity of the system is to determine the stability boundaries of the regions in parameter space which define regions of qualitatively similar solutions. The objective is to explain how numerical continuation and bifurcation techniques can be used to investigate the parametric nonlinear programming problem in a global sense. Thus, first the problem is converted to a closed system of parameterized nonlinear equations whose solution set contains all local minimizers of the original problem. This system, which will be represented as F(z,alpha) = O, will include all Karush-Kuhn-Tucker and Fritz John points, both feasible and infeasible solutions, and relative minima, maxima, and saddle points of the problem. The local existence and uniqueness of a solution path (z(alpha), alpha) of this system as well as the solution type persist as long as a singularity in the Jacobian D(sub z)F(z,alpha) is not encountered. Thus the nonsingularity of this Jacobian is characterized in terms of conditions on the problem itself. Then, a class of efficient predictor-corrector continuation procedures for tracing solution paths of the system F(z,alpha) = O which are tailored specifically to the parametric programming problem are described. Finally, these procedures and the obtained information are illustrated
Normal dispersion femtosecond fiber optical parametric oscillator.
Nguyen, T N; Kieu, K; Maslov, A V; Miyawaki, M; Peyghambarian, N
2013-09-15
We propose and demonstrate a synchronously pumped fiber optical parametric oscillator (FOPO) operating in the normal dispersion regime. The FOPO generates chirped pulses at the output, allowing significant pulse energy scaling potential without pulse breaking. The output average power of the FOPO at 1600 nm was ∼60 mW (corresponding to 1.45 nJ pulse energy and ∼55% slope power conversion efficiency). The output pulses directly from the FOPO were highly chirped (∼3 ps duration), and they could be compressed outside of the cavity to 180 fs by using a standard optical fiber compressor. Detailed numerical simulation was also performed to understand the pulse evolution dynamics around the laser cavity. We believe that the proposed design concept is useful for scaling up the pulse energy in the FOPO using different pumping wavelengths.
Compact, flexible, frequency agile parametric wavelength converter
Velsko, Stephan P.; Yang, Steven T.
2002-01-01
This improved Frequency Agile Optical Parametric Oscillator provides near on-axis pumping of a single QPMC with a tilted periodically poled grating to overcome the necessity to find a particular crystal that will permit collinear birefringence in order to obtain a desired tuning range. A tilted grating design and the elongation of the transverse profile of the pump beam in the angle tuning plane of the FA-OPO reduces the rate of change of the overlap between the pumped volume in the crystal and the resonated and non-resonated wave mode volumes as the pump beam angle is changed. A folded mirror set relays the pivot point for beam steering from a beam deflector to the center of the FA-OPO crystal. This reduces the footprint of the device by as much as a factor of two over that obtained when using the refractive telescope design.
Hybrid-free Josephson Parametric Converter
NASA Astrophysics Data System (ADS)
Frattini, N. E.; Narla, A.; Sliwa, K. M.; Shankar, S.; Hatridge, M.; Devoret, M. H.
A necessary component for any quantum computation architecture is the ability to perform efficient quantum operations. In the microwave regime of superconducting qubits, these quantum-limited operations can be realized with a non-degenerate Josephson junction based three-wave mixer, the Josephson Parametric Converter (JPC). Currently, the quantum signal of interest must pass through a lossy 180 degree hybrid to be presented as a differential drive to the JPC. This hybrid therefore places a limit on the quantum efficiency of the system and also increases the device footprint. We present a new design for the JPC eliminating the need for any external hybrid. We also show that this design has nominally identical performance to the conventional JPC. Work supported by ARO, AFOSR and YINQE.
Simplifying the circuit of Josephson parametric converters
NASA Astrophysics Data System (ADS)
Abdo, Baleegh; Brink, Markus; Chavez-Garcia, Jose; Keefe, George
Josephson parametric converters (JPCs) are quantum-limited three-wave mixing devices that can play various important roles in quantum information processing in the microwave domain, including amplification of quantum signals, transduction of quantum information, remote entanglement of qubits, nonreciprocal amplification, and circulation of signals. However, the input-output and biasing circuit of a state-of-the-art JPC consists of bulky components, i.e. two commercial off-chip broadband 180-degree hybrids, four phase-matched short coax cables, and one superconducting magnetic coil. Such bulky hardware significantly hinders the integration of JPCs in scalable quantum computing architectures. In my talk, I will present ideas on how to simplify the JPC circuit and show preliminary experimental results
Parametric analysis of open plan offices
NASA Astrophysics Data System (ADS)
Nogueira, Flavia F.; Viveiros, Elvira B.
2002-11-01
The workspace has been undergoing many changes. Open plan offices are being favored instead of ones of traditional design. In such offices, workstations are separated by partial height barriers, which allow a certain degree of visual privacy and some sound insulation. The challenge in these offices is to provide acoustic privacy for the workstations. Computer simulation was used as a tool for this investigation. Two simple models were generated and their results compared to experimental data measured in two real offices. After validating the approach, models with increasing complexity were generated. Lastly, an ideal office with 64 workstations was created and a parametric survey performed. Nine design parameters were taken as variables and the results are discussed in terms of sound pressure level, in octave bands, and intelligibility index.
Parametric phase diffusion analysis of irregular oscillations
NASA Astrophysics Data System (ADS)
Schwabedal, Justus T. C.
2014-09-01
Parametric phase diffusion analysis (ΦDA), a method to determine variability of irregular oscillations, is presented. ΦDA is formulated as an analysis technique for sequences of Poincaré return times found in numerous applications. The method is unbiased by the arbitrary choice of Poincaré section, i.e. isophase, which causes a spurious component in the Poincaré return times. Other return-time variability measures can be biased drastically by these spurious return times, as shown for the Fano factor of chaotic oscillations in the Rössler system. The empirical use of ΦDA is demonstrated in an application to heart rate data from the Fantasia Database, for which ΦDA parameters successfully classify heart rate variability into groups of age and gender.
Ultrafast Airy beam optical parametric oscillator
Apurv Chaitanya, N.; Kumar, S. Chaitanya; Aadhi, A.; Samanta, G. K.; Ebrahim-Zadeh, M.
2016-01-01
We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm. PMID:27476910
Parametric modeling of quantile regression coefficient functions.
Frumento, Paolo; Bottai, Matteo
2016-03-01
Estimating the conditional quantiles of outcome variables of interest is frequent in many research areas, and quantile regression is foremost among the utilized methods. The coefficients of a quantile regression model depend on the order of the quantile being estimated. For example, the coefficients for the median are generally different from those of the 10th centile. In this article, we describe an approach to modeling the regression coefficients as parametric functions of the order of the quantile. This approach may have advantages in terms of parsimony, efficiency, and may expand the potential of statistical modeling. Goodness-of-fit measures and testing procedures are discussed, and the results of a simulation study are presented. We apply the method to analyze the data that motivated this work. The described method is implemented in the qrcm R package.
Ultrafast Airy beam optical parametric oscillator.
Apurv Chaitanya, N; Kumar, S Chaitanya; Aadhi, A; Samanta, G K; Ebrahim-Zadeh, M
2016-08-01
We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm.
uvmcmcfit: Parametric models to interferometric data fitter
NASA Astrophysics Data System (ADS)
Bussmann, Shane; Leung, Tsz Kuk (Daisy); Conley, Alexander
2016-06-01
Uvmcmcfit fits parametric models to interferometric data. It is ideally suited to extract the maximum amount of information from marginally resolved observations with interferometers like the Atacama Large Millimeter Array (ALMA), Submillimeter Array (SMA), and Plateau de Bure Interferometer (PdBI). uvmcmcfit uses emcee (ascl:1303.002) to do Markov Chain Monte Carlo (MCMC) and can measure the goodness of fit from visibilities rather than deconvolved images, an advantage when there is strong gravitational lensing and in other situations. uvmcmcfit includes a pure-Python adaptation of Miriad’s (ascl:1106.007) uvmodel task to generate simulated visibilities given observed visibilities and a model image and a simple ray-tracing routine that allows it to account for both strongly lensed systems (where multiple images of the lensed galaxy are detected) and weakly lensed systems (where only a single image of the lensed galaxy is detected).
mu analysis with real parametric uncertainty
NASA Technical Reports Server (NTRS)
Young, Peter M.; Newlin, Matthew P.; Doyle, John C.
1991-01-01
The authors give a broad overview, from a LFT (linear fractional transformation)/mu perspective, of some of the theoretical and practical issues associated with robustness in the presence of real parametric uncertainty, with a focus on computation. Recent results on the properties of mu in the mixed case are reviewed, including issues of NP completeness, continuity, computation of bounds, the equivalence of mu and its bounds, and some direct comparisons with Kharitonov-type analysis methods. In addition, some advances in the computational aspects of the problem, including a novel branch and bound algorithm, are briefly presented together with numerical results. The results suggest that while the mixed mu problem may have inherently combinatoric worst-case behavior, practical algorithms with modest computational requirements can be developed for problems of medium size (less than 100 parameters) that are of engineering interest.
Parametric systems analysis for tandem mirror hybrids
Lee, J.D.; Chapin, D.L.; Chi, J.W.H.
1980-09-01
Fusion fission systems, consisting of fissile producing fusion hybrids combining a tandem mirror fusion driver with various blanket types and net fissile consuming LWR's, have been modeled and analyzed parametrically. Analysis to date indicates that hybrids can be competitive with mined uranium when U/sub 3/O/sub 8/ cost is about 100 $/lb., adding less than 25% to present day cost of power from LWR's. Of the three blanket types considered, uranium fast fission (UFF), thorium fast fission (ThFF), and thorium fission supressed (ThFS), the ThFS blanket has a modest economic advantage under most conditions but has higher support ratios and potential safety advantages under all conditions.
Parametric study of double cellular detonation structure
NASA Astrophysics Data System (ADS)
Khasainov, B.; Virot, F.; Presles, H.-N.; Desbordes, D.
2013-05-01
A parametric numerical study is performed of a detonation cellular structure in a model gaseous explosive mixture whose decomposition occurs in two successive exothermic reaction steps with markedly different characteristic times. Kinetic and energetic parameters of both reactions are varied in a wide range in the case of one-dimensional steady and two-dimensional (2D) quasi-steady self-supported detonations. The range of governing parameters of both exothermic steps is defined where a "marked" double cellular structure exists. It is shown that the two-level cellular structure is completely governed by the kinetic parameters and the local overdrive ratio of the detonation front propagating inside large cells. Furthermore, since it is quite cumbersome to use detailed chemical kinetics in unsteady 2D case, the proposed work should help to identify the mixtures and the domain of their equivalence ratio where double detonation structure could be observed.
Multidimensional Scaling Visualization Using Parametric Entropy
NASA Astrophysics Data System (ADS)
Lopes, António M.; Tenreiro Machado, J. A.; Galhano, Alexandra M.
2015-12-01
This paper studies complex systems using a generalized multidimensional scaling (MDS) technique. Complex systems are characterized by time-series responses, interpreted as a manifestation of their dynamics. Two types of time-series are analyzed, namely 18 stock markets and the gross domestic product per capita of 18 countries. For constructing the MDS charts, indices based on parametric entropies are adopted. Multiparameter entropies allow the variation of the parameters leading to alternative sets of charts. The final MDS maps are then assembled by means of Procrustes’ method that maximizes the fit between the individual charts. Therefore, the proposed method can be interpreted as a generalization to higher dimensions of the standard technique that represents (and discretizes) items by means of single “points” (i.e. zero-dimensional “objects”). The MDS plots, involving one-, two- and three-dimensional “objects”, reveal a good performance in capturing the correlations between data.
Parametric thermal evaluations of waste package emplacement
Bahney, R.H. III; Doering, T.W.
1996-02-01
Parametric thermal evaluations of spent nuclear fuel (SNF) waste packages (WPs) emplaced in the potential repository were performed to determine the impact of thermal loading, WP spacing, drift diameter, SNF aging, backfill, and relocation on the design of the Engineered Barrier System. Temperatures in the WP and near-field host rock are key to radionuclide containment, as they directly affect oxidation rates of the metal barriers and the ability of the rock to impede particle movement which must be demonstrated for a safe and licensable repository. Maximum allowable temperatures are based on material performance criteria and are specified as the following design goals for the WP/EBS design: SNF cladding 350{degrees}C, drift wall 200{degrees}C, and TSw3 rock 115{degrees}C.
Stellar parametrization from Gaia RVS spectra
NASA Astrophysics Data System (ADS)
Recio-Blanco, A.; de Laverny, P.; Allende Prieto, C.; Fustes, D.; Manteiga, M.; Arcay, B.; Bijaoui, A.; Dafonte, C.; Ordenovic, C.; Ordoñez Blanco, D.
2016-01-01
Context. Among the myriad of data collected by the ESA Gaia satellite, about 150 million spectra will be delivered by the Radial Velocity Spectrometer (RVS) for stars as faint as GRVS~ 16. A specific stellar parametrization will be performed on most of these RVS spectra, i.e. those with enough high signal-to-noise ratio (S/N), which should correspond to single stars that have a magnitude in the RVS band brighter than ~14.5. Some individual chemical abundances will also be estimated for the brightest targets. Aims: We describe the different parametrization codes that have been specifically developed or adapted for RVS spectra within the GSP-Spec working group of the analysis consortium. The tested codes are based on optimisation (FERRE and GAUGUIN), projection (MATISSE), or pattern-recognition methods (Artificial Neural Networks). We present and discuss each of their expected performances in the recovered stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity) for B- to K-type stars. The performances for determining of [α/Fe] ratios are also presented for cool stars. Methods: Each code has been homogeneously tested with a large grid of RVS simulated synthetic spectra of BAFGK-spectral types (dwarfs and giants), with metallicities varying from 10-2.5 to 10+ 0.5 the solar metallicity, and taking variations of ±0.4 dex in the composition of the α-elements into consideration. The tests were performed for S/N ranging from ten to 350. Results: For all the stellar types we considered, stars brighter than GRVS~ 12.5 are very efficiently parametrized by the GSP-Spec pipeline, including reliable estimations of [α/Fe]. Typical internal errors for FGK metal-rich and metal-intermediate stars are around 40 K in Teff, 0.10 dex in log(g), 0.04 dex in [M/H], and 0.03 dex in [α/Fe] at GRVS = 10.3. They degrade to 155 K in Teff, 0.15 dex in log(g), 0.10 dex in [M/H], and 0.1 dex in [α/Fe] at GRVS~ 12. Similar accuracies in Teff and [M/H] are
Parametric instability of two coupled nonlinear oscillators
NASA Astrophysics Data System (ADS)
Denardo, Bruce; Earwood, John; Sazonova, Vera
1999-03-01
One of the two normal modes of a system of two coupled nonlinear oscillators is subject to an instability. Several demonstration apparatus of weakly coupled oscillators that exhibit the instability are described. The effect is due to one normal mode parametrically driving the other, and occurs for the broad range of systems where the nonlinearity has a cubic contribution to the restoring force of each oscillator, which includes pendulums. The instability has an amplitude threshold that increases as the coupling is increased. A naive physical approach predicts that the mode opposite to that observed should be unstable. This is resolved by a weakly nonlinear analysis which reveals that the nonlinearity causes the linear frequency of a normal mode to depend upon the finite amplitude of the other mode. Numerical simulations confirm the theory, and extend the existence of the instability and the accuracy of the theoretical amplitude threshold beyond the regime of weak nonlinearity and weak coupling.
Large-scale parametric survival analysis.
Mittal, Sushil; Madigan, David; Cheng, Jerry Q; Burd, Randall S
2013-10-15
Survival analysis has been a topic of active statistical research in the past few decades with applications spread across several areas. Traditional applications usually consider data with only a small numbers of predictors with a few hundreds or thousands of observations. Recent advances in data acquisition techniques and computation power have led to considerable interest in analyzing very-high-dimensional data where the number of predictor variables and the number of observations range between 10(4) and 10(6). In this paper, we present a tool for performing large-scale regularized parametric survival analysis using a variant of the cyclic coordinate descent method. Through our experiments on two real data sets, we show that application of regularized models to high-dimensional data avoids overfitting and can provide improved predictive performance and calibration over corresponding low-dimensional models.
Large-Scale Parametric Survival Analysis†
Mittal, Sushil; Madigan, David; Cheng, Jerry; Burd, Randall S.
2013-01-01
Survival analysis has been a topic of active statistical research in the past few decades with applications spread across several areas. Traditional applications usually consider data with only small numbers of predictors with a few hundreds or thousands of observations. Recent advances in data acquisition techniques and computation power has led to considerable interest in analyzing very high-dimensional data where the number of predictor variables and the number of observations range between 104 – 106. In this paper, we present a tool for performing large-scale regularized parametric survival analysis using a variant of cyclic coordinate descent method. Through our experiments on two real data sets, we show that application of regularized models to high-dimensional data avoids overfitting and can provide improved predictive performance and calibration over corresponding low-dimensional models. PMID:23625862
Lensed: Forward parametric modelling of strong lenses
NASA Astrophysics Data System (ADS)
Tessore, Nicolas; Bellagamba, Fabio; Metcalf, R. Benton
2015-05-01
Lensed performs forward parametric modelling of strong lenses. Using a provided model, Lensed renders the expected image of the lensing event for a large number of parameter settings, thereby exploring the space of possible realizations of the observation. It compares the expectation to the observed image by calculating the likelihood that the observation was indeed produced by the assumed model, thus reconstructing the probability distribution over the parameter space of the model. Written in C, the code uses a massively parallel ray-tracing kernel to perform the necessary calculations on a graphics processing unit (GPU), making the precise rendering of the background lensed sources fast and allowing the simultaneous optimization of tens of parameters for the selected model.
Parametric study on propulsion performance of microtubes
NASA Astrophysics Data System (ADS)
Tantos, Ch.; Valougeorgis, D.
2017-06-01
The pressure-driven rarefied gas §ow of polyatomic gases through short tubes in a wide range of the Knudsen number is numerically investigated. The downstream over the upstream pressure ratio is taken very close to zero. Such flows are characterized by low Reynolds numbers and high viscous losses and, therefore, short circular microtubes may be used instead of typical micronozzles. The main computed quantities include the flow rate, the discharge coefficient, the thrust, and the impulse factor which are provided in terms of the gas rarefaction and the tube dimensionless length. Based on the above, a parametric study on the propulsion characteristics of microtubes is provided. Furthermore, a comparison between corresponding polyatomic and monoatomic results is performed and the effect of the internal degrees of freedom on the results is investigated.
Parametric reconstruction method in optical tomography.
Gu, Xuejun; Ren, Kui; Masciotti, James; Hielscher, Andreas H
2006-01-01
Optical tomography consists of reconstructing the spatial of a medium's optical properties from measurements of transmitted light on the boundary of the medium. Mathematically this problem amounts to parameter identification for the radiative transport equation (ERT) or diffusion approximation (DA). However, this type of boundary-value problem is highly ill-posed and the image reconstruction process is often unstable and non-unique. To overcome this problem, we present a parametric inverse method that considerably reduces the number of variables being reconstructed. In this way the amount of measured data is equal or larger than the number of unknowns. Using synthetic data, we show examples that demonstrate how this approach leads to improvements in imaging quality.
Spherical parametrization of the Higgs boson candidate.
Gainer, James S; Lykken, Joseph; Matchev, Konstantin T; Mrenna, Stephen; Park, Myeonghun
2013-07-26
The latest results from the ATLAS and CMS experiments at the CERN Large Hadron Collider unequivocally confirm the existence of a resonance X with mass near 125 GeV which could be the Higgs boson of the standard model. Measuring the properties (quantum numbers and couplings) of this resonance is of paramount importance. Initial analyses by the LHC Collaborations disfavor specific alternative benchmark hypotheses, e.g., pure pseudoscalars or gravitons. However, this is just the first step in a long-term program of detailed measurements. We consider the most general set of operators in the decay channels X→ZZ, WW, Zγ, γγ, and derive the constraint implied by the measured rate. This allows us to provide a useful parametrization of the orthogonal independent Higgs coupling degrees of freedom as coordinates on a suitably defined sphere.
A parametric approach to irregular fatigue prediction
NASA Technical Reports Server (NTRS)
Erismann, T. H.
1972-01-01
A parametric approach to irregular fatigue protection is presented. The method proposed consists of two parts: empirical determination of certain characteristics of a material by means of a relatively small number of well-defined standard tests, and arithmetical application of the results obtained to arbitrary loading histories. The following groups of parameters are thus taken into account: (1) the variations of the mean stress, (2) the interaction of these variations and the superposed oscillating stresses, (3) the spectrum of the oscillating-stress amplitudes, and (4) the sequence of the oscillating-stress amplitudes. It is pointed out that only experimental verification can throw sufficient light upon possibilities and limitations of this (or any other) prediction method.
Ultrafast Airy beam optical parametric oscillator
NASA Astrophysics Data System (ADS)
Apurv Chaitanya, N.; Kumar, S. Chaitanya; Aadhi, A.; Samanta, G. K.; Ebrahim-Zadeh, M.
2016-08-01
We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm.
Mechanism for an absolute parametric instability of an inhomogeneous plasma
NASA Astrophysics Data System (ADS)
Arkhipenko, V. I.; Budnikov, V. N.; Gusakov, E. Z.; Romanchuk, I. A.; Simonchik, L. V.
1984-05-01
The structure of plasma oscillations in a region of parametric spatial amplification has been studied experimentally for the first time. A new mechanism for an absolute parametric instability has been observed. This mechanism operates when a pump wave with a spatial structure more complicated than a plane wave propagates through a plasma which is inhomogeneous along more than one dimension.
Using a Parametric Solid Modeler as an Instructional Tool
ERIC Educational Resources Information Center
Devine, Kevin L.
2008-01-01
This paper presents the results of a quasi-experimental study that brought 3D constraint-based parametric solid modeling technology into the high school mathematics classroom. This study used two intact groups; a control group and an experimental group, to measure the extent to which using a parametric solid modeler during instruction affects…
Parametrization of the SCC-DFTB Method for Halogens.
Kubař, Tomáš; Bodrog, Zoltán; Gaus, Michael; Köhler, Christof; Aradi, Bálint; Frauenheim, Thomas; Elstner, Marcus
2013-07-09
Parametrization of the approximative DFT method SCC-DFTB for halogen elements is presented. The new parameter set is intended to describe halogenated organic as well as inorganic molecules, and it is compatible with the established parametrization of SCC-DFTB for carbon, hydrogen, oxygen, and nitrogen. The performance of the parameter set is tested on a representative set of molecules and discussed.
Injection-seeded optical parametric oscillator and system
Lucht, Robert P.; Kulatilaka, Waruna D.; Anderson, Thomas N.; Bougher, Thomas L.
2007-10-09
Optical parametric oscillators (OPO) and systems are provided. The OPO has a non-linear optical material located between two optical elements where the product of the reflection coefficients of the optical elements are higher at the output wavelength than at either the pump or idler wavelength. The OPO output may be amplified using an additional optical parametric amplifier (OPA) stage.
Parametric Equations: Push 'Em Back, Push 'Em Back, Way Back!
ERIC Educational Resources Information Center
Cieply, Joseph F.
1993-01-01
Stresses using the features of graphing calculators to teach parametric equations much earlier in the curriculum than is presently done. Examples using parametric equations to teach slopes and lines in beginning algebra, inverse functions in advanced algebra, the wrapping function, and simulations of physical phenomena are presented. (MAZ)
Using a Parametric Solid Modeler as an Instructional Tool
ERIC Educational Resources Information Center
Devine, Kevin L.
2008-01-01
This paper presents the results of a quasi-experimental study that brought 3D constraint-based parametric solid modeling technology into the high school mathematics classroom. This study used two intact groups; a control group and an experimental group, to measure the extent to which using a parametric solid modeler during instruction affects…
Concomitant information in bioassay and semi-parametric estimation.
Kim, Peter T; Lee, Christine H
2005-05-15
This paper presents a flexible modern approach to handling concomitant information for estimating the relative potency parameter in quantitative bioassays. This is accomplished in a semi-parametric framework where the concomitant variable is included non-parametrically. Estimation is then performed using smoothing splines where the point and interval estimators of the relative potency parameter exhibits desirable asymptotic properties.
Penalized Likelihood for General Semi-Parametric Regression Models.
1985-05-01
should be stressed that q, while it may be somewhat less than n, will still be ’large’, and parametric estimation of £ will not be appropriate...Partial spline models for the semi- parametric estimation of functions of several variables, in Statistical Analysis of Time Series, Tokyo: Institute of
Tuneable, non-degenerated, nonlinear, parametrically-excited amplifier
NASA Astrophysics Data System (ADS)
Dolev, Amit; Bucher, Izhak
2016-01-01
The proposed parametric amplifier scheme can be tuned to amplify a wide range of input frequencies by altering the parametric excitation with no need to physically modify the oscillator. Parametric amplifiers had been studied extensively, although most of the work focused on amplifiers that are parametrically excited at a frequency twice the amplifier's natural frequency. These amplifiers are confined to amplifying predetermined frequencies. The proposed parametric amplifier's bandwidth is indeed tuneable to nearly any input frequency, not bound to be an integer multiple of a natural frequency. In order to tune the stiffness and induce a variable frequency parametric excitation, a digitally controlled electromechanical element must be incorporated in the realization. We introduce a novel parametric amplifier with nonlinearity, Duffing type hardening, that bounds the otherwise unlimited amplitude. Moreover, we present a multi degree of freedom system in which a utilization of the proposed method enables the projection of low frequency vector forces on any eigenvector and corresponding natural frequency of the system, and thus to transform external excitations to a frequency band where signal levels are considerably higher. Using the method of multiple scales, analytical expressions for the responses have been retrieved and verified numerically. Parametric studies of the amplifiers' gain, sensitivities and spatial projection of the excitation on the system eigenvectors were carried out analytically. The results demonstrate the advantage of the proposed approach over existing schemes. Practical applications envisaged for the proposed method will be outlined.
Schwinger-type parametrization of open string worldsheets
NASA Astrophysics Data System (ADS)
Playle, Sam; Sciuto, Stefano
2017-03-01
A parametrization of (super) moduli space near the corners corresponding to bosonic or Neveu-Schwarz open string degenerations is introduced for worldsheets of arbitrary topology. With this parametrization, Feynman graph polynomials arise as the α‧ → 0 limit of objects on moduli space. Furthermore, the integration measures of string theory take on a very simple and elegant form.
Evaluation of Two Energy Balance Closure Parametrizations
NASA Astrophysics Data System (ADS)
Eder, Fabian; De Roo, Frederik; Kohnert, Katrin; Desjardins, Raymond L.; Schmid, Hans Peter; Mauder, Matthias
2014-05-01
A general lack of energy balance closure indicates that tower-based eddy-covariance (EC) measurements underestimate turbulent heat fluxes, which calls for robust correction schemes. Two parametrization approaches that can be found in the literature were tested using data from the Canadian Twin Otter research aircraft and from tower-based measurements of the German Terrestrial Environmental Observatories (TERENO) programme. Our analysis shows that the approach of Huang et al. (Boundary-Layer Meteorol 127:273-292, 2008), based on large-eddy simulation, is not applicable to typical near-surface flux measurements because it was developed for heights above the surface layer and over homogeneous terrain. The biggest shortcoming of this parametrization is that the grid resolution of the model was too coarse so that the surface layer, where EC measurements are usually made, is not properly resolved. The empirical approach of Panin and Bernhofer (Izvestiya Atmos Oceanic Phys 44:701-716, 2008) considers landscape-level roughness heterogeneities that induce secondary circulations and at least gives a qualitative estimate of the energy balance closure. However, it does not consider any feature of landscape-scale heterogeneity other than surface roughness, such as surface temperature, surface moisture or topography. The failures of both approaches might indicate that the influence of mesoscale structures is not a sufficient explanation for the energy balance closure problem. However, our analysis of different wind-direction sectors shows that the upwind landscape-scale heterogeneity indeed influences the energy balance closure determined from tower flux data. We also analyzed the aircraft measurements with respect to the partitioning of the "missing energy" between sensible and latent heat fluxes and we could confirm the assumption of scalar similarity only for Bowen ratios 1.
Parametrization of turbulent fluxes over inhomogeneous landscapes
NASA Astrophysics Data System (ADS)
Panin, G. N.; Bernhofer, Ch.
2008-12-01
Reasons for the nonclosure of the heat balance in the atmospheric boundary layers over natural land surfaces are analyzed. Results of measuring the heat-balance components over different land surfaces are used. The Cabauw (Netherlands) data (obtained throughout 1996 over a grass surface with intermittent shrubs and single trees) and the data from the Anchor station in Germany (measured over coniferous forest in 2000-2001) are analyzed. In all, the analysis involves about fifty thousand independent values of the heat-balance components measured in the experiments, which should be indicative of the reliability of the results obtained in the paper. The data have shown that the heat balance is not closed and the imbalance is 50-250 W/m2. The sum of the latent and sensible heat fluxes λ E + H = STF is found to be systematically smaller than the difference between the net radiation and the heat flux into the ground R n - G. It is shown that the main cause of a systematic heat imbalance in the atmospheric boundary layers over inhomogeneous land surfaces is that the methods of surface-flux measurement and estimation are based on the theory that requires the hypothesis of stationarity and horizontal homogeneity. Direct data analysis has shown that the heat imbalance increases with landscape inhomogeneity. In the paper, a parametrization of the heat imbalance is carried out and the coefficient k f ( z {0/ ef }/ L ef ) is introduced as a measure of inhomogeneity. For this, data from the experiments FIFE, KUREX, TARTEX, SADE, etc., are also used. Empirical formulas are presented to refine the results of direct measurements and calculations of surface fluxes over natural (inhomogeneous) land surfaces from profile and standard (using bulk parametrizations) data. These formulas can also be used to determine surface fluxes over inhomogeneous underlying land surfaces in order to take into account so-called subgrid-scale effects in constructing prediction models.
Parametric cost estimation for space science missions
NASA Astrophysics Data System (ADS)
Lillie, Charles F.; Thompson, Bruce E.
2008-07-01
Cost estimation for space science missions is critically important in budgeting for successful missions. The process requires consideration of a number of parameters, where many of the values are only known to a limited accuracy. The results of cost estimation are not perfect, but must be calculated and compared with the estimates that the government uses for budgeting purposes. Uncertainties in the input parameters result from evolving requirements for missions that are typically the "first of a kind" with "state-of-the-art" instruments and new spacecraft and payload technologies that make it difficult to base estimates on the cost histories of previous missions. Even the cost of heritage avionics is uncertain due to parts obsolescence and the resulting redesign work. Through experience and use of industry best practices developed in participation with the Aerospace Industries Association (AIA), Northrop Grumman has developed a parametric modeling approach that can provide a reasonably accurate cost range and most probable cost for future space missions. During the initial mission phases, the approach uses mass- and powerbased cost estimating relationships (CER)'s developed with historical data from previous missions. In later mission phases, when the mission requirements are better defined, these estimates are updated with vendor's bids and "bottoms- up", "grass-roots" material and labor cost estimates based on detailed schedules and assigned tasks. In this paper we describe how we develop our CER's for parametric cost estimation and how they can be applied to estimate the costs for future space science missions like those presented to the Astronomy & Astrophysics Decadal Survey Study Committees.
Time reversal of parametrical driving and the stability of the parametrically excited pendulum
NASA Astrophysics Data System (ADS)
Stannarius, Ralf
2009-02-01
It is well known that the periodic driving of a parametrically excited pendulum can stabilize or destabilize its stationary states, depending upon the frequency, wave form, and amplitude of the parameter modulations. We discuss the effect of time reversal of the periodic driving function for the parametric pendulum at small elongations. Such a time reversal usually leads to different solutions of the equations of motion and to different stability properties of the system. Two interesting exceptions are discussed, and two conditions are formulated for which the character of the solutions of the system is not influenced by a time reversal of the driving function, even though the trajectories of the dynamic variables are different.
Aniolek, K W; Schmitt, R L; Kulp, T J; Richman, B A; Bisson, S E; Powers, P E
2000-04-15
For what is believed to be the first time, a single-longitudinal-mode passively Q-switched Nd:YAG microlaser is used to pump a narrow-bandwidth periodically poled lithium niobate (PPLN) optical parametric generator-optical parametric amplifier (OPG-OPA). Before amplification in the OPA, the output of the OPG stage was spectrally filtered with an air-spaced etalon, resulting in spectroscopically useful radiation (bandwidth, ~0.05 cm(-1) FWHM) that was tunable in 15-cm(-1) segments anywhere in the signal range 6820-6220 cm(-1) and the idler range 2580-3180 cm(-1). The ability to pump an OPG-OPA with compact, high-repetition-rate, intrinsically narrow-bandwidth microlasers is made possible by the high gain of PPLN. The result is a tunable light source that is well suited for use in portable spectroscopic gas sensors.
A new parametrization and minimal model for glacier calving
NASA Astrophysics Data System (ADS)
Lüthi, Martin; Vieli, Andreas; Mercenier, Rémy
2017-04-01
The iceberg calving process influences the geometry of a tidewater glacier, and is in turn controlled by the terminus geometry through the stress field which controls damage and fracture of the ice. A simple parametrization of the stress field at the glacier terminus is obtained from the results of a Finite Element model with varying water depths. Using this stress field in an isotropic damage evolution equation yields calving rates in dependence of calving front thickness and water depth. These parametrized calving rates compare favorably with observations, and extend well established parametrizations. The proposed calving parametrization is easy to implement in numerical ice sheet models. Using these parametrized calving rates in a minimal calving model allows us to analyze the intricate feedbacks of the calving process, to reproduce observed tidewater glacier dynamics, and to analyze the stability of glacier termini.
Computation of Parametric Adaptive Fuzzy Controller for Wood Drying System
NASA Astrophysics Data System (ADS)
Situmorang, Zakarias; Wardoyo, Retantyo; Hartati, Sri; Istiyanto, Jazi Eko
2009-08-01
The paper reports the computation of parametric adaptive fuzzy controller for used to wood drying system. Parametric of adaptive fuzzy controller is control period system. Control period system is how long time need to hoist of temperature drying or humidity drying if the actuator in on-conditions. The parametric is implemented for control system of wood drying process at prototype chamber with solar is source of energy. The actuator of system is heater, damper and sprayer. From result of measurement, that data were doing to analysis statistic to have the parametric. Whenever the parametric want to implemented with mechanism adaptive. Membership Functions of variable control of system to became something is difficult to have effect to temperature and humidity drying. The result of implemented of adaptive fuzzy control is described in graphic typical. The control system is able to adapt change of humidity drying in system schedule of wood drying system.
Non-parametric approach to the study of phenotypic stability.
Ferreira, D F; Fernandes, S B; Bruzi, A T; Ramalho, M A P
2016-02-19
The aim of this study was to undertake the theoretical derivations of non-parametric methods, which use linear regressions based on rank order, for stability analyses. These methods were extension different parametric methods used for stability analyses and the result was compared with a standard non-parametric method. Intensive computational methods (e.g., bootstrap and permutation) were applied, and data from the plant-breeding program of the Biology Department of UFLA (Minas Gerais, Brazil) were used to illustrate and compare the tests. The non-parametric stability methods were effective for the evaluation of phenotypic stability. In the presence of variance heterogeneity, the non-parametric methods exhibited greater power of discrimination when determining the phenotypic stability of genotypes.
NASA Technical Reports Server (NTRS)
Coverse, G. L.
1984-01-01
A turbine modeling technique has been developed which will enable the user to obtain consistent and rapid off-design performance from design point input. This technique is applicable to both axial and radial flow turbine with flow sizes ranging from about one pound per second to several hundred pounds per second. The axial flow turbines may or may not include variable geometry in the first stage nozzle. A user-specified option will also permit the calculation of design point cooling flow levels and corresponding changes in efficiency for the axial flow turbines. The modeling technique has been incorporated into a time-sharing program in order to facilitate its use. Because this report contains a description of the input output data, values of typical inputs, and example cases, it is suitable as a user's manual. This report is the second of a three volume set. The titles of the three volumes are as follows: (1) Volume 1 CMGEN USER's Manual (Parametric Compressor Generator); (2) Volume 2 PART USER's Manual (Parametric Turbine); (3) Volume 3 MODFAN USER's Manual (Parametric Modulation Flow Fan).
Foster, Adam L.; Katz, Brian G.; Meyer, Michael T.
2012-01-01
An increased demand for fresh groundwater resources in South Florida has prompted Miami-Dade County to expand its water reclamation program and actively pursue reuse plans for aquifer recharge, irrigation, and wetland rehydration. The U.S. Geological Survey, in cooperation with the Miami-Dade Water and Sewer Department (WASD) and the Miami-Dade Department of Environmental Resources Management (DERM), initiated a study in 2008 to assess the presence of selected pharmaceuticals and other organic wastewater compounds in the influent and effluent at three regional wastewater-treatment plants (WWTPs) operated by the WASD and at one WWTP operated by the City of Homestead, Florida (HSWWTP).
Optimal parametrization of electrodynamical battery model using model selection criteria
NASA Astrophysics Data System (ADS)
Suárez-García, Andrés; Alfonsín, Víctor; Urréjola, Santiago; Sánchez, Ángel
2015-07-01
This paper describes the mathematical parametrization of an electrodynamical battery model using different model selection criteria. A good modeling technique is needed by the battery management units in order to increase battery lifetime. The elements of battery models can be mathematically parametrized to enhance their implementation in simulation environments. In this work, the best mathematical parametrizations are selected using three model selection criteria: the coefficient of determination (R2), the Akaike Information Criterion (AIC) and the Bayes Information Criterion (BIC). The R2 criterion only takes into account the error of the mathematical parametrizations, whereas AIC and BIC consider complexity. A commercial 40 Ah lithium iron phosphate (LiFePO4) battery is modeled and then simulated for contrasting. The OpenModelica open-source modeling and simulation environment is used for doing the battery simulations. The mean percent error of the simulations is 0.0985% for the models parametrized with R2 , 0.2300% for the AIC ones, and 0.3756% for the BIC ones. As expected, the R2 selected the most precise, complex and slowest mathematical parametrizations. The AIC criterion chose parametrizations with similar accuracy, but simpler and faster than the R2 ones.
Parametric generation of quadrature squeezing of mirrors in cavity optomechanics
Liao, Jie-Qiao; Law, C. K.
2011-03-15
We propose a method to generate quadrature-squeezed states of a moving mirror in a Fabry-Perot cavity. This is achieved by exploiting the fact that when the cavity is driven by an external field with a large detuning, the moving mirror behaves as a parametric oscillator. We show that parametric resonance can be reached approximately by modulating the driving field amplitude at a frequency matching the frequency shift of the mirror. The parametric resonance leads to an efficient generation of squeezing, which is limited by the thermal noise of the environment.
Average power effects in parametric oscillators and amplifiers
NASA Technical Reports Server (NTRS)
Barnes, Norman P.; Williams-Byrd, Julie A.
1995-01-01
Average power effects relative to the operation of parametric oscillators and amplifiers have been calculated. Temperature gradients have been calculated for both radial and longitudinal heat extraction. In many instances, the thermal load on a parametric oscillator is higher than the thermal load on a parametric amplifier with the same pump power. Having one or both these wavelengths resonant increases the chances that a generated photon will be absorbed by the nonlinear crystal. Temperature profiles and thermal diffusion time constants have been calculated for Gaussian beams, given the heat-deposition rate. With radical heat extraction the temperature profile can be expressed in a power series or approximated by a Gaussian distribution function.
Parametric interaction of coronal loops with p modes
NASA Astrophysics Data System (ADS)
Stepanov, A. V.; Zaitsev, V. V.; Kisliakov, A. G.; Urpo, S.
2009-03-01
Parametric resonance between p modes and eigenoscillations of coronal loops is studied. Observations of solar radio bursts revealed this effect in simultaneous excitation of loop oscillations with periods corresponding to the pumping-up frequency (5 min), subharmonic (10 min), and to the first upper frequency of parametric resonance (3.3 min). An interpretation in terms of a coronal magnetic loop as an equivalent electric circuit is given. Parametric resonance can work as a channel for transfer of energy from photospheric motions to stellar coronae.
Variable selection in semi-parametric models
Zhang, Hongmei; Maity, Arnab; Arshad, Hasan; Holloway, John; Karmaus, Wilfried
2014-01-01
We propose Bayesian variable selection methods in semi-parametric models in the framework of partially linear Gaussian and problit regressions. Reproducing kernels are utilized to evaluate possibly non-linear joint effect of a set of variables. Indicator variables are introduced into the reproducing kernels for the inclusion or exclusion of a variable. Different scenarios based on posterior probabilities of including a variable are proposed to select important variables. Simulations are used to demonstrate and evaluate the methods. It was found that the proposed methods can efficiently select the correct variables regardless of the feature of the effects, linear or non-linear in an unknown form. The proposed methods are applied to two real data sets to identify cytosine phosphate guanine methylation sites associated with maternal smoking and cytosine phosphate guanine sites associated with cotinine levels with creatinine levels adjusted. The selected methylation sites have the potential to advance our understanding of the underlying mechanism for the impact of smoking exposure on health outcomes, and consequently benefit medical research in disease intervention. PMID:23990355
Strain-Gage Loads Calibration Parametric Study
NASA Technical Reports Server (NTRS)
Lokos, William A.; Stauf, Rick
2004-01-01
This paper documents a parametric study of various aircraft wing-load test features that affect the quality of the resultant derived shear, bending-moment, and torque strain-gage load equations. The effect of the following on derived strain-gage equation accuracy are compared: single-point loading compared with distributed loading, variation in applied test load magnitude, number of applied load cases, and wing-box-only compared with control-surface loading. The subject of this study is an extensive wing-load calibration test of the Active Aeroelastic Wing F/A-18 airplane. Selected subsets of the available test data were used to derive load equations using the linear regression method. Results show the benefit of distributed loading and the diminishing-return benefits of test load magnitudes and number of load cases. The use of independent check cases as a quality metric for the derived load equations is shown to overcome blind extrapolating beyond the load data used to derive the load equations.
Design criteria for ultrafast optical parametric amplifiers
NASA Astrophysics Data System (ADS)
Manzoni, C.; Cerullo, G.
2016-10-01
Optical parametric amplifiers (OPAs) exploit second-order nonlinearity to transfer energy from a fixed frequency pump pulse to a variable frequency signal pulse, and represent an easy way of tuning over a broad range the frequency of an otherwise fixed femtosecond laser system. OPAs can also act as broadband amplifiers, transferring energy from a narrowband pump to a broadband signal and thus considerably shortening the duration of the pump pulse. Due to these unique properties, OPAs are nowadays ubiquitous in ultrafast laser laboratories, and are employed by many users, such as solid state physicists, atomic/molecular physicists, chemists and biologists, who are not experts in ultrafast optics. This tutorial paper aims at providing the non-specialist reader with a self-consistent guide to the physical foundations of OPAs, deriving the main equations describing their performance and discussing how they can be used to understand their most important working parameters (frequency tunability, bandwidth, pulse energy/repetition rate scalability, control over the carrier-envelope phase of the generated pulses). Based on this analysis, we derive practical design criteria for OPAs, showing how their performance depends on the type of the nonlinear interaction (crystal type, phase-matching configuration, crystal length), on the characteristics of the pump pulse (frequency, duration, energy, repetition rate) and on the OPA architecture.
Optical parametric osicllators with improved beam quality
Smith, Arlee V.; Alford, William J.
2003-11-11
An optical parametric oscillator (OPO) having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.
Visual to Parametric Interaction (V2PI)
Maiti, Dipayan; Endert, Alex; North, Chris
2013-01-01
Typical data visualizations result from linear pipelines that start by characterizing data using a model or algorithm to reduce the dimension and summarize structure, and end by displaying the data in a reduced dimensional form. Sensemaking may take place at the end of the pipeline when users have an opportunity to observe, digest, and internalize any information displayed. However, some visualizations mask meaningful data structures when model or algorithm constraints (e.g., parameter specifications) contradict information in the data. Yet, due to the linearity of the pipeline, users do not have a natural means to adjust the displays. In this paper, we present a framework for creating dynamic data displays that rely on both mechanistic data summaries and expert judgement. The key is that we develop both the theory and methods of a new human-data interaction to which we refer as “ Visual to Parametric Interaction” (V2PI). With V2PI, the pipeline becomes bi-directional in that users are embedded in the pipeline; users learn from visualizations and the visualizations adjust to expert judgement. We demonstrate the utility of V2PI and a bi-directional pipeline with two examples. PMID:23555552
Selected Parametric Effects on Materials Flammability Limits
NASA Technical Reports Server (NTRS)
Hirsch, David B.; Juarez, Alfredo; Peyton, Gary J.; Harper, Susana A.; Olson, Sandra L.
2011-01-01
NASA-STD-(I)-6001B Test 1 is currently used to evaluate the flammability of materials intended for use in habitable environments of U.S. spacecraft. The method is a pass/fail upward flame propagation test conducted in the worst case configuration, which is defined as a combination of a material s thickness, test pressure, oxygen concentration, and temperature that make the material most flammable. Although simple parametric effects may be intuitive (such as increasing oxygen concentrations resulting in increased flammability), combinations of multi-parameter effects could be more complex. In addition, there are a variety of material configurations used in spacecraft. Such configurations could include, for example, exposed free edges where fire propagation may be different when compared to configurations commonly employed in standard testing. Studies involving combined oxygen concentration, pressure, and temperature on flammability limits have been conducted and are summarized in this paper. Additional effects on flammability limits of a material s thickness, mode of ignition, burn-length criteria, and exposed edges are presented. The information obtained will allow proper selection of ground flammability test conditions, support further studies comparing flammability in 1-g with microgravity and reduced gravity environments, and contribute to persuasive scientific cases for rigorous space system fire risk assessments.
Parametric Study of Variable Emissivity Radiator Surfaces
NASA Technical Reports Server (NTRS)
Grob, Lisa M.; Swanson, Theodore D.
2000-01-01
The goal of spacecraft thermal design is to accommodate a high function satellite in a low weight and real estate package. The extreme environments that the satellite is exposed during its orbit are handled using passive and active control techniques. Heritage passive heat rejection designs are sized for the hot conditions and augmented for the cold end with heaters. The active heat rejection designs to date are heavy, expensive and/or complex. Incorporating an active radiator into the design that is lighter, cheaper and more simplistic will allow designers to meet the previously stated goal of thermal spacecraft design Varying the radiator's surface properties without changing the radiating area (as with VCHP), or changing the radiators' views (traditional louvers) is the objective of the variable emissivity (vary-e) radiator technologies. A parametric evaluation of the thermal performance of three such technologies is documented in this paper. Comparisons of the Micro-Electromechanical Systems (MEMS), Electrochromics, and Electrophoretics radiators to conventional radiators, both passive and active are quantified herein. With some noted limitations, the vary-e radiator surfaces provide significant advantages over traditional radiators and a promising alternative design technique for future spacecraft thermal systems.
Program Predicts Performance of Optical Parametric Oscillators
NASA Technical Reports Server (NTRS)
Cross, Patricia L.; Bowers, Mark
2006-01-01
A computer program predicts the performances of solid-state lasers that operate at wavelengths from ultraviolet through mid-infrared and that comprise various combinations of stable and unstable resonators, optical parametric oscillators (OPOs), and sum-frequency generators (SFGs), including second-harmonic generators (SHGs). The input to the program describes the signal, idler, and pump beams; the SFG and OPO crystals; and the laser geometry. The program calculates the electric fields of the idler, pump, and output beams at three locations (inside the laser resonator, just outside the input mirror, and just outside the output mirror) as functions of time for the duration of the pump beam. For each beam, the electric field is used to calculate the fluence at the output mirror, plus summary parameters that include the centroid location, the radius of curvature of the wavefront leaving through the output mirror, the location and size of the beam waist, and a quantity known, variously, as a propagation constant or beam-quality factor. The program provides a typical Windows interface for entering data and selecting files. The program can include as many as six plot windows, each containing four graphs.
Action Quantization, Energy Quantization, and Time Parametrization
NASA Astrophysics Data System (ADS)
Floyd, Edward R.
2017-03-01
The additional information within a Hamilton-Jacobi representation of quantum mechanics is extra, in general, to the Schrödinger representation. This additional information specifies the microstate of ψ that is incorporated into the quantum reduced action, W. Non-physical solutions of the quantum stationary Hamilton-Jacobi equation for energies that are not Hamiltonian eigenvalues are examined to establish Lipschitz continuity of the quantum reduced action and conjugate momentum. Milne quantization renders the eigenvalue J. Eigenvalues J and E mutually imply each other. Jacobi's theorem generates a microstate-dependent time parametrization t-τ =partial _E W even where energy, E, and action variable, J, are quantized eigenvalues. Substantiating examples are examined in a Hamilton-Jacobi representation including the linear harmonic oscillator numerically and the square well in closed form. Two byproducts are developed. First, the monotonic behavior of W is shown to ease numerical and analytic computations. Second, a Hamilton-Jacobi representation, quantum trajectories, is shown to develop the standard energy quantization formulas of wave mechanics.
Parametric Cost Analysis: A Design Function
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1989-01-01
Parametric cost analysis uses equations to map measurable system attributes into cost. The measures of the system attributes are called metrics. The equations are called cost estimating relationships (CER's), and are obtained by the analysis of cost and technical metric data of products analogous to those to be estimated. Examples of system metrics include mass, power, failure_rate, mean_time_to_repair, energy _consumed, payload_to_orbit, pointing_accuracy, manufacturing_complexity, number_of_fasteners, and percent_of_electronics_weight. The basic assumption is that a measurable relationship exists between system attributes and the cost of the system. If a function exists, the attributes are cost drivers. Candidates for metrics include system requirement metrics and engineering process metrics. Requirements are constraints on the engineering process. From optimization theory we know that any active constraint generates cost by not permitting full optimization of the objective. Thus, requirements are cost drivers. Engineering processes reflect a projection of the requirements onto the corporate culture, engineering technology, and system technology. Engineering processes are an indirect measure of the requirements and, hence, are cost drivers.
A Parametric Study of Spur Gear Dynamics
NASA Technical Reports Server (NTRS)
Lin, Hsiang Hsi; Liou, Chuen-Huei
1998-01-01
A parametric study of a spur gear system was performed through a numerical analysis approach. This study used the gear dynamic program DANST, a computer simulator, to determine the dynamic behavior of a spur gear system. The analytical results have taken the deflection of shafts and bearings into consideration for static analysis, and the influence of these deflections on gear dynamics was investigated. Damping in the gear system usually is an unknown quantity, but it has an important effect in resonance vibration. Typical values as reported in the literature were used in the present analysis. The dynamic response due to different damping factors was evaluated and compared. The effect of the contact ratio on spur gear dynamic load and dynamic stress was investigated through a parameter study. The contact ratio was varied over the range of 1.26 to 2.46 by adjusting the tooth addendum. Gears with contact ratio near 2.0 were found to have the most favorable dynamic performance.
Parametric probability distributions for anomalous change detection
Theiler, James P; Foy, Bernard R; Wohlberg, Brendt E; Scovel, James C
2010-01-01
The problem of anomalous change detection arises when two (or possibly more) images are taken of the same scene, but at different times. The aim is to discount the 'pervasive differences' that occur thoughout the imagery, due to the inevitably different conditions under which the images were taken (caused, for instance, by differences in illumination, atmospheric conditions, sensor calibration, or misregistration), and to focus instead on the 'anomalous changes' that actually take place in the scene. In general, anomalous change detection algorithms attempt to model these normal or pervasive differences, based on data taken directly from the imagery, and then identify as anomalous those pixels for which the model does not hold. For many algorithms, these models are expressed in terms of probability distributions, and there is a class of such algorithms that assume the distributions are Gaussian. By considering a broader class of distributions, however, a new class of anomalous change detection algorithms can be developed. We consider several parametric families of such distributions, derive the associated change detection algorithms, and compare the performance with standard algorithms that are based on Gaussian distributions. We find that it is often possible to significantly outperform these standard algorithms, even using relatively simple non-Gaussian models.
Improvement of Statistical Decisions under Parametric Uncertainty
NASA Astrophysics Data System (ADS)
Nechval, Nicholas A.; Nechval, Konstantin N.; Purgailis, Maris; Berzins, Gundars; Rozevskis, Uldis
2011-10-01
A large number of problems in production planning and scheduling, location, transportation, finance, and engineering design require that decisions be made in the presence of uncertainty. Decision-making under uncertainty is a central problem in statistical inference, and has been formally studied in virtually all approaches to inference. The aim of the present paper is to show how the invariant embedding technique, the idea of which belongs to the authors, may be employed in the particular case of finding the improved statistical decisions under parametric uncertainty. This technique represents a simple and computationally attractive statistical method based on the constructive use of the invariance principle in mathematical statistics. Unlike the Bayesian approach, an invariant embedding technique is independent of the choice of priors. It allows one to eliminate unknown parameters from the problem and to find the best invariant decision rule, which has smaller risk than any of the well-known decision rules. To illustrate the proposed technique, application examples are given.
Parametric investigation of scalable tactile sensors
NASA Astrophysics Data System (ADS)
Saadatzi, Mohammad Nasser; Yang, Zhong; Baptist, Joshua R.; Sahasrabuddhe, Ritvij R.; Wijayasinghe, Indika B.; Popa, Dan O.
2017-05-01
In the near future, robots and humans will share the same environment and perform tasks cooperatively. For intuitive, safe, and reliable physical human-robot interaction (pHRI), sensorized robot skins for tactile measurements of contact are necessary. In a previous study, we presented skins consisting of strain gauge arrays encased in silicone encapsulants. Although these structures could measure normal forces applied directly onto the sensing elements, they also exhibited blind spots and response asymmetry to certain loading patterns. This study presents a parametric investigation of piezoresistive polymeric strain gauge that exhibits a symmetric omniaxial response thanks to its novel star-shaped structure. This strain gauge relies on the use of gold micro-patterned star-shaped structures with a thin layer of PEDOT:PSS which is a flexible polymer with piezoresistive properties. In this paper, the sensor is first modeled and comprehensively analyzed in the finite-element simulation environment COMSOL. Simulations include stress-strain loading for a variety of structure parameters such as gauge lengths, widths, and spacing, as well as multiple load locations relative to the gauge. Subsequently, sensors with optimized configurations obtained through simulations were fabricated using cleanroom photolithographic and spin-coating processes, and then experimentally tested. Results show a trend-wise agreement between experiments and simulations.
Parametric analysis of a magnetized cylindrical plasma
Ahedo, Eduardo
2009-11-15
The relevant macroscopic model, the spatial structure, and the parametric regimes of a low-pressure plasma confined by a cylinder and an axial magnetic field is discussed for the small-Debye length limit, making use of asymptotic techniques. The plasma response is fully characterized by three-dimensionless parameters, related to the electron gyroradius, and the electron and ion collision mean-free-paths. There are the unmagnetized regime, the main magnetized regime, and, for a low electron-collisionality plasma, an intermediate-magnetization regime. In the magnetized regimes, electron azimuthal inertia is shown to be a dominant phenomenon in part of the quasineutral plasma region and to set up before ion radial inertia. In the main magnetized regime, the plasma structure consists of a bulk diffusive region, a thin layer governed by electron inertia, a thinner sublayer controlled by ion inertia, and the non-neutral Debye sheath. The solution of the main inertial layer yields that the electron azimuthal energy near the wall is larger than the electron thermal energy, making electron resistivity effects non-negligible. The electron Boltzmann relation is satisfied only in the very vicinity of the Debye sheath edge. Ion collisionality effects are irrelevant in the magnetized regime. Simple scaling laws for plasma production and particle and energy fluxes to the wall are derived.
Parametric optimization of inverse trapezoid oleophobic surfaces.
Cavalli, Andrea; Bøggild, Peter; Okkels, Fridolin
2012-12-18
In this paper, we introduce a comprehensive and versatile approach to the parametric shape optimization of oleophobic surfaces. We evaluate the performance of inverse trapezoid microstructures in terms of three objective parameters: apparent contact angle, maximum sustainable hydrostatic pressure, and mechanical robustness (Im, M.; Im, H:; Lee, J.H.; Yoon, J.B.; Choi, Y.K. A robust superhydrophobic and superoleophobic surface with inverse-trapezoidal microstructures on a large transparent flexible substrate. Soft Matter 2010, 6, 1401-1404; Im, M.; Im, H:; Lee, J.H.; Yoon, J.B.; Choi, Y.K. Analytical Modeling and Thermodynamic Analysis of Robust Superhydrophobic Surfaces with Inverse-Trapezoidal Microstructures. Langmuir 2010, 26, 17389-17397). We find that each of these parameters, if considered alone, would give trivial optima, while their interplay provides a well-defined optimal shape and aspect ratio. The inclusion of mechanical robustness in combination with conventional performance characteristics favors solutions relevant for practical applications, as mechanical stability is a critical issue not often addressed in idealized models.
Parametric instabilities in picosecond time scales
Baldis, H.A.; Rozmus, W.; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S.; Tikhonchuk, V.T.
1993-03-01
The coupling of intense laser light with plasmas is a rich field of plasma physics, with many applications. Among these are inertial confinement fusion (ICF), x-ray lasers, particle acceleration, and x-ray sources. Parametric instabilities have been studied for many years because of their importance to ICF; with laser pulses with duration of approximately a nanosecond, and laser intensities in the range 10{sup 14}--10{sup 15}W/cm{sup 2} these instabilities are of crucial concern because of a number of detrimental effects. Although the laser pulse duration of interest for these studies are relatively long, it has been evident in the past years that to reach an understanding of these instabilities requires their characterization and analysis in picosecond time scales. At the laser intensities of interest, the growth rate for stimulated Brillouin scattering (SBS) is of the order of picoseconds, and of an order of magnitude shorter for stimulated Raman scattering (SRS). In this paper the authors discuss SBS and SRS in the context of their evolution in picosecond time scales. They describe the fundamental concepts associated with their growth and saturation, and recent work on the nonlinear treatment required for the modeling of these instabilities at high laser intensities.
Optical parametric oscillators for medical applications
NASA Astrophysics Data System (ADS)
Gloster, Lawrie A. W.; Golding, Paul S.; King, Terence A.
1996-04-01
In recent years optical parametric oscillators (OPOs) have undergone a renaissance largely due to the discovery of new nonlinear materials capable of wide continuous tuning ranges spanning from the UV to the near-infrared spectral regions. To date, however, OPOs have not been exploited in the medical field despite their advantages over the dye laser in terms of tuning range and solid state structure. We consider the development of an OPO based on barium borate (BBO) which can be tailored to suit applications in medicine. Converting the maximum number of pump photons to tunable signal and idler photons is of great importance to secure high-fluence radiation necessary for many treatments. With this in mind, we report on an all- solid-state system using BBO which has been optimized by computer modeling with the potential of delivering amplification factors of typically up to 20 over a continuous tuning range of 700 nm to 1000 nm. As an example of its biomedical application, we describe the selective excitation of biomolecules and chromophores for cell destruction using malachite green isothiocyanate labelled bacteria. The potential for development is reviewed towards other medical applications such as diagnostic sensing and phototherapy.
Parametric approach to linear induction accelerator design
Bresie, D.A.; Andrews, J.A.; Ingram, S.W. . Center for Electromechanics)
1991-01-01
Past work on the design of linear induction accelerators has centered on the development of computer codes to analyze accelerator designs, using the current filament method. While these filament models are a very valuable tool for evaluating the performance of an induction launcher design, they provide little insight into the selection of dimensions, materials, and operation points for accelerators with interesting performance. Described in this paper is a parametric approach to defining effective accelerator designs. This method uses a computer optimization routine to iteratively seek out effective designs. The optimization routine is forced to search within a parameter space restricted to interesting and realistic parameters such as size, weight, voltage, and temperature rises. A filament model is used as the filter for the optimizer. Several linear induction accelerators have been designed using this method. The accelerators designed all used a switched capacitor power supply. While the run time of this code on The University of Texas' CRAY XMP-24 computer is moderately long, the resulting designs have good predicted performance. With realistic power supplies and materials, accelerator efficiencies in the 20 to 40% range were easily obtained. This paper describes the effect of armature diameter, length-to-diameter ratio, and weight, as well as other parameters, on the optimum accelerator design.
Visual to Parametric Interaction (V2PI).
Leman, Scotland C; House, Leanna; Maiti, Dipayan; Endert, Alex; North, Chris
2013-01-01
Typical data visualizations result from linear pipelines that start by characterizing data using a model or algorithm to reduce the dimension and summarize structure, and end by displaying the data in a reduced dimensional form. Sensemaking may take place at the end of the pipeline when users have an opportunity to observe, digest, and internalize any information displayed. However, some visualizations mask meaningful data structures when model or algorithm constraints (e.g., parameter specifications) contradict information in the data. Yet, due to the linearity of the pipeline, users do not have a natural means to adjust the displays. In this paper, we present a framework for creating dynamic data displays that rely on both mechanistic data summaries and expert judgement. The key is that we develop both the theory and methods of a new human-data interaction to which we refer as " Visual to Parametric Interaction" (V2PI). With V2PI, the pipeline becomes bi-directional in that users are embedded in the pipeline; users learn from visualizations and the visualizations adjust to expert judgement. We demonstrate the utility of V2PI and a bi-directional pipeline with two examples.
Parametric Testing of Launch Vehicle FDDR Models
NASA Technical Reports Server (NTRS)
Schumann, Johann; Bajwa, Anupa; Berg, Peter; Thirumalainambi, Rajkumar
2011-01-01
For the safe operation of a complex system like a (manned) launch vehicle, real-time information about the state of the system and potential faults is extremely important. The on-board FDDR (Failure Detection, Diagnostics, and Response) system is a software system to detect and identify failures, provide real-time diagnostics, and to initiate fault recovery and mitigation. The ERIS (Evaluation of Rocket Integrated Subsystems) failure simulation is a unified Matlab/Simulink model of the Ares I Launch Vehicle with modular, hierarchical subsystems and components. With this model, the nominal flight performance characteristics can be studied. Additionally, failures can be injected to see their effects on vehicle state and on vehicle behavior. A comprehensive test and analysis of such a complicated model is virtually impossible. In this paper, we will describe, how parametric testing (PT) can be used to support testing and analysis of the ERIS failure simulation. PT uses a combination of Monte Carlo techniques with n-factor combinatorial exploration to generate a small, yet comprehensive set of parameters for the test runs. For the analysis of the high-dimensional simulation data, we are using multivariate clustering to automatically find structure in this high-dimensional data space. Our tools can generate detailed HTML reports that facilitate the analysis.
Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation
NASA Astrophysics Data System (ADS)
Pentaris, Fragkiskos P.; Fouskitakis, George N.
2014-05-01
The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5
Kalicka, Renata; Pietrenko-Dabrowska, Anna
2007-03-01
In the paper MRI measurements are used for assessment of brain tissue perfusion and other features and functions of the brain (cerebral blood flow - CBF, cerebral blood volume - CBV, mean transit time - MTT). Perfusion is an important indicator of tissue viability and functioning as in pathological tissue blood flow, vascular and tissue structure are altered with respect to normal tissue. MRI enables diagnosing diseases at an early stage of their course. The parametric and non-parametric approaches to the identification of MRI models are presented and compared. The non-parametric modeling adopts gamma variate functions. The parametric three-compartmental catenary model, based on the general kinetic model, is also proposed. The parameters of the models are estimated on the basis of experimental data. The goodness of fit of the gamma variate and the three-compartmental models to the data and the accuracy of the parameter estimates are compared. Kalman filtering, smoothing the measurements, was adopted to improve the estimate accuracy of the parametric model. Parametric modeling gives a better fit and better parameter estimates than non-parametric and allows an insight into the functioning of the system. To improve the accuracy optimal experiment design related to the input signal was performed.
NASA Astrophysics Data System (ADS)
Verrelst, Jochem; Rivera, Juan Pablo; Veroustraete, Frank; Muñoz-Marí, Jordi; Clevers, Jan G. P. W.; Camps-Valls, Gustau; Moreno, José
2015-10-01
Given the forthcoming availability of Sentinel-2 (S2) images, this paper provides a systematic comparison of retrieval accuracy and processing speed of a multitude of parametric, non-parametric and physically-based retrieval methods using simulated S2 data. An experimental field dataset (SPARC), collected at the agricultural site of Barrax (Spain), was used to evaluate different retrieval methods on their ability to estimate leaf area index (LAI). With regard to parametric methods, all possible band combinations for several two-band and three-band index formulations and a linear regression fitting function have been evaluated. From a set of over ten thousand indices evaluated, the best performing one was an optimized three-band combination according to (ρ560 -ρ1610 -ρ2190) / (ρ560 +ρ1610 +ρ2190) with a 10-fold cross-validation RCV2 of 0.82 (RMSECV : 0.62). This family of methods excel for their fast processing speed, e.g., 0.05 s to calibrate and validate the regression function, and 3.8 s to map a simulated S2 image. With regard to non-parametric methods, 11 machine learning regression algorithms (MLRAs) have been evaluated. This methodological family has the advantage of making use of the full optical spectrum as well as flexible, nonlinear fitting. Particularly kernel-based MLRAs lead to excellent results, with variational heteroscedastic (VH) Gaussian Processes regression (GPR) as the best performing method, with a RCV2 of 0.90 (RMSECV : 0.44). Additionally, the model is trained and validated relatively fast (1.70 s) and the processed image (taking 73.88 s) includes associated uncertainty estimates. More challenging is the inversion of a PROSAIL based radiative transfer model (RTM). After the generation of a look-up table (LUT), a multitude of cost functions and regularization options were evaluated. The best performing cost function is Pearson's χ -square. It led to a R2 of 0.74 (RMSE: 0.80) against the validation dataset. While its validation went fast
Zhao, Yongjun; Zhang, Yuejin; Ge, Zhigang; Hu, Changwei; Zhang, Hui
2014-03-01
This research focused on the nutrient removal and the simultaneous CO2, CH4, and N2O emission rates of various combinations of vertical subsurface flow constructed wetlands (VSFCWs) and earthworm eco-filters (EEs) under different influent C/N ratios in synthetic wastewater. The optimal parameters for nutrient removal were influent C/N ratios of 5 : 1 and 10 : 1 as well as the combination VSFCW-EE. Relatively low values of greenhouse gas (GHG) emission rates measured in situ were obtained at a C/N ratio of 5 : 1. The emission rates of CH4 and N2O were considerably lower than that of CO2. The VSFCW-EE and EE-VSFCW combinations showed similar GHG emission results. The C/N ratio of 5 : 1 and the VSFCW-EE combination exhibited the highest nutrient removal efficiency with the lowest GHG emission rate. Wastewater nutrient removal and GHG emission were both high during summer (June to August) and low during winter (December to February).
Direct Estimation of Kinetic Parametric Images for Dynamic PET
Wang, Guobao; Qi, Jinyi
2013-01-01
Dynamic positron emission tomography (PET) can monitor spatiotemporal distribution of radiotracer in vivo. The spatiotemporal information can be used to estimate parametric images of radiotracer kinetics that are of physiological and biochemical interests. Direct estimation of parametric images from raw projection data allows accurate noise modeling and has been shown to offer better image quality than conventional indirect methods, which reconstruct a sequence of PET images first and then perform tracer kinetic modeling pixel-by-pixel. Direct reconstruction of parametric images has gained increasing interests with the advances in computing hardware. Many direct reconstruction algorithms have been developed for different kinetic models. In this paper we review the recent progress in the development of direct reconstruction algorithms for parametric image estimation. Algorithms for linear and nonlinear kinetic models are described and their properties are discussed. PMID:24396500
Nondegenerate Parametric Resonance in a Tunable Superconducting Cavity
NASA Astrophysics Data System (ADS)
Wustmann, Waltraut; Shumeiko, Vitaly
2017-08-01
We develop a theory for nondegenerate parametric resonance in a tunable superconducting cavity. We focus on nonlinear effects that are caused by nonlinear Josephson elements connected to the cavity. We analyze parametric amplification in a strong nonlinear regime at the parametric-instability threshold, and we calculate maximum gain values. Above the threshold, in the parametric-oscillator regime, the cavity linear response diverges at the oscillator frequency at all pump strengths. We show that this divergence is related to the continuous degeneracy of the free oscillator state with respect to the phase. Applying on-resonance input lifts the degeneracy and removes the divergence. We also investigate quantum noise squeezing. It is shown that in the strong amplification regime, the noise undergoes four-mode squeezing, and that, in this regime, the output signal-to-noise ratio can significantly exceed the input value. We also analyze the intermode frequency conversion and identify the parameters at which full conversion is achieved.
Forecasting Marine Corps Enlisted Attrition Through Parametric Modeling
2009-03-01
OF PAGES 85 14. SUBJECT TERMS Forecasting, Attrition, Marine Corps NEAS losses, Gompertz Model, Survival Analysis 16. PRICE CODE 17. SECURITY...18 1. Parametric Proportional Hazards Models ......................................18 2. Gompertz Models...19 a. Gompertz Hazard Function....................................................19 b. Gompertz Cumulative
Evaluating forest management policies by parametric linear programing
Daniel I. Navon; Richard J. McConnen
1967-01-01
An analytical and simulation technique, parametric linear programing explores alternative conditions and devises an optimal management plan for each condition. Its application in solving policy-decision problems in the management of forest lands is illustrated in an example.
Higher Order Crossings from a Parametric Family of Linear Filters
1989-09-01
HIGHER ORDER CROSSINGS FROM A PARAMETRIC FAMILY OF LINEAR FILTERS DTIC DTC Benjamin Kedem and Ta-hsin Li E! U 4C99 Department of MathematicsS4 9...NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED Higher order crossings from a parametric family Technical Report of linear filters...corresponding family of zero-crossing counts. The resulting family of counts is referred to as higher order crossings or HOC. Thus, HOC are zero-crossing
Finding Rational Parametric Curves of Relative Degree One or Two
ERIC Educational Resources Information Center
Boyles, Dave
2010-01-01
A plane algebraic curve, the complete set of solutions to a polynomial equation: f(x, y) = 0, can in many cases be drawn using parametric equations: x = x(t), y = y(t). Using algebra, attempting to parametrize by means of rational functions of t, one discovers quickly that it is not the degree of f but the "relative degree," that describes how…
Finding Rational Parametric Curves of Relative Degree One or Two
ERIC Educational Resources Information Center
Boyles, Dave
2010-01-01
A plane algebraic curve, the complete set of solutions to a polynomial equation: f(x, y) = 0, can in many cases be drawn using parametric equations: x = x(t), y = y(t). Using algebra, attempting to parametrize by means of rational functions of t, one discovers quickly that it is not the degree of f but the "relative degree," that describes how…
Effects of mergers on non-parametric morphologies
NASA Astrophysics Data System (ADS)
Bignone, Lucas A.; Tissera, Patricia B.; Sillero, Emanuel; Pedrosa, Susana E.; Pellizza, Leonardo J.; Lambas, Diego G.
2017-06-01
We study the effects of mergers on non-parametric morphologies of galaxies. We compute the Gini index, M20, asymmetry and concentration statistics for z = 0 galaxies in the Illustris simulation and compare non-parametric morphologies of major mergers, minor merges, close pairs, distant pairs and unperturbed galaxies. We determine the effectiveness of observational methods based on these statistics to select merging galaxies.
The Performance of a Parametric Receiver in an Inhomogeneous Medium.
1980-08-18
subject considered in this thesis is the performance of a parametric acoustic receiving array in an inhomogeneous medium. Develop- ment of this subject... ment presented. Of necessity, topics have been treated briefly. Some 42 topics, such as the use of arrays of parametric receivers, the phase mod- 41...that the agree- ment of the Kolmogorov theory with their experimental results was a conse- quence of the ’freezing’ of the thermal patches after their
Two-parametric PT-symmetric quartic family
NASA Astrophysics Data System (ADS)
Eremenko, Alexandre; Gabrielov, Andrei
2012-05-01
We describe a parametrization of the real spectral locus of the two-parametric family of PT-symmetric quartic oscillators. For this family, we find a parameter region where all eigenvalues are real, extending the results of Dorey et al (2007 J. Phys. A: Math Theor. 40 R205-83) and Shin (2005 J. Phys. A: Math. Gen. 38 6147-66 2002 Commun. Math. Phys. 229 543-64).
CFD parametric study of consortium impeller
NASA Astrophysics Data System (ADS)
Cheng, Gary C.; Chen, Y. S.; Garcia, Roberto; Williams, Robert W.
1993-07-01
Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design impact in a productive manner. The main goal of this study is to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A Finite Difference Navier-Stokes flow solver, FDNS, which includes the extended k-epsilon turbulence model and appropriate moving interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. A second-order central difference scheme plus adaptive dissipation terms was employed in the FDNS code, along with a predictor plus multi-corrector pressure-based solution procedure. The multi-zone, multi-block capability allows the FDNS code to efficiently solve flow fields with complicated geometry. The FDNS code has been benchmarked by analyzing the pump consortium inducer, and it provided satisfactory results. In the present study, a CFD parametric study of the pump consortium impeller was conducted using the FDNS code. The pump consortium impeller, with partial blades, is a new design concept of the advanced rocket engines. The parametric study was to analyze the baseline design of the consortium impeller and its modification which utilizes TANDEM blades. In the present study, the TANDEM blade configuration of the consortium impeller considers cut full blades for about one quarter chord length from the leading edge and clocks the leading edge portion with an angle of 7.5 or 22.5 degrees. The purpose of the present study is to investigate the effect and trend of the TANDEM blade modification and provide the result as a design guideline. A 3-D flow analysis, with a 103 x 23 x 30 mesh grid system and with the inlet flow conditions measured by Rocketdyne, was performed for the baseline consortium impeller. The numerical result shows that the mass flow rate splits through various blade passages are relatively uniform
CFD Parametric Study of Consortium Impeller
NASA Technical Reports Server (NTRS)
Cheng, Gary C.; Chen, Y. S.; Garcia, Roberto; Williams, Robert W.
1993-01-01
Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design impact in a productive manner. The main goal of this study is to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A Finite Difference Navier-Stokes flow solver, FDNS, which includes the extended k-epsilon turbulence model and appropriate moving interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. A second-order central difference scheme plus adaptive dissipation terms was employed in the FDNS code, along with a predictor plus multi-corrector pressure-based solution procedure. The multi-zone, multi-block capability allows the FDNS code to efficiently solve flow fields with complicated geometry. The FDNS code has been benchmarked by analyzing the pump consortium inducer, and it provided satisfactory results. In the present study, a CFD parametric study of the pump consortium impeller was conducted using the FDNS code. The pump consortium impeller, with partial blades, is a new design concept of the advanced rocket engines. The parametric study was to analyze the baseline design of the consortium impeller and its modification which utilizes TANDEM blades. In the present study, the TANDEM blade configuration of the consortium impeller considers cut full blades for about one quarter chord length from the leading edge and clocks the leading edge portion with an angle of 7.5 or 22.5 degrees. The purpose of the present study is to investigate the effect and trend of the TANDEM blade modification and provide the result as a design guideline. A 3-D flow analysis, with a 103 x 23 x 30 mesh grid system and with the inlet flow conditions measured by Rocketdyne, was performed for the baseline consortium impeller. The numerical result shows that the mass flow rate splits through various blade passages are relatively uniform
Optical Parametric Technology for Methane Measurements
NASA Technical Reports Server (NTRS)
Dawsey, Martha; Numata, Kenji; Wu, Stewart; Riris, Haris
2015-01-01
Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. Yet, lack of understanding of the processes that control CH4 sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH4 from orbit. Our concept for a CH4 lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth's surface to measure CH4. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH4 detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 microJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH4 measurements with 1% precision (10-20 ppb).
Optical parametric technology for methane measurements
NASA Astrophysics Data System (ADS)
Dawsey, Martha; Numata, Kenji; Wu, Stewart; Riris, Haris
2015-09-01
Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. Yet, lack of understanding of the processes that control CH4 sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH4 from orbit. Our concept for a CH4 lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth's surface to measure CH4. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH4 detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 μJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH4 measurements with 1% precision (10-20 ppb).
Parametric Wave Transformation Models on Natural Beaches
NASA Astrophysics Data System (ADS)
Apotsos, A. A.; Raubenheimer, B.; Elgar, S.; Guza, R. T.
2006-12-01
Seven parametric models for wave height transformation across the surf zone [e.g., Thornton and Guza, 1983] are tested with observations collected between the shoreline and about 5-m water depth during 2 experiments on a barred beach near Duck, NC, and between the shoreline and about 3.5-m water depth during 2 experiments on unbarred beaches near La Jolla, CA. Offshore wave heights ranged from about 0.1 to 3.0 m. Beach profiles were surveyed approximately every other day. The models predict the observations well. Root-mean-square errors between observed and simulated wave heights are small in water depths h > 2 m (average rms errors < 10%), and increase with decreasing depth for h < 2 m (average rms errors > 20%). The lowest rms errors (i.e., the most accurate predictions) are achieved by tuning a free parameter, γ, in each model. To tune the models accurately to the data considered here, observations are required at 3 to 5 locations, and must span the surf zone. No tuned or untuned model provides the best predictions for all data records in any one experiment. The best fit γ's for each model-experiment pair are represented well with an empirical hyperbolic tangent curve based on the inverse Iribarren number. In 3 of the 4 data sets, estimating γ for each model using an average curve based on the predictions and observations from all 4 experiments typically improves model-data agreement relative to using a constant or previously determined empirical γ. The best fit γ's at the 4th experiment (conducted off La Jolla, CA) are roughly 20% smaller than the γ's for the other 3 experiments, and thus using the experiment-averaged curve increases prediction errors. Possible causes for the smaller γ's at the 4th experiment will be discussed. Funded by ONR and NSF.
Hamiltonian constraint in polymer parametrized field theory
NASA Astrophysics Data System (ADS)
Laddha, Alok; Varadarajan, Madhavan
2011-01-01
Recently, a generally covariant reformulation of two-dimensional flat spacetime free scalar field theory known as parametrized field theory was quantized using loop quantum gravity (LQG) type “polymer” representations. Physical states were constructed, without intermediate regularization structures, by averaging over the group of gauge transformations generated by the constraints, the constraint algebra being a Lie algebra. We consider classically equivalent combinations of these constraints corresponding to a diffeomorphism and a Hamiltonian constraint, which, as in gravity, define a Dirac algebra. Our treatment of the quantum constraints parallels that of LQG and obtains the following results, expected to be of use in the construction of the quantum dynamics of LQG: (i) the (triangulated) Hamiltonian constraint acts only on vertices, its construction involves some of the same ambiguities as in LQG and its action on diffeomorphism invariant states admits a continuum limit, (ii) if the regulating holonomies are in representations tailored to the edge labels of the state, all previously obtained physical states lie in the kernel of the Hamiltonian constraint, (iii) the commutator of two (density weight 1) Hamiltonian constraints as well as the operator correspondent of their classical Poisson bracket converge to zero in the continuum limit defined by diffeomorphism invariant states, and vanish on the Lewandowski-Marolf habitat, (iv) the rescaled density 2 Hamiltonian constraints and their commutator are ill-defined on the Lewandowski-Marolf habitat despite the well-definedness of the operator correspondent of their classical Poisson bracket there, (v) there is a new habitat which supports a nontrivial representation of the Poisson-Lie algebra of density 2 constraints.
Hamiltonian constraint in polymer parametrized field theory
Laddha, Alok; Varadarajan, Madhavan
2011-01-15
Recently, a generally covariant reformulation of two-dimensional flat spacetime free scalar field theory known as parametrized field theory was quantized using loop quantum gravity (LQG) type ''polymer'' representations. Physical states were constructed, without intermediate regularization structures, by averaging over the group of gauge transformations generated by the constraints, the constraint algebra being a Lie algebra. We consider classically equivalent combinations of these constraints corresponding to a diffeomorphism and a Hamiltonian constraint, which, as in gravity, define a Dirac algebra. Our treatment of the quantum constraints parallels that of LQG and obtains the following results, expected to be of use in the construction of the quantum dynamics of LQG: (i) the (triangulated) Hamiltonian constraint acts only on vertices, its construction involves some of the same ambiguities as in LQG and its action on diffeomorphism invariant states admits a continuum limit, (ii) if the regulating holonomies are in representations tailored to the edge labels of the state, all previously obtained physical states lie in the kernel of the Hamiltonian constraint, (iii) the commutator of two (density weight 1) Hamiltonian constraints as well as the operator correspondent of their classical Poisson bracket converge to zero in the continuum limit defined by diffeomorphism invariant states, and vanish on the Lewandowski-Marolf habitat, (iv) the rescaled density 2 Hamiltonian constraints and their commutator are ill-defined on the Lewandowski-Marolf habitat despite the well-definedness of the operator correspondent of their classical Poisson bracket there, (v) there is a new habitat which supports a nontrivial representation of the Poisson-Lie algebra of density 2 constraints.
Parametric study of electrostatically charged sprays
Barnhart, J.S.; Durbin, T.E.; Peters, J.E. . Dept. of Mechanical and Industrial Engineering); Leong, K.H. )
1989-12-01
Electrostatically charged sprays are used in a wide range of applications. They include the coating of surfaces as with paint spraying, the production of fine powders and the control of pollutants. The phenomenon of electrostatic spraying has been much researched particularly for the cases of dielectric fluids in paint spraying and conductive fluids in fine metallic powder production. although the literature on electrostatic spraying is voluminous, the parametric dependence of the size distribution of the spray under various conditions still lacks precise definition. The focus of this study is the generation of charged water droplets for the production of ions and radicals in flue gases by pulsed corona discharges to control SO{sub 2} and NO{sub x}. As a first step in evaluating charged sprays for such use, a laboratory-scale injection system was evaluated by measuring atomization performance of needle injectors over a wide range of parameters. Sauter mean diameter (SMD) determined with a Phase/Doppler Particle Analyzer (PDPA) was used as the measure of atomization performance. The independent parameters investigated include applied voltage, needle size, flow rate and NaNO{sub 3} concentration (used to vary the solution conductivity). Because the spray was only about 2 mm wide at the sampling point, SMD measured at a single location was taken to be representative of the spray. This assumption was tested by taking radial traverses through the spray. Current flow from the needle to a collector plate 6 cm below was measured with and without solution flow to quantify the relative current-carrying capacities of the spray and the surrounding air. 4 refs., 6 figs.
Parametric Decay Instability Control By Nonmonochromatic Pumps
NASA Astrophysics Data System (ADS)
Arkhipenko, V.,; Gusakov, E.; Simonchik, L.
2010-07-01
The results of comprehensive experimental and theoretical investigations of the last decade are reviewed, revealing a complicated and interesting behavior of nonlinear inhomogeneous wave system. It is shown that the wide variety of physical effects is accompanying the parametric decay instability (PDI) driven by the frequency modulated pump. The experiment is carried out in the linear plasma device "Granit", where the PDI l ? l' + s is excited at the microwave power less than 20 mW. It is shown that pump frequency modulation does not influence the PDI when the modulation frequency is much faster than the decay wave transient time in the interaction region. In the case of slower modulation, the PDI resonant enhancement and suppression may take place instead. The physical reason for the observed PDI resonant enhancement is provided by suppression of convective losses of the daughter wave from the decay region, drifting due to the slow pump frequency modulation at the ion acoustic velosity. The strong resonant suppression of the most dangerous absolute PDI is observed at a minimal frequency deviation (less than 1%) when the modulation frequency is equal to frequency separation of the stable lines observed in the backscattering spectrum which correspond to ion acoustic wave eigen modes excited in plasma by the absolute PDI. Based on this effect a scheme of active PDI feed-back control is proposed. A possibility of deep PDI suppression by launching of an additional (small power) pump wave possessing a frequency shifted by the value equal to the frequency separation of ion acoustic eigen modes is demonstrated as well. The recovery of microwave power absorption at the PDI suppression is shown using measurements of the plasma luminosity and fluxes of accelerated electrons.
Fast parametric beamformer for synthetic aperture imaging.
Nikolov, Svetoslav Ivanov; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev
2008-08-01
This paper describes the design and implementation of a real-time delay-and-sum synthetic aperture beamformer. The beamforming delays and apodization coefficients are described parametrically. The image is viewed as a set of independent lines that are defined in 3D by their origin, direction, and inter-sample distance. The delay calculation is recursive and inspired by the coordinate rotation digital computer (CORDIC) algorithm. Only 3 parameters per channel and line are needed for their generation. The calculation of apodization coefficients is based on a piece- wise linear approximation. The implementation of the beamformer is optimized with respect to the architecture of a novel synthetic aperture real-time ultrasound scanner (SARUS), in which 4 channels are processed by the same set of field-programmable gate arrays (FPGA). In synthetic transmit aperture imaging, low-resolution images are formed after every emission. Summing all low-resolution images produces a perfectly focused high-resolution image. The design of the beamformer is modular, and a single beamformation unit can produce 4600 low-resolution images per second, each consisting of 32 lines and 1024 complex samples per line. In its present incarnation, 3 such modules fit in a single device. The summation of low-resolution images is performed internally in the FPGA to reduce the required bandwidth. The delays are calculated with a precision of 1/16th of a sample, and the apodization coefficients with 7-bit precision. The accumulation of low-resolution images is performed with 24-bit precision. The level of the side- and grating lobes, introduced by the use of integer numbers in the calculations and truncation of intermediate results, is below -86 dB from the peak.
Interacting parametrized post-Friedmann method
NASA Astrophysics Data System (ADS)
Richarte, Martín G.; Xu, Lixin
2016-04-01
We apply the interacting parametrized post-Friedmann (IPPF) method to coupled dark energy models where the interaction is proportional to dark matter density at background level. In the first case, the dark components are treated as fluids and the growth of dark matter perturbations only feel the interaction via the modification of background quantities provided dark matter follows geodesic. We also perform a Markov Chain Monte-Carlo analysis which combines several cosmological probes including the cosmic microwave background (WMAP9+Planck) data, baryon acoustic oscillation (BAO) measurements, JLA sample of supernovae, Hubble constant (HST), and redshift-space distortion (RSD) measurements through the fσ 8(z) data points. The joint observational analysis of Planck+WP+JLA+BAO+HST+ RSD data leads to a coupling parameter, ξ c=0.00140_{-0.00080}^{+0.00079} at 1σ level for vanishing momentum transfer potential. On the other hand, we deal with a coupled quintessence model which exhibits a violation of the equivalence principle coming form a coupling term in the modified Euler equation; as a result of that the local Hubble expansion rate and the effective gravitational coupling are both enhanced. Provided that the interaction is parallel to scalar field velocity the momentum transfer potential is switched on, leading to a lower interaction coupling ξ c=0.00136_{-0.00073}^{+0.00080} at 1σ level when Planck+WP+JLA+BAO+HST+RSD data are combined. Besides, the CMB power spectrum shows up a correlation between the coupling parameter ξ c and the position of acoustic peaks or their amplitudes. The first peak's height increases when ξ c takes larger values and its position is shifted. We also obtain the matter power spectrum may be affected by the strength of interaction coupling over scales bigger than 10^{-2} h Mpc^{-1}, reducing its amplitude in relation to the vanilla model.
Housing price prediction: parametric versus semi-parametric spatial hedonic models
NASA Astrophysics Data System (ADS)
Montero, José-María; Mínguez, Román; Fernández-Avilés, Gema
2017-08-01
House price prediction is a hot topic in the economic literature. House price prediction has traditionally been approached using a-spatial linear (or intrinsically linear) hedonic models. It has been shown, however, that spatial effects are inherent in house pricing. This article considers parametric and semi-parametric spatial hedonic model variants that account for spatial autocorrelation, spatial heterogeneity and (smooth and nonparametrically specified) nonlinearities using penalized splines methodology. The models are represented as a mixed model that allow for the estimation of the smoothing parameters along with the other parameters of the model. To assess the out-of-sample performance of the models, the paper uses a database containing the price and characteristics of 10,512 homes in Madrid, Spain (Q1 2010). The results obtained suggest that the nonlinear models accounting for spatial heterogeneity and flexible nonlinear relationships between some of the individual or areal characteristics of the houses and their prices are the best strategies for house price prediction.
Scene Parsing With Integration of Parametric and Non-Parametric Models
NASA Astrophysics Data System (ADS)
Shuai, Bing; Zuo, Zhen; Wang, Gang; Wang, Bing
2016-05-01
We adopt Convolutional Neural Networks (CNNs) to be our parametric model to learn discriminative features and classifiers for local patch classification. Based on the occurrence frequency distribution of classes, an ensemble of CNNs (CNN-Ensemble) are learned, in which each CNN component focuses on learning different and complementary visual patterns. The local beliefs of pixels are output by CNN-Ensemble. Considering that visually similar pixels are indistinguishable under local context, we leverage the global scene semantics to alleviate the local ambiguity. The global scene constraint is mathematically achieved by adding a global energy term to the labeling energy function, and it is practically estimated in a non-parametric framework. A large margin based CNN metric learning method is also proposed for better global belief estimation. In the end, the integration of local and global beliefs gives rise to the class likelihood of pixels, based on which maximum marginal inference is performed to generate the label prediction maps. Even without any post-processing, we achieve state-of-the-art results on the challenging SiftFlow and Barcelona benchmarks.
Scene Parsing With Integration of Parametric and Non-Parametric Models.
Shuai, Bing; Zuo, Zhen; Wang, Gang; Wang, Bing
2016-05-01
We adopt convolutional neural networks (CNNs) to be our parametric model to learn discriminative features and classifiers for local patch classification. Based on the occurrence frequency distribution of classes, an ensemble of CNNs (CNN-Ensemble) are learned, in which each CNN component focuses on learning different and complementary visual patterns. The local beliefs of pixels are output by CNN-Ensemble. Considering that visually similar pixels are indistinguishable under local context, we leverage the global scene semantics to alleviate the local ambiguity. The global scene constraint is mathematically achieved by adding a global energy term to the labeling energy function, and it is practically estimated in a non-parametric framework. A large margin-based CNN metric learning method is also proposed for better global belief estimation. In the end, the integration of local and global beliefs gives rise to the class likelihood of pixels, based on which maximum marginal inference is performed to generate the label prediction maps. Even without any post-processing, we achieve the state-of-the-art results on the challenging SiftFlow and Barcelona benchmarks.
Stochastic parametrizations and model uncertainty in the Lorenz '96 system.
Arnold, H M; Moroz, I M; Palmer, T N
2013-05-28
Simple chaotic systems are useful tools for testing methods for use in numerical weather simulations owing to their transparency and computational cheapness. The Lorenz system was used here; the full system was defined as 'truth', whereas a truncated version was used as a testbed for parametrization schemes. Several stochastic parametrization schemes were investigated, including additive and multiplicative noise. The forecasts were started from perfect initial conditions, eliminating initial condition uncertainty. The stochastically generated ensembles were compared with perturbed parameter ensembles and deterministic schemes. The stochastic parametrizations showed an improvement in weather and climate forecasting skill over deterministic parametrizations. Including a temporal autocorrelation resulted in a significant improvement over white noise, challenging the standard idea that a parametrization should only represent sub-gridscale variability. The skill of the ensemble at representing model uncertainty was tested; the stochastic ensembles gave better estimates of model uncertainty than the perturbed parameter ensembles. The forecasting skill of the parametrizations was found to be linked to their ability to reproduce the climatology of the full model. This is important in a seamless prediction system, allowing the reliability of short-term forecasts to provide a quantitative constraint on the accuracy of climate predictions from the same system.
Signal-to-noise ratio in parametrically driven oscillators.
Batista, Adriano A; Moreira, Raoni S N
2011-12-01
We report a theoretical model based on Green's functions and averaging techniques that gives analytical estimates to the signal-to-noise ratio (SNR) near the first parametric instability zone in parametrically driven oscillators in the presence of added ac drive and added thermal noise. The signal term is given by the response of the parametrically driven oscillator to the added ac drive, while the noise term has two different measures: one is dc and the other is ac. The dc measure of noise is given by a time average of the statistically averaged fluctuations of the displacement from equilibrium in the parametric oscillator due to thermal noise. The ac measure of noise is given by the amplitude of the statistically averaged fluctuations at the frequency of the parametric pump. We observe a strong dependence of the SNR on the phase between the external drive and the parametric pump. For some range of the phase there is a high SNR, while for other values of phase the SNR remains flat or decreases with increasing pump amplitude. Very good agreement between analytical estimates and numerical results is achieved.
Fitting C² continuous parametric surfaces to frontiers delimiting physiologic structures.
Bayer, Jason D; Epstein, Matthew; Beaumont, Jacques
2014-01-01
We present a technique to fit C(2) continuous parametric surfaces to scattered geometric data points forming frontiers delimiting physiologic structures in segmented images. Such mathematical representation is interesting because it facilitates a large number of operations in modeling. While the fitting of C(2) continuous parametric curves to scattered geometric data points is quite trivial, the fitting of C(2) continuous parametric surfaces is not. The difficulty comes from the fact that each scattered data point should be assigned a unique parametric coordinate, and the fit is quite sensitive to their distribution on the parametric plane. We present a new approach where a polygonal (quadrilateral or triangular) surface is extracted from the segmented image. This surface is subsequently projected onto a parametric plane in a manner to ensure a one-to-one mapping. The resulting polygonal mesh is then regularized for area and edge length. Finally, from this point, surface fitting is relatively trivial. The novelty of our approach lies in the regularization of the polygonal mesh. Process performance is assessed with the reconstruction of a geometric model of mouse heart ventricles from a computerized tomography scan. Our results show an excellent reproduction of the geometric data with surfaces that are C(2) continuous.
NASA Technical Reports Server (NTRS)
Converse, G. L.
1984-01-01
A modeling technique for single stage flow modulating fans or centrifugal compressors has been developed which will enable the user to obtain consistent and rapid off-design performnce from design point input. The fan flow modulation may be obtained by either a VIGV (variable inlet guide vane) or a VPF (variable pitch rotor) option. Only the VIGV option is available for the centrifugal compressor. The modeling technique has been incorporated into a time-sharing program to facilitate its use. Because this report contains a description of the input output data, values of typical inputs, and examples cases, it is suitable as a user's manual. This report is the last of a three volume set describing the parametric representation of compressor fans, and turbines. The titles of the three volumes are as follows: (1) Volume 1 CMGEN USER's Manual (Parametric Compressor Generator); (2) Volume 2 PART USER's Manual (Parametric Turbine); (3) Volume 3 MODFAN USER's Manual (Parametric Modulating Flow Fan).
Rabeson, H; Ratiney, H; van Ormondt, D; Graveron-Demilly, D
2007-01-01
Semi-parametric disentanglement of parametric parts from non-parametric parts of a signal is a universal problem. This study concerns estimation of metabolite concentrations from in vivo Magnetic Resonance Spectroscopy (MRS) signals. Due to in vivo conditions, so-called macro-molecules contribute non-parametric components to the signals. Disentanglement is achieved by exploiting prior knowledge about the parametric and non-parametric parts directly in the measurement domain. Moreover, Cramér-Rao bounds on the non-parametric part are derived. These expressions are used to automate the disentanglement procedure.
NASA Astrophysics Data System (ADS)
Magri, Alphonso; Krol, Andrzej; Lipson, Edward; Mandel, James; McGraw, Wendy; Lee, Wei; Tillapaugh-Fay, Gwen; Feiglin, David
2009-02-01
This study was undertaken to register 3D parametric breast images derived from Gd-DTPA MR and F-18-FDG PET/CT dynamic image series. Nonlinear curve fitting (Levenburg-Marquardt algorithm) based on realistic two-compartment models was performed voxel-by-voxel separately for MR (Brix) and PET (Patlak). PET dynamic series consists of 50 frames of 1-minute duration. Each consecutive PET image was nonrigidly registered to the first frame using a finite element method and fiducial skin markers. The 12 post-contrast MR images were nonrigidly registered to the precontrast frame using a free-form deformation (FFD) method. Parametric MR images were registered to parametric PET images via CT using FFD because the first PET time frame was acquired immediately after the CT image on a PET/CT scanner and is considered registered to the CT image. We conclude that nonrigid registration of PET and MR parametric images using CT data acquired during PET/CT scan and the FFD method resulted in their improved spatial coregistration. The success of this procedure was limited due to relatively large target registration error, TRE = 15.1+/-7.7 mm, as compared to spatial resolution of PET (6-7 mm), and swirling image artifacts created in MR parametric images by the FFD. Further refinement of nonrigid registration of PET and MR parametric images is necessary to enhance visualization and integration of complex diagnostic information provided by both modalities that will lead to improved diagnostic performance.
Ruiz-Sanchez, Eduardo
2015-12-01
The Neotropical woody bamboo genus Otatea is one of five genera in the subtribe Guaduinae. Of the eight described Otatea species, seven are endemic to Mexico and one is also distributed in Central and South America. Otatea acuminata has the widest geographical distribution of the eight species, and two of its recently collected populations do not match the known species morphologically. Parametric and non-parametric methods were used to delimit the species in Otatea using five chloroplast markers, one nuclear marker, and morphological characters. The parametric coalescent method and the non-parametric analysis supported the recognition of two distinct evolutionary lineages. Molecular clock estimates were used to estimate divergence times in Otatea. The results for divergence time in Otatea estimated the origin of the speciation events from the Late Miocene to Late Pleistocene. The species delimitation analyses (parametric and non-parametric) identified that the two populations of O. acuminata from Chiapas and Hidalgo are from two separate evolutionary lineages and these new species have morphological characters that separate them from O. acuminata s.s. The geological activity of the Trans-Mexican Volcanic Belt and the Isthmus of Tehuantepec may have isolated populations and limited the gene flow between Otatea species, driving speciation. Based on the results found here, I describe Otatea rzedowskiorum and Otatea victoriae as two new species, morphologically different from O. acuminata.
Group Parametrized Tunneling and Local Symmetry Conditions
NASA Astrophysics Data System (ADS)
Harter, William; Mitchell, Justin
2010-06-01
Recently, Hougen showed an ad hoc symmetry-based parameterization scheme for analyzing tunneling dynamics and high resolution spectra of fluxional molecular structure similar to S-parameter analysis of superfine structure in SF_6 or NH_3 maser inversion dynamics by Feynman et.al. The problem is that ad hoc parametrization, like path integration in general, can lead to logjams of parameters or ``paths'' with no way to pick out the relevant ones. We show a way to identify and use relevant parameters for a tunneling Hamiltonian H having global G-symmetry-defined bases by first expressing H as a linear combination bar γ ^i {bar g}_i of operators in dual symmetry group bar G. The coefficients bar γ ^i are parameters that define a complete set of allowed paths for any H with G-symmetry and are related thru spectral decomposition of G to eigensolutions of H. Quantum G vs.bar G duality generalizes lab -vs. -body and state -vs. -particle. The number of relevant bar γ ^i-parameters is reduced if a system tends to stick in states of a local symmetry subgroup LsubsetG so the H spectrum forms level clusters labeled by induced representations d(ℓ)(L)\\uparrowG. A cluster-(ℓ) has one E(epsilon)-level labeled by G species (epsilon) for each L species (ℓ) in Depsilon(G)downarrowL by Frobenius reciprocity. Then we apply local symmetry conditions to each irrep Depsilon(bar γ ^i {bar g}_i) that has already been reduced with respect to local symmetry L. This amounts to setting each off-diagonal component Dj,kepsilon(H) to zero. Local symmetry conditions may tell which bar γ ^i-parameters are redundant or zero and directly determine d(ℓ)\\uparrowG tunneling matrix eigenvalues that give E(epsilon)-levels as well as eigenvectors. Otherwise one may need to choose a particular localizing subgroup chain LsubsetL_1subsetL_2...G and further reduce the number of path parameters to facilitate spectral fitting. J.T. Hougen, 2009 MSS RJ01, {J Mol Spect 123, 197 (1987) W.G. Harter and
Mixing parametrizations for ocean climate modelling
NASA Astrophysics Data System (ADS)
Gusev, Anatoly; Moshonkin, Sergey; Diansky, Nikolay; Zalesny, Vladimir
2016-04-01
The algorithm is presented of splitting the total evolutionary equations for the turbulence kinetic energy (TKE) and turbulence dissipation frequency (TDF), which is used to parameterize the viscosity and diffusion coefficients in ocean circulation models. The turbulence model equations are split into the stages of transport-diffusion and generation-dissipation. For the generation-dissipation stage, the following schemes are implemented: the explicit-implicit numerical scheme, analytical solution and the asymptotic behavior of the analytical solutions. The experiments were performed with different mixing parameterizations for the modelling of Arctic and the Atlantic climate decadal variability with the eddy-permitting circulation model INMOM (Institute of Numerical Mathematics Ocean Model) using vertical grid refinement in the zone of fully developed turbulence. The proposed model with the split equations for turbulence characteristics is similar to the contemporary differential turbulence models, concerning the physical formulations. At the same time, its algorithm has high enough computational efficiency. Parameterizations with using the split turbulence model make it possible to obtain more adequate structure of temperature and salinity at decadal timescales, compared to the simpler Pacanowski-Philander (PP) turbulence parameterization. Parameterizations with using analytical solution or numerical scheme at the generation-dissipation step of the turbulence model leads to better representation of ocean climate than the faster parameterization using the asymptotic behavior of the analytical solution. At the same time, the computational efficiency left almost unchanged relative to the simple PP parameterization. Usage of PP parametrization in the circulation model leads to realistic simulation of density and circulation with violation of T,S-relationships. This error is majorly avoided with using the proposed parameterizations containing the split turbulence model
A Stochastic Parametrization of Ocean Mesoscale Eddies (Invited)
NASA Astrophysics Data System (ADS)
Zanna, L.; Mana, L.
2013-12-01
The ocean contains a vigorous mesoscale eddy field important in establishing the ocean's circulation and tracer properties. Mesoscale eddies have spatial scales of approximately 10 to 100km and their effect needs to be parametrized in ocean climate models. Current deterministic parametrizations of mesoscale eddies do not, for example, account for the fluctuations in sub-grid transport or do not represent upscale turbulent cascades therefore leading to model error in the representation of present and future climate change. The goal of our study is to construct a stochastic parametrization of ocean mesoscale eddies in order to include such effects and account for model error associated with the uncertainty in the parameters and the parametrization. The parametrization is constructed by using the output of a high resolution model in order to derive the statistics of the eddy source term as function of the resolved (coarse) scales. The simulations are done in a quasi-geostrophic model in a double-gyre configuration to provide a tractable framework. Probability density functions (PDFs) of the eddy source term conditional on the intrinsic resolved large scale dynamics are calculated and therefore capture the fluctuations associated with mesoscale eddies and their impact on the mean flow. The conditional PDFs are based on a Rivlin-Ericksen tensor and a theory for their mean, standard deviation, skewness and kurtosis is provided as function of the coarse resolution model grid size, its forcing and stratification. The conditional PDFs are then implemented as the basis for a new parametrization of mesoscale eddies in a coarse resolution model. The results of the implementation of the stochastic parametrization are shown to improve the representation of the mean flow, its variability at most frequencies and the kinetic energy power spectrum as function of wavelength.
Physiological responses at short distances from a parametric speaker.
Lee, Soomin; Shimomura, Yoshihiro; Katsuura, Tetsuo
2012-06-13
In recent years, parametric speakers have been used in various circumstances. In our previous studies, we verified that the physiological burden of the sound of parametric speaker set at 2.6 m from the subjects was lower than that of the general speaker. However, nothing has yet been demonstrated about the effects of the sound of a parametric speaker at the shorter distance between parametric speakers the human body. Therefore, we studied this effect on physiological functions and task performance. Nine male subjects participated in this study. They completed three consecutive sessions: a 20-minute quiet period as a baseline, a 30-minute mental task period with general speakers or parametric speakers, and a 20-minute recovery period. We measured electrocardiogram (ECG) photoplethysmogram (PTG), electroencephalogram (EEG), systolic and diastolic blood pressure. Four experiments, one with a speaker condition (general speaker and parametric speaker), the other with a distance condition (0.3 m and 1.0 m), were conducted respectively at the same time of day on separate days. To examine the effects of the speaker and distance, three-way repeated measures ANOVA (speaker factor x distance factor x time factor) were conducted. In conclusion, we found that the physiological responses were not significantly different between the speaker condition and the distance condition. Meanwhile, it was shown that the physiological burdens increased with progress in time independently of speaker condition and distance condition. In summary, the effects of the parametric speaker at the 2.6 m distance were not obtained at the distance of 1 m or less.
Comparison of thawing and freezing dark energy parametrizations
NASA Astrophysics Data System (ADS)
Pantazis, G.; Nesseris, S.; Perivolaropoulos, L.
2016-05-01
Dark energy equation of state w (z ) parametrizations with two parameters and given monotonicity are generically either convex or concave functions. This makes them suitable for fitting either freezing or thawing quintessence models but not both simultaneously. Fitting a data set based on a freezing model with an unsuitable (concave when increasing) w (z ) parametrization [like Chevallier-Polarski-Linder (CPL)] can lead to significant misleading features like crossing of the phantom divide line, incorrect w (z =0 ), incorrect slope, etc., that are not present in the underlying cosmological model. To demonstrate this fact we generate scattered cosmological data at both the level of w (z ) and the luminosity distance DL(z ) based on either thawing or freezing quintessence models and fit them using parametrizations of convex and of concave type. We then compare statistically significant features of the best fit w (z ) with actual features of the underlying model. We thus verify that the use of unsuitable parametrizations can lead to misleading conclusions. In order to avoid these problems it is important to either use both convex and concave parametrizations and select the one with the best χ2 or use principal component analysis thus splitting the redshift range into independent bins. In the latter case, however, significant information about the slope of w (z ) at high redshifts is lost. Finally, we propose a new family of parametrizations w (z )=w0+wa(z/1 +z )n which generalizes the CPL and interpolates between thawing and freezing parametrizations as the parameter n increases to values larger than 1.
Semi-parametric and non-parametric methods for clinical trials with incomplete data.
O'Brien, Peter C; Zhang, David; Bailey, Kent R
2005-02-15
Last observation carried forward (LOCF) and analysis using only data from subjects who complete a trial (Completers) are commonly used techniques for analysing data in clinical trials with incomplete data when the endpoint is change from baseline at last scheduled visit. We propose two alternative methods. The semi-parametric method, which cumulates changes observed between consecutive time points, is conceptually similar to the familiar life-table method and corresponding Kaplan-Meier estimation when the primary endpoint is time to event. A non-parametric analogue of LOCF is obtained by carrying forward, not the observed value, but the rank of the change from baseline at the last observation for each subject. We refer to this method as the LRCF method. Both procedures retain the simplicity of LOCF and Completers analyses and, like these methods, do not require data imputation or modelling assumptions. In the absence of any incomplete data they reduce to the usual two-sample tests. In simulations intended to reflect chronic diseases that one might encounter in practice, LOCF was observed to produce markedly biased estimates and markedly inflated type I error rates when censoring was unequal in the two treatment arms. These problems did not arise with the Completers, Cumulative Change, or LRCF methods. Cumulative Change and LRCF were more powerful than Completers, and the Cumulative Change test provided more efficient estimates than the Completers analysis, in all simulations. We conclude that the Cumulative Change and LRCF methods are preferable to LOCF and Completers analyses. Mixed model repeated measures (MMRM) performed similarly to Cumulative Change and LRCF and makes somewhat less restrictive assumptions about missingness mechanisms, so that it is also a reasonable alternative to LOCF and Completers analyses.
Parametric vs. non-parametric daily weather generator: validation and comparison
NASA Astrophysics Data System (ADS)
Dubrovsky, Martin
2016-04-01
As the climate models (GCMs and RCMs) fail to satisfactorily reproduce the real-world surface weather regime, various statistical methods are applied to downscale GCM/RCM outputs into site-specific weather series. The stochastic weather generators are among the most favourite downscaling methods capable to produce realistic (observed like) meteorological inputs for agrological, hydrological and other impact models used in assessing sensitivity of various ecosystems to climate change/variability. To name their advantages, the generators may (i) produce arbitrarily long multi-variate synthetic weather series representing both present and changed climates (in the latter case, the generators are commonly modified by GCM/RCM-based climate change scenarios), (ii) be run in various time steps and for multiple weather variables (the generators reproduce the correlations among variables), (iii) be interpolated (and run also for sites where no weather data are available to calibrate the generator). This contribution will compare two stochastic daily weather generators in terms of their ability to reproduce various features of the daily weather series. M&Rfi is a parametric generator: Markov chain model is used to model precipitation occurrence, precipitation amount is modelled by the Gamma distribution, and the 1st order autoregressive model is used to generate non-precipitation surface weather variables. The non-parametric GoMeZ generator is based on the nearest neighbours resampling technique making no assumption on the distribution of the variables being generated. Various settings of both weather generators will be assumed in the present validation tests. The generators will be validated in terms of (a) extreme temperature and precipitation characteristics (annual and 30 years extremes and maxima of duration of hot/cold/dry/wet spells); (b) selected validation statistics developed within the frame of VALUE project. The tests will be based on observational weather series
Johnson, H.O.; Gupta, S.C.; Vecchia, A.V.; Zvomuya, F.
2009-01-01
Excessive loading of sediment and nutrients to rivers is a major problem in many parts of the United States. In this study, we tested the non-parametric Seasonal Kendall (SEAKEN) trend model and the parametric USGS Quality of Water trend program (QWTREND) to quantify trends in water quality of the Minnesota River at Fort Snelling from 1976 to 2003. Both methods indicated decreasing trends in flow-adjusted concentrations of total suspended solids (TSS), total phosphorus (TP), and orthophosphorus (OP) and a generally increasing trend in flow-adjusted nitrate plus nitrite-nitrogen (NO3-N) concentration. The SEAKEN results were strongly influenced by the length of the record as well as extreme years (dry or wet) earlier in the record. The QWTREND results, though influenced somewhat by the same factors, were more stable. The magnitudes of trends between the two methods were somewhat different and appeared to be associated with conceptual differences between the flow-adjustment processes used and with data processing methods. The decreasing trends in TSS, TP, and OP concentrations are likely related to conservation measures implemented in the basin. However, dilution effects from wet climate or additional tile drainage cannot be ruled out. The increasing trend in NO3-N concentrations was likely due to increased drainage in the basin. Since the Minnesota River is the main source of sediments to the Mississippi River, this study also addressed the rapid filling of Lake Pepin on the Mississippi River and found the likely cause to be increased flow due to recent wet climate in the region. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.
Towards an Empirically Based Parametric Explosion Spectral Model
Ford, S R; Walter, W R; Ruppert, S; Matzel, E; Hauk, T; Gok, R
2009-08-31
Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before been tested. The focus of our work is on the local and regional distances (< 2000 km) and phases (Pn, Pg, Sn, Lg) necessary to see small explosions. We are developing a parametric model of the nuclear explosion seismic source spectrum that is compatible with the earthquake-based geometrical spreading and attenuation models developed using the Magnitude Distance Amplitude Correction (MDAC) techniques (Walter and Taylor, 2002). The explosion parametric model will be particularly important in regions without any prior explosion data for calibration. The model is being developed using the available body of seismic data at local and regional distances for past nuclear explosions at foreign and domestic test sites. Parametric modeling is a simple and practical approach for widespread monitoring applications, prior to the capability to carry out fully deterministic modeling. The achievable goal of our parametric model development is to be able to predict observed local and regional distance seismic amplitudes for event identification and yield determination in regions with incomplete or no prior history of underground nuclear testing. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.
Incorporating parametric uncertainty into population viability analysis models
McGowan, Conor P.; Runge, Michael C.; Larson, Michael A.
2011-01-01
Uncertainty in parameter estimates from sampling variation or expert judgment can introduce substantial uncertainty into ecological predictions based on those estimates. However, in standard population viability analyses, one of the most widely used tools for managing plant, fish and wildlife populations, parametric uncertainty is often ignored in or discarded from model projections. We present a method for explicitly incorporating this source of uncertainty into population models to fully account for risk in management and decision contexts. Our method involves a two-step simulation process where parametric uncertainty is incorporated into the replication loop of the model and temporal variance is incorporated into the loop for time steps in the model. Using the piping plover, a federally threatened shorebird in the USA and Canada, as an example, we compare abundance projections and extinction probabilities from simulations that exclude and include parametric uncertainty. Although final abundance was very low for all sets of simulations, estimated extinction risk was much greater for the simulation that incorporated parametric uncertainty in the replication loop. Decisions about species conservation (e.g., listing, delisting, and jeopardy) might differ greatly depending on the treatment of parametric uncertainty in population models.
Optimization of output power in a fiber optical parametric oscillator.
Jin, Lei; Martinez, Amos; Yamashita, Shinji
2013-09-23
Fiber optical parametric oscillators (FOPOs) are coherent sources that can provide ultra-broadband tunability and high output power levels and are been considered for applications such as medical imaging and sensing. While most recent literature has focused on advancing the performance of these devices experimentally, theoretical studies are still scarce. In contrast, ordinary laser theory is very mature, has been thoroughly studied and is now well understood from the point of view of fundamental physics. In this work, we present a theoretical study of OPOs and in particular we theoretically discuss the process of gain saturation in optical parametric amplifiers. In order to emphasize the significant difference between the two coherent sources, we compare the optimized coupling ratios for maximum output powers of the ordinary laser and the optical parametric oscillator and demonstrate that in contrast to ordinary lasers, highest output powers in optical parametric oscillators are achieved with output coupling ratios close to 1. We confirm experimentally our theoretical studies by building a narrowband fiber optical parametric oscillator at 1450nm with multi-watt output power. We show that the device is robust to intracavity losses and achieve peak power as high as 2.4W.
A capacitive ultrasonic transducer based on parametric resonance
NASA Astrophysics Data System (ADS)
Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F.
2017-07-01
A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.
Marginally specified priors for non-parametric Bayesian estimation
Kessler, David C.; Hoff, Peter D.; Dunson, David B.
2014-01-01
Summary Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables. PMID:25663813
Marginally specified priors for non-parametric Bayesian estimation.
Kessler, David C; Hoff, Peter D; Dunson, David B
2015-01-01
Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables.
Impacts of advanced manufacturing technology on parametric estimating
NASA Astrophysics Data System (ADS)
Hough, Paul G.
1989-12-01
The introduction of advanced manufacturing technology in the aerospace industry poses serious challenges for government cost analysts. Traditionally, the analysts have relied on parametric estimating techniques for both planning and budgeting. Despite its problems, this approach has proven to be a remarkably useful and robust tool for estimating new weapon system costs. However, rapid improvements in both product and process technology could exacerbate current difficulties, and diminish the utility of the parametric approach. This paper reviews some weakness associated with parametrics, then proceeds to examine how specific aspects of the factory of the future may further impact parametric estimating, and suggests avenues of research for their resolution. This paper is an extended version of Cost Estimating for the Factory of the Future. Parametric estimating is a method by which aggregated costs are derived as a function of high-level product characteristics or parameters. The resulting equations are known as cost estimating relationships (CERs). Such equations are particularly useful when detailed technical specifications are not available.
Distributed parametric effect in long lines and its applications
NASA Astrophysics Data System (ADS)
Shestopaloff, Yuri K.
2011-10-01
The article considers a parametric effect which takes place when the velocity of signal propagation in a long line changes. We found the analytical solution describing the form of the transformed signal for a line with losses, when line parameters change symmetrically. We also considered lines without losses, with asymmetrical change of parameters. Our theoretical results comply with experimental data. In certain conditions, such a line can be used as an amplifier. The parametric effect in optics is described by Maxwell's equations, while in case of a long line, the analysis is based on telegrapher's equations. However, it turns out that in the end, both in optics and electronics, the parametric effect is described by wave equations that are mathematically similar. This is because fundamentally, when the parameters of the propagating medium change, the parametric effect is physically based on energy interchange between the controlling (pump) signal and the transformed one. So, the obtained results can be used for analysis of parametric effects in optics and electronics.
A capacitive ultrasonic transducer based on parametric resonance.
Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F
2017-07-24
A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.
Elliptic Volume Grid Generation for Viscous CFD Parametric Design Studies
NASA Technical Reports Server (NTRS)
Alter, Stephen J.; Cheatwood, F. McNeil
1996-01-01
This paper presents a robust method for the generation of zonal volume grids of design parametrics for aerodynamic configurations. The process utilizes simple algebraic techniques with parametric splines coupled with elliptic volume grid generation to generate isolated zonal grids for changes in body configuration needed to perform parametric design studies. Speed of the algorithm is maximized through the algebraic methods and reduced number of grid points to be regenerated for each design parametric without sacrificing grid quality and continuity within the volume domain. The method is directly applicable to grid reusability, because it modifies existing ow adapted volume grids and enables the user to restart the CFD solution process with an established flow field. Use of this zonal approach reduces computer usage time to create new volume grids for design parametric studies by an order of magnitude, as compared to current methods which require the regeneration of an entire volume grid. A sample configuration of a proposed Single Stage-to-Orbit Vehicle is used to illustrate an application of this method.
Schlüsener, Michael P; Bester, Kai
2005-01-01
In this study we present a high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method which has been elaborated to analyse steroid hormones, hormone conjugates, oral contraceptives and macrolide antibiotics unchanged in unfiltered influents and effluents of sewage treatment plants (STPs). HPLC separation of the steroid hormones was achieved in 35 min, as well as those of the antibiotics. The analytes were extracted by solid-phase extraction, followed by clean-up using size exclusion chromatography (SEC). For the final quantification HPLC/MS/MS was used. The two ionisation modes, electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI), in HPLC/MS/MS were compared for the analysis of steroid hormones. For quantitative results drastic matrix effects were observed while using ESI. These effects were less pronounced while using APCI. These pitfalls were additionally reduced by clean-up using SEC as well as isotope dilution. Additionally, two multiple reaction monitoring (MRM) transitions per compound were used to prevent false positive results. Recovery experiments with spiked tap water with concentrations varying from 1 to 1000 ng/L gave constant recovery rates: The recovery rates for the hormones and conjugates ranged from 58 to 107%, those of the contraceptives ranged from 83 to 109%. The relative standard deviation was found to be 7 to 24% and the limits of detection were 0.1 to 4.5 ng/L. The recovery rates of the macrolide antibiotics ranged from 76 to 103%, while the relative standard deviation was found to be 7 to 14% and the limits of detection ranged from 0.6 to 1.8 ng/L. The maximum concentrations found in influents of a STP was 470 ng/L for estriol and 1200 ng/L for erythromycin. Copyright (c) 2005 John Wiley & Sons, Ltd.
Cosmic slowing down of acceleration for several dark energy parametrizations
Magaña, Juan; Cárdenas, Víctor H.; Motta, Verónica E-mail: victor.cardenas@uv.cl
2014-10-01
We further investigate slowing down of acceleration of the universe scenario for five parametrizations of the equation of state of dark energy using four sets of Type Ia supernovae data. In a maximal probability analysis we also use the baryon acoustic oscillation and cosmic microwave background observations. We found the low redshift transition of the deceleration parameter appears, independently of the parametrization, using supernovae data alone except for the Union 2.1 sample. This feature disappears once we combine the Type Ia supernovae data with high redshift data. We conclude that the rapid variation of the deceleration parameter is independent of the parametrization. We also found more evidence for a tension among the supernovae samples, as well as for the low and high redshift data.
Feedback-Enhanced Parametric Squeezing of Mechanical Motion
NASA Astrophysics Data System (ADS)
Vinante, A.; Falferi, P.
2013-11-01
We present a single-quadrature feedback scheme able to overcome the conventional 3 dB limit on parametric squeezing. The method is experimentally demonstrated in a micromechanical system based on a cantilever with a magnetic tip. The cantilever is detected at low temperature by a SQUID susceptometer, while parametric pumping is obtained by modulating the magnetic field gradient at twice the cantilever frequency. A maximum squeezing of 11.5 dB and 11.3 dB is observed, respectively, in the response to a sinusoidal test signal and in the thermomechanical noise. So far, the maximum squeezing factor is limited only by the maximum achievable parametric modulation. The proposed technique might be used to squeeze one quadrature of a mechanical resonator below the quantum noise level, even without the need for a quantum limited detector.
Epicyclic helical channels for parametric resonance ionization cooling
Johson, Rolland Paul; Derbenev, Yaroslav
2015-08-23
Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.
Global Nonlinear Parametric Modeling with Application to F-16 Aerodynamics
NASA Technical Reports Server (NTRS)
Morelli, Eugene A.
1998-01-01
A global nonlinear parametric modeling technique is described and demonstrated. The technique uses multivariate orthogonal modeling functions generated from the data to determine nonlinear model structure, then expands each retained modeling function into an ordinary multivariate polynomial. The final model form is a finite multivariate power series expansion for the dependent variable in terms of the independent variables. Partial derivatives of the identified models can be used to assemble globally valid linear parameter varying models. The technique is demonstrated by identifying global nonlinear parametric models for nondimensional aerodynamic force and moment coefficients from a subsonic wind tunnel database for the F-16 fighter aircraft. Results show less than 10% difference between wind tunnel aerodynamic data and the nonlinear parameterized model for a simulated doublet maneuver at moderate angle of attack. Analysis indicated that the global nonlinear parametric models adequately captured the multivariate nonlinear aerodynamic functional dependence.
Coupled parametric design of flow control and duct shape
NASA Technical Reports Server (NTRS)
Florea, Razvan (Inventor); Bertuccioli, Luca (Inventor)
2009-01-01
A method for designing gas turbine engine components using a coupled parametric analysis of part geometry and flow control is disclosed. Included are the steps of parametrically defining the geometry of the duct wall shape, parametrically defining one or more flow control actuators in the duct wall, measuring a plurality of performance parameters or metrics (e.g., flow characteristics) of the duct and comparing the results of the measurement with desired or target parameters, and selecting the optimal duct geometry and flow control for at least a portion of the duct, the selection process including evaluating the plurality of performance metrics in a pareto analysis. The use of this method in the design of inter-turbine transition ducts, serpentine ducts, inlets, diffusers, and similar components provides a design which reduces pressure losses and flow profile distortions.
The parametric resonance—from LEGO Mindstorms to cold atoms
NASA Astrophysics Data System (ADS)
Kawalec, Tomasz; Sierant, Aleksandra
2017-07-01
We show an experimental setup based on a popular LEGO Mindstorms set, allowing us to both observe and investigate the parametric resonance phenomenon. The presented method is simple but covers a variety of student activities like embedded software development, conducting measurements, data collection and analysis. It may be used during science shows, as part of student projects and to illustrate the parametric resonance in mechanics or even quantum physics, during lectures or classes. The parametrically driven LEGO pendulum gains energy in a spectacular way, increasing its amplitude from 10° to about 100° within a few tens of seconds. We provide also a short description of a wireless absolute orientation sensor that may be used in quantitative analysis of driven or free pendulum movement.
THz-wave parametric sources and imaging applications
NASA Astrophysics Data System (ADS)
Kawase, Kodo
2004-12-01
We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We have also developed a novel basic technology for THz imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral trasillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.
Ultrasensitive hysteretic force sensing with parametric nonlinear oscillators
NASA Astrophysics Data System (ADS)
Papariello, Luca; Zilberberg, Oded; Eichler, Alexander; Chitra, R.
2016-08-01
We propose a method for linear detection of weak forces using parametrically driven nonlinear resonators. The method is based on a peculiar feature in the response of the resonator to a near resonant periodic external force. This feature stems from a complex interplay among the parametric drive, external force, and nonlinearities. For weak parametric drive, the response exhibits the standard Duffing-like single jump hysteresis. For stronger drive amplitudes, we find a qualitatively new double jump hysteresis which arises from stable solutions generated by the cubic Duffing nonlinearity. The additional jump exists only if the external force is present and the frequency at which it occurs depends linearly on the amplitude of the external force, permitting a straightforward ultrasensitive detection of weak forces. With state-of-the-art nanomechanical resonators, our scheme should permit force detection in the attonewton range.
Ultrasensitive hysteretic force sensing with parametric nonlinear oscillators.
Papariello, Luca; Zilberberg, Oded; Eichler, Alexander; Chitra, R
2016-08-01
We propose a method for linear detection of weak forces using parametrically driven nonlinear resonators. The method is based on a peculiar feature in the response of the resonator to a near resonant periodic external force. This feature stems from a complex interplay among the parametric drive, external force, and nonlinearities. For weak parametric drive, the response exhibits the standard Duffing-like single jump hysteresis. For stronger drive amplitudes, we find a qualitatively new double jump hysteresis which arises from stable solutions generated by the cubic Duffing nonlinearity. The additional jump exists only if the external force is present and the frequency at which it occurs depends linearly on the amplitude of the external force, permitting a straightforward ultrasensitive detection of weak forces. With state-of-the-art nanomechanical resonators, our scheme should permit force detection in the attonewton range.
Comparisons of some parametrizations of wind direction variability with observations
NASA Astrophysics Data System (ADS)
Davies, Belinda M.; Thomson, David J.
An understanding of wind direction variability is important in predicting the dispersion of pollutants in the atmosphere. Parametrizations of wind direction variability over different time scales are compared with turbulence observations made at the Meteorological Research Unit (MRU) at Cardington. Observations of the variability averaged over one hour in stable conditions are compared with the parametrizations proposed by Hanna and by Joffre and Laurila for light winds and show broad agreement with these parametrizations. The formula proposed by Hanna, suitably matched to a similarity approach at strong winds, can be recommended for general use. The direction variability over longer time periods (up to 12 h) has also been investigated. Results show only a weak dependence on averaging time with the wind direction variability roughly proportional to averaging time to the power 1/4.
Virtual charts of solutions for parametrized nonlinear equations
NASA Astrophysics Data System (ADS)
Vitse, Matthieu; Néron, David; Boucard, Pierre-Alain
2014-12-01
During many decades, engineers relied on experimental abaci to design and optimize mechanical structures. Virtual charts are based on numerical computations and aim at making the design and optimization of structures faster and cheaper as it requires less (or no) experimentation. The parametric problems are solved offline and the associated charts are used for online design. However, in this context, the cost associated to the resolution of parametric problems can be extremely prohibitive. Model reduction techniques are an answer to circumvent this issue. This paper provides the developments of an algorithm for solving nonlinear parametric problems, based on the LATIN method for the treatment of the nonlinear aspects and the PGD for the parameter dependency. A full time-space-parameter decomposition of the solution is introduced into the LATIN algorithm, numerical examples on academic problems are given so as to point out the advantages of this extension and leads on possible improvements to the strategy are given.
A quadratic-shaped-finger comb parametric resonator
NASA Astrophysics Data System (ADS)
Guo, Congzhong; Fedder, Gary K.
2013-09-01
A large-stroke (8 µm) parametric resonator excited by an in-plane ‘shaped-finger’ electrostatic comb drive is fabricated using a 15 µm thick silicon-on-insulator microelectromechanical systems (SOI-MEMS) process. A quadratic capacitance-engagement response is synthesized by engineering a custom-shaped comb finger profile. A folded-flexure suspension allows lateral motion while constraining rotational modes. The excitation of the nonlinear parametric resonance is realized by selecting an appropriate combination of the linear and cubic electrostatic stiffness coefficients through a specific varying-gap comb-finger design. The large-amplitude parametric resonance promotes high signal-to-noise ratio for potential use in sensitive chemical gravimetric sensors, strain gauges, and mode-matched gyroscope applications.
Semi-parametric estimation in failure time mixture models.
Taylor, J M
1995-09-01
A mixture model is an attractive approach for analyzing failure time data in which there are thought to be two groups of subjects, those who could eventually develop the endpoint and those who could not develop the endpoint. The proposed model is a semi-parametric generalization of the mixture model of Farewell (1982). A logistic regression model is proposed for the incidence part of the model, and a Kaplan-Meier type approach is used to estimate the latency part of the model. The estimator arises naturally out of the EM algorithm approach for fitting failure time mixture models as described by Larson and Dinse (1985). The procedure is applied to some experimental data from radiation biology and is evaluated in a Monte Carlo simulation study. The simulation study suggests the semi-parametric procedure is almost as efficient as the correct fully parametric procedure for estimating the regression coefficient in the incidence, but less efficient for estimating the latency distribution.
Terahertz-wave parametric gain of stimulated polariton scattering
NASA Astrophysics Data System (ADS)
Takida, Yuma; Shikata, Jun-ichi; Nawata, Kouji; Tokizane, Yu; Han, Zhengli; Koyama, Mio; Notake, Takashi; Hayashi, Shin'ichiro; Minamide, Hiroaki
2016-04-01
We have experimentally determined the terahertz- (THz-) wave parametric gain of stimulated Raman scattering (SRS) by phonon-polaritons in LiNb O3 . Our approach is based on ultrabright THz-wave generation from SRS under stimulated Brillouin scattering suppression with subnanosecond pump pulses. To obtain the frequency dependence of the parametric gain, we measured the crystal-length dependence of the THz-wave output directly using a surface-coupling configuration. We found that the product of the parametric gain and the threshold crystal length is constant throughout the tuning range. Our result provides a physical basis for the design and performance enhancement of SRS-based ultrabright tabletop THz-wave sources for various applications.
Maydeu-Olivares, Albert
2005-04-01
Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in their data. To verify this conjecture, we compare the fit of these models to the Social Problem Solving Inventory-Revised, whose scales were designed to be unidimensional. A calibration and a cross-validation sample of new observations were used. We also included the following parametric models in the comparison: Bock's nominal model, Masters' partial credit model, and Thissen and Steinberg's extension of the latter. All models were estimated using full information maximum likelihood. We also included in the comparison a normal ogive model version of Samejima's model estimated using limited information estimation. We found that for all scales Samejima's model outperformed all other parametric IRT models in both samples, regardless of the estimation method employed. The non-parametric model outperformed all parametric models in the calibration sample. However, the graded model outperformed MFS in the cross-validation sample in some of the scales. We advocate employing the graded model estimated using limited information methods in modeling Likert-type data, as these methods are more versatile than full information methods to capture the multidimensionality that is generally present in personality data.
The impact of parametrized convection on cloud feedback.
Webb, Mark J; Lock, Adrian P; Bretherton, Christopher S; Bony, Sandrine; Cole, Jason N S; Idelkadi, Abderrahmane; Kang, Sarah M; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D; Zhao, Ming
2015-11-13
We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that 'ConvOff' models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback
The impact of parametrized convection on cloud feedback
Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming
2015-01-01
We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud
Generalized parametric down conversion, many particle interferometry, and Bell's theorem
NASA Technical Reports Server (NTRS)
Choi, Hyung Sup
1992-01-01
A new field of multi-particle interferometry is introduced using a nonlinear optical spontaneous parametric down conversion (SPDC) of a photon into more than two photons. The study of SPDC using a realistic Hamiltonian in a multi-mode shows that at least a low conversion rate limit is possible. The down converted field exhibits many stronger nonclassical phenomena than the usual two photon parametric down conversion. Application of the multi-particle interferometry to a recently proposed many particle Bell's theorem on the Einstein-Podolsky-Rosen problem is given.
Parametric oscillatory instability in a signal-recycled LIGO interferometer
Vyatchanin, S P; Strigin, S E
2007-12-31
The undesirable effect of parametric oscillatory instability in a LIGO (Laser Interferometer Gravitational-Wave Observatory) laser gravitational-wave antenna with a signal-recirculation mirror is analysed in detail. The instability is manifested in excitation of the Stokes optical mode and elastic mechanical mode of the mirror. It is shown that, if the eigenfrequencies of Fabry-Perot resonators in the interferometer arms are different, the parametric instability is quite small due to a small passband band width. (fifth seminar in memory of d.n. klyshko)
Resonant Phase Matching of Josephson Junction Traveling Wave Parametric Amplifiers
2014-10-06
Resonant Phase Matching of Josephson Junction Traveling Wave Parametric Amplifiers Kevin O’Brien,1 Chris Macklin,2 Irfan Siddiqi,2 and Xiang Zhang1,3...overcome phase mismatch in Josephson-junction traveling wave parametric amplifiers in order to achieve high gain over a broad bandwidth. Using “resonant...achieves a gain of 20 dB, an instantaneous bandwidth of 3 GHz, and a saturation power of −98 dBm. Such an amplifier is well suited to cryogenic
Electro-optically spectrum tailorable intracavity optical parametric oscillator.
Chung, H P; Chang, W K; Tseng, C H; Geiss, R; Pertsch, T; Chen, Y H
2015-11-15
We report a unique, pulsed intracavity optical parametric oscillator (IOPO) whose output spectrum is electro-optically (EO) tailorable based on an aperiodically poled lithium niobate (APPLN) working simultaneously as an optical parametric gain medium and an active gain spectrum filter in the system. We have successfully obtained from the IOPO the emission of single to multiple narrow-line signal spectral peaks in a near-infrared (1531 nm) band simply by electro-optic control. The power spectral density of the EO tailored signal can be enhanced by up to 10 times over the original (nontailored) signal.
Optimal feedback in efficient single-cavity optical parametric oscillators
Petnikova, V M; Shuvalov, Vladimir V
2010-09-10
An approach based on the description of competition of quadratic processes of merging and decomposition of quanta resulting in the formation of cnoidal waves on an effective cascade cubic Kerr-type nonlinearity is used to optimise the scheme of a single-cavity optical parametric oscillator. It is shown that the use of a feedback circuit (cavity) decreases the period of cnoidal waves produced in a nonlinear crystal, while the optimisation procedure of the transfer constant of this circuit (reflectivity of the output mirror of the cavity) is reduced to matching this period with the nonlinear crystal length. (optical parametric oscillators)
Parametric-Resonance Ionization Cooling in Twin-Helix.
V.S. Morozov, Ya.S. Derbenev, A. Afanasev, R.P. Johnson, Erdelyi. B., J.A. Maloney
2011-09-01
Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a highluminosity muon collider. For the implementation of PIC, we developed an epicyclic twin-helix channel with correlated optics. Wedge-shaped absorbers immediately followed by short rf cavities are placed into the twin-helix channel. Parametric resonances are induced in both planes using helical quadrupole harmonics. We demonstrate resonant dynamics and cooling with stochastic effects off using GEANT4/G4beamline. We illustrate compensation of spherical aberrations and benchmark COSY Infinity, a powerful tool for aberration analysis and compensation.
Extreme prepulse contrast utilizing cascaded-optical parametric amplification
Jovanovic, I; Haefner, C; Wattellier, B; Barty, C J
2006-06-15
It has been shown recently that an optical parametric chirped-pulse amplifier can be easily reconfigured into a cascaded-optical parametric amplifier (COPA), enabling complete prepulse removal and optical switching with a window defined by the pump pulse duration. We have demonstrated instrument-limited measurement of the COPA prepulse contrast >1.4 x 10{sup 11} using 30-mJ pulses. The COPA technique is applicable to all energy ranges and pulse durations. A convenient millijoule-scale implementation of this technique is presented using a single, large-aspect-ratio quasi-phase-matched nonlinear crystal.
Parametric study of prospective early commercial OCMHD power plants /PSPEC/
NASA Technical Reports Server (NTRS)
Marston, C. H.; Bender, D. J.; Hnat, J. G.; Dellinger, T. C.
1980-01-01
The paper presents a parametric study conducted to obtain the performance, economics, natural resource requirements, and environmental impact of moderate technology MHD/steam power plants that do not require development of direct-fired high-temperature air heaters. The study was divided into three base cases, each with a reference case and parametric variations. The case using recuperative air preheat in the range of 1000 F to 1300 F, combined with O2 enrichment to 42% by volume has been selected for conceptual design.
Parametric Resonance of Magnetization Excited by Electric Field.
Chen, Yu-Jin; Lee, Han Kyu; Verba, Roman; Katine, Jordan A; Barsukov, Igor; Tiberkevich, Vasil; Xiao, John Q; Slavin, Andrei N; Krivorotov, Ilya N
2017-01-11
Manipulation of magnetization by electric field is a central goal of spintronics because it enables energy-efficient operation of spin-based devices. Spin wave devices are promising candidates for low-power information processing, but a method for energy-efficient excitation of short-wavelength spin waves has been lacking. Here we show that spin waves in nanoscale magnetic tunnel junctions can be generated via parametric resonance induced by electric field. Parametric excitation of magnetization is a versatile method of short-wavelength spin wave generation, and thus, our results pave the way toward energy-efficient nanomagnonic devices.
Dispersion-Engineered Traveling Wave Kinetic Inductance Parametric Amplifier
NASA Technical Reports Server (NTRS)
Zmuidzinas, Jonas (Inventor); Day, Peter K. (Inventor)
2014-01-01
A traveling wave kinetic inductance parametric amplifier comprises a superconducting transmission line and a dispersion control element. The transmission line can include periodic variations of its dimension along its length. The superconducting material can include a high normal state resistivity material. In some instances the high normal state resistivity material includes nitrogen and a metal selected from the group consisting of titanium, niobium and vanadium. The traveling wave kinetic inductance parametric amplifier is expected to exhibit a noise temperature below 100 mK/GHz.
Spin effect on parametric interactions of waves in magnetoplasmas
Shahid, M.; Melrose, D. B.; Jamil, M.; Murtaza, G.
2012-11-15
The parametric decay instability of upper hybrid wave into low-frequency electromagnetic Shear Alfven wave and Ordinary mode radiation (O-mode) has been investigated in an electron-ion plasma immersed in the uniform external magnetic field. Incorporating quantum effect due to electron spin, the fluid model has been used to investigate the linear and nonlinear response of the plasma species for three-wave coupling in a magnetoplasma. It is shown that the spin of electrons has considerable effect on the parametric decay of upper hybrid wave into Ordinary mode radiation (O-mode) and Shear Alfven wave even in classical regime.
Three thermodynamically based parametrizations of the deceleration parameter
NASA Astrophysics Data System (ADS)
del Campo, Sergio; Duran, Ivan; Herrera, Ramón; Pavón, Diego
2012-10-01
We propose and constrain with the latest observational data, three model-independent parametrizations of the cosmic deceleration parameter q(z). They are well behaved and stay finite at all redshifts. We construct them by fixing the value of q at high redshift, q(z≫1)=1/2 (as demanded by cosmic structure formation), and at the far future q(z=-1)=-1, and smoothly interpolating q(z) between them. The fixed point at z=-1 is not arbitrarily chosen; it readily follows from the second law of thermodynamics. This fairly reduces the ample latitude in parametrizing q(z).
Improve microwave quantum illumination via optical parametric amplifier
NASA Astrophysics Data System (ADS)
Xiong, Biao; Li, Xun; Wang, Xiao-Yu; Zhou, Ling
2017-10-01
Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Entangled sources between microwave and optical fields can be exploited to improve detection in microwave quantum illumination technique. We proposed a scheme to enhance the entanglement between the output fields of microwave and optical cavity by introducing optical parametric amplifier medium in cavity optomechanical system. We show that improving signal-to-noise ratio and decreasing error probability of detection can be obtained consequently even for objects with low reflectivity in the presence of optical parametric amplifier.
Epicyclic Helical Channels for Parametric Resonance Ionization Cooling
Andrei Afanaciev, Alex Bogacz, Yaroslav Derbenev, Kevin Beard, Valentin Ivanov, Rolland Johnson, Guimei Wang, Katsuya Yonehara
2009-05-01
In order to achieve cooling of muons in addition to 6D helical cooling channel (HCC) [1], we develop a technique based on a parametric resonance. The use of parametric resonances requires alternating dispersion, minimized at locations of thin absorbers, but maximized in between in order to compensate for chromatic aberrations [2]. These solutions can be combined in an Epicyclic Helical Cooling Channel (EHCC) that meets requirements of alternating dispersion of beam periodic orbit with best conditions for maintenance of stable beam transport in a continuous solenoid-type field [3]. We discuss here basic features and new simulation results for EHCC.
May chaos always be suppressed by parametric perturbations?
Schwalger, Tilo; Dzhanoev, Arsen; Loskutov, Alexander
2006-06-01
The problem of chaos suppression by parametric perturbations is considered. Despite the widespread opinion that chaotic behavior may be stabilized by perturbations of any system parameter, we construct a counterexample showing that this is not necessarily the case. In general, chaos suppression means that parametric perturbations should be applied within a set of parameters at which the system has a positive maximal Lyapunov exponent. Analyzing the known Duffing-Holmes model by a Melnikov method, we showed that chaotic dynamics cannot be suppressed by harmonic perturbations of a certain parameter, independently from the other parameter values. Thus, to stabilize the behavior of chaotic systems, the perturbation and parameters should be carefully chosen.
Enhancement of entanglement in distant micromechanical mirrors using parametric interactions
NASA Astrophysics Data System (ADS)
Hu, Chang-Sheng; Huang, Xi-Rong; Shen, Li-Tuo; Yang, Zhen-Biao; Wu, Huai-Zhi
2017-02-01
We theoretically investigate the stability of a two cascaded cavity optomechanical system with optical parametric amplifiers (OPAs) inside the two coupled cavities, and study the steady-state entanglement between two distant mechanical resonators. We show that the parameter regime where the system is unstable without OPAs, such as relatively high laser intensity and blue detuning, can be exploited to build the steady-state mechanical entanglement by modulating the parametric gain. The application of OPAs is helpful to preserve the mechanical entanglement suffered from the dissipation at some finite temperature. The scheme provides an alternative way for improving and engineering the quantum entanglement of two distant mechanical oscillators.
Stimulated parametric fluorescence induced by picosecond pump pulses.
NASA Technical Reports Server (NTRS)
Rabson, T. A.; Ruiz, H. J.; Shah, P. L.; Tittel, F. K.
1972-01-01
Stimulated parametric fluorescence emission tunable over the range from 0.96 to 1.16 microns has been obtained using a barium sodium niobate crystal pumped by a frequency-doubled and mode-locked neodymium:glass laser. The pump radiation in the form of a train of picosecond pulses produced infrared parametric fluorescence pulses, less than 10 psec in duration and with average peak powers on the order of 300 W when pumped with a power density of 300 MW/sq cm.
Traveling pulse on a periodic background in parametrically driven systems.
León, Alejandro O; Clerc, Marcel G; Coulibaly, Saliya
2015-05-01
Macroscopic systems with dissipation and time-modulated injection of energy, parametrically driven systems, can self-organize into localized states and/or patterns. We investigate a pulse that travels over a one-dimensional pattern in parametrically driven systems. Based on a minimal prototype model, we show that the pulses emerge through a subcritical Andronov-Hopf bifurcation of the underlying pattern. We describe a simple physical system, a magnetic wire forced with a transverse oscillatory magnetic field, which displays these traveling pulses.
Photon number amplification/duplication through parametric conversion
NASA Technical Reports Server (NTRS)
Dariano, G. M.; Macchiavello, C.; Paris, M.
1993-01-01
The performance of parametric conversion in achieving number amplification and duplication is analyzed. It is shown that the effective maximum gains G(sub *) remain well below their integer ideal values, even for large signals. Correspondingly, one has output Fano factors F(sub *) which are increasing functions of the input photon number. On the other hand, in the inverse (deamplifier/recombiner) operating mode quasi-ideal gains G(sub *) and small factors F(sub *) approximately equal to 10 percent are obtained. Output noise and non-ideal gains are ascribed to spontaneous parametric emission.
Validation of two (parametric vs non-parametric) daily weather generators
NASA Astrophysics Data System (ADS)
Dubrovsky, M.; Skalak, P.
2015-12-01
As the climate models (GCMs and RCMs) fail to satisfactorily reproduce the real-world surface weather regime, various statistical methods are applied to downscale GCM/RCM outputs into site-specific weather series. The stochastic weather generators are among the most favourite downscaling methods capable to produce realistic (observed-like) meteorological inputs for agrological, hydrological and other impact models used in assessing sensitivity of various ecosystems to climate change/variability. To name their advantages, the generators may (i) produce arbitrarily long multi-variate synthetic weather series representing both present and changed climates (in the latter case, the generators are commonly modified by GCM/RCM-based climate change scenarios), (ii) be run in various time steps and for multiple weather variables (the generators reproduce the correlations among variables), (iii) be interpolated (and run also for sites where no weather data are available to calibrate the generator). This contribution will compare two stochastic daily weather generators in terms of their ability to reproduce various features of the daily weather series. M&Rfi is a parametric generator: Markov chain model is used to model precipitation occurrence, precipitation amount is modelled by the Gamma distribution, and the 1st order autoregressive model is used to generate non-precipitation surface weather variables. The non-parametric GoMeZ generator is based on the nearest neighbours resampling technique making no assumption on the distribution of the variables being generated. Various settings of both weather generators will be assumed in the present validation tests. The generators will be validated in terms of (a) extreme temperature and precipitation characteristics (annual and 30-years extremes and maxima of duration of hot/cold/dry/wet spells); (b) selected validation statistics developed within the frame of VALUE project. The tests will be based on observational weather series
Schuitemaker, Alie; van Berckel, Bart N M; Kropholler, Marc A; Veltman, Dick J; Scheltens, Philip; Jonker, Cees; Lammertsma, Adriaan A; Boellaard, Ronald
2007-05-01
(R)-[11C]PK11195 has been used for quantifying cerebral microglial activation in vivo. In previous studies, both plasma input and reference tissue methods have been used, usually in combination with a region of interest (ROI) approach. Definition of ROIs, however, can be labourious and prone to interobserver variation. In addition, results are only obtained for predefined areas and (unexpected) signals in undefined areas may be missed. On the other hand, standard pharmacokinetic models are too sensitive to noise to calculate (R)-[11C]PK11195 binding on a voxel-by-voxel basis. Linearised versions of both plasma input and reference tissue models have been described, and these are more suitable for parametric imaging. The purpose of this study was to compare the performance of these plasma input and reference tissue parametric methods on the outcome of statistical parametric mapping (SPM) analysis of (R)-[11C]PK11195 binding. Dynamic (R)-[11C]PK11195 PET scans with arterial blood sampling were performed in 7 younger and 11 elderly healthy subjects. Parametric images of volume of distribution (Vd) and binding potential (BP) were generated using linearised versions of plasma input (Logan) and reference tissue (Reference Parametric Mapping) models. Images were compared at the group level using SPM with a two-sample t-test per voxel, both with and without proportional scaling. Parametric BP images without scaling provided the most sensitive framework for determining differences in (R)-[11C]PK11195 binding between younger and elderly subjects. Vd images could only demonstrate differences in (R)-[11C]PK11195 binding when analysed with proportional scaling due to intersubject variation in K1/k2 (blood-brain barrier transport and non-specific binding).
Fanjoux, Gil; Lantz, Eric; Michaud, Jérémy; Sylvestre, Thibaut
2012-11-19
In a way analogous to a light pulse that can be optically delayed via slow light propagation in Kerr-type nonlinear media, we theoretically demonstrate that beam steering and spatial walk-off compensation can be achieved in noncollinear optical parametric amplification. We identify this effect as a result of the quadratic phase shift induced by parametric amplification that leads to the cancellation of the spatial walk-off and collinear propagation of all beams though they have different wavevectors. Experimental evidence is reported of a soliton array steering in a Kerr slab waveguide.
Trend Analysis of Golestan's Rivers Discharges Using Parametric and Non-parametric Methods
NASA Astrophysics Data System (ADS)
Mosaedi, Abolfazl; Kouhestani, Nasrin
2010-05-01
One of the major problems in human life is climate changes and its problems. Climate changes will cause changes in rivers discharges. The aim of this research is to investigate the trend analysis of seasonal and yearly rivers discharges of Golestan province (Iran). In this research four trend analysis method including, conjunction point, linear regression, Wald-Wolfowitz and Mann-Kendall, for analyzing of river discharges in seasonal and annual periods in significant level of 95% and 99% were applied. First, daily discharge data of 12 hydrometrics stations with a length of 42 years (1965-2007) were selected, after some common statistical tests such as, homogeneity test (by applying G-B and M-W tests), the four mentioned trends analysis tests were applied. Results show that in all stations, for summer data time series, there are decreasing trends with a significant level of 99% according to Mann-Kendall (M-K) test. For autumn time series data, all four methods have similar results. For other periods, the results of these four tests were more or less similar together. While, for some stations the results of tests were different. Keywords: Trend Analysis, Discharge, Non-parametric methods, Wald-Wolfowitz, The Mann-Kendall test, Golestan Province.
PARAMETRIC DISTANCE WEIGHTING OF LANDSCAPE INFLUENCE ON STREAMS
We present a parametric model for estimating the areas within watersheds whose land use best predicts indicators of stream ecological condition. We regress a stream response variable on the distance-weighted proportion of watershed area that has a specific land use, such as agric...
Steady States of the Parametric Rotator and Pendulum
ERIC Educational Resources Information Center
Bouzas, Antonio O.
2010-01-01
We discuss several steady-state rotation and oscillation modes of the planar parametric rotator and pendulum with damping. We consider a general elliptic trajectory of the suspension point for both rotator and pendulum, for the latter at an arbitrary angle with gravity, with linear and circular trajectories as particular cases. We treat the…
Absolute measurement of detector quantum efficiency using parametric downconversion.
Rarity, J G; Ridley, K D; Tapster, P R
1987-11-01
We show that a parametric downconversion crystal emitting angle resolved coincident photon pairs can be used to measure the absolute quantum efficiency of a photon counting detection system. We have measured the quantum efficiency of a silicon avalanche photodiode, operated in Geiger mode, as a function of operating voltage and compare this to results obtained using a conventional method.
Update on Parametric Cost Models for Space Telescopes
NASA Technical Reports Server (NTRS)
Stahl. H. Philip; Henrichs, Todd; Luedtke, Alexander; West, Miranda
2011-01-01
Since the June 2010 Astronomy Conference, an independent review of our cost data base discovered some inaccuracies and inconsistencies which can modify our previously reported results. This paper will review changes to the data base, our confidence in those changes and their effect on various parametric cost models
Dark energy parametrization motivated by scalar field dynamics
NASA Astrophysics Data System (ADS)
de la Macorra, Axel
2016-05-01
We propose a new dark energy (DE) parametrization motivated by the dynamics of a scalar field ϕ. We use an equation of state w parametrized in terms of two functions L and y, closely related to the dynamics of scalar fields, which is exact and has no approximation. By choosing an appropriate ansatz for L we obtain a wide class of behavior for the evolution of DE without the need to specify the scalar potential V. We parametrize L and y in terms of only four parameters, giving w a rich structure and allowing for a wide class of DE dynamics. Our w can either grow and later decrease, or it can happen the other way around; the steepness of the transition is not fixed and it contains the ansatz w={w}o+{w}a(1-a). Our parametrization follows closely the dynamics of a scalar field, and the function L allows us to connect it with the scalar potential V(φ ). While the Universe is accelerating and the slow roll approximation is valid, we get L≃ {({V}\\prime /V)}2. To determine the dynamics of DE we also calculate the background evolution and its perturbations, since they are important to discriminate between different DE models.
AgGaS2 infrared parametric oscillator
NASA Technical Reports Server (NTRS)
Fan, Y. X.; Eckardt, R. C.; Byer, R. L.; Route, R. K.; Feigelson, R. S.
1984-01-01
A report is presented of the first operation of an optical parametric oscillator in a chalcopyrite crystal, AgGaS2. Tuning from 1.4 to 4.0 microns is demonstrated for 1.06-micron Nd:yttrium aluminum garnet pumping. The potential tuning range extends to the 12-micron transparency limit of the crystal.
Connecting the Dots Parametrically: An Alternative to Cubic Splines.
ERIC Educational Resources Information Center
Hildebrand, Wilbur J.
1990-01-01
Discusses a method of cubic splines to determine a curve through a series of points and a second method for obtaining parametric equations for a smooth curve that passes through a sequence of points. Procedures for determining the curves and results of each of the methods are compared. (YP)
Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models
ERIC Educational Resources Information Center
Song, Xin-Yuan; Xia, Ye-Mao; Pan, Jun-Hao; Lee, Sik-Yum
2011-01-01
Structural equation models have wide applications. One of the most important issues in analyzing structural equation models is model comparison. This article proposes a Bayesian model comparison statistic, namely the "L[subscript nu]"-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider…
Parametric resonance in the early Universe—a fitting analysis
NASA Astrophysics Data System (ADS)
Figueroa, Daniel G.; Torrentí, Francisco
2017-02-01
Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in 3+1 dimensions, we parametrize the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasize the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequent non-linear dynamics. We provide simple fits to the relevant time scales and particle energy fractions at each stage. Our fits can be applied to post-inflationary preheating scenarios, where the oscillatory field is the inflaton, or to spectator-field scenarios, where the oscillatory field can be e.g. a curvaton, or the Standard Model Higgs.
Acoustic attenuation design requirements established through EPNL parametric trades
NASA Technical Reports Server (NTRS)
Veldman, H. F.
1972-01-01
An optimization procedure for the provision of an acoustic lining configuration that is balanced with respect to engine performance losses and lining attenuation characteristics was established using a method which determined acoustic attenuation design requirements through parametric trade studies using the subjective noise unit of effective perceived noise level (EPNL).
A new parametric method of estimating the joint probability density
NASA Astrophysics Data System (ADS)
Alghalith, Moawia
2017-04-01
We present simple parametric methods that overcome major limitations of the literature on joint/marginal density estimation. In doing so, we do not assume any form of marginal or joint distribution. Furthermore, using our method, a multivariate density can be easily estimated if we know only one of the marginal densities. We apply our methods to financial data.
Parametric Design Studies on a Direct Liquid Feed Fuel Cell
NASA Technical Reports Server (NTRS)
Frank, H. A.; Narayanan, S. R.; Nakamura, B.; Surampudi, S.; Halpert, G.
1995-01-01
Parametric design studies were carried out on a direct methanol liquid feed fuel cell employing 1 M MeOH fuel, air and oxygen as oxidant in a 2 inch x 2 inch cell employing polymeric electrolyte membranes. Measurements include voltage-current output parameters, methanol crossover rate, and impedance as a function of several design and operational variables. Design variables are described.
Simple parametrization of the π-N amplitude
NASA Astrophysics Data System (ADS)
McLeod, R. J.; Afnan, I. R.
1985-07-01
We present a simple parametrization of the S-, P-, and D-wave π-N amplitudes using separable potentials for Tπ<1 GeV. The effect of the inelasticity is included in the Green's function while maintaining consistency with unitarity. The P11 amplitude is written as a pole plus nonpole in order to describe pion absorption in A>=2.
Parametric resonance induced chaos in magnetic damped driven pendulum
NASA Astrophysics Data System (ADS)
Khomeriki, Giorgi
2016-07-01
A damped driven pendulum with a magnetic driving force, appearing from a solenoid, where ac current flows is considered. The solenoid acts on the magnet, which is located at a free end of the pendulum. In this system the existence and interrelation of chaos and parametric resonance is theoretically examined. Derived analytical results are supported by numerical simulations and conducted experiments.
Rotary bistable and Parametrically Excited Vibration Energy Harvesting
NASA Astrophysics Data System (ADS)
Kurmann, L.; Jia, Y.; Hoffmann, D.; Manoli, Y.; Woias, P.
2016-11-01
Parametric resonance is a type of nonlinear vibration phenomenon [1], [2] induced from the periodic modulation of at least one of the system parameters and has the potential to exhibit interesting higher order nonlinear behaviour [3]. Parametrically excited vibration energy harvesters have been previously shown to enhance both the power amplitude [4] and the frequency bandwidth [5] when compared to the conventional direct resonant approach. However, to practically activate the more profitable regions of parametric resonance, additional design mechanisms [6], [7] are required to overcome a critical initiation threshold amplitude. One route is to establish an autoparametric system where external direct excitation is internally coupled to parametric excitation [8]. For a coupled two degrees of freedom (DoF) oscillatory system, principal autoparametric resonance can be achieved when the natural frequency of the first DoF f1 is twice that of the second DoF f2 and the external excitation is in the vicinity of f1. This paper looks at combining rotary and translatory motion and use autoparametric resonance phenomena.
Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models
ERIC Educational Resources Information Center
Song, Xin-Yuan; Xia, Ye-Mao; Pan, Jun-Hao; Lee, Sik-Yum
2011-01-01
Structural equation models have wide applications. One of the most important issues in analyzing structural equation models is model comparison. This article proposes a Bayesian model comparison statistic, namely the "L[subscript nu]"-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider…
Soil Analysis using the semi-parametric NAA technique
Zamboni, C. B.; Silveira, M. A. G.; Medina, N. H.
2007-10-26
The semi-parametric Neutron Activation Analysis technique, using Au as a flux monitor, was applied to measure element concentrations of Br, Ca, Cl, K, Mn and Na for soil characterization. The results were compared with those using the Instrumental Neutron Activation Analysis technique and they found to be compatible. The viability, advantages, and limitations of using these two analytic methodologies are discussed.
A unified framework for weighted parametric multiple test procedures.
Xi, Dong; Glimm, Ekkehard; Maurer, Willi; Bretz, Frank
2017-09-01
We describe a general framework for weighted parametric multiple test procedures based on the closure principle. We utilize general weighting strategies that can reflect complex study objectives and include many procedures in the literature as special cases. The proposed weighted parametric tests bridge the gap between rejection rules using either adjusted significance levels or adjusted p-values. This connection is made by allowing intersection hypotheses of the underlying closed test procedure to be tested at level smaller than α. This may be also necessary to take certain study situations into account. For such cases we introduce a subclass of exact α-level parametric tests that satisfy the consonance property. When the correlation is known only for certain subsets of the test statistics, a new procedure is proposed to fully utilize this knowledge within each subset. We illustrate the proposed weighted parametric tests using a clinical trial example and conduct a simulation study to investigate its operating characteristics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
An Optical Parametric Amplifier for Profiling Gases of Atmospheric Interest
NASA Technical Reports Server (NTRS)
Heaps, William (Technical Monitor); Burris, John; Richter, Dale
2004-01-01
This paper describes the development of a lidar transmitter using an optical parametric amplifier. It is designed for profiling gases of atmospheric interest at high spatial and temporal precision in the near-IR. Discussions on desirable characteristics for such a transmitter with specific reference to the case of CO, are made.
Steady States of the Parametric Rotator and Pendulum
ERIC Educational Resources Information Center
Bouzas, Antonio O.
2010-01-01
We discuss several steady-state rotation and oscillation modes of the planar parametric rotator and pendulum with damping. We consider a general elliptic trajectory of the suspension point for both rotator and pendulum, for the latter at an arbitrary angle with gravity, with linear and circular trajectories as particular cases. We treat the…
Modeling shell morphology of an epitoniid species with parametric equations
NASA Astrophysics Data System (ADS)
Bernido, Christopher C.; Carpio-Bernido, M. Victoria; Sadudaquil, Jerome A.; Salas, Rochelle I.; Mangyao, Justin Ericson A.; Halasan, Lorenzo C.; Baja, Paz Kenneth S.; Jumawan, Ethel Jade V.
2017-08-01
An epitoniid specimen under the genus Cycloscala is mathematically modeled using parametric equations which allow comparison of growth functions and parameter values with other specimens of the same genus. This mathematical modeling approach may supplement the currently used genetic and microscopy methods in the taxonomic classification of species.
Infra-red parametric generation: Phase mismatch condition
NASA Astrophysics Data System (ADS)
Ghosh, S.; Dubey, Swati; Jain, Kamal
2015-07-01
An analytical investigation is made for the Infrared parametric generation in doped semiconductor plasma under phase mismatch condition. Theoretical formulations are undertaken to determine induced polarization and threshold pump field for the onset of parametric generation in semiconductor plasma medium. The origin of this nonlinear interaction lies in the second order optical susceptibility arising due to the induced nonlinear current density in piezoelectric medium. Numerical estimations are made for n- type InSb at 77 K duly irradiated by a pulsed 10.6µm CO2 laser. It is very difficult to attain exact phase matching in experimental frame so we have considered a tolerable small phase mismatch in order to attain a new result. Its effect on the Infrared parametric generation in compound semiconductor is examined through induced polarization. Transmitted intensity is determined to have an idea about conversion efficiency of the said process. Phase mismatch tends to raise the required pump field to stimulate the parametric generation. Transmitted intensity is found to decrease with coherence length lc and increase carrier concentration n0, which is favorable for improved conversion efficiency.
Optical parametric oscillation in one-dimensional microcavities
NASA Astrophysics Data System (ADS)
Lecomte, Timothée; Ardizzone, Vincenzo; Abbarchi, Marco; Diederichs, Carole; Miard, Audrey; Lemaitre, Aristide; Sagnes, Isabelle; Senellart, Pascale; Bloch, Jacqueline; Delalande, Claude; Tignon, Jerome; Roussignol, Philippe
2013-04-01
We present a comprehensive investigation of optical parametric oscillation in resonantly excited one-dimensional semiconductor microcavities with embedded quantum wells. Such solid-state structures feature a fine control over light-matter coupling and produce a photonic/polaritonic mode fan that is exploited for the efficient emission of parametric beams. We implement an energy-degenerate optical parametric oscillator with balanced signal and idler intensities via a polarization-inverting mechanism. In this paper, we (i) precisely review the multimode photonic/polaritonic structure of individual emitters, (ii) provide a thorough comparison between experiment and theory, focusing on the power and the threshold dependence on the exciton-photon detuning, (iii) discuss the influence of inhomogeneous broadening of the excitonic transition and finite size, and (iv) find that a large exciton-photon detuning is a key parameter to reach a high output power and a high conversion efficiency. Our study highlights the predictive character of the polariton interaction theory and the flexibility of one-dimensional semiconductor microcavities as a platform to study parametric phenomena.
The Importance of Structure Coefficients in Parametric Analyses.
ERIC Educational Resources Information Center
Friedrich, Katherine R.
The recognition that all parametric methods are interrelated, coupled with the notion that structure coefficients are often vital in factor and canonical analyses, suggests that structure coefficients may be important in univariate analysis as well. Using a small, heuristic data set, this paper discusses the importance of structure coefficients…
ANSYS PARAMETRIC MODEL FOR TANK DST-AY
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This report documents the parametric ANSYS models developed for dome load analyses of double-shell tanks. The default model parameters are specific to the AY tanks but can be easily modified for tank-specific analysis of AN, AW, AP, AZ or SY tanks. Both axisymmetric slice and full 360 degree models are provided. The purpose of this calculation is to develop a parametric finite element analysis model of the Hanford Site underground waste storage tanks. This is not an analysis. Instead, the present calculation develops a parametric model of the double shell tank DST-AY, which is based on Buyer-supplied as-built drawings and information for the analyses of record (AOR) for Double-Shell Tanks (DSTs), encompassing the existing tank load conditions. The computer model has various parameters that can be either changed directly or easily added by a knowledgeable ANSYS user. These parameters are modified to consider field conditions, such as in-situ wall thickness of primary steel tank, dead and live loads, moving loads, berm loads, soil overburden depth plus surrounding soil, internal waste level and waste specific gravity, internal vapor pressure, and thermal loads within the tank. This document contains sample calculations that demonstrate how various aspects of the parametric model function. These sample calculations in this document are not to be used for assessing the structural integrity of the DST-AY tanks at the Hanford Site.
Universal parametrization of thermal photon rates in hadronic matter
NASA Astrophysics Data System (ADS)
Heffernan, Matthew; Hohler, Paul; Rapp, Ralf
2015-02-01
Electromagnetic (EM) radiation off strongly interacting matter created in high-energy heavy-ion collisions (HICs) encodes information on the high-temperature phases of nuclear matter. Microscopic calculations of thermal EM emission rates are usually rather involved and not readily accessible to broad applications in models of the fireball evolution which are required to compare with experimental data. An accurate and universal parametrization of the microscopic calculations is thus key to honing the theory behind the EM spectra. Here we provide such a parametrization for photon emission rates from hadronic matter, including the contributions from in-medium ρ mesons (which incorporate effects from baryons and antibaryons), as well as bremsstrahlung from π π scattering. Individual parametrizations for each contribution are numerically determined through nested fitting functions for photon energies from 0.2 to 5 GeV in chemically equilibrated matter of temperatures 100-180 MeV and baryon chemical potentials 0-400 MeV. Special care is taken to extent the parametrizations to chemical off-equilibrium as encountered in HICs after chemical freeze-out. This provides a functional description of thermal photon rates within a 20% variation of the microscopically calculated values.
Spacelab mission dependent training parametric resource requirements study
NASA Technical Reports Server (NTRS)
Ogden, D. H.; Watters, H.; Steadman, J.; Conrad, L.
1976-01-01
Training flows were developed for typical missions, resource relationships analyzed, and scheduling optimization algorithms defined. Parametric analyses were performed to study the effect of potential changes in mission model, mission complexity and training time required on the resource quantities required to support training of payload or mission specialists. Typical results of these analyses are presented both in graphic and tabular form.
Infra-red parametric generation: Phase mismatch condition
Ghosh, S.; Dubey, Swati; Jain, Kamal
2015-07-31
An analytical investigation is made for the Infrared parametric generation in doped semiconductor plasma under phase mismatch condition. Theoretical formulations are undertaken to determine induced polarization and threshold pump field for the onset of parametric generation in semiconductor plasma medium. The origin of this nonlinear interaction lies in the second order optical susceptibility arising due to the induced nonlinear current density in piezoelectric medium. Numerical estimations are made for n- type InSb at 77 K duly irradiated by a pulsed 10.6µm CO{sub 2} laser. It is very difficult to attain exact phase matching in experimental frame so we have considered a tolerable small phase mismatch in order to attain a new result. Its effect on the Infrared parametric generation in compound semiconductor is examined through induced polarization. Transmitted intensity is determined to have an idea about conversion efficiency of the said process. Phase mismatch tends to raise the required pump field to stimulate the parametric generation. Transmitted intensity is found to decrease with coherence length lc and increase carrier concentration n{sub 0}, which is favorable for improved conversion efficiency.
Connecting the Dots Parametrically: An Alternative to Cubic Splines.
ERIC Educational Resources Information Center
Hildebrand, Wilbur J.
1990-01-01
Discusses a method of cubic splines to determine a curve through a series of points and a second method for obtaining parametric equations for a smooth curve that passes through a sequence of points. Procedures for determining the curves and results of each of the methods are compared. (YP)
Surface and Volume Grid Generation in Parametric Form
NASA Technical Reports Server (NTRS)
Yu, Tzuyi; Soni, Bharat K.; Benjamin, Ted; Williams, Robert
1996-01-01
The algorithm for surface modeling and volume grid generation using parametric Non-Uniform Rational B-splines (NURBS) geometric representation are presented. The enhanced re-parameterization algorithm which can yield a desired physical distribution on the curve, surface, and volume is also presented. This approach bridges the gap between computer aided design surface/volume definition and surface/volume grid generation.
Raman-Enhanced Phase-Sensitive Fibre Optical Parametric Amplifier
Fu, Xuelei; Guo, Xiaojie; Shu, Chester
2016-01-01
Phase-sensitive amplification is of great research interest owing to its potential in noiseless amplification. One key feature in a phase-sensitive amplifier is the gain extinction ratio defined as the ratio of the maximum to the minimum gains. It quantifies the capability of the amplifier in performing low-noise amplification for high phase-sensitive gain. Considering a phase-sensitive fibre optical parametric amplifier for linear amplification, the gain extinction ratio increases with the phase-insensitive parametric gain achieved from the same pump. In this work, we use backward Raman amplification to increase the phase-insensitive parametric gain, which in turn improves the phase-sensitive operation. Using a 955 mW Raman pump, the gain extinction ratio is increased by 9.2 dB. The improvement in the maximum phase-sensitive gain is 18.7 dB. This scheme can significantly boost the performance of phase-sensitive amplification in a spectral range where the parametric pump is not sufficiently strong but broadband Raman amplification is available. PMID:26830136
Parametrization of Drag and Turbulence for Urban Neighbourhoods with Trees
NASA Astrophysics Data System (ADS)
Krayenhoff, E. S.; Santiago, J.-L.; Martilli, A.; Christen, A.; Oke, T. R.
2015-08-01
Urban canopy parametrizations designed to be coupled with mesoscale models must predict the integrated effect of urban obstacles on the flow at each height in the canopy. To assess these neighbourhood-scale effects, results of microscale simulations may be horizontally-averaged. Obstacle-resolving computational fluid dynamics (CFD) simulations of neutrally-stratified flow through canopies of blocks (buildings) with varying distributions and densities of porous media (tree foliage) are conducted, and the spatially-averaged impacts on the flow of these building-tree combinations are assessed. The accuracy with which a one-dimensional (column) model with a one-equation (-) turbulence scheme represents spatially-averaged CFD results is evaluated. Individual physical mechanisms by which trees and buildings affect flow in the column model are evaluated in terms of relative importance. For the treed urban configurations considered, effects of buildings and trees may be considered independently. Building drag coefficients and length scale effects need not be altered due to the presence of tree foliage; therefore, parametrization of spatially-averaged flow through urban neighbourhoods with trees is greatly simplified. The new parametrization includes only source and sink terms significant for the prediction of spatially-averaged flow profiles: momentum drag due to buildings and trees (and the associated wake production of turbulent kinetic energy), modification of length scales by buildings, and enhanced dissipation of turbulent kinetic energy due to the small scale of tree foliage elements. Coefficients for the Santiago and Martilli (Boundary-Layer Meteorol 137: 417-439, 2010) parametrization of building drag coefficients and length scales are revised. Inclusion of foliage terms from the new parametrization in addition to the Santiago and Martilli building terms reduces root-mean-square difference (RMSD) of the column model streamwise velocity component and turbulent
Aircraft conceptual design - an adaptable parametric sizing methodology
NASA Astrophysics Data System (ADS)
Coleman, Gary John, Jr.
Aerospace is a maturing industry with successful and refined baselines which work well for traditional baseline missions, markets and technologies. However, when new markets (space tourism) or new constrains (environmental) or new technologies (composite, natural laminar flow) emerge, the conventional solution is not necessarily best for the new situation. Which begs the question "how does a design team quickly screen and compare novel solutions to conventional solutions for new aerospace challenges?" The answer is rapid and flexible conceptual design Parametric Sizing. In the product design life-cycle, parametric sizing is the first step in screening the total vehicle in terms of mission, configuration and technology to quickly assess first order design and mission sensitivities. During this phase, various missions and technologies are assessed. During this phase, the designer is identifying design solutions of concepts and configurations to meet combinations of mission and technology. This research undertaking contributes the state-of-the-art in aircraft parametric sizing through (1) development of a dedicated conceptual design process and disciplinary methods library, (2) development of a novel and robust parametric sizing process based on 'best-practice' approaches found in the process and disciplinary methods library, and (3) application of the parametric sizing process to a variety of design missions (transonic, supersonic and hypersonic transports), different configurations (tail-aft, blended wing body, strut-braced wing, hypersonic blended bodies, etc.), and different technologies (composite, natural laminar flow, thrust vectored control, etc.), in order to demonstrate the robustness of the methodology and unearth first-order design sensitivities to current and future aerospace design problems. This research undertaking demonstrates the importance of this early design step in selecting the correct combination of mission, technologies and configuration to
Parametric perfusion imaging based on low-cost ultrasound platform.
Gu, Xiaolin; Zhong, Hui; Wan, Mingxi; Hu, Xiaowen; Lv, Dan; Shen, Liang; Zhang, Xiaomei
2010-01-01
In this study, we attempted to implement parametric perfusion imaging to quantify blood perfusion based on modified low-cost ultrasound platform. A novel ultrasound contrast-specific imaging method called pulse-inversion harmonic sum-squared-differences (PIHSSD) was proposed for improving the sensitivity for detecting contrast agents and the accuracy of parametric perfusion imaging, which combined pulse-inversion harmonic (PIH) with pulse-inversion sum-squared-differences (PISSD) threshold-based decision. PIHSSD method just involved simple operations including addition and multiplication and was easy to realize. The sequences of contrast images without logarithmic compression were used to acquire time intensity curves (TICs) from numerous equal-sized regions-of-interest (ROI) covering the entire image plane. Parametric perfusion images were obtained based on the parameters extracted from the TICs, including peak value (PV), area under curve (AUC), mean transit time (MTT), peak value time (PVT), peak width (PW) and climbing rate (CR). Flow phantom was used for validation and the results suggested that PIHSSD method provided 9.6 to 20.3 dB higher contrast-to-tissue ratio (CTR) than PIH method. The results of the experiments of rabbit kidney also showed that the CTR of PIHSSD images was higher than that of PIH images, and the parametric perfusion images based on PIHSSD method provided more accurate quantification of blood perfusion compared with those based on PIH and PISSD methods. It demonstrated that the parametric perfusion imaging achieved good performance though implemented on low-cost ultrasound platform. (E-mail: mxwan@mail.xjtu.edu.cn).
ERIC Educational Resources Information Center
Maydeu-Olivares, Albert
2005-01-01
Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in…
ERIC Educational Resources Information Center
Maydeu-Olivares, Albert
2005-01-01
Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in…
Structure of pump resonances during optical parametric oscillation in whispering gallery resonators.
Breunig, I; Sturman, B; Bückle, A; Werner, C S; Buse, K
2013-09-01
In optical parametric oscillators, the line shape of the pump resonance becomes strongly distorted above the oscillation threshold. We model this behavior and find good agreement with the literature data and our original experimental data. A fit of the model to the data provides valuable information about the loss mechanisms in the parametric process. In particular, the modal properties of the parametric waves can be gained, which is important for both classical and quantum aspects of optical parametric oscillation.
Revisiting the quark-lepton complementarity and triminimal parametrization of neutrino mixing matrix
Kang, Sin Kyu
2011-05-01
We examine how a parametrization of neutrino mixing matrix reflecting quark-lepton complementarity can be probed by considering phase-averaged oscillation probabilities, flavor composition of neutrino fluxes coming from atmospheric and astrophysical neutrinos and lepton flavor violating radiative decays. We discuss some distinct features of the parametrization by comparing the triminimal parametrization of perturbations to the tribimaximal neutrino mixing matrix.
Creating Efficient Instrumentation Networks to Support Parametric Risk Transfer
NASA Astrophysics Data System (ADS)
Rockett, P.
2009-04-01
The development and institutionalisation of Catastrophe modelling during the 1990s opened the way for Catastrophe risk securitization transactions in which catastrophe risk held by insurers is transferred to the capital markets in the form of a bond. Cat Bonds have been one of the few areas of the capital markets in which the risk modelling has remained secure and the returns on the bonds have held up well through the 2008 Credit Crunch. There are three ways of structuring the loss triggers on bonds: ‘indemnity triggers' - reflecting the actual losses to the issuers; ‘index triggers' reflecting the losses to some index such as reported insurance industry loss and ‘parametric triggers' reflecting the parameters of the underlying catastrophe event itself. Indemnity triggers require that the investors trust that the insurer is reporting all their underlying exposures, while both indemnity and index losses may take 1-2 years to settle before all the claims are reported and resolved. Therefore parametric structures have many advantages, in particular in that the bond can be settled rapidly after an event. The challenge is to create parametric indices that closely reflect the actual losses to the insurer - ie that minimise ‘basis risk'. First generation parametric indices had high basis risk as they were crudely based on the magnitude of an earthquake occurring within some defined geographical box, or the intensity of a hurricane relative to the distance of the storm from some location. Second generation triggers involve taking measurements of ground motion or windspeed or flood depths at many locations and weighting each value so that the overall index closely mimics insurance loss. Cat bonds with second generation parametric triggers have been successfully issued for European Windstorm, UK Flood and California and Japan Earthquake. However the spread of second generation parametric structures is limited by the availability of suitable networks of
Universal Parametrization of Thermal Photon Production in Hadronic Matter
NASA Astrophysics Data System (ADS)
Heffernan, Matthew; Hohler, Paul; Rapp, Ralf
2014-09-01
As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of thermal photon production largely within an unprecedented 20% of the calculated values from the spectral function, a significant reduction in error from available parametrizations. The contribution of photons and dileptons from pion-pion bremsstrahlung is evaluated for the importance of its contribution. The functional form, coupled with the comparison to the bremsstrahlung production of thermal photons, will provide a baseline for guiding future studies. As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of
Pion cross section parametrizations for intermediate energy, nucleus-nucleus collisions
Norbury, John W.
2009-03-15
Space radiation and cosmic ray transport codes require simple and accurate models for hadron production in intermediate energy, nucleus-nucleus collisions. Several arithmetic parametrization models for pion production are compared to laboratory frame data. It is found that models based on high energy parametrizations are unable to describe intermediate energy, differential cross section data. However, simple thermal model parametrizations, when appropriately transformed from the center of momentum to the laboratory frame, are able to account for the data. Heavy ion transport codes that require algebraic cross section formulas can therefore use arithmetic parametrizations at high energy, but should use thermal model parametrizations at intermediate energy.
Reversible conveyer computation in array of parametric quantrons
NASA Astrophysics Data System (ADS)
Liharev, K. K.; Rylov, S. V.; Semenov, V. K.
1985-03-01
A possibility of physically and logically reversible processing of digital information in Josephson-junction circuits of a reasonable complexity has been considered. As an example, an 8-bit 1024-point fast convolver has been designed on the basis of a two-dimensional quasiuniform array of about 250 x 30,000 parametric quantrons. This completely reversible conveyor device can operate with the estimated rate of at least 10 to the 9th numbers per second, which corresponds to 10 to the 14th binary logical operations per second. At this rate the power dissipation in the whole device can still be as low as 30 nW. A new mode of the parametric quantron operation with large parameter margins is also described.
A divergence-free parametrization for dynamical dark energy
Akarsu, Özgür; Dereli, Tekin; Vazquez, J. Alberto E-mail: tdereli@ku.edu.tr
2015-06-01
We introduce a new parametrization for the dark energy, led by the same idea to the linear expansion of the equation of state in scale factor a and in redshift z, which diverges neither in the past nor future and contains the same number of degrees of freedom with the former two. We present constraints of the cosmological parameters using the most updated baryon acoustic oscillation (BAO) measurements along with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. This new parametrization allowed us to carry out successive observational analyses by decreasing its degrees of freedom systematically until ending up with a dynamical dark energy model that has the same number of parameters with ΛCDM . We found that the dark energy source with a dynamical equation of state parameter equal −2/3 at the early universe and −1 today fits the data slightly better than Λ.
Additive empirical parametrization and microscopic study of deuteron breakup
NASA Astrophysics Data System (ADS)
Avrigeanu, M.; Avrigeanu, V.
2017-02-01
Comparative assessment of the total breakup proton-emission cross sections measured for 56 MeV deuteron interaction with target nuclei from 12C to 209Bi, with an empirical parametrization and recently calculated microscopic neutron-removal cross sections was done at the same time with similar data measured at 15, 25.5, 70, and 80 MeV. Comparable mass dependencies of the elastic-breakup (EB) cross sections provided by the empirical parametrization and the microscopic results have been also found at the deuteron energy of 56 MeV, while the assessment of absolute-values variance up to a factor of two was not possible because of the lack of EB measurements at energies higher than 25.5 MeV. While the similarities represent an additional validation of the microscopic calculations, the cross-section difference should be considered within the objectives of further measurements.