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Sample records for anammox process rates

  1. Oxygen at nanomolar levels reversibly suppresses process rates and gene expression in anammox and denitrification in the oxygen minimum zone off Northern Chil

    DEFF Research Database (Denmark)

    Dalsgaard, Tage; Stewart, Frank J.; Thamdrup, Bo;

    2014-01-01

    and metatranscriptomic analyses. IMPORTANCE: The removal of fixed nitrogen via anammox and denitrification associated with low O2 concentrations in oceanic oxygen minimum zones (OMZ) is a major sink in oceanic N budgets, yet the sensitivity and dynamics of these processes with respect to O2 are poorly known. The present...... study elucidated how nanomolar O2 concentrations affected nitrogen removal rates and expression of key nitrogen cycle genes in water from the eastern South Pacific OMZ, applying state-of-the-art (15)N techniques and metatranscriptomics. Rates of both denitrification and anammox responded rapidly...

  2. [Application and obstacles of ANAMMOX process].

    Science.gov (United States)

    Jin Rencun; Zhang, Zhengzhe; Ji, Yuxin; Chen, Hui; Guo, Qiong; Zhou, Yuhuang; Wu, Conghui; Jin, Rencun

    2014-12-01

    Anaerobic ammonium oxidation (ANAMMOX), as its essential advantages of high efficiency and low cost, is a promising novel biological nitrogen elimination process with attractive application prospects. Over the past two decades, many processes based on the ANAMMOX reaction have been continuously studied and applied to practical engineering, with the perspective of reaching 100 full-scale installations in operation worldwide by 2014. Our review summarizes various forms of ANAMMOX processes, including partial nitritation-ANAMMOX, completely autotrophic nitrogen removal over nitrite, oxygen limited autotrophic nitrification and denitrification, denitrifying ammonium oxidation, aerobic deammonification, simultaneous partial nitrification, ANAMMOX and denitrification, single-stage nitrogen removal using ANAMMOX and partial nitritation. We also compare the operating conditions for one-stage and two-stage processes and summarize the obstacles and countermeasures in engineering application of ANAMMOX systems, such as moving bed biofilm reactor, sequencing batch reactor and granular sludge reactor. Finally, we discuss the future research and application direction, which should focus on the optimization of operating conditions and applicability of the process to the actual wastewater, especially on automated control and the impact of special wastewater composition on process performance. PMID:26016370

  3. Start-up of the SHARON and ANAMMOX process in landfill bioreactors using aerobic and anaerobic ammonium oxidising biomass.

    Science.gov (United States)

    Shalini, S Sri; Joseph, Kurian

    2013-12-01

    The main aim of this study is to analyse the feasibility to use aerobic ammonium oxidising bacteria (AOB) and anammox/AnAOB biomass enriched from mined municipal solid waste for in situ SHARON and ANAMMOX processes in laboratory scale landfill bioreactors (LFBR) for ammonia nitrogen removal. For this purpose, three LFBRs were operated as Control (without biomass seed), SHARON (with AOB biomass seed) and ANAMMOX (with anammox biomass seed) for 315 days. Results showed nitrogen loading rate of 1.0 kg N/d was effectively removed in SHARON and ANAMMOX LFBR. In SHARON LFBR, partial nitritation efficiency reached up to 98.5% with AOB population of MPN of 5.1 × 10(6)/mL obtained. ANAMMOX LFBR gave evolution of 95% of nitrogen gas as the end product confirmed the ANAMMOX process. Nitrogen transformations, biomass development and hydrazine and hydroxylamine formation authenticated the enriched AOB and anammox biomass activity in landfill bioreactors.

  4. The ANAMMOX reactor under transient-state conditions: process stability with fluctuations of the nitrogen concentration, inflow rate, pH and sodium chloride addition.

    Science.gov (United States)

    Yu, Jin-Jin; Jin, Ren-Cun

    2012-09-01

    The process stability of an anaerobic ammonium oxidation (ANAMMOX) was investigated in an upflow anaerobic sludge blanket reactor subjected to overloads of 2.0- to 3.0-fold increases in substrate concentrations, inflow rates lasting 12 or 24h, extreme pH levels of 4 and 10 for 12h and a 12-h 30 g l(-1) NaCl addition. During the overloads, the nitrogen removal rate improved, and the shock period was an important factor affecting the reactor performance. In the high pH condition, the reactor performance significantly degenerated; while in the low pH condition, it did not happen. The NaCl addition caused the most serious deterioration in the reactor, which took 108 h to recover and was accompanied by a stoichiometric ratio divergence. There are well correlations between the total nitrogen and the electrical conductivity which is considered to be a convenient signal for controlling and monitoring the ANAMMOX process under transient-state conditions. PMID:22728197

  5. The Increasing Interest of ANAMMOX Research in China: Bacteria, Process Development, and Application

    Directory of Open Access Journals (Sweden)

    Mohammad Ali

    2013-01-01

    Full Text Available Nitrogen pollution created severe environmental problems and increasingly has become an important issue in China. Since the first discovery of ANAMMOX in the early 1990s, this related technology has become a promising as well as sustainable bioprocess for treating strong nitrogenous wastewater. Many Chinese research groups have concentrated their efforts on the ANAMMOX research including bacteria, process development, and application during the past 20 years. A series of new and outstanding outcomes including the discovery of new ANAMMOX bacterial species (Brocadia sinica, sulfate-dependent ANAMMOX bacteria (Anammoxoglobus sulfate and Bacillus benzoevorans, and the highest nitrogen removal performance (74.3–76.7 kg-N/m3/d in lab scale granule-based UASB reactors around the world were achieved. The characteristics, structure, packing pattern and floatation mechanism of the high-rate ANAMMOX granules in ANAMMOX reactors were also carefully illustrated by native researchers. Nowadays, some pilot and full-scale ANAMMOX reactors were constructed to treat different types of ammonium-rich wastewater including monosodium glutamate wastewater, pharmaceutical wastewater, and leachate. The prime objective of the present review is to elucidate the ongoing ANAMMOX research in China from lab scale to full scale applications, comparative analysis, and evaluation of significant findings and to set a design to usher ANAMMOX research in culmination.

  6. Kinetic models for nitrogen inhibition in ANAMMOX and nitrification process on deammonification system at room temperature.

    Science.gov (United States)

    De Prá, Marina C; Kunz, Airton; Bortoli, Marcelo; Scussiato, Lucas A; Coldebella, Arlei; Vanotti, Matias; Soares, Hugo M

    2016-02-01

    In this study were fitted the best kinetic model for nitrogen removal inhibition by ammonium and/or nitrite in three different nitrogen removal systems operated at 25 °C: a nitrifying system (NF) containing only ammonia oxidizing bacteria (AOB), an ANAMMOX system (AMX) containing only ANAMMOX bacteria, and a deammonification system (DMX) containing both AOB and ANAMMOX bacteria. NF system showed inhibition by ammonium and was best described by Andrews model. The AMX system showed a strong inhibition by nitrite and Edwards model presented a best system representation. For DMX system, the increased substrate concentration (until 1060 mg NH3-N/L) tested was not limiting for the ammonia consumption rate and the Monod model was the best model to describe this process. The AOB and ANAMMOX sludges combined in the DMX system displayed a better activity, substrate affinity and excellent substrate tolerance than in nitrifying and ANAMMOX process. PMID:26700756

  7. Kinetics of nitrogen removal in high rate anammox upflow filter

    International Nuclear Information System (INIS)

    The process kinetics for laboratory-scale anammox (anaerobic ammonium oxidation) upflow filter using synthetic wastewater as feed were investigated. The experimental unit consisted of a 2.0 L reactor filled with three-dimensional plastic media. The filter was tested for different influent substrate concentrations and hydraulic retention time (HRT). The substrate loading removal rate was compared with prediction of Stover-Kincannon, second-order and the first-order substrate removal models. Upon approaching pseudo-steady-state condition, substrate ammonium or nitrite concentrations were increased from 280 to 462 mg N/L, while HRT was stepwise decreased from 14.4 to 2 h, with a concomitant increase in nitrogen loading rate (NLR) from 0.93 to 7.34 g/L day. Based on calculations, Stover-Kincannon model and second-order 'Grau' model were found to be the appropriate models to describe the upflow filter. According to Stover-Kincannon model, the maximum total substrate removal rate constant (Umax) and saturation value constant (KB) were suggested as 12.4 and 12.0 g N/L day, respectively. As Stover-Kincannon model and second-order model gave high correlation coefficients (97.9% and 98.6%, respectively), these models may be used in predicting the behavior or design of the anammox filter.

  8. Evaluation of COD effect on anammox process and microbial communities in the anaerobic baffled reactor (ABR).

    Science.gov (United States)

    Chen, Chongjun; Sun, Faqian; Zhang, Haiqing; Wang, Jianfang; Shen, Yaoliang; Liang, Xinqiang

    2016-09-01

    Nitrogen removal with different organic carbon effect was investigated using anaerobic baffled reactor (ABR) anammox reactor. Results indicated that organic carbon exert an important effect on nitrogen removal through anammox process. When the feeding COD concentration was lower than 99.7mgL(-1), nitrogen removal could be enhanced via the coexistence of denitrification and anammox. Elevated COD could further deteriorate the anammox activity with almost complete inhibition at the COD concentration of 284.1mgL(-1). The nitrogen removal contribution rate of anammox was varied from 92.7% to 6.9%. However, the anammox activity was recovered when the COD/TN was decreased from 2.33 to 1.25 with influent nitrite addition. And, the anammox process was again intensified from 27.0 to 51.2%. High-throughput Miseq sequencing analyses revealed that the predominant phylum changed from Chloroflexi to Proteobacteria with the elevated COD addition, which indicated COD concentration was the most important factor regulating the bacterial community structure. PMID:27285572

  9. [Effect of HCO3- on Nitrogen Removal Efficiency in Partial Nitritation-ANAMMOX Process].

    Science.gov (United States)

    Li, Xiang; Cheng, Zong-heng; Huang, Yong; Yuan, Yi; Liu, Xin; Zhang, Da-lin

    2015-11-01

    The effect of HCO3- on nitrogen removal efficiency in partial nitritation-ANAMMOX process was studied by using the combined process of partial nitritation and ANAMMOX has been started and achieved the stable operation of nitrogen removal. The results showed that, when the ratio of C/N decreased from 2 to 0.17 in influent, the nitrogen removal rate decreased from 1.3 kg- ( M3 x d)(-1) to 0.40 kg x (M3 x d)(-1), the decrease range arrived at 69.3%. The nitrogen conversion efficiency was limited, because of the added amount of HCO3- was decreased, which leading to the pH value declined sharply in nitritation and ANAMMOX zone. In the partial nitritation-ANAMMOX process, the effect of HCO3- limitation on activity of ammonium oxidizing bacteria, ANAMMOX bacteria and nitrifying bacteria was decreased in turn. When the C/N ratio increased to 1, the nitrogen removal rate of combined process was quickly restored to 1 kg x (m3 x d)(-1). It indicated that short HCO3- limitation on nitrogen conversion efficiency of the combined process can be fast recovery. The resulted also showed that the relationship between influent C/N ratio and nitrogen removal efficiency has obvious relativity in partial nitritation-ANAMMOX process. PMID:26911008

  10. Anammox for ammonia removal from pig manure effluents: Effect of organic matter content on process performance

    DEFF Research Database (Denmark)

    Salces, Beatriz Molinuevo; García, M. C.; Karakashev, Dimitar Borisov;

    2009-01-01

    The anammox process, under different organic loading rates (COD), was evaluated using a semi-continous UASB reactor at 37 degrees C. Three different substrates were used: initially, synthetic wastewater, and later, two different pig manure effluents (after UASB-post-digestion and after partial...... (from 95 mg COD L-1 to 237 mg COD L-1 and from 121 mg COD L-1 to 290 mg COD L-1 for the UASB-post-digested effluent and the partially oxidized effluent, respectively) negatively affected the anammox process and facilitated heterotrophic denitrification. Partial oxidation as a pre-treatment method...... and anammox process were simultaneously occurring in the reactor. Denitrification became the dominant ammonium removal process when the COD loading was increased....

  11. Numerical modeling of nitrogen removal processes in biofilters with simultaneous nitritation and anammox.

    Science.gov (United States)

    Shi, Shun; Tao, Wendong

    2013-01-01

    This study developed a simple numerical model for nitrogen removal in biofilters, which was designed to enhance simultaneous nitritation and anaerobic ammonium oxidation (anammox). It is the first attempt to simulate anammox together with two-step nitrification in natural treatment systems, which may have different kinetic parameters and temperature effects from conventional bioreactors. Prediction accuracy was improved by adjusting kinetic coefficients over the startup period of the biofilters. The maximum rates of nitritation and nitrite oxidation increased linearly over time during the startup period. Simulations confirmed successful enhancement of simultaneous nitritation and anammox (SNA) in the biofilters, with anammox contributing 35% of ammonium removal. Effluent ammonium concentration was affected by influent ammonium concentration and the maximum nitritation rate, and was insensitive to the maximum nitrite oxidation rate and anammox substrate factor. Ammonium removal via SNA was likely limited by biomass of aerobic ammonia oxidizing bacteria in the biofilters. The developed model is a promising tool for studying the dynamics of nitrogen removal processes including SNA in natural treatment systems.

  12. The inhibition effects of salt on Anammox process:A review

    Institute of Scientific and Technical Information of China (English)

    QI Pan-qing

    2016-01-01

    Anaerobic ammonium oxidation was a novel biological nitrogen elimination process and attached more and more attention owing to its effectivity and economic saving. But, many kinds of factor especially salinity could affect the activity of Anammox bacteria which had some disadvantages to the application of Anammox process. In this article, a short review about the effects of salinity on Anammox bacteria was summarized and some advices were proposed to the research and the application of Anammox process in the future.

  13. Start-up and stabilization of an Anammox process from a non-acclimatized sludge in CSTR.

    Science.gov (United States)

    Bagchi, Samik; Biswas, Rima; Nandy, Tapas

    2010-09-01

    Development of an Anammox (anaerobic ammonium oxidation) process using non-acclimatized sludge requires a long start-up period owing to the very slow growth rate of Anammox bacteria. This article addresses the issue of achieving a shorter start-up period for Anammox activity in a well-mixed continuously stirred tank reactor (CSTR) using non-acclimatized anaerobic sludge. Proper selection of enrichment conditions and low stirring speed of 30 +/- 5 rpm resulted in a shorter start-up period (82 days). Activity tests revealed the microbial community structure of Anammox micro-granules. Ammonia-oxidizing bacteria (AOB) were found on the surface and on the outer most layers of granules while nitrite-oxidizing bacteria (NOB) and Anammox bacteria were present inside. Fine-tuning of influent NO2(-)/NH4+ ratio allowed Anammox activity to be maintained when mixed microbial populations were present. The maximum nitrogen removal rate achieved in the system was 0.216 kg N/(m(3) day) with a maximum specific nitrogen removal rate of 0.434 g N/(g VSS day). During the study period, Anammox activity was not inhibited by pH changes and free ammonia toxicity.

  14. Implementation of the anammox process for improved nitrogen removal

    NARCIS (Netherlands)

    Guven, D.; Pas-Schoonen, K.T. van de; Schmid, M.C.; Strous, M.; Jetten, M.S.M.; Sozen, S.; Orhon, D.; Schmidt, I.

    2004-01-01

    Stringent standards for nitrogen discharge necessitate the implementation of new systems for the sustainable removal of ammonium from wastewater. One of such systems is based on the process of anaerobic ammonium oxidation (Anammox), which is a new powerful tool especially for strong nitrogenous wast

  15. ANAMMOX process start up and stabilization with an anaerobic seed in Anaerobic Membrane Bioreactor (AnMBR).

    Science.gov (United States)

    Suneethi, S; Joseph, Kurian

    2011-10-01

    ANaerobic AMMonium OXidation (ANAMMOX) process, an advanced biological nitrogen removal alternative to traditional nitrification--denitrification removes ammonia using nitrite as the electron acceptor without oxygen. The feasibility of enriching anammox bacteria from anaerobic seed culture to start up an Anaerobic Membrane Bioreactor (AnMBR) for N-removal is reported in this paper. The Anammox activity was established in the AnMBR with anaerobic digester seed culture from a Sewage Treatment Plant in batch mode with recirculation followed by semi continuous process and continuous modes of operation. The AnMBR performance under varying Nitrogen Loading Rates (NLR) and HRTs is reported for a year, in terms of nitrogen transformations to ammoniacal nitrogen, nitrite and nitrate along with hydrazine and hydroxylamine. Interestingly ANAMMOX process was evident from simultaneous Amm-N and nitrite reduction, consistent nitrate production, hydrazine and hydroxylamine presence, notable organic load reduction and bicarbonate consumption. PMID:21775136

  16. Preliminary research on the anammox process and control of nitrogen compounds in a recirculating aquaculture system

    Directory of Open Access Journals (Sweden)

    Savin Cristian

    2013-01-01

    Full Text Available Using anammox process in biological filtration of technological water within recirculatingaquaculture system is an alternative to nitrification / denitrification process which can reduce productioncosts, especially energy by replacing aerobic biological processes that require high oxygen consumption,provided through the addition for optimal function of biofilter (conversion of N-NH4 and N-NO2. Aim ofthis paper is to highlight the first steps in the control of nitrogen compounds in recirculating aquaculturesystems using anammox process. Data shown are obtained after 78 researching days (research stillongoing, the results being encouraging, registering an ammonium removal efficiency of 77% in SC1 andof 32% in SC2. Nitrites registered an increase in SC1 and a decrease in SC2 and there are allprerequisites showing that in SC2 anammox activity is more advanced than in SC1. The average ofoxygen consumption rate was 0.73 mgL-1 in SC1 smaller than 0.99 mgL-1 from SC2, which reinforces theidea that there are anammox process in SC2.

  17. Long-term performance and microbial ecology of a two-stage PN-ANAMMOX process treating mature landfill leachate.

    Science.gov (United States)

    Li, Huosheng; Zhou, Shaoqi; Ma, Weihao; Huang, Pengfei; Huang, Guotao; Qin, Yujie; Xu, Bin; Ouyang, Hai

    2014-05-01

    Long-term performance of a two-stage partial nitritation (PN)-anaerobic ammonium oxidation (ANAMMOX) process treating mature landfill leachate was investigated. Stable partial nitritation performance was achieved in a sequencing batch reactor (SBR) using endpoint pH control, providing an effluent with a ratio of NO2(-)-N/NH4(+)-N at 1.23 ± 0.23. High rate nitrogen removal over 4 kg N/m(3)/d was observed in the ANAMMOX reactor in the first three months. However, during long-term operation, the ANAMMOX reactor can only stably operate under nitrogen load of 1 kg N/m(3)/d, with 85 ± 1% of nitrogen removal. The ammonium oxidizing bacteria (AOB) in the PN-SBR were mainly affiliated to Nitrosomonas sp. IWT514, Nitrosomonas eutropha and Nitrosomonas eutropha, the anaerobic ammonium oxidizing bacteria (AnAOB) in the ANAMMOX reactor were mainly affiliated to Kuenenia stuttgartiensis. PMID:24681301

  18. Long-term performance and microbial ecology of a two-stage PN-ANAMMOX process treating mature landfill leachate.

    Science.gov (United States)

    Li, Huosheng; Zhou, Shaoqi; Ma, Weihao; Huang, Pengfei; Huang, Guotao; Qin, Yujie; Xu, Bin; Ouyang, Hai

    2014-05-01

    Long-term performance of a two-stage partial nitritation (PN)-anaerobic ammonium oxidation (ANAMMOX) process treating mature landfill leachate was investigated. Stable partial nitritation performance was achieved in a sequencing batch reactor (SBR) using endpoint pH control, providing an effluent with a ratio of NO2(-)-N/NH4(+)-N at 1.23 ± 0.23. High rate nitrogen removal over 4 kg N/m(3)/d was observed in the ANAMMOX reactor in the first three months. However, during long-term operation, the ANAMMOX reactor can only stably operate under nitrogen load of 1 kg N/m(3)/d, with 85 ± 1% of nitrogen removal. The ammonium oxidizing bacteria (AOB) in the PN-SBR were mainly affiliated to Nitrosomonas sp. IWT514, Nitrosomonas eutropha and Nitrosomonas eutropha, the anaerobic ammonium oxidizing bacteria (AnAOB) in the ANAMMOX reactor were mainly affiliated to Kuenenia stuttgartiensis.

  19. The role of paraffin oil on the interaction between denitrifying anaerobic methane oxidation and Anammox processes.

    Science.gov (United States)

    Fu, Liang; Ding, Zhao-Wei; Ding, Jing; Zhang, Fang; Zeng, Raymond J

    2015-10-01

    Methane is sparingly soluble in water, resulting in a slow reaction rate in the denitrifying anaerobic methane oxidation (DAMO) process. The slow rate limits the feasibility of research to examine the interaction between the DAMO and the anaerobic ammonium oxidation (Anammox) process. In this study, optimized 5 % (v/v) paraffin oil was added as a second liquid phase to improve methane solubility in a reactor containing DAMO and Anammox microbes. After just addition, methane solubility was found to increase by 25 % and DAMO activity was enhanced. After a 100-day cultivation, the paraffin reactor showed almost two times higher consumption rates of NO3 (-) (0.2268 mmol/day) and NH4 (+) (0.1403 mmol/day), compared to the control reactor without paraffin oil. The microbes tended to distribute in the oil-water interface. The quantitative (q) PCR result showed the abundance of gene copies of DAMO archaea, DAMO bacteria, and Anammox bacteria in the paraffin reactor were higher than those in the control reactor after 1 month. Fluorescence in situ hybridization revealed that the percentages of the three microbes were 55.5 and 77.6 % in the control and paraffin reactors after 100 days, respectively. A simple model of mass balance was developed to describe the interactions between DAMO and Anammox microbes and validate the activity results. A mechanism was proposed to describe the possible way that paraffin oil enhanced DAMO activity. It is quite clear that paraffin oil enhances not only DAMO activity but also Anammox activity via the interaction between them; both NO3 (-) and NH4 (+) consumption rates were about two times those of the control.

  20. Continuous-flow combined process of nitritation and ANAMMOX for treatment of landfill leachate.

    Science.gov (United States)

    Wang, Zhong; Peng, Yongzhen; Miao, Lei; Cao, Tianhao; Zhang, Fangzhai; Wang, Shuying; Han, Jinhao

    2016-08-01

    Due to the difficulty in removing nitrogen from landfill leachate, a combined continuous-flow process of nitritation and anammox was applied to process mature leachate. The transformation rate of ammonia and nitrite accumulation ratio in A/O reactor were kept above 95% and 92% respectively through associated inhibition of free ammonia (FA) and free nitrous acid (FNA) to NOB. The total nitrogen volumetric load of anammox in an UASB reactor was brought up from 0.5kg/(m(3)·d) to 1.2kg/(m(3)·d) by gradually increasing influent substrate concentration and reducing hydraulic retention time (HRT). The results show that COD from mature leachate did not bring obvious inhibition effects to anammox. Under concentrations of influent ammonia and COD which were respectively 1330mg/L and 2250mg/L, the removal efficiencies of TN and COD reached 94% and 62% respectively. In the quantitative PCR reactions, the proportions occupied by AOB, NOB and anammox in A/O were 11.39%, 1.76% and 0.05% respectively; and proportions of those in UASB were 0.35%, 4.01% and 7.78% respectively. PMID:27176671

  1. Effect of HCO3- concentration on anammox nitrogen removal rate in a moving bed biofilm reactor.

    Science.gov (United States)

    Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Vabamäe, Priit; Kroon, Kristel; Loorits, Liis; Saluste, Alar; Tenno, Taavo

    2012-01-01

    Anammox biomass enriched in a moving bed biofilm reactor (MBBR) fed by actual sewage sludge reject water and synthetically added NO2- was used to study the total nitrogen (TN) removal rate of the anammox process depending on bicarbonate (HCO3-) concentration. MBBR performance resulted in the maximum TN removal rate of 1100 g N m(-3) d(-1) when the optimum HCO3- concentration (910 mg L(-1)) was used. The average reaction ratio of NO2- removal, NO3- production and NH4+ removal were 1.18/0.20/1. When the HCO3- concentration was increased to 1760mg L(-1) the TN removal rate diminished to 270 g N m(-3) d(-1). The process recovered from bicarbonate inhibition within 1 week. The batch tests performed with biomass taken from the MBBR showed that for the HCO3- concentration of 615 mg L(-1) the TN removal rate was 3.3 mg N L(-1) h(-1), whereas for both lower (120 mg L(-1)) and higher (5750 mg L(-1)) HCO3- concentrations the TN removal rates were 2.3 (+/- 0.15) and 1.6 (+/- 0.12) mg N L(-1) d(-1), respectively. PCR and DGGE analyses resulted in the detection of uncultured Planctomycetales bacterium clone P4 and, surprisingly, low-oxygen-tolerant aerobic ammonia oxidizers. The ability of anammox bacteria for mixotrophy was established by diminished amounts of nitrate produced when comparing the experiments with an organic carbon source and an inorganic carbon source.

  2. Integrating landfill bioreactors, partial nitritation and anammox process for methane recovery and nitrogen removal from leachate.

    Science.gov (United States)

    Sun, Faqian; Su, Xiaomei; Kang, Tingting; Wu, Songwei; Yuan, Mengdong; Zhu, Jing; Zhang, Xiayun; Xu, Fang; Wu, Weixiang

    2016-01-01

    A new process consisting of a landfill bioreactor, partial-nitritation (PN) and the anammox process has been developed for landfill leachate treatment. In this study, the landfill bioreactor exhibited excellent performance in methane-rich biogas recovery, with a specific biogas yield of 0.47 L gas g(-1) COD and methane percentages of 53-76%. PN was achieved in the aerobic reactor by high free ammonia (101 ± 83 mg NH3 L(-1)) inhibition for nitrite-oxidizing bacteria, and the desired PN effluent composition (effluent nitrite: ammonium ratio of 1.1 ± 0.3) was controlled by adjusting the alkalinity concentration per unit of ammonium oxidized to approximately 14.3 mg CaCO3 mg(-1) N in the influent. The startup of anammox process was successfully achieved with a membrane bioreactor in 160 d, and a maximum nitrogen removal rate of 216 mg N L(-1) d(-1) was attained for real landfill leachate treatment. The quantitative polymerase chain reaction results confirmed that the cell-specific anammox activity was approximately 68-95 fmol N cell(-1) d(-1), which finally led to the stable operation of the system. PMID:27279481

  3. Integrating landfill bioreactors, partial nitritation and anammox process for methane recovery and nitrogen removal from leachate

    Science.gov (United States)

    Sun, Faqian; Su, Xiaomei; Kang, Tingting; Wu, Songwei; Yuan, Mengdong; Zhu, Jing; Zhang, Xiayun; Xu, Fang; Wu, Weixiang

    2016-06-01

    A new process consisting of a landfill bioreactor, partial-nitritation (PN) and the anammox process has been developed for landfill leachate treatment. In this study, the landfill bioreactor exhibited excellent performance in methane-rich biogas recovery, with a specific biogas yield of 0.47 L gas g‑1 COD and methane percentages of 53–76%. PN was achieved in the aerobic reactor by high free ammonia (101 ± 83 mg NH3 L‑1) inhibition for nitrite-oxidizing bacteria, and the desired PN effluent composition (effluent nitrite: ammonium ratio of 1.1 ± 0.3) was controlled by adjusting the alkalinity concentration per unit of ammonium oxidized to approximately 14.3 mg CaCO3 mg‑1 N in the influent. The startup of anammox process was successfully achieved with a membrane bioreactor in 160 d, and a maximum nitrogen removal rate of 216 mg N L‑1 d‑1 was attained for real landfill leachate treatment. The quantitative polymerase chain reaction results confirmed that the cell-specific anammox activity was approximately 68–95 fmol N cell‑1 d‑1, which finally led to the stable operation of the system.

  4. The effects of oxygen on process rates and gene expression of anammox and denitrification in the Eastern South Pacific oxygen minimum zone

    DEFF Research Database (Denmark)

    Dalsgaard, Tage; Stewart, Frank; De Brabandere, Loreto;

    Oxygen concentrations were consistently below our detection limit of 90 nM for a distance of > 2000 km in the oxygen minimum zone (OMZ) along the coasts of Chile and Peru. In most cases, anammox and denitrification were only detected when in situ oxygen concentrations were below detection, with d......B), and nitrous oxide reductase (nosZ) were inhibited by oxygen...... differently to oxygen. When normalized to a housekeeping gene (rpoB), the expression of 4 out of 9 N-cycle-genes changed with increasing oxygen concentration: The expression of ammonium monooxygenase (amoC) was stimulated, whereas expression of nitrite reductase (nirS), nitric oxide reductase (nor...

  5. Discrepant membrane fouling of partial nitrification and anammox membrane bioreactor operated at the same nitrogen loading rate.

    Science.gov (United States)

    Niu, Zhao; Zhang, Zuotao; Liu, Sitong; Miyoshi, Taro; Matsuyama, Hideo; Ni, Jinren

    2016-08-01

    In this study, two times more serious membrane fouling was found in anammox membrane bioreactor, compared to partial nitrification membrane bioreactor (PN-MBR) operated at the same nitrogen loading rate. By protein, polysaccharide, amino acids and functional groups analysis, it was found that the discrepancy in membrane fouling was virtually due to the difference in microbial products of nitrifiers and anammox bacteria. Protein and polysaccharide were main foulants on membrane surface; meanwhile theirs content and ratio in the EPS, supernatant and membrane surface were significantly different in PN-MBR and anammox-MBR. The anammox metabolism products contained much more hydrophobic organics, hydrophobic amino acids, and hydrophobic functional groups than nitrifiers. A mass of anammox bacteria as well as hydrophobic metabolism products deposited on the hydrophobic membrane surface and formed serious fouling. In further, hydrophilic modification is more urgently needed to mitigate membrane fouling when running anammox-MBR, than PN-MBR. PMID:27209455

  6. Methods for increasing the rate of anammox attachment in a sidestream deammonification MBBR.

    Science.gov (United States)

    Klaus, Stephanie; McLee, Patrick; Schuler, Andrew J; Bott, Charles

    2016-01-01

    Deammonification (partial nitritation-anammox) is a proven process for the treatment of high-nitrogen waste streams, but long startup time is a known drawback of this technology. In a deammonification moving bed biofilm reactor (MBBR), startup time could potentially be decreased by increasing the attachment rate of anammox bacteria (AMX) on virgin plastic media. Previous studies have shown that bacterial adhesion rates can be increased by surface modification or by the development of a preliminary biofilm. This is the first study on increasing AMX attachment rates in a deammonification MBBR using these methods. Experimental media consisted of three different wet-chemical surface treatments, and also media transferred from a full-scale mainstream fully nitrifying integrated fixed-film activated sludge (IFAS) reactor. Following startup of a full-scale deammonification reactor, the experimental media were placed in the full-scale reactor and removed for activity rate measurements and biomass testing after 1 and 2 months. The media transferred from the IFAS process exhibited a rapid increase in AMX activity rates (1.1 g/m(2)/day NH(4)(+) removal and 1.4 g/m(2)/day NO(2)(-) removal) as compared to the control (0.2 g/m(2)/day NH(4)(+) removal and 0.1 g/m(2)/day NO(2)(-) removal) after 1 month. Two out of three of the surface modifications resulted in significantly higher AMX activity than the control at 1 and 2 months. No nitrite oxidizing bacteria activity was detected in either the surface modified media or IFAS media batch tests. The results indicate that startup time of a deammonification MBBR could potentially be decreased through surface modification of the plastic media or through the transfer of media from a mature IFAS process. PMID:27386988

  7. Ammonium removal from municipal wastewater with application of ion exchange and partial nitritation/Anammox process

    OpenAIRE

    Malovanyy, Andriy

    2014-01-01

    Nitrogen removal from municipal wastewater with application of Anammox process offers cost reduction, especially if it is combined with maximal use of organic content of wastewater for biogas production. In this study a new technology is proposed, which is based on ammonium concentration from municipal wastewater by ion exchange followed by biological removal of ammonium from the concentrated stream by partial nitritation/Anammox process. In experiments on ammonium concentration four the most...

  8. Start-up of the anammox process from the conventional activated sludge in a hybrid bioreactor

    Institute of Scientific and Technical Information of China (English)

    Xiumei Duan; Jiti Zhou; Sen Qiao; Xin Yin; Tian Tian; Fangdi Xu

    2012-01-01

    The anaerobic ammonium oxidation (anammox) process was successfully started up from conventional activated sludge using a hybrid bioreactor within 2 months.The average removal efficiencies of ammonia and nitrite were both over 80%,and the maximum total nitrogen removal rate of 1.85 kg1 N/(m3·day) was obtained on day 362 with the initial sludge concentration of 0.7 g mixed liquor suspended solids (MLSS)/L.Scanning electron microscope (SEM) observation of the granular sludge in the hybrid reactor clearly showed a high degree of compactness and cell sphericity,and the cell size was quite uniform.Transmission electron microscope photos showed that cells were round or oval,the cellular diameter was 0.6-1.0 μm,and the percentage of the anammoxosome compartment was 51%-85% of the whole cell volume.Fluorescence in situ hybridization analysis (FISH) indicated that anammox bacteria became the dominant population in the community (accounting for more than 51% of total bacteria on day 250).Seven planctomycete 16S rRNA gene sequences were present in the 16S rRNA gene clone library generated from the biomass and affiliated to Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia sp.,a new anammox species.In addition,the average effluent suspended solid (MLSS) concentrations of outlets Ⅰ (above the non-woven carrier) and Ⅱ (below the non-woven carrier) were 0.0009 and 0.0035 g/L,respectively.This showed that the non-woven carrier could catch the biomass effectively,which increased biomass and improved the nitrogen removal rate in the reactor.

  9. Mainstream partial nitritation and anammox: long-term process stability and effluent quality at low temperatures.

    Science.gov (United States)

    Laureni, Michele; Falås, Per; Robin, Orlane; Wick, Arne; Weissbrodt, David G; Nielsen, Jeppe Lund; Ternes, Thomas A; Morgenroth, Eberhard; Joss, Adriano

    2016-09-15

    The implementation of autotrophic anaerobic ammonium oxidation processes for the removal of nitrogen from municipal wastewater (known as "mainstream anammox") bears the potential to bring wastewater treatment plants close to energy autarky. The aim of the present work was to assess the long-term stability of partial nitritation/anammox (PN/A) processes operating at low temperatures and their reliability in meeting nitrogen concentrations in the range of typical discharge limits below 2  [Formula: see text] and 10 mgNtot·L(-1). Two main 12-L sequencing batch reactors were operated in parallel for PN/A on aerobically pre-treated municipal wastewater (21 ± 5 [Formula: see text] and residual 69 ± 19 mgCODtot·L(-1)) for more than one year, including over 5 months at 15 °C. The two systems consisted of a moving bed biofilm reactor (MBBR) and a hybrid MBBR (H-MBBR) with flocculent biomass. Operation at limiting oxygen concentrations (0.15-0.18 [Formula: see text] ) allowed stable suppression of the activity of nitrite-oxidizing bacteria at 15 °C with a production of nitrate over ammonium consumed as low as 16% in the MBBR. Promising nitrogen removal rates of 20-40 mgN·L(-1)·d(-1) were maintained at hydraulic retention times of 14 h. Stable ammonium and total nitrogen removal efficiencies over 90% and 70% respectively were achieved. Both reactors reached average concentrations of total nitrogen below 10 mgN·L(-1) in their effluents, even down to 6 mgN·L(-1) for the MBBR, with an ammonium concentration of 2 mgN·L(-1) (set as operational threshold to stop aeration). Furthermore, the two PN/A systems performed almost identically with respect to the biological removal of organic micropollutants and, importantly, to a similar extent as conventional treatments. A sudden temperature drop to 11 °C resulted in significant suppression of anammox activity, although this was rapidly recovered after the temperature was increased back to 15 °C. Analyses of 16S

  10. [Distribution and influence factors of Anammox bacteria in sewage treatment systems].

    Science.gov (United States)

    Zheng, Bingyu; Peng, Yongzhen; Zhang, Liang; Yang, Anming; Zhang, Shujun

    2014-12-01

    Nitrogen removal techniques based on Anammox process are developing rapidly these years. The distribution and diversity of Anammox have become important research directions. A variety of Anammox have been detected till now, of which only Kuenenia and Brocadia are often detected in wastewater treatment systems. In addition, in a single niche there is only one type of Anammox bacteria. However, the distribution mechanism and transformation of Anammox bacteria in different niches are still ambiguous. Therefore, the distribution of Anammox in various conditions was summarized and analyzed in this article. And the key factors influencing the distribution of Anammox were concluded, including substrate concentration and the specific growth rate, sludge properties and microbial niche, the joint action and influence of multiple factors. The engineering significance research on the distribution and influencing factors of Anammox bacteria in the sewage system and proposed research prospects were expounded. PMID:26016371

  11. Operational strategy for nitrogen removal from centrate in a two-stage partial nitrification--anammox process.

    Science.gov (United States)

    Kosari, S F; Rezania, B; Lo, K V; Mavinic, D S

    2014-01-01

    This paper presents the operational strategy for nitrogen removal in a two-stage, partial nitrification (PN) process coupled with anaerobic ammonium oxidation (Anammox) process. The process was used to remove ammonium from centrate obtained from a full-scale, wastewater treatment plant in British Columbia, Canada. The PN, which was carried out in a sequencing batch reactor (SBR), successfully converted approximately 49.5 +/- 1.0% of ammonium to nitrite. The operation of SBR under higher dissolved oxygen in combination with slow feeding resulted in significant reduced HRT without nitrate accumulation. Partially nitrified centrate was further treated in Anammox reactors, where the mixture of ammonium and nitrite was converted mainly to nitrogen gas. Anammox treatment was carried out in two different types of Anammox reactors: a moving bed hybrid reactor and an up-flow fixed-bed biofilm reactor. The hybrid Anammox reactor removed an average of 55.8% of NH4-N, versus the 48.3% NH4-N removed in the up-flow fixed-bed reactor. Nitrite removal in the hybrid and up-flow fixed-bed Anammox reactors averaged 80.8% and 62.5%, respectively. This study also illustrated that in both Anammox reactors, better ammonium removal was achieved when the nitrite to ammonium ratio is between 1.35 and 1.45. As such, alkalinity was found to neither control nor limit the Anammox reaction. PMID:24701906

  12. Deammonification process start-up after enrichment of anammox microorganisms from reject water in a moving-bed biofilm reactor.

    Science.gov (United States)

    Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Kroon, Kristel; Vabamäe, Priit; Salo, Erik; Loorits, Liis; Rubin, Sergio S C dC; Vlaeminck, Siegfried E; Tenno, Taavo

    2013-01-01

    Deammonification via intermittent aeration in biofilm process for the treatment of sewage sludge digester supernatant (reject water) was started up using two opposite strategies. Two moving-bed biofilm reactors were operated for 2.5 years at 26 (+/- 0.5 degree C with spiked influent(and hence free ammonia (FA)) addition. In the first start-up strategy, an enrichment of anammox biomass was first established, followed by the development of nitrifying biomass in the system (R1). In contrast, the second strategy aimed at the enrichment of anammox organisms into a nitrifying biofilm (R2). The first strategy was most successful, reaching higher maximum total nitrogen (TN) removal rates over a shorter start-up period. For both reactors, increasing FA spiking frequency and increasing effluent concentrations of the anammox intermediate hydrazine correlated to decreasing aerobic nitrate production (nitritation). The bacterial consortium of aerobic and anaerobic ammonium oxidizing bacteria in the bioreactor was determined via denaturing gel gradient electrophoresis, polymerase chain reaction and pyrosequencing. In addition to a shorter start-up with a better TN removal rate, nitrite oxidizing bacteria (Nitrospira) were outcompeted by spiked ammonium feeding from R1.

  13. Impact of free ammonia on anammox rates (anoxic ammonium oxidation) in a moving bed biofilm reactor.

    Science.gov (United States)

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2012-06-01

    Using a bench scale moving bed bioreactor (MBBR), the effect of free ammonia (FA, NH(3), the un-ionized form of ammonium NH(4)(+)) concentration on anoxic ammonium oxidation (anammox) was evaluated based on the volumetric nitrogen removal rate (NRR). Although, a detailed microbial analysis was not conducted, the major NRR observed was assumed to be by anammox, based on the nitrogen conversion ratios of nitrite to ammonium and nitrate to ammonium. Since the concentration of free ammonia as a proportion of the total ammonia concentration is pH-dependent, the impact of changing the operating pH from 6.9 to 8.2, was investigated under constant nitrogen loading conditions during continuous reactor operation. Furthermore, the effect of sudden nitrogen load changes was investigated under constant pH conditions. Batch tests were conducted to determine the immediate response of the anammox consortium to shifts in pH and FA concentrations. It was found that FA was inhibiting NRR at concentrations exceeding 2 mg N L(-1). In the pH range 7-8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 120 mg N L(-1) did not negatively affect NRR for up to 3.5 h. It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2 mg N L(-1) when the pH was maintained between 7 and 8.

  14. Impact of free ammonia on anammox rates (anoxic ammonium oxidation) in a moving bed biofilm reactor.

    Science.gov (United States)

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2012-06-01

    Using a bench scale moving bed bioreactor (MBBR), the effect of free ammonia (FA, NH(3), the un-ionized form of ammonium NH(4)(+)) concentration on anoxic ammonium oxidation (anammox) was evaluated based on the volumetric nitrogen removal rate (NRR). Although, a detailed microbial analysis was not conducted, the major NRR observed was assumed to be by anammox, based on the nitrogen conversion ratios of nitrite to ammonium and nitrate to ammonium. Since the concentration of free ammonia as a proportion of the total ammonia concentration is pH-dependent, the impact of changing the operating pH from 6.9 to 8.2, was investigated under constant nitrogen loading conditions during continuous reactor operation. Furthermore, the effect of sudden nitrogen load changes was investigated under constant pH conditions. Batch tests were conducted to determine the immediate response of the anammox consortium to shifts in pH and FA concentrations. It was found that FA was inhibiting NRR at concentrations exceeding 2 mg N L(-1). In the pH range 7-8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 120 mg N L(-1) did not negatively affect NRR for up to 3.5 h. It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2 mg N L(-1) when the pH was maintained between 7 and 8. PMID:22483855

  15. [Nitrogen removal performance of ANAMMOX ABR process in tannery wastewater treatment].

    Science.gov (United States)

    Zeng, Guo-Qu; Jia, Xiao-Shan

    2014-12-01

    Anaerobic ammonium-N removal from tannery wastewater was investigated using a lab-scale anaerobic baffled reactor (ABR). The results indicated that ABR could be used as a good anaerobic ammonium oxidation reactor, the stable and effective performance of ammonium-N and COD removal from tannery wastewater was demonstrated in the ANAMMOX ABR. When the NH4(+) -N concentration of the influents were in the range of 25.0 mg x L(-1) to 76.2 mg x L(-1) and COD ranged from 131 mg x L(-1) to 237 mg x L(-1), under the volumetric loading of 0.05 kg x (m3 x d)(-1) to 0.15 kg x (m3 x d)(-1), the NH4(+)-N and COD of the effluents were from 0.20 mg x L(-1) to 7.12 mg x L(-1) and from 35.1 mg x L(-1) to 69.2 mg x L(-1), respectively, and the removal efficiency of NH4(+) -N and COD were 90.8% to 99.6% and 66.9% to 74.7%, respectively. In addition, the brown-red, brown-yellow, red granular sludges were developed in ABR. SEM observation confirmed the presence of ANAMMOX bacteria in granular sludge of all four compartments of ANAMMOX ABR. According to FISH results, ANAMMOX bacteria had grown in all four compartments to various degrees during the acclimatization and running process, the percentage of ANAMMOX bacteria in sludge increased from 4% to 9%, 8%, 12% and 30% in compartment 1, compartment 2, compartment 3 and compartment 4, respectively, and a higher population percentage of ANAMMOX bacteria existed in the rear than in the front compartments. PMID:25826933

  16. Kinetic models for nitrogen inhibition in ANAMMOX and nitrification process on deammonification system at room temperature

    Science.gov (United States)

    The performance of the deammonification process depends on the microbial activity of ammonia oxidizing bacteria (AOB) and ANAMMOX bacteria. These autotrophic organisms have different preferences for substrate, operating conditions and some external factors that may cause inhibition or imbalance of t...

  17. Preliminary research on the anammox process and control of nitrogen compounds in a recirculating aquaculture system

    OpenAIRE

    Savin Cristian; Păsărin Benone; Patriche Neculai; Talpeş Marilena; Cristea Victor; Tenciu Magdalena

    2013-01-01

    Using anammox process in biological filtration of technological water within recirculatingaquaculture system is an alternative to nitrification / denitrification process which can reduce productioncosts, especially energy by replacing aerobic biological processes that require high oxygen consumption,provided through the addition for optimal function of biofilter (conversion of N-NH4 and N-NO2). Aim ofthis paper is to highlight the first steps in the control of nitrogen compounds in recirculat...

  18. [Community Characteristics of ANAMMOX Bacteria in Subsurface Flow Constructed Wetland (SSFCW) for Processing of Aquaculture Waster Water].

    Science.gov (United States)

    Zeng, Xian-lei; Liu, Xing-guo; Wu, Zong-fan; Shi, Xu; Lu, Shi-min

    2016-02-15

    Anaerobic ammonium oxidation (ANAMMOX) is one of the important functions in waste water treatment by subsurface flow constructed wetland (SSFCW), however, there are few studies on ANAMMOX in SSFCW environment at present. The community characteristics of ANAMMOX in the SSFCW of processing aquaculture waste water were explored in this study. In order to analyze the structure, diversity and abundance of ANAMMOX bacteria, several 16S rRNA clone libraries were constructed and real-time PCR targeting specific 16S rRNA genes together with diversity analysis was adopted. The obtained results showed that the SSFCW identified a total of three unknown clusters and two known clusters including Candidatus brocadia and Candidatus kuenenia. The dominant cluster was Candidatus brocadia. The highest diversity levels of ANAMMOX bacteria occurred in autumn (H', 1.21), while the lowest in spring (H', 0.64). The abundance of ANAMMOX bacteria in SSFCW environment ranged from 8.0 x 10(4) to 9.4 x 10(6) copies x g(-1) of fresh weight and the copy number of total bacterial 16S rRNA genes ranged from 7.3 x 10(9) to 9.1 x 10(10) copies x g(-1) of fresh weight during culture cycle. There were significant differences in the ANAMMOX bacteria abundances of different stratum and seasons in SSFCW environment, but the differences in total bacterial abundances were not obvious. In addition, the differences in ANAMMOX bacteria abundances in different stratum and seasons in SSFCW environment were irregular in different culture cycle. According to the distribution characteristics of ANAMMOX bacteria in the wetland, the denitrification effect of SSFCW could be improved by changing the supplying manners of aquaculture wastewater and adjusting the structure of wetland. The research results will provide reference for further optimizing the SSFCW and improving the efficiency of purification.

  19. [Community Characteristics of ANAMMOX Bacteria in Subsurface Flow Constructed Wetland (SSFCW) for Processing of Aquaculture Waster Water].

    Science.gov (United States)

    Zeng, Xian-lei; Liu, Xing-guo; Wu, Zong-fan; Shi, Xu; Lu, Shi-min

    2016-02-15

    Anaerobic ammonium oxidation (ANAMMOX) is one of the important functions in waste water treatment by subsurface flow constructed wetland (SSFCW), however, there are few studies on ANAMMOX in SSFCW environment at present. The community characteristics of ANAMMOX in the SSFCW of processing aquaculture waste water were explored in this study. In order to analyze the structure, diversity and abundance of ANAMMOX bacteria, several 16S rRNA clone libraries were constructed and real-time PCR targeting specific 16S rRNA genes together with diversity analysis was adopted. The obtained results showed that the SSFCW identified a total of three unknown clusters and two known clusters including Candidatus brocadia and Candidatus kuenenia. The dominant cluster was Candidatus brocadia. The highest diversity levels of ANAMMOX bacteria occurred in autumn (H', 1.21), while the lowest in spring (H', 0.64). The abundance of ANAMMOX bacteria in SSFCW environment ranged from 8.0 x 10(4) to 9.4 x 10(6) copies x g(-1) of fresh weight and the copy number of total bacterial 16S rRNA genes ranged from 7.3 x 10(9) to 9.1 x 10(10) copies x g(-1) of fresh weight during culture cycle. There were significant differences in the ANAMMOX bacteria abundances of different stratum and seasons in SSFCW environment, but the differences in total bacterial abundances were not obvious. In addition, the differences in ANAMMOX bacteria abundances in different stratum and seasons in SSFCW environment were irregular in different culture cycle. According to the distribution characteristics of ANAMMOX bacteria in the wetland, the denitrification effect of SSFCW could be improved by changing the supplying manners of aquaculture wastewater and adjusting the structure of wetland. The research results will provide reference for further optimizing the SSFCW and improving the efficiency of purification. PMID:27363152

  20. Performance and kinetic process analysis of an Anammox reactor in view of application for landfill leachate treatment.

    Science.gov (United States)

    Gao, Junling; Chys, Michael; Audenaert, Wim; He, Yanling; Van Hulle, Stijn W H

    2014-01-01

    Anammox has shown its promise and low cost for removing nitrogen from high strength wastewater such as landfill leachate. A reactor was inoculated with nitrification-denitrification sludge originating from a landfill leachate treating waste water treatment plant. During the operation, the sludge gradually converted into red Anammox granular sludge with high and stable Anammox activity. At a maximal nitrogen loading rate of 0.6 g N l(-1) d(-1), the reactor presented ammonium and nitrite removal efficiencies of above 90%. In addition, a modified Stover-Kincannon model was applied to simulate and assess the performance of the Anammox reactor. The Stover-Kincannon model was appropriate for the description of the nitrogen removal in the reactor with the high regression coefficient values (R2 = 0.946) and low Theil's inequality coefficient (TIC) values (TIC reactor should be 3.69 g N l(-1) d(-).

  1. Oxygen sensitivity of anammox and coupled N-cycle processes in oxygen minimum zones.

    Directory of Open Access Journals (Sweden)

    Tim Kalvelage

    Full Text Available Nutrient measurements indicate that 30-50% of the total nitrogen (N loss in the ocean occurs in oxygen minimum zones (OMZs. This pelagic N-removal takes place within only ~0.1% of the ocean volume, hence moderate variations in the extent of OMZs due to global warming may have a large impact on the global N-cycle. We examined the effect of oxygen (O(2 on anammox, NH(3 oxidation and NO(3(- reduction in (15N-labeling experiments with varying O(2 concentrations (0-25 µmol L(-1 in the Namibian and Peruvian OMZs. Our results show that O(2 is a major controlling factor for anammox activity in OMZ waters. Based on our O(2 assays we estimate the upper limit for anammox to be ~20 µmol L(-1. In contrast, NH(3 oxidation to NO(2(- and NO(3(- reduction to NO(2(- as the main NH(4(+ and NO(2(- sources for anammox were only moderately affected by changing O(2 concentrations. Intriguingly, aerobic NH(3 oxidation was active at non-detectable concentrations of O(2, while anaerobic NO(3(- reduction was fully active up to at least 25 µmol L(-1 O(2. Hence, aerobic and anaerobic N-cycle pathways in OMZs can co-occur over a larger range of O(2 concentrations than previously assumed. The zone where N-loss can occur is primarily controlled by the O(2-sensitivity of anammox itself, and not by any effects of O(2 on the tightly coupled pathways of aerobic NH(3 oxidation and NO(3(- reduction. With anammox bacteria in the marine environment being active at O(2 levels ~20 times higher than those known to inhibit their cultured counterparts, the oceanic volume potentially acting as a N-sink increases tenfold. The predicted expansion of OMZs may enlarge this volume even further. Our study provides the first robust estimates of O(2 sensitivities for processes directly and indirectly connected with N-loss. These are essential to assess the effects of ocean de-oxygenation on oceanic N-cycling.

  2. Systematic design of an optimal control system for the SHARON-Anammox process

    DEFF Research Database (Denmark)

    Valverde Perez, Borja; Mauricio Iglesias, Miguel; Sin, Gürkan

    2016-01-01

    to be dissolved oxygen (DO) and pH in the SHARON reactor. Furthermore, to relate the controller actions to process operation objective, nitrogen removal efficiency, two cascade control systems are designed. The first cascade loop controls TNN/TAN ratio in the influent to the Anammox reactor by adjusting the set...... point for DO in the regulatory layer, while the second cascade loop controls the nitrogen removal efficiency (i.e. effluent TNN and TAN) by adjusting the TNN/TAN ratio at the effluent of the SHARON reactor. The control system is evaluated and benchmarked using a set of realistic dynamic scenario...

  3. Differentiation in the microbial ecology and activity of suspended and attached bacteria in a nitritation-anammox process.

    Science.gov (United States)

    Park, Hongkeun; Sundar, Suneethi; Ma, Yiwei; Chandran, Kartik

    2015-02-01

    A directed differentiation between the biofilm and suspension was observed in the molecular microbial ecology and gene expression of different bacteria in a biofilm nitritation-anammox process operated at varying hydraulic residence times (HRT) and nitrogen loading rates (NLR). The highest degree of enrichment observed in the biofilm was of anaerobic ammonia-oxidizing bacteria (AMX) followed by that of Nitrospira spp. related nitrite-oxidizing bacteria (NOB). For AMX, a major shift from Candidatus "Brocadia fulgida" to Candidatus "Kuenenia stuttgartiensis" in both suspension and biofilm was observed with progressively shorter HRT, using discriminatory biomarkers targeting the hydrazine synthase (hzsA) gene. In parallel, expression of the hydrazine oxidoreductase gene (hzo), a functional biomarker for AMX energy metabolism, became progressively prominent in the biofilm. A marginal but statistically significant enrichment in the biofilm was observed for Nitrosomonas europaea related ammonia-oxidizing bacteria (AOB). In direct contrast to AMX, the gene expression of ammonia monooxygenase subunit A (amoA), a functional biomarker for AOB energy metabolism, progressively increased in suspension. Using gene expression and biomass concentration measures in conjunction, it was determined that signatures of AOB metabolism were primarily present in the biofilm throughout the study. On the other hand, AMX metabolism gradually shifted from being uniformly distributed in both the biofilm and suspension to primarily the biofilm at shorter HRTs and higher NLRs. These results therefore highlight the complexity and key differences in the microbial ecology, gene expression and activity between the biofilm and suspension of a nitritation-anammox process and the biokinetic and metabolic drivers for such niche segregation. PMID:25115980

  4. Mixing Intensity Effects of Attached Growth on Enriched Anammox Cultures

    Directory of Open Access Journals (Sweden)

    Pongsak Noophan

    2015-01-01

    Full Text Available Anaerobic ammonium oxidation (anammox is a promising new technology for the treatment of wastewater with high ammonium and low carbon concentrations. Earlier work suggests that optimal processing would be realized within a sequencing batch reactor (SBR. However, the relatively slow growth of anammox bacteria inhibits the rates of nitrogen removal and biomass yielding. Improved anammox performance has been demonstrated when the bacteria are in granular form or attached to a growth medium. Little has been reported concerning the effect of mixing rate on nitrogen (N removal with attached anammox bacteria. This work subjected anammox bacteria attached to polystyrene sponge in SBR to various intensities of impeller mixing and studied the effect on NH4+ and NO2- removal. Nitrogen processing was virtually the same with velocity gradient values between 13.5 and 222 s-1. More vigorous mixing at 407 and 666 s-1 values significantly inhibited N removal, likely due to detachment of bacteria from the growth medium. Following the poor N removal at the two higher mixing intensities, agitation was reduced to 24.8 s-1 velocity gradient value. Recovery of N removal rates required 2-3 weeks, the slow time attributed to slow reattachment to the growth medium. Denaturing gradient gel electrophoresis (DGGE analysis identified the prominent anammox species in the experimental study as Candidatus Brocadia anammoxidans and Candidatus Kuenenia stuttgartiensis.

  5. Plant-wide (BSM2) evaluation of reject water treatment with a SHARON-Anammox process

    DEFF Research Database (Denmark)

    Volcke, Eveline; Gernaey, Krist; Vrecko, Darko;

    2006-01-01

    In wastewater treatment plants (WWTPs) equipped with sludge digestion and dewatering systems, the reject water originating from these facilities contributes significantly to the nitrogen load of the activated sludge tanks, to which it is typically recycled. In this paper, the impact of reject water...... streams on the performance of a WWTP is assessed in a simulation study, using the Benchmark Simulation Model no. 2 (BSM2), that includes the processes describing sludge treatment and in this way allows for plant-wide evaluation. Comparison of performance of a WWTP without reject water with a WWTP where...... treatment plant, reject water treatment with a combined SHARON-Anammox process seems a promising option. The simulation results indicate that significant improvements of the effluent quality of the main wastewater treatment plant can be realized. An economic evaluation of the different scenarios...

  6. Step-wise temperature decreasing cultivates a biofilm with high nitrogen removal rates at 9°C in short-term anammox biofilm tests.

    Science.gov (United States)

    Zekker, Ivar; Rikmann, Ergo; Mandel, Anni; Kroon, Kristel; Seiman, Andrus; Mihkelson, Jana; Tenno, Taavo; Tenno, Toomas

    2016-08-01

    The anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used for N-rich wastewater treatment. When deammonification applications move towards low temperature applications (mainstream wastewater has low temperature), temperature effect has to be studied. In current research, in a deammonification moving bed biofilm reactor a maximum total nitrogen removal rate (TNRR) of 1.5 g N m(-2 )d(-1) (0.6 kg N m(-3 )d(-1)) was achieved. Temperature was gradually lowered by 0.5°C per week, and a similar TNRR was sustained at 15°C during biofilm cultivation. Statistical analysis confirmed that a temperature decrease from 20°C down to 15° did not cause instabilities. Instead, TNRR rose and treatment efficiency remained stable at lower temperatures as well. Quantitative polymerase chain reaction analyses showed an increase in Candidatus Brocadia quantities from 5 × 10(3) to 1 × 10(7) anammox gene copies g(-1) total suspended solids (TSS) despite temperature lowered to 15°C. Fluctuations in TNRR were rather related to changes in influent [Formula: see text] concentration. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed sufficient TNRRs even at 9-15°C (1.24-3.43 mg N g(-1 )TSS h(-1), respectively) with anammox temperature constants (Q10) ranging 1.3-1.6. Experiments showed that a biofilm adapted to 15°C can perform N-removal most sufficiently at temperatures down to 9°C as compared with biofilm adapted to higher temperature. After biomass was adapted to 15°C, the decrease in TNRR in batch tests at 9°C was lower (15-20%) than that for biomass adapted to 17-18°C.

  7. Nitrate reduction by organotrophic Anammox bacteria in a nitritation/anammox granular sludge and a moving bed biofilm reactor.

    Science.gov (United States)

    Winkler, Mari K H; Yang, Jingjing; Kleerebezem, Robbert; Plaza, Elzbieta; Trela, Jozef; Hultman, Bengt; van Loosdrecht, Mark C M

    2012-06-01

    The effects of volatile fatty acids (VFAs) on nitrogen removal and microbial community structure in nitritation/anammox process were compared within a granular sludge reactor and a moving bed biofilm reactor. Nitrate productions in both systems were lower by 40-68% in comparison with expected nitrate production. Expected sludge production on VFAs was estimated to be 67-77% higher if heterotrophs were the main acetate degraders suggesting that Anammox bacteria used its organotrophic capability and successfully competed with general heterotrophs for organic carbon, which led to a reduced sludge production. FISH measurements showed a population consisting of mainly Anammox and AOB in both reactors and oxygen uptake rate (OUR) tests also confirmed that flocculent biomass consisted of a minor proportion of heterotrophs with a large proportion of AOBs. The dominant Anammox bacterium was Candidatus "Brocadia fulgida" with a minor fraction of Candidatus "Anammoxoglobus propionicus", both known to be capable of oxidizing VFAs.

  8. Laboratory study of nitrification, denitrification and anammox processes in membrane bioreactors considering periodic aeration.

    Science.gov (United States)

    Abbassi, Rouzbeh; Yadav, Asheesh Kumar; Huang, Shan; Jaffé, Peter R

    2014-09-01

    The possibility of using membrane bioreactors (MBRs) in simultaneous nitrification-anammox-denitrification (SNAD) by considering periodic aeration cycles was investigated. Two separate reactors were operated to investigate the effect of different anammox biomass in the presence of nitrifying and denitrifying biomass on the final nitrogen removal efficiency. The results illustrated that the reactor with higher anammox biomass was more robust to oxygen cycling. Around 98% Total Nitrogen (TN) and 83% Total Organic Carbon (TOC) removal efficiencies were observed by applying one hour aeration over a four-hour cycle. Decreasing the aeration time to 30, 15, and 2 min during a four-hour cycle affected the final TN removal efficiencies. However, the effect of decreasing aeration on the TN removal efficiencies in the reactor with higher anammox biomass was much lower compared to the regular reactor. The nitrous oxide (N2O) emission was a function of aeration as well, and was lower in the reactor with higher anammox biomass. The results of q-PCR analysis confirmed the simultaneous co-existence of nitrifiers, anammox, and denitrifiers in both of the reactors. To simulate the TN removal in these reactors as a function of the aeration time, a new model, based on first order reaction kinetics for both denitrification and anammox was developed and yielded a good agreement with the experimental observations.

  9. Two-step partial nitritation/Anammox process in granulation reactors: Start-up operation and microbial characterization.

    Science.gov (United States)

    Dosta, J; Vila, J; Sancho, I; Basset, N; Grifoll, M; Mata-Álvarez, J

    2015-12-01

    A two-stage Partial Nitritation (PN)/Anammox process was carried out at lab-scale conditions to treat reject water from a municipal WWTP. PN was achieved in a granular SBR obtaining an effluent with a NH4(+)-N/NO2(-)-N molar ratio around 1.0. The microbial characterization of this reactor revealed a predominance of Betaproteobacteria, with a member of Nitrosomonas as the main autotrophic ammonium oxidizing bacterium (AOB). Nitrite oxidizing bacteria (NOB) were under the detection limit of 16S rRNA gene pyrosequencing, indicating their effective inhibition. The effluent of the PN reactor was fed to an Anammox SBR where stable operation was achieved with a NH4(+)-N:NO2(-)-N:NO3(-)-N stoichiometry of 1:1.25:0.14. The deviation to the theoretical stoichiometry could be attributed to the presence of heterotrophic biomass in the Anammox reactor (mainly members of Chlorobi and Chloroflexi). Planctomycetes accounted for 7% of the global community, being members of Brocadia (1.4% of the total abundance) the main anaerobic ammonium oxidizer detected. PMID:26386756

  10. Advances in applications of Anammox process%厌氧氨氧化工艺的应用进展

    Institute of Scientific and Technical Information of China (English)

    张正哲; 金仁村; 程雅菲; 周煜璜; 布阿依·谢姆古丽

    2015-01-01

    厌氧氨氧化(anaerobic ammonium oxidation,Anammox)工艺因其高效低耗的优势,在废水生物脱氮领域具有广阔的应用前景。该工艺在实际废水处理中的应用已成为国内外的热点。本文结合厌氧氨氧化菌的生境和菌种多样性,以及厌氧氨氧化工艺形式的多样性,并对一体式和分体式工艺运行条件进行了比较,重点综述了厌氧氨氧化技术在处理各类废水中的实验室研究和工程应用情况,主要包括:污泥消化液和压滤液、垃圾渗滤液、养殖废水、味精废水、焦化废水、生活污水、粪便污水、含盐废水等废水的水质特点、研究进展和应用障碍。最后,总结厌氧氨氧化工艺在处理实际废水过程中的潜在问题,并提出今后的研究重点是深入研究厌氧氨氧化的水质障碍因子及其调控策略,并在此基础上大力开发和优化组合工艺。%Anaerobic ammonium oxidation(Anammox)has advantages of high efficiency and low consumption. This method has become a promising biological nitrogen elimination process. This paper compared the operation conditions of one- and two-stage Anammox processes,analyzed the habitat and species diversity of anaerobic ammonium oxidizing bacteria and process versatility of Anammox,and summarized the laboratory research and engineering applications of Anammox in the treatment of various types of ammonium-rich wastewater. The characteristics,research progress and application barriers of sludge digestate,reject water,landfill leachate,livestock wastewater, municipal sewage, saline wastewateretcwere introduced. Moreover,the potential problems of Anammox process in practical applications were discussed and further research focuses were suggested.

  11. Incremental design of control system of SHARON-Anammox process for autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Valverde Perez, Borja; Sin, Gürkan

    2012-01-01

    With the perspective of investigating a suitable control design for autotrophic nitrogen removal, this work explores the control design for a SHARON-Anammox reactor sequence. With this aim, a full model is developed, including the pH dependency, in order to simulate the reactor and determine...... the optimal operating conditions. Then, the screening of controlled variables and pairing is carried out by an assessment of the effect of the disturbances based on the closed loop disturbance gain plots. Three control structures are obtained and benchmarked by their capacity to reject the disturbances before...... the Anammox reactor....

  12. Start-up of single-stage partial nitrification-anammox process treating low-strength swage and its restoration from nitrate accumulation.

    Science.gov (United States)

    Miao, Yuanyuan; Zhang, Liang; Yang, Yandong; Peng, Yongzhen; Li, Baikun; Wang, Shuying; Zhang, Qian

    2016-10-01

    A single-stage partial nitrification-anammox (PN/A) reactor treating low-strength swage was operated for 288days to investigate the recovery of nitrogen removal from nitrate accumulation. The reactor was quickly started up by inoculating anammox sludge. However, nitrite oxidizing bacteria (NOB) abundance gradually increased on day 25, leading to high effluent nitrate concentration. Two strategies were executed to control the effluent nitrate. In strategy I, dissolved oxygen (DO) concentration was kept low (0.17±0.08mg/L), but nitrate production increased from 4.71 to 38.18mg-N/L. In strategy II, intermittent aeration operation mode (aeration 7min/anoxic 21min) was adopted, which significantly lowered the nitrate concentration to 1.3mg-N/L, indicating the NOB was inhibited. The high nitrogen removal rate of 73mg-N/(L·d) was achieved. The evolution of bacterial activity and abundance verified the changes of the nitrogen removal performance and proved the intermittent aeration strategy could successfully solve the problem of nitrate build-up in the PN/A process. PMID:27423544

  13. Oxygen sensitivity of anammox and coupled N-cycle processes in oxygen minimum zones

    DEFF Research Database (Denmark)

    Kalvelage, Tim; Jensen, Marlene Mark; Contreras, Sergio;

    2011-01-01

    Nutrient measurements indicate that 30–50% of the total nitrogen (N) loss in the ocean occurs in oxygen minimum zones (OMZs). This pelagic N-removal takes place within only ,0.1% of the ocean volume, hence moderate variations in the extent of OMZs due to global warming may have a large impact on...... the global N-cycle. We examined the effect of oxygen (O2) on anammox, NH3 oxidation and NO3 2 reduction in 15N-labeling experiments with varying O2 concentrations (0–25 mmol L21) in the Namibian and Peruvian OMZs. Our results show that O2 is a major controlling factor for anammox activity in OMZ...... waters. Based on our O2 assays we estimate the upper limit for anammox to be ,20 mmol L21. In contrast, NH3 oxidation to NO2 2 and NO3 2 reduction to NO2 2 as the main NH4 + and NO2 2 sources for anammox were only moderately affected by changing O2 concentrations. Intriguingly, aerobic NH3 oxidation was...

  14. Growth and metabolism of Anammox Bacteria

    NARCIS (Netherlands)

    Van der Star, W.R.L.

    2008-01-01

    The anoxic ammonium oxidation (anammox) process is the conversion of nitrite and ammonium under anoxic conditions- to form dinitrogen gas. The process is performed by deep-branching Planctomycetes. The startup of the first full-scale anammox reactor in the world is described in Chapter 2. The desc

  15. Removal of Nitrogen and Phosphorus From Reject Water Using Chlorella vulgaris Algae After Partial Nitrification/Anammox Process.

    Science.gov (United States)

    Gutwinski, Piotr; Cema, Grzegorz

    2016-01-01

    Wastewater containing nutrients like ammonia, nitrite, nitrate and phosphates have been identified as the main cause of eutrophication in natural waters. Therefore, a suitable treatment is needed. In classical biological processes, nitrogen and phosphorus removal is expensive, especially due to the lack of biodegradable carbon, thus new methods are investigated. In this paper, the new possibility of nitrogen and phosphorus removal in side stream after the partial nitrification/Anammox process is proposed. Research was carried out in a lab-scale vertical tubular photobioreactor (VTR) fed with real reject water, from dewatering of digested sludge, after partial nitrification/Anammox process from lab-scale sequencing batch reactor (SBR). Nitrogen and phosphorus concentrations were measured every three days. The average nitrogen and phosphorus loads were 0.0503 ± 0.036 g N g(vss)/d and 0.0389 ± 0.013 g P g(vss)/d accordingly. Results have shown that microalgae were able to efficiently remove nitrogen and phosphorus. The average nitrogen removal was 36.46% and phosphorus removal efficiency varied between 93 and 100%. PMID:26803028

  16. Nitrogen removal by anammox and denitrification in a subtropical seagrass ecosystem

    Science.gov (United States)

    Salk, K.; Ostrom, N. E.; Erler, D.; Eyre, B.; Carlson-Perret, N.

    2015-12-01

    Anammox is now recognized as a globally important process that may rival denitrification in its removal of inorganic N from aquatic systems. Owing to its fairly recent discovery, however, measurements of anammox in coastal environments are sparse. This study measured the N removal processes, denitrification and anammox, in a seagrass ecosystem in New South Wales, Australia, using a modified version of the isotope pairing technique. This previously published method has yet to be applied to seagrass environments and relies on the measurement of both N2O and N2 to calculate rates of anammox and denitrification. Intact sediment cores were incubated under in situ conditions and amended with 15N-NO3- as a tracer. The role of organic C quality in controlling N removal rates was evaluated through addition of seagrass or phytoplankton detritus. In control cores (i.e., no C addition), the total N removal rate was 0.48 ± 0.22 μmol N m-2 h-1. These are among the lowest rates measured in seagrasses and other coastal areas. N removal rates were stimulated when seagrass detritus was added (3.3 times higher than control) whereas the addition of phytoplankton detritus did not stimulate N removal. This is surprising, as phytoplankton detritus is generally a more labile C source than seagrass detritus. These results indicate that the microbial community responds more quickly to organic matter they are conditioned to process. Regardless of C treatment, anammox made up a greater proportion of N2 production (71 ± 16%) than denitrification (24 ± 13%), in contrast to most other studies. The high proportion of anammox-derived N2 production implies that previous N removal rates measured in other systems without anammox inclusion could be significantly underestimated.

  17. Mainstream partial nitritation and anammox in a 200,000 m(3)/day activated sludge process in Singapore: scale-down by using laboratory fed-batch reactor.

    Science.gov (United States)

    Yeshi, Cao; Hong, Kwok Bee; van Loosdrecht, Mark C M; Daigger, Glen T; Yi, Png Hui; Wah, Yuen Long; Chye, Chua Seng; Ghani, Yahya Abd

    2016-01-01

    A laboratory fed-batch reactor has been used to study under controlled conditions the performance of partial nitritation/anammox for the 200,000 m(3)/day step-feed activated sludge process at the Changi Water Reclamation Plant, Singapore. The similarity of the concentrations of NH4, NO2, NO3, PO4, suspended chemical oxygen demand (sCOD), pH, and alkalinity (ALK) between the on-site process and laboratory reactor illustrates that the laboratory fed-batch reactor can be used to simulate the site performance. The performance of the reactor fed by primary effluent illustrated the existence of anammox and heterotrophic denitrification and apparent excessive biological phosphorus removal as observed from the site. The performance of the reactor fed by final effluent proved the presence of anammox process on site. Both the laboratory reactor and on-site process showed that higher influent 5-day biochemical oxygen demand/total nitrogen (BOD5/TN) (COD/TN) ratio increases the nitrogen removal efficiency of the process. PMID:27386982

  18. Mainstream partial nitritation and anammox in a 200,000 m3/day activated sludge process in Singapore: scale-down by using laboratory fed-batch reactor.

    Science.gov (United States)

    Yeshi, Cao; Hong, Kwok Bee; van Loosdrecht, Mark C M; Daigger, Glen T; Yi, Png Hui; Wah, Yuen Long; Chye, Chua Seng; Ghani, Yahya Abd

    2016-01-01

    A laboratory fed-batch reactor has been used to study under controlled conditions the performance of partial nitritation/anammox for the 200,000 m(3)/day step-feed activated sludge process at the Changi Water Reclamation Plant, Singapore. The similarity of the concentrations of NH(4), NO(2), NO(3), PO(4), suspended chemical oxygen demand (sCOD), pH, and alkalinity (ALK) between the on-site process and laboratory reactor illustrates that the laboratory fed-batch reactor can be used to simulate the site performance. The performance of the reactor fed by primary effluent illustrated the existence of anammox and heterotrophic denitrification and apparent excessive biological phosphorus removal as observed from the site. The performance of the reactor fed by final effluent proved the presence of anammox process on site. Both the laboratory reactor and on-site process showed that higher influent 5-day biochemical oxygen demand/total nitrogen (BOD(5)/TN) (COD/TN) ratio increases the nitrogen removal efficiency of the process.

  19. N2O emissions from a one stage partial nitrification/anammox process in moving bed biofilm reactors.

    Science.gov (United States)

    Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta; Tjus, Kåre

    2013-01-01

    Nitrous oxide (N2O) emissions from wastewater treatment are getting increased attention because their global warming potential is around 300 times that of carbon dioxide. The aim of the study was to measure nitrous oxide emissions from one stage partial nitrification/anammox (Anaerobic Ammonium Oxidation) reactors, where nitrogen is removed in a biological way. The first part of the experimental study was focused on the measurements of nitrous oxide emissions from two pilot scale reactors in the long term; one reactor with intermittent aeration at 25 °C and the other reactor with continuous aeration at 22-23 °C. The second part of the experiment was done to evaluate the influence of different nitrogen loads and aeration strategies, described by the ratio between the non-aerated and aerated phase and the dissolved oxygen concentrations, on nitrous oxide emissions from the process. The study showed that 0.4-2% of the nitrogen load was converted into nitrous oxide from two reactors. With higher nitrogen load, the amount of nitrous oxide emission was also higher. A larger fraction of nitrous oxide was emitted to the gas phase while less was emitted with the liquid effluent. It was also found that nitrous oxide emissions were similar under intermittent and continuous aeration.

  20. NOx and ammonium isotopic fingerprints of anammox in natural and engineered systems: Implications for N isotope budgets and the use of NOx isotopes to diagnose process stability in wastewater treatment

    Science.gov (United States)

    Lehmann, M. F.; Stöcklin, N.; Brunner, B.; Frame, C. H.; Joss, A.; Kipf, M.; Kuhn, T.; Wunderlin, P.

    2014-12-01

    The anaerobic oxidation of ammonium with nitrite (anammox) has been identified as a very important fixed nitrogen (N) sink, accounting for a large fraction of global fixed N loss in marine, freshwater, and semi-terrestrial environments. In engineered systems, combined nitritation-anammox is an efficient process to remove N from ammonium-rich wastewater, with nitrite as the central intermediate. During the anammox process, nitrate is being produced, providing reducing equivalents for carbon fixation. Measuring the N isotope ratios in fixed N species (i.e., ammonium, nitrite, nitrate) has proven to be a valuable tool to track N cycling in freshwater and marine ecosystems, yet its application in wastewater treatment as a tool to diagnose nitrate production pathways is novel. In this presentation we will elucidate, and compare, the N isotope effects associated with anammox 1) in vitro, 2) in a lacustrine setting, and 3) in a small-scale batch reactor for wastewater treatment. We demonstrate that the anammox nitrite/nitrate isotopic signatures are modulated by the superposition of strong kinetic (normal and inverse) and equilibrium (nitrite-nitrate) N isotope fractionation. The ammonium N isotope effect is driven by kinetic N isotope fractionation, and is similar to that of nitrification. We will discuss the possible controls on the expression of the anammox N isotope effects in the natural environment. We will also evaluate the use of nitrate/nitrite N (and O) isotope signatures to distinguish between nitrate production by anammox versus nitrite oxidation, which is important for optimizing process efficiency during wastewater treatment.

  1. 匹配厌氧氨氧化的SHARON工艺启动研究%STUDY ON START-UP OF A SHARON REACTOR MATCHED WITH ANAMMOX PROCESS

    Institute of Scientific and Technical Information of China (English)

    钟琼; 方丽

    2012-01-01

    One of the most sustainable and successful technologies developed recently for high concentration ammonium wastewater treatment is well known as SHARON-ANAMMOX process, which partially oxidized ammonium to nitrite and subsequently anammox to nitrogen gas. One of the key points of this process is to accumulate nitrosomas in SHARON reactor and at the same time to control the conversion ratio of nitrite to ammonium around 50% , which meets the requirements for the following ANAMMOX process. At influent pH 7.6, and ammonium nitrogen 750 mg/L, the SHARON reactor was successfully started up, and an about 50% conversion ratio of nitrite to ammonium was also reached. Further investigation indicated that with increasing influant pH and ammonium concentration, the system kept running stable.%氧化部分氨氮到亚硝酸氮,然后进行完全自养厌氧氨氧化反应,即称SHARON-ANAMMOX工艺,该工艺是近年开发的针对高浓度氨氮废水生物处理较为经济合理的技术之一。其过程控制的关键是第一步亚硝化(SHARON)工艺积累亚硝酸菌,并使氨氮氧化到亚硝酸氮的转化率控制在50%左右,以最合理满足厌氧氨氧化对底物的需求。在进水pH=7.6,ρ(氨氮)=750 mg/L时顺利启动了SHARON反应器,氨氮的转化率达50%左右。研究结果表明,进一步提高氨氮浓度和进水pH,反应器可以维持稳定运行。

  2. Differential effects of crude oil on denitrification and anammox, and the impact on N2O production.

    Science.gov (United States)

    Ribeiro, Hugo; Mucha, Ana P; Azevedo, Isabel; Salgado, Paula; Teixeira, Catarina; Almeida, C Marisa R; Joye, Samantha B; Magalhães, Catarina

    2016-09-01

    Denitrification and anammox are key processes for reducing the external nitrogen loads delivered to coastal ecosystems, and these processes can be affected by pollutants. In this study, we investigated the effect of crude oil on denitrification and anammox. Controlled laboratory experiments were performed using sediment slurries from the Lima Estuary (NW Portugal). Anammox and denitrification rates were measured using (15)N-labeled NO3(-), and the production of (29)N2 and (30)N2 quantified by membrane inlet mass spectrometry. Results revealed that while denitrification rates were stimulated between 10 and 25 000 times after crude oil amendment, anammox activity was partially (between 2 and 5 times) or completely inhibited by the addition of crude oil when comparing to rates in unamended controls. Similar results were observed across four estuarine sediment types, despite their different physical-chemical characteristics. Moreover, N2O production was reduced by 2-36 times following crude oil addition. Further work is required to fully understand the mechanism(s) of the observed reduction in N2O production. This study represents one of the first contributions to the understanding of the impact of crude oil pollution on denitrification and anammox, with profound implications for the management of aquatic ecosystems regarding eutrophication (N-removal).

  3. The relationship between anammox and denitrification in the sediment of an inland river

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Sheng, E-mail: zhous@outlook.com [Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, No. 1000 Jinqi Road, Shanghai 201403 (China); Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Borjigin, Sodbilig; Riya, Shohei; Terada, Akihiko; Hosomi, Masaaki [Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)

    2014-08-15

    This study measured the microbial processes of anaerobic ammonium oxidation (anammox) and denitrification in sediment sampled from two sites in the estuary of an inland river (Koisegawa River, Ibaragi prefecture, Japan) using a nitrogen isotope pairing technique (IPT). The responses of anammox and denitrification activities to temperature and nitrate concentration were also evaluated. Further, to elucidate the correlation between anammox and denitrification processes, an inhibition experiment was conducted, using chlorate to inhibit the first step of denitrification. Denitrification activity was much higher than anammox activity, and it reached a maximum at the surface layer in February 2012. Denitrification activity decreased as sediment depth increased, and a similar phenomenon was observed for anammox activity in the sediment of site A, where aquatic plants were absent from the surroundings. The activities of both denitrification and anammox were temperature-dependent, but they responded differently to changes in incubation temperature. Compared to a linear increase in denitrification as temperature rose to 35 °C, the optimal temperature for anammox was 25 °C, after which the activity decreased sharply. At the same time, both anammox and denitrification activities increased with NO{sub 3}{sup −} concentration. The Michaelis–Menten kinetic constants (V{sub max} and K{sub m}) of denitrification were significantly higher than those of the anammox process. Furthermore, anammox activity decreased accordingly when the first step of denitrification was inhibited, which probably reduced the amount of the intermediate NO{sub 2}{sup −}. Our study provides the first direct exploration of the denitrification-dependent correlation of anammox activity in the sediment of inland river. - Highlights: • The activity of denitrification in river sediment was much higher than anammox. • Denitrification and anammox respond differently to changes in temperature.

  4. Effect of Different Filling Materials in Anammox Bacteria Enrichment

    Directory of Open Access Journals (Sweden)

    Dilek ÖZGÜN

    2012-12-01

    Full Text Available Purpose: Anaerobic ammonium oxidation (Anammox is a process that ammonium as electron donor is oxidized to nitrogen gas using nitrite as electron acceptor. Compared to conventional nitrification-denitrification processes, this process is used less oxygen and no organic material (methanol, glucose. However, the slow growth rate of Anammox bacteria (11-30 days is disadvantages. Therefore, batch reactors have been carried out in these bacteria enrichment. In this study continuously operated upflow anaerobic sludge reactor (UASB using different filling materials disposing of sensitive and slow-growing Anammox bacteria out of the system is purposed. Design and Methods: System is operated up-flow column reactor at 2 days hydraulic retention time (HRT in 45 days. In this study, ceramic stones and Linpor filling material are used. Using synthetic wastewater containing ammonium and nitrite, Ar/CO2 anaerobic conditions (95/5% supplied with gas. System is operated at a temperature 253 C in UASB. Temperature, pH, ammonia-nitrogen and nitrite nitrogen are measured. Results: Both filling material reactors are operated in 45 days. Ceramic stones filling reactor is observed quickly reaches 90% were used reactor ammonium removal. The ammonium nitrogen removal was slower in Linpor filling materials reactor. Nitrite removal is reached up to 90% in both the reactor. When compared to the stoichiometric equation in Linpor was composed of large amounts of nitrate. At the end of 25 days the results were similar to ceramic stone filling reactor with Linpor filling material reactors. Conclusions and Original Value: Anammox process as from nitrogen removal processes was discovered in 1995. Anammox bacteria that make up this process due to very low growth rates of microbial bacteria in the system must be kept in the system. Most of the studies in the literature, these bacteria enrichment stage is started instead of a continuous batch reactor system. In this study

  5. Inhibition of anaerobic ammonium oxidizing (anammox) enrichment cultures by substrates, metabolites and common wastewater constituents.

    Science.gov (United States)

    Carvajal-Arroyo, José M; Sun, Wenjie; Sierra-Alvarez, Reyes; Field, Jim A

    2013-03-01

    Anaerobic ammonium oxidation (anammox) is an emerging technology for nitrogen removal that provides a more environmentally sustainable and cost effective alternative compared to conventional biological treatment methods. The objective of this study was to investigate the inhibitory impact of anammox substrates, metabolites and common wastewater constituents on the microbial activity of two different anammox enrichment cultures (suspended and granular), both dominated by bacteria from the genus Brocadia. Inhibition was evaluated in batch assays by comparing the N(2) production rates in the absence or presence of each compound supplied in a range of concentrations. The optimal pH was 7.5 and 7.3 for the suspended and granular enrichment cultures, respectively. Among the substrates or products, ammonium and nitrate caused low to moderate inhibition, whereas nitrite caused almost complete inhibition at concentrations higher than 15 mM. The intermediate, hydrazine, either stimulated or caused low inhibition of anammox activity up to 3mM. Of the common constituents in wastewater, hydrogen sulfide was the most severe inhibitor, with 50% inhibitory concentrations (IC(50)) as low as 0.03 mM undissociated H(2)S. Dissolved O(2) showed moderate inhibition (IC(50)=2.3-3.8 mg L(-1)). In contrast, phosphate and salinity (NaCl) posed very low inhibition. The suspended- and granular anammox enrichment cultures had similar patterns of response to the various inhibitory stresses with the exception of phosphate. The findings of this study provide comprehensive insights on the tolerance of the anammox process to a wide variety of potential inhibiting compounds.

  6. Microbial Community Composition and Ultrastructure of Granules from a Full-Scale Anammox Reactor

    KAUST Repository

    Gonzalez-Gil, Graciela

    2014-12-11

    Granules in anammox reactors contain besides anammox bacteria other microbial communities whose identity and relationship with the anammox bacteria are not well understood. High calcium concentrations are often supplied to anammox reactors to obtain sufficient bacterial aggregation and biomass retention. The aim of this study was to provide the first characterization of bacterial and archaeal communities in anammox granules from a full-scale anammox reactor and to explore on the possible role of calcium in such aggregates. High magnification imaging using backscattered electrons revealed that anammox bacteria may be embedded in calcium phosphate precipitates. Pyrosequencing of 16S rRNA gene fragments showed, besides anammox bacteria (Brocadiacea, 32 %), substantial numbers of heterotrophic bacteria Ignavibacteriacea (18 %) and Anaerolinea (7 %) along with heterotrophic denitrifiers Rhodocyclacea (9 %), Comamonadacea (3 %), and Shewanellacea (3 %) in the granules. It is hypothesized that these bacteria may form a network in which heterotrophic denitrifiers cooperate to achieve a well-functioning denitrification system as they can utilize the nitrate intrinsically produced by the anammox reaction. This network may provide a niche for the proliferation of archaea. Hydrogenotrophic methananogens, which scavenge the key fermentation product H2, were the most abundant archaea detected. Cells resembling the polygon-shaped denitrifying methanotroph Candidatus Methylomirabilis oxyfera were observed by electron microscopy. It is hypothesized that the anammox process in a full-scale reactor triggers various reactions overall leading to efficient denitrification and a sink of carbon as biomass in anammox granules.

  7. Macroscale and microscale analysis of Anammox in anaerobic rotating biological contactor

    Institute of Scientific and Technical Information of China (English)

    Yongtao Lv; Lei Wang; Xudong Wang; Yongzhe Yang; Zhiying Wang; Jie Li

    2011-01-01

    Inoculated with conventional anaerobic activated sludge,the Anammox process was successfully developed in an anaerobic rotating biological contactor (AnRBC) fed with a low ratio of C/N synthetic wastewater.Operated in a single point feed mode,the AnRBC removed 92.1% (n =126) of the influent N at the highest surface load of 12 g/(m2.day).The biomass increased by 25% and 17.1 g/(m2.day) of maximum N removal surface load was achieved by elevating flow rate with another feed point.Fluorescence in situ hybridization and polymerase chain reaction analysis indicated that the Anammox genus Candidatus Kuenenia stuttgartiensis dominated the community.Both Anammox and denitrifying activity were detected in biofilm by the application of microelectrodes.In the outer layer of the biofilm (0-2500 μm),nitrite and ammonium consumed simultaneously in a ratio of 1.12/1,revealing the occurrence of Anammox.In the inner layer (> 2500 μm),a decrease of nitrate was caused by denitrification in the absence of nitrite and ammonium.

  8. Inhibition and recovery of continuous electric field application on the activity of anammox biomass.

    Science.gov (United States)

    Qiao, Sen; Yin, Xin; Zhou, Jiti; Furukawa, Kenji

    2014-07-01

    In this study, the effects of electric field on the activity of anammox biomass were investigated. In batch mode, experimental results demonstrated that the nitrogen removal rate enhanced by 25.6 % compared with the control experiment at the electric field of 2 V/cm with application time of 20 min. However, continuous application (24 h) of electric field impacted a mal-effect on anammox biomass during the intensity between 1 and 4 V/cm. After the electric field was removed, the activity of anammox biomass could recover within 2 weeks. This implied that the mal-effect of electric field on anammox biomass was reversible. The decrease of heme c contents and crude enzyme activity demonstrated to be the main reason for the depress of the anammox biomass activity. Transmission electron microscope observation also proved the morphological change of anammox biomass under electric field.

  9. Study on one-stage Partial Nitritation-Anammox process in Moving Bed Biofilm Reactors: a sustainable nitrogen removal.

    OpenAIRE

    Bertino, Andrea

    2011-01-01

    In the last decade, several novel and cost-effective biological nitrogen removal technologies have been developed. The discovery of anaerobic ammonium oxidation (Anammox), about 15 years ago, has resulted in new opportunities for research and development of sustainable nitrogen removal systems. Compared to conventional nitrification/denitrification, Anammox eliminates necessity of external organic carbon source, has a smaller production of excess sludge, reduces energy demand for aeration (up...

  10. Metatranscriptomics reveals the molecular mechanism of large granule formation in granular anammox reactor

    Science.gov (United States)

    Bagchi, Samik; Lamendella, Regina; Strutt, Steven; van Loosdrecht, Mark C. M.; Saikaly, Pascal E.

    2016-06-01

    Granules enriched with anammox bacteria are essential in enhancing the treatment of ammonia-rich wastewater, but little is known about how anammox bacteria grow and multiply inside granules. Here, we combined metatranscriptomics, quantitative PCR and 16S rRNA gene sequencing to study the changes in community composition, metabolic gene content and gene expression in a granular anammox reactor with the objective of understanding the molecular mechanism of anammox growth and multiplication that led to formation of large granules. Size distribution analysis revealed the spatial distribution of granules in which large granules having higher abundance of anammox bacteria (genus Brocadia) dominated the bottom biomass. Metatranscriptomics analysis detected all the essential transcripts for anammox metabolism. During the later stage of reactor operation, higher expression of ammonia and nitrite transport proteins and key metabolic enzymes mainly in the bottom large granules facilitated anammox bacteria activity. The high activity resulted in higher growth and multiplication of anammox bacteria and expanded the size of the granules. This conceptual model for large granule formation proposed here may assist in the future design of anammox processes for mainstream wastewater treatment.

  11. Metatranscriptomics reveals the molecular mechanism of large granule formation in granular anammox reactor

    KAUST Repository

    Bagchi, Samik

    2016-06-20

    Granules enriched with anammox bacteria are essential in enhancing the treatment of ammonia-rich wastewater, but little is known about how anammox bacteria grow and multiply inside granules. Here, we combined metatranscriptomics, quantitative PCR and 16S rRNA gene sequencing to study the changes in community composition, metabolic gene content and gene expression in a granular anammox reactor with the objective of understanding the molecular mechanism of anammox growth and multiplication that led to formation of large granules. Size distribution analysis revealed the spatial distribution of granules in which large granules having higher abundance of anammox bacteria (genus Brocadia) dominated the bottom biomass. Metatranscriptomics analysis detected all the essential transcripts for anammox metabolism. During the later stage of reactor operation, higher expression of ammonia and nitrite transport proteins and key metabolic enzymes mainly in the bottom large granules facilitated anammox bacteria activity. The high activity resulted in higher growth and multiplication of anammox bacteria and expanded the size of the granules. This conceptual model for large granule formation proposed here may assist in the future design of anammox processes for mainstream wastewater treatment.

  12. [Start-up of a full-scale system for short-cut nitrification and Anammox in treatment of pharmaceutical wastewater].

    Science.gov (United States)

    Ding, Shuang; Zheng, Ping; Zhang, Zonghe; Lu, Huifeng; Zhang, Meng; Wu, Datian; Wu, Zegao

    2014-12-01

    In order to broaden the application area of the new nitrogen removal technology, a full-scale system for short-cut nitrification and anaerobic ammonium oxidation (Anammox) was investigated in the nitrogen removal from a strong-ammonium pharmaceutical wastewater. When the influent ammonium concentration was (430.40 ± 55.43) mg/L, ammonia removal efficiency was (81.75 ± 9.10)%. The short-cut nitrification and Anammox system could successfully remove nitrogen from the pharmaceutical wastewater. The start-up of short-cut nitrification system took about 74 d and the nitrite accumulation efficiency was (52.11 ± 9.13)%, the two-step mode using synthetic wastewater and actual wastewater was suitable for the start-up of short-cut nitrification system. The start-up of Anammox system took about 145 d and the maximum volumetric nitrogen removal rate was 6.35 kg N/(m3·d), dozens of times higher than those for the conventional nitrification-denitrification process. The strategy achieving Anammox sludge by self-growth and biocatalyst addition was suitable for the start-up of Anammox system. PMID:26016378

  13. One-stage partial nitritation and anammox in membrane bioreactor.

    Science.gov (United States)

    Huang, Xiaowu; Sun, Kaihang; Wei, Qiaoyan; Urata, Kohei; Yamashita, Yuki; Hong, Nian; Hama, Takehide; Kawagoshi, Yasunori

    2016-06-01

    Partial nitritation and anammox (PN/A) was applied in a lab-scale membrane bioreactor (MBR) to investigate its technical feasibility for treating ammonium-rich wastewater with low C/N ratio. The bacterial community was analyzed by molecular cloning and 16S rRNA sequence analysis. Partial nitritation (PN) was first realized in MBR by seeding aerobic activated sludge. With dissolved oxygen control, a steady effluent mixture with NO2 (-)-N/NH4 (+)-N ratio of 1.13 ± 0.08 was generated from the PN process. Subsequently, the MBR was seeded with anammox biomass on day 59. After running 300 days, the one-stage PN/A achieved a maximum nitrogen removal rate of 1.45 kg N/m(3)/day at the nitrogen removal efficiency of 89.5 %. Microbial community analysis revealed that Nitrosomonas sp. HKU and Nitrosospira sp. YKU corresponded to nitritation; meanwhile, Candidatus Brocadia TKU sp. accounted for nitrogen removal of the PN/A system. Specifically, Nitrosomonas sp. were enriched in the reactor at the PN/A phase and then conquered Nitrosospira sp. to be the predominant ammonia oxidizers. Nitrite oxidizers and denitrifiers were detected in symbiosis with aforementioned microbes. Denitrification promised potential plus nitrogen depletion. The present one-stage PN/A process allows a significant decrease in operational costs compared with classical nitrification/denitrification. PMID:26916267

  14. Isolation and characterization of a prokaryotic cell organelle from the anammox bacterium

    NARCIS (Netherlands)

    Neumann, S.; Wessels, H.J.C.T.; Rijpstra, W.I.C.; Sinninghe Damsté, J.S.; Kartal, B.; Jetten, M.S.M.; van Niftrik, L.

    2014-01-01

    Anaerobic ammonium oxidizing (anammox) bacteria oxidize ammonium with nitrite to nitrogen gas in the absence of oxygen. These microorganisms form a significant sink for fixed nitrogen in the oceans and the anammox process is applied as a cost-effective and environment-friendly nitrogen removal syste

  15. Effects of cycle duration of an external electrostatic field on anammox biomass activity

    Science.gov (United States)

    Yin, Xin; Qiao, Sen; Zhou, Jiti

    2016-01-01

    In this study, the effects of different cycle durations of an external electrostatic field on an anammox biomass were investigated. The total application time per day was 12 h at 2 V/cm for different cycle durations (i.e., continuous application-resting time) of 3 h-3 h, 6 h-6 h, and 12 h-12 h. Compared with the control reactor, the nitrogen removal rates (NRRs) increased by 18.7%, 27.4% and 8.50% using an external electrostatic field application with a continuous application time of 3 h, 6 h and 12 h. Moreover, after the reactor was running smoothly for approximately 215 days under the optimal electrostatic field condition (mode 2, continuous application-rest time: 6 h-6 h), the total nitrogen (TN) removal rate reached a peak value of approximately 6468 g-N/m3/d, which was 44.7% higher than the control. The increase in 16S rRNA gene copy numbers, heme c content and enzyme activities were demonstrated to be the main reasons for enhancement of the NRR of the anammox process. Additionally, transmission electron microscope observations proved that a morphological change in the anammox biomass occurred under an electrostatic field application.

  16. Evidence for anaerobic ammonium oxidation process in freshwater sediments of aquaculture ponds.

    Science.gov (United States)

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu; Ruan, Yun-jie; Xu, Xiang-hua; Li, Ji; Ma, Shi-jie; Zheng, Pei-hui

    2016-01-01

    The anaerobic ammonium oxidation (anammox) process, which can simultaneously remove ammonium and nitrite, both toxic to aquatic animals, can be very important to the aquaculture industry. Here, the presence and activity of anammox bacteria in the sediments of four different freshwater aquaculture ponds were investigated by using Illumina-based 16S rRNA gene sequencing, quantitative PCR assays and (15)N stable isotope measurements. Different genera of anammox bacteria were detected in the examined pond sediments, including Candidatus Brocadia, Candidatus Kuenenia and Candidatus Anammoxoglobus, with Candidatus Brocadia being the dominant anammox genus. Quantitative PCR of hydrazine synthase genes showed that the abundance of anammox bacteria ranged from 5.6 × 10(4) to 2.1 × 10(5) copies g(-1) sediment in the examined ponds. The potential anammox rates ranged between 3.7 and 19.4 nmol N2 g(-1) sediment day(-1), and the potential denitrification rates varied from 107.1 to 300.3 nmol N2 g(-1) sediment day(-1). The anammox process contributed 1.2-15.3% to sediment dinitrogen gas production, while the remainder would be due to denitrification. It is estimated that a total loss of 2.1-10.9 g N m(-2) per year could be attributed to the anammox process in the examined ponds, suggesting that this process could contribute to nitrogen removal in freshwater aquaculture ponds.

  17. Effect of organics on Anammox process for treatment of landfill leachate%垃圾渗滤液中有机物对其厌氧氨氧化的影响

    Institute of Scientific and Technical Information of China (English)

    苗蕾; 王凯; 王淑莹; 李忠明; 朱如龙; 彭永臻

    2014-01-01

    In order to investigate the effect of organics in the mature landfill leachate on the Anam-mox process treating mature landfill leachate,a combined process consisting of nitritation sequencing batch reactor (SBR)and anaerobic ammonium oxidation sequencing batch reactor (ASBR)was de-veloped.The real mature landfill leachate with ammonia of (2000 ±100)mg/L and COD of (2200 ±200)mg/L was used in this study.After 100 days,the ratio of NO2 -/NOx -reached 95% or more in SBRni .ASBR was acclimated under the filling mode of increasing the mature landfill leachate gradually to supply the ammonia.The results show that the biodegradable COD is increased with the ratio of mature landfill leachate in the filling of ASBR.When the biodegradable COD in the filling increases to 150 mg/L,nitrogen loading rate (NLR)of ASBR decreases from 1 .20 kg/(m3 ·d)to 0.28 kg/(m3 ·d),and nitrogen removal rate (NRR)decreases from 1 .10 kg/(m3 ·d)to 0.19 kg/(m3 ·d).This indicates that the system tends to collapse.When the biodegradable COD decreases to 50 mg/L,the maximum NLR and NRR increases to 1 .55 kg/(m3 ·d)and 1 .20 kg/(m3 ·d),respectively,which indicates that the activity of Anammox is recovered.Besides,the quantitative PCR(polymerase chain reaction)shows that the proportion of Anammox in the bacteria increases to 1 .94% when activity of Anammox becteria is recovered.%为了考察垃圾渗滤液中有机物对其厌氧氨氧化反应的影响,保证晚期垃圾渗滤液的深度脱氮,采用短程硝化SBR联合厌氧氨氧化SBR(ASBR)两级系统处理氨氮为(2000±100)mg/L、COD为(2200±200)mg/L的实际晚期垃圾渗滤液进行试验研究.短程硝化SBR运行了100 d,亚硝酸盐积累率达到了95%以上.ASBR采用进水逐步加大渗滤液掺入比例的方式进行驯化.实验结果表明,随着掺入比例的增大,进水可降解COD增加到150 mg/L左右时,ASBR的氮负荷速率从1.20 kg/(m3·d)降到了0.28 kg/(m3

  18. Fate of 17β-Estradiol as a model estrogen in source separated urine during integrated chemical P recovery and treatment using partial nitritation-anammox process.

    Science.gov (United States)

    Huang, Pei; Mukherji, Sachiyo T; Wu, Sha; Muller, James; Goel, Ramesh

    2016-10-15

    Recently, research on source separation followed by the treatment of urine and/or resource recovery from human urine has shown promise as an emerging management strategy. Despite contributing only 1% of the total volume of wastewater, human urine contributes about 80% of the nitrogen, 70% of the potassium, and up to 50% of the total phosphorus in wastewater. It is also a known fact that many of the micropollutants, especially selected estrogens, get into municipal wastewater through urine excretion. In this research, we investigated the fate of 17β-estradiol (E2) as a model estrogen during struvite precipitation from synthetic urine followed by the treatment of urine using a partial nitritation-anammox (PN/A) system. Single-stage and two-stage suspended growth PN/A configurations were used to remove the nitrogen in urine after struvite precipitation. The results showed an almost 95% phosphorous and 5% nitrogen recovery/removal from the synthetic urine due to struvite precipitation. The single and two stage PN/A processes were able to remove around 50% and 75% of ammonia and nitrogen present in the post struvite urine solution, respectively. After struvite precipitation, more than 95% of the E2 remained in solution and the transformation of E2 to E1 happened during urine storage. Most of the E2 removal that occurred during the PN/A process was due to sorption on the biomass and biodegradation (transformation of E2 to E1, and slow degradation of E1 to other metabolites). These results demonstrate that a combination of chemical and biological unit processes will be needed to recover and manage nutrients in source separated urine. PMID:27566951

  19. Evaluation on the microbial interactions of anaerobic ammonium oxidizers and heterotrophs in Anammox biofilm

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Ruscalleda, Mael; Smets, Barth F.

    2012-01-01

    and the affecting factors were evaluated with both experimental and modeling approaches. Fluorescent in situ hybridization (FISH) analysis illustrated that Anammox bacteria and heterotrophs accounted for 77% and 23% of the total bacteria, respectively, even without addition of an external carbon source......Anaerobic ammonium oxidation (Anammox) is a cost-effective new process to treat high-strength nitrogenous wastewater. In this work, the microbial interactions of anaerobic ammonium oxidizers and heterotrophs through the exchange of soluble microbial products (SMP) in Anammox biofilm....... Experimental results showed the heterotrophs could grow both on SMP and decay released substrate from the metabolism of the Anammox bacteria. However, heterotrophic growth in Anammox biofilm (23%) was significantly lower than that of nitrifying biofilm (30–50%). The model predictions matched well...

  20. Enrichment culture of marine anaerobic ammonium oxidation (anammox) bacteria

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jie

    2016-01-01

    The present study investigates the enrichment of anaerobic ammonium oxidation (anammox) bacteria in the marine environment using sediment samples obtained from the East China Sea and discusses the nitrogen removal efficiency of marine anammox bioreactor. Enrichment of anammox bacteria with simultaneous removal of nitrite and ammonium ions was observed in the Anaerobic Sequencing Batch Reactor under a total nitrogen loading rate of 0.37kg-N m-3day-1. In this study, The nitrogen removal efficiency was up to 80% and the molar-reaction ratio of ammonium, nitrite and nitrate was 1.0:1.22:0.22 which was a little different from a previously reported ratio of 1.0:1.32:0.26 in a freshwater system.

  1. Effects of organic matter in livestock manure digester liquid on microbial community structure and in situ activity of anammox granules.

    Science.gov (United States)

    Kindaichi, Tomonori; Awata, Takanori; Mugimoto, Yuichiro; Rathnayake, Rathnayake M L D; Kasahara, Shinsuke; Satoh, Hisashi

    2016-09-01

    Anaerobic ammonium oxidation (anammox) is a promising process for NH4(+)-rich wastewaters such as anaerobic digester liquids. In the present study, we investigated various properties of an up-flow column reactor containing anammox granules and fed with a real digester liquid at four different concentrations (Phases 1 to 4). The efficiencies of NH4(+) and NO2(-) removal decreased by up to 32% and 42%, respectively, in the digester-liquid-fed reactor (reactor-DL). When the performance of reactor-DL deteriorated, the community structure, spatial distribution, and in situ anammox activity in the two reactors were further investigated using 16S rRNA gene-based phylogenetic analysis, fluorescence in situ hybridization (FISH), and microelectrode measurements. The phylogenetic analysis and FISH results showed that non-anammox bacteria were predominant in the granule outer layers in reactor-DL, whereas anammox bacteria still dominated the granule interiors. Microelectrode measurements showed clear evidence of NH4(+) oxidation activity in the interiors of granules from reactor-DL. Batch experiments using anammox granules at different acetate concentrations indicated that concentrations up to 50 mM had no effects on the anammox activity, whereas inorganic carbon uptake decreased in the presence of acetate. The present study clearly shows that the anammox activity and anammox bacterial density in the granules were maintained after feeding the digester liquid to the reactor for 140 days. PMID:27314631

  2. Role of Anaerobic Ammonium Oxidation (Anammox) in Nitrogen Removal from a Freshwater Aquifer.

    Science.gov (United States)

    Smith, Richard L; Böhlke, J K; Song, Bongkeun; Tobias, Craig R

    2015-10-20

    Anaerobic ammonium oxidation (anammox) couples the oxidation of ammonium with the reduction of nitrite, producing N2. The presence and activity of anammox bacteria in groundwater were investigated at multiple locations in an aquifer variably affected by a large, wastewater-derived contaminant plume. Anammox bacteria were detected at all locations tested using 16S rRNA gene sequencing and quantification of hydrazine oxidoreductase (hzo) gene transcripts. Anammox and denitrification activities were quantified by in situ (15)NO2(-) tracer tests along anoxic flow paths in areas of varying ammonium, nitrate, and organic carbon abundances. Rates of denitrification and anammox were determined by quantifying changes in (28)N2, (29)N2, (30)N2, (15)NO3(-), (15)NO2(-), and (15)NH4(+) with groundwater travel time. Anammox was present and active in all areas tested, including where ammonium and dissolved organic carbon concentrations were low, but decreased in proportion to denitrification when acetate was added to increase available electron supply. Anammox contributed 39-90% of potential N2 production in this aquifer, with rates on the order of 10 nmol N2-N L(-1) day(-1). Although rates of both anammox and denitrification during the tracer tests were low, they were sufficient to reduce inorganic nitrogen concentrations substantially during the overall groundwater residence times in the aquifer. These results demonstrate that anammox activity in groundwater can rival that of denitrification and may need to be considered when assessing nitrogen mass transport and permanent loss of fixed nitrogen in aquifers. PMID:26401911

  3. Selection of controlled variables in bioprocesses. Application to a SHARON-Anammox process for autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Valverde Perez, Borja; Sin, Gürkan

    Selecting the right controlled variables in a bioprocess is challenging since the objectives of the process (yields, product or substrate concentration) are difficult to relate with a given actuator. We apply here process control tools that can be used to assist in the selection of controlled var...

  4. Performance and control of biofilm systems with partial nitritation and Anammox for supernatant treatment

    OpenAIRE

    Szatkowska, Beata

    2007-01-01

    Separate treatment of supernatant with dewatering of digested sludge with application of partial nitritation/Anammox process is assessed to be a cost-effective way to remove about 10-15% of influent nitrogen and, thereby, facilitate possibilities to reach required effluent requirements from the plant. The combined partial nitritation/Anammox process can be performed in two separate reactors or in one-stage. Both process options have been investigated in technical- and laboratory-scale pilot p...

  5. Microbial Aggregate and Functional Community Distribution in a Sequencing Batch Reactor with Anammox Granules

    KAUST Repository

    Sun, Shan

    2013-05-01

    Anammox (anaerobic ammonium oxidation) process is a one-step conversion of ammonia into nitrogen gas with nitrite as an electron acceptor. It has been developed as a sustainable technology for ammonia removal from wastewater in the last decade. For wastewater treatment, anammox biomass was widely developed as microbial aggregate where the conditions for enrichment of anammox community must be delicately controlled and growth of other bacteria especially NOB should be suppressed to enhance nitrogen removal efficiency. Little is known about the distribution of microbial aggregates in anammox process. Thus the objective of our study was to assess whether segregation of biomass occurs in granular anammox system. In this study, a laboratory-scale sequential batch reactor (SBR) was successfully operated for a period of 80 days with granular anammox biomass. Temporal and spatial distribution of microbial aggregates was studied by particle characterization system and the distribution of functional microbial communities was studied with qPCR and 16s rRNA amplicon pyrosequencing. Our study revealed the spatial and temporal distribution of biomass aggregates based on their sizes and density. Granules (>200 μm) preferentially accumulated in the bottom of the reactor while floccules (30-200 μm) were relatively rich at the top layer. The average density of aggregate was higher at the bottom than the density of those at the top layer. Degranulation caused by lack of hydrodynamic shear force in the top layer was considered responsible for this phenomenon. NOB was relatively rich in the top layer while percentage of anammox population was higher at the bottom, and anammox bacteria population gradually increased over a period of time. NOB growth was supposed to be associated with the increase of floccules based on the concurrent occurrence. Thus, segregation of biomass can be utilized to develop an effective strategy to enrich anammox and wash out NOB by shortening the settling

  6. Research progress of Anammox-denitrification coupling start up and Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    GUO Pi-jian

    2014-01-01

    Since anammox can simultaneously remove ammonia and nitrite nitrogen,And low cost,have been researched by many scholars,Its high ammonia wastewater treatment has great application value. However, high concentrations of organic carbon on anaerobic ammonium oxidation significantly inhibited. How to achieve anaerobic ammonium oxidation and denitrification coupling, is now a focus of research in the training process, anammox bacteria and denitrifying bacteria on pH, organic matter with different requirements, this paper summarizes the anammox and denitrification startup method and pH, organic matter on anaerobic ammonia oxidation and denitrification coupling and explore control strategies for anaerobic ammonium oxidation and denitrification coupling recommendations.

  7. Distribution and microbial community structure analysis of a single-stage partial nitritation/anammox granular sludge bioreactor operating at low temperature.

    Science.gov (United States)

    Rodriguez-Sanchez, Alejandro; Purswani, Jessica; Lotti, Tommaso; Maza-Marquez, Paula; van Loosdrecht, M C M; Vahala, Riku; Gonzalez-Martinez, Alejandro

    2016-09-01

    In the last decade, autotrophic nitrogen removal technologies based on anammox metabolism have become state of the art in urban and industrial wastewater treatment systems, due to their advantages over traditional nitrogen removal processes. However, their application is currently limited to the treatment of warm wastewater (25-40°C) mainly due to the low growth rate of the anammox bacteria. The extension of the application field to wastewater characterized by lower temperatures (8-20°C), such as those typical for municipal sewage, allows the design of treatment systems with a net energy production. In this study, the distribution and bacterial community structure of a lab-scale single-stage partial nitritation/anammox (PN/A) granular sludge bioreactor operating at low temperatures was analysed using next-generation sequencing techniques. The presence of ammonium-oxidizing bacteria and anammox bacteria was found, but the appearance of other bacterial species shows a complex microbial ecosystem. Evaluation of ecological roles of representative species inside the single-stage PN/A bioreactor was accomplished. Results obtained will be helpful for the future design and operation of PN/A systems performing at low temperatures. PMID:26829222

  8. Abundance and Diversity of Denitrifying and Anammox Bacteria in Seasonally Hypoxic and Sulfidic Sediments of the Saline Lake Grevelingen

    NARCIS (Netherlands)

    Lipsewers, Y.A.; Hopmans, E.C.; Meysman, F.J.R.; Sinninghe Damsté, J.S.; Villanueva, L.

    2016-01-01

    Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, an

  9. 基于厌氧氨氧化的城市污水处理厂能耗分析%Energy Consumption of the Municipal Wastewater Treatment Plant With Anammox Process

    Institute of Scientific and Technical Information of China (English)

    彭永臻; 邵和东; 杨延栋; 张树军; 甘一萍; 张亮

    2015-01-01

    Based on the experimental results of the lab-scale reactor and the operational data of the demonstration project, the wastewater treatment plant with one-stage anammox process was comprehensively evaluated and analyzed in this paper. Firstly, the mass balance of the COD and nitrogen was analyzed. The analysis showed that the effluent of wastewater treatment plant based on anammox process could meet one-class A permitted criteria and the recovery of organic matter doubled when comparing to the traditional A2 O wastewater treatment process. We further investigated the effect of anammox process on energy consumption of the wastewater treatment plant. Due to the reduction of aeration energy consumption and the improvement of methane production in anaerobic digestion process, the theory energy self-sufficiency efficiency of 90% could be achieved. The analysis of mass balance and energy consumption indicated that the separate removal of organic matter and nitrogen in the wastewater pollutants was the key to enhance energy self-sufficiency efficiency.%基于小试和示范工程的试验研究结果,对基于一体化厌氧氨氧化工艺的城市污水处理厂进行了综合分析和评价。首先针对主要污染物质进行物质平衡分析,结果表明:与传统A2 O城市污水处理工艺技术相比,基于厌氧氨氧化工艺的污水处理厂能在保证出水总氮达一级A排放标准的同时,有机物回收量增加1倍。进一步考察了厌氧氨氧化工艺对城市污水处理厂能耗的影响。曝气能耗的降低和厌氧消化工艺中甲烷产量的提高,使得城市污水处理厂的理论能量自给率达到90%。物质平衡分析和能耗分析表明:厌氧氨氧化工艺提高污水厂能量自给率的关键在于实现了污水中有机物和氮污染物去除的分离。

  10. Denitrification, anammox and fixed nitrogen removal in the water column of a tropical great lake

    Science.gov (United States)

    Darchambeau, François; Roland, Fleur; Crowe, Sean A.; De Brabandere, Loreto; Llirós, Marc; Garcia-Armisen, Tamara; Inceoglu, Ozgul; Michiels, Céline; Servais, Pierre; Morana, Cédric D. T.; Bouillon, Steven; Meysman, Filip; Veuger, Bart; Masilya, Pascal M.; Descy, Jean-Pierre; Borges, Alberto V.

    2013-04-01

    If rates of microbial denitrification in aquatic systems are poorly constrained, it is much more the case for tropical water bodies. Lake Kivu [2.50° S 1.59° S, 29.37° E 28.83° E] is one of the great lakes of the East African Rift. It is an oligotrophic lake characterized by anoxic deep waters rich in dissolved gases (methane and carbon dioxide) and nutrients, and by well oxygenated and nutrient-depleted surface waters. During the seasonally stratified rainy season (October to May), a nitrogenous zone characterized by the accumulation of nitrite (NO2-) and nitrate (NO3-) is often observed in the lower layer of the mixolimnion. It results from nitrification of ammonium released by decaying organic matter. With the seasonal uplift of the oxygen minimum zone, the nitrogenous zone becomes anoxic and might be the most preferential area for fixed nitrogen (N) removal in Lake Kivu. Our work aimed at identifying and quantifying the processes of N losses by denitrification and/or anammox in the nitrogenous zone of the Lake Kivu water column. During 5 sampling campaigns (March 2010, October 2010, June 2011, February 2012 and September 2012), isotopic labelling experiments were used to quantify denitrification and anammox rates along vertical profiles at two pelagic stations of the main lake. Moreover, N2:Ar ratios were estimated during the September 2012 campaign, and 16S rDNA pyrosequencing was used to describe bacterial community composition during the last 2 campaigns. No bacteria related to organisms performing anammox was observed and labelling experiments failed to detect anammox at any locations and any depths. In Lake Kivu, denitrifying bacteria were mainly related to Denitratisoma and Thiobacillus genus. Significant denitrification rates were observed at several occasions, especially under the oxic-anoxic interface in the bottom of the nitracline. The annual average denitrification rate was estimated at ~150 μmoles N m-2 d-1. Denitrification was not the only

  11. 基于能源回收的城市污水厌氧氨氧化生物脱氮新工艺%A Novel Municipal Wastewater Treating Process for Energy Production and Autotrophic Nitrogen Removal Based on ANAMMOX

    Institute of Scientific and Technical Information of China (English)

    卢健聪; 高大文; 孙学影

    2013-01-01

    采用“甲烷化+半亚硝化+厌氧氨氧化自养脱氮”新工艺,实现了生活污水能源质回收及氮素低碳化去除.结果表明,联合工艺出水NH4+-N≈0,NO2--N≤0.5 mg·L-1,NO3--N平均为3.6mg· L-1,溶解性COD< 10 mg·L-1,去除率高达98%.其中采用升流式厌氧污泥同定床(UAFB)实现甲烷化,能去除80%以上的进水溶解性COD,甲烷平均日产气量为3.3L,产气量与COD去除量之间的关系为0.3 L·g-1,39.2%的进水溶解性COD转化为CODCH4,只有6.52%转化为CODVFAs.采用序批式反应器(SBR)实现半亚硝化,亚硝化累积率达到97%,出水基本达到厌氧氨氧化进水基质配比(NH4+-N:NO2--N=1:1.13),半亚硝化的主要作用是转化NH4+-N,转化率为36.59%.厌氧氨氧化(ANAMMOX)反应器氨氮去除量、亚硝态氮去除量和硝态氮生成量之比为1:1.18:1.25,总氮容积去除负荷为0.62 kg·(m3·d)-1,对氮素去除的贡献率为56.91%,为氮素脱除的主导工艺环节.新工艺通过厌氧产甲烷实现能源质回收,并通过亚硝化-厌氧氨氧化实现自养脱氮,为现有城市污水处理厂工艺改造提供了一种新的思路和技术.%Using a innovative system consisted of methanogenesis, partial nitritation and anaerobic ammonium oxidation (ANAMMOX) reactors, simultaneous methane production and autotrophic nitrogen removal from domestic sewage was successfully achieved. The results showed that the effluent NH4+ -N of the combined treatment process was below the detection limit. The effluent NO3- -N and NO2 -N were less than 0.5 mg·L and 3.6 mg·L-1 respectively. The effluent COD of the combined treatment process was 10 mg·L-1 and a COD removal rate of 98% was achieved. More than 80% COD was removed by the up-flow anaerobic sludge fixed bed (UAFB) and the anaerobic gas production was 3. 3 L·d-1 with a methane yield of 0. 3 L·g-1. About 39. 2% of influent COD was removed in form of methane and about 6. 52% was transferred to VFAs. Partial

  12. Anammox moving bed biofilm reactor pilot at the 26th Ward wastewater treatment plants in Brooklyn, New York: start-up, biofilm population diversity and performance optimization.

    Science.gov (United States)

    Mehrdad, M; Park, H; Ramalingam, K; Fillos, J; Beckmann, K; Deur, A; Chandran, K

    2014-01-01

    New York City Environmental Protection in conjunction with City College of New York assessed the application of the anammox process in the reject water treatment using a moving bed biofilm reactor (MBBR) located at the 26th Ward wastewater treatment plant, in Brooklyn, NY. The single-stage nitritation/anammox MBBR was seeded with activated sludge and consequently was enriched with its own 'homegrown' anammox bacteria (AMX). Objectives of this study included collection of additional process kinetic and operating data and assessment of the effect of nitrogen loading rates on process performance. The initial target total inorganic nitrogen removal of 70% was limited by the low alkalinity concentration available in the influent reject water. Higher removals were achieved after supplementing the alkalinity by adding sodium hydroxide. Throughout startup and process optimization, quantitative real-time polymerase chain reaction (qPCR) analyses were used for monitoring the relevant species enriched in the biofilm and in the suspension. Maximum nitrogen removal rate was achieved by stimulating the growth of a thick biofilm on the carriers, and controlling the concentration of dissolved oxygen in the bulk flow and the nitrogen loading rates per surface area; all three appear to have contributed in suppressing nitrite-oxidizing bacteria activity while enriching AMX density within the biofilm.

  13. Impact of inocula and operating conditions on the microbial community structure of two anammox reactors.

    Science.gov (United States)

    Costa, Maria Cristina Monteiro S; Carvalho, Luciana; Leal, Cintia Dutra; Dias, Marcela França; Martins, Karoline L; Garcia, Guilherme Brugger; Mancuelo, Isabella Daldegan; Hipólito, Thais; Conell, Erika F Abreu Mac; Okada, Dagoberto; Etchebehere, Claudia; Chernicharo, Carlos Augusto L; Araujo, Juliana Calabria

    2014-08-01

    The microbial community structure of the biomass selected in two distinctly inoculated anaerobic oxidation of ammonium (anammox) reactors was investigated and compared with the help of data obtained from 454-pyrosequencing analyses. The anammox reactors were operated for 550 days and seeded with different sludges: sediment from a constructed wetland (reactor I) and biomass from an aerated lagoon part of the oil-refinery wastewater treatment plant (reactor II). The anammox diversity in the inocula was evaluated by 16S rRNA gene-cloning analysis. The diversity of anammox bacteria was greater in the sludge from the oil-refinery (three of the five known genera of anammox were detected) than in the wetland sludge, in which only Candidatus Brocadia was observed. Pyrosequencing analysis demonstrated that the community enriched in both reactors had differing compositions despite the nearly similar operational conditions applied. The dominant phyla detected in both reactors were Proteobacteria, Chloroflexi, Planctomycetes, and Acidobacteria. The phylum Bacteroidetes, which is frequently observed in anammox reactors, was not detected. However, Acidobacteria and GN04 phyla were observed for the first time, suggesting their importance for this process. Our results suggest that, under similar operational conditions, anammox populations (Ca. Brocadia sinica and Ca. Brocadia sp. 40) were selected in both reactors despite the differences between the two initial inocula. Taken together, these results indicated that the type of inoculum and the culture conditions are key determinants of the general microbial composition of the biomass produced in the reactors. Operational conditions alone might play an important role in anammox selection. PMID:24956774

  14. Anammox transited from denitrification in upflow biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shao-hui; ZHENG Ping; HUA Yu-mei

    2004-01-01

    Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen removal efficiency in the reactor transited from heterotrophic denitrification were higher than that in its counterpart. When the hydraulic retention time was 12 h or so, the total nitrogen loading rate was about 0.609 kg N/(m3·d), and the effluent ammonia and nitrite concentrations were less than 8.5 mg/L and 2.5 mg/L, respectively. The upflow anammox biofilm reactor was capable of keeping and accumulating the slow-growing bacteria efficiently. During operation of the reactor, the biomass color was gradually turned from brownish to red, and the ratio of ammonia consumption, nitrite consumption and nitrate production approached the theoretical one. These changes could be used as an indicator for working state of the reactor.

  15. Modelling and control design for SHARON/Anammox reactor sequence

    OpenAIRE

    Valverde Perez, Borja; Mauricio Iglesias, Miguel; Sin, Gürkan

    2012-01-01

    With the perspective of investigating a suitable control design for autotrophic nitrogen removal, this work presents a complete model of the SHARON/Anammox reactor sequence. The dynamics of the reactor were explored pointing out the different scales of the rates in the system: slow microbial metabolism against fast chemical reaction and mass transfer. Likewise, the analysis of the dynamics contributed to establish qualitatively the requirements for control of the reactors, both for regulation...

  16. Inactivation of ANAMMOX communities under concurrent operation of anaerobic ammonium oxidation (ANAMMOX) and denitrification

    DEFF Research Database (Denmark)

    Chamchoi, N.; Nitisoravut, S.; Schmidt, Jens Ejbye

    2008-01-01

    A concurrent operation of anaerobic ammonium oxidation (ANAMMOX) and denitrification was investigated in a well known UASB reactor seeding with both ANAMMOX and anaerobic granular sludges. ANAMMOX activity was confirmed by hydroxylamine test and the hybridization of biomass using the gene probes...... of Amx 820 and EUB 338 mixed. Denitrification was observed through the reductions of both COD and nitrate–nitrite concentrations under anaerobic/anoxic conditions. By providing a stoichiometric ratio of nitrite to ammonium nitrogen with addition nitrate nitrogen, a gradual reduction of ANAMMOX activity...

  17. Molecular detection of Candidatus Scalindua pacifica and environmental responses of sediment anammox bacterial community in the Bohai Sea, China.

    Directory of Open Access Journals (Sweden)

    Hongyue Dang

    Full Text Available The Bohai Sea is a large semi-enclosed shallow water basin, which receives extensive river discharges of various terrestrial and anthropogenic materials such as sediments, nutrients and contaminants. How these terrigenous inputs may influence the diversity, community structure, biogeographical distribution, abundance and ecophysiology of the sediment anaerobic ammonium oxidation (anammox bacteria was unknown. To answer this question, an investigation employing both 16S rRNA and hzo gene biomarkers was carried out. Ca. Scalindua bacteria were predominant in the surface sediments of the Bohai Sea, while non-Scalindua anammox bacteria were also detected in the Yellow River estuary and inner part of Liaodong Bay that received strong riverine and anthropogenic impacts. A novel 16S rRNA gene sequence clade was identified, putatively representing an anammox bacterial new candidate species tentatively named "Ca. Scalindua pacifica". Several groups of environmental factors, usually with distinct physicochemical or biogeochemical natures, including general marine and estuarine physicochemical properties, availability of anammox substrates (inorganic N compounds, alternative reductants and oxidants, environmental variations caused by river discharges and associated contaminants such as heavy metals, were identified to likely play important roles in influencing the ecology and biogeochemical functioning of the sediment anammox bacteria. In addition to inorganic N compounds that might play a key role in shaping the anammox microbiota, organic carbon, organic nitrogen, sulfate, sulfide and metals all showed the potentials to participate in the anammox process, releasing the strict dependence of the anammox bacteria upon the direct availability of inorganic N nutrients that might be limiting in certain areas of the Bohai Sea. The importance of inorganic N nutrients and certain other environmental factors to the sediment anammox microbiota suggests that these

  18. 两种典型滤料厌氧氨氧化效果与工艺运行优化%Comparison of performance and optimizing process for two typical filter medias of ANAMMOX biofilters

    Institute of Scientific and Technical Information of China (English)

    杨庆; 谷鹏超; 刘秀红; 周瑶; 彭永臻

    2015-01-01

    为促进厌氧氨氧化在城市污水处理中的应用,针对陶粒和火山岩两种典型滤料滤池的厌氧氨氧化脱氮效果和关键性工艺参数进行了研究。试验结果表明,接种挂膜启动生物滤池,10 d可实现稳定的厌氧氨氧化生物膜,火山岩滤池生物膜量和EPS均高于陶粒。滤料和反冲洗对厌氧氨氧化滤池实现稳定脱氮具有重要影响,低滤速条件下火山岩和陶粒滤池厌氧氨氧化效果基本相同,火山岩滤池和陶粒滤池反冲洗周期均较长,宜采用单独水冲方式;但高滤速条件下火山岩滤池比陶粒滤池更易堵塞,滤层有效深度小,反冲洗方式宜采用气水联合反冲方式,并相应缩短反冲洗周期、延长反冲洗时间。火山岩和陶粒滤池滤速均不宜高于2 m·h−1,最高总氮负荷分别可达3.81 kg·m−3·d−1和3.56 kg·m−3·d−1。%To promote the engineering applications of anaerobic ammonium oxidation (ANAMMOX) for sewage treatment, nitrogen removal rate and key operational parameters were studied in two typical filters with ceramsite or volcanic rock as filter media were studied. The obtained results showed that the anammox biofim in both biofilters was successfully cultivated after 10 days of inoculation. Filter media and backwash both played important role in achieving stable anammox in biofilter. At low filtration velocity, in both biofilter, not only nitrogen removal rate was almost similar, but also water backwash and long backwash cycle were optimal. However, at high filtration velocity, volcanic rock biofilter was more easily blocked up than ceramsite biofilter. The effective depth of filter layer in volcanic rock biofilter was also thinner than that in ceramsite biofilter. Besides, air+water backwash style was optimal, backwash cycle should be shortened and backwash time should be prolonged. Filtration velocity in both biofilters should be controlled lower than 2 m·h−1. The highest

  19. Aggregate Size and Architecture Determine Microbial Activity Balance for One-Stage Partial Nitritation and Anammox

    DEFF Research Database (Denmark)

    Vlaeminck, S.E.; Terada, Akihiko; Smets, Barth F.;

    2010-01-01

    Aerobic ammonium-oxidizing bacteria (AerAOB) and anoxic ammonium-oxidizing bacteria (AnAOB) cooperate in partial nitritation/anammox systems to remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about granulation so far......AOB abundance and the activity balance for the different aggregate sizes and (ii) to relate aggregate morphology, size distribution, and architecture putatively to the inoculation and operation of the three reactors. A nitrite accumulation rate ratio (NARR) was defined as the net aerobic nitrite production rate...... divided by the anoxic nitrite consumption rate. The smallest reactor A, B, and C aggregates were nitrite sources (NARR, > 1.7). Large reactor A and C aggregates were granules capable of autonomous nitrogen removal (NARR, 0.6 to 1.1) with internal AnAOB zones surrounded by an AerAOB rim. Around 50% of the...

  20. Comparison of sidestream treatment technologies: post aerobic digestion and Anammox.

    Science.gov (United States)

    Bauer, Heidi; Johnson, Thomas D; Johnson, Bruce R; Oerke, David; Graziano, Steven

    2016-01-01

    Post aerobic digestion (PAD) and anaerobic ammonium oxidation (Anammox) are sidestream treatment technologies which are both excellent options for the reduction of nitrogen recycled back to the liquid stream without the need for supplemental carbon or alkalinity. However, the achievement of this goal is where the similarities between the two technologies end. PAD is an advanced digestion process where aerobic digestion is designed to follow anaerobic digestion. Other benefits of PAD include volatile solids reduction, odor reduction, and struvite formation reduction. Anammox harnesses a specific species of autotrophic bacteria that can help achieve partial nitritation/deammonification. Other benefits of Anammox include lower energy consumption due to requiring less oxygen compared with conventional nitrification. This manuscript describes the unique benefits and challenges of each technology. Example installations are presented with a narrative of how and why the technology was selected. A whole plant simulator is used to compare and contrast the mass balances and net present value costs on an 'apples to apples' basis. The discussion includes descriptions of conditions under which each technology would potentially be the most beneficial and cost-effective against a baseline facility without sidestream treatment. PMID:27232417

  1. Nitrogen polishing in a fully anoxic anammox MBBR treating mainstream nitritation-denitritation effluent.

    Science.gov (United States)

    Regmi, Pusker; Holgate, Becky; Miller, Mark W; Park, Hongkeun; Chandran, Kartik; Wett, Bernhard; Murthy, Sudhir; Bott, Charles B

    2016-03-01

    As nitrogen discharge limits are becoming more stringent, short-cut nitrogen systems and tertiary nitrogen polishing steps are gaining popularity. For partial nitritation or nitritation-denitritation systems, anaerobic ammonia oxidation (anammox) polishing may be feasible to remove residual ammonia and nitrite from the effluent. Nitrogen polishing of mainstream nitritation-denitritation system effluent via anammox was studied at 25°C in a fully anoxic moving bed bioreactor (MBBR) (V = 0.45 m(3) ) over 385 days. Unlike other anammox based processes, a very fast startup of anammox MBBR was demonstrated, despite nitrite limited feeding conditions (influent nitrite = 0.7 ± 0.59 mgN/L, ammonia = 6.13 ± 2.86 mgN/L, nitrate = 3.41 ± 1.92 mgN/L). The nitrogen removal performance was very stable within a wide range of nitrogen inputs. Anammox bacteria (AMX) activity up to 1 gN/m(2) /d was observed which is comparable to other biofilm-based systems. It is generally believed that nitrate production limits nitrogen removal through AMX metabolism. However, in this study, anammox MBBR demonstrated ammonia, nitrite, and nitrate removal at limited chemical oxygen demand (COD) availability. AMX and heterotrophs contributed to 0.68 ± 0.17 and 0.32 ± 0.17 of TIN removal, respectively. It was speculated that nitrogen removal might be aided by denitratation which could be due to heterotrophs or the recently discovered ability for AMX to use short-chain fatty acids to reduce nitrate to nitrite. This study demonstrates the feasibility of anammox nitrogen polishing in an MBBR is possible for nitritation-denitration systems. PMID:26333200

  2. Anammox enrichment from reject water on blank biofilm carriers and carriers containing nitrifying biomass: operation of two moving bed biofilm reactors (MBBR).

    Science.gov (United States)

    Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Lemmiksoo, Vallo; Menert, Anne; Loorits, Liis; Vabamäe, Priit; Tomingas, Martin; Tenno, Taavo

    2012-07-01

    The anammox bacteria were enriched from reject water of anaerobic digestion of municipal wastewater sludge onto moving bed biofilm reactor (MBBR) system carriers-the ones initially containing no biomass (MBBR1) as well as the ones containing nitrifying biomass (MBBR2). Duration of start-up periods of the both reactors was similar (about 100 days), but stable total nitrogen (TN) removal efficiency occurred earlier in the system containing nitrifying biomass. Anammox TN removal efficiency of 70% was achieved by 180 days in both 20 l volume reactors at moderate temperature of 26.0°C. During the steady state phase of operation of MBBRs the average TN removal efficiencies and maximum TN removal rates in MBBR1 were 80% (1,000 g-N/m(3)/day, achieved by 308 days) and in MBBR2 85% (1,100 g-N/m(3)/day, achieved by 266 days). In both reactors mixed bacterial cultures were detected. Uncultured Planctomycetales bacterium clone P4, Candidatus Nitrospira defluvii and uncultured Nitrospira sp. clone 53 were identified by PCR-DGGE from the system initially containing blank biofilm carriers as well as from the nitrifying biofilm system; from the latter in addition to these also uncultured ammonium oxidizing bacterium clone W1 and Nitrospira sp. clone S1-62 were detected. FISH analysis revealed that anammox microorganisms were located in clusters in the biofilm. Using previously grown nitrifying biofilm matrix for anammox enrichment has some benefits over starting up the process from zero, such as less time for enrichment and protection against severe inhibitions in case of high substrate loading rates.

  3. Laboratory study on factors influencing nitrogen removal in marble chip biofilters incorporating nitritation and anammox.

    Science.gov (United States)

    Tao, Wendong; Wen, Jianfeng; Norton, Christopher

    2011-01-01

    It remains challenging to integrate nitritation and anammox in ecologically engineered treatment systems such as passive biofilters that are packed with natural materials and have low energy inputs. This study explored the factors influencing nitritation-anammox through parallel operation of two laboratory-scale biofilters packed with large and small marble chips respectively. Clean marble chips (mainly CaCO3) had an alkalinity dissolution rate of 130 mg CaCO3/kg marble d when water pH approached 6.5. Marble chips effectively increased water pH and provided sufficient alkalinity to support nitritation-anammox in the biofilters. Ammonium and total nitrogen removal decreased by 47 and 26%, respectively, when nutrients were not amended to influent. An influent nitrite concentration above 8.9 mg N/L could inhibit anammox in thin biofilms of biofilters. Nitritation-anammox was enhanced with a hydraulic retention time of 2 d relative to 7 d, likely due to enhanced air entrainment. Size of marble chips rarely made a significant difference in nitrogen removal, possibly due to sufficient surface area available for bacterial attachment and alkalinity dissolution.

  4. Partial nitritation ANAMMOX in submerged attached growth bioreactors with smart aeration at 20 °C.

    Science.gov (United States)

    Shannon, James M; Hauser, Lee W; Liu, Xikun; Parkin, Gene F; Mattes, Timothy E; Just, Craig L

    2015-01-01

    Submerged attached growth bioreactors (SAGBs) were operated at 20 °C for 30 weeks in smart-aerated, partial nitritation ANAMMOX mode and in a timer-controlled, cyclic aeration mode. The smart-aerated SAGBs removed 48-53% of total nitrogen (TN) compared to 45% for SAGBs with timed aeration. Low dissolved oxygen concentrations and cyclic pH patterns in the smart-aerated SAGBs suggested conditions favorable to partial nitritation ANAMMOX and stoichiometrically-derived and numerically modeled estimations attributed 63-68% and 14-44% of TN removal to partial nitritation ANAMMOX in these bioreactors, respectively. Ammonia removals of 36-67% in the smart-aerated SAGBs, with measured oxygen and organic carbon limitations, further suggest partial nitritation ANAMMOX. The smart-aerated SAGBs required substantially less aeration to achieve TN removals similar to SAGBs with timer-controlled aeration. Genomic DNA testing confirmed that the dominant ANAMMOX seed bacteria, received from a treatment plant utilizing the DEMON® sidestream deammonification process, was a Candidatus Brocadia sp. (of the Planctomycetales order). The DNA from these bacteria was also present in the SAGBs at the conclusion of the study providing evidence for attached growth and limited biomass washout.

  5. Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor.

    Science.gov (United States)

    Ali, Muhammad; Rathnayake, Rathnayake M L D; Zhang, Lei; Ishii, Satoshi; Kindaichi, Tomonori; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

    2016-10-01

    Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4(+) concentration. The average emission of N2O was 0.98 ± 0.42% and 1.35 ± 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2(-) reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox N2O production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifier denitrification and heterotrophic denitrification in the NO2(-) reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that approximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifier-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2(-) reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the

  6. Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor

    KAUST Repository

    Ali, Muhammad

    2016-06-16

    Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4+ concentration. The average emission of N2O was 0.98 ± 0.42% and 1.35 ± 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2− reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox N2O production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifier denitrification and heterotrophic denitrification in the NO2− reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that approximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifier-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2− reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the key N2O

  7. Modelling and control design for SHARON/Anammox reactor sequence

    DEFF Research Database (Denmark)

    Valverde Perez, Borja; Mauricio Iglesias, Miguel; Sin, Gürkan

    2012-01-01

    metabolism against fast chemical reaction and mass transfer. Likewise, the analysis of the dynamics contributed to establish qualitatively the requirements for control of the reactors, both for regulation and for optimal operation. Work in progress on quantitatively analysing different control structure......With the perspective of investigating a suitable control design for autotrophic nitrogen removal, this work presents a complete model of the SHARON/Anammox reactor sequence. The dynamics of the reactor were explored pointing out the different scales of the rates in the system: slow microbial...

  8. Three-Dimensional Stratification of Bacterial Biofilm Populations in a Moving Bed Biofilm Reactor for Nitritation-Anammox

    Directory of Open Access Journals (Sweden)

    Robert Almstrand

    2014-01-01

    Full Text Available Moving bed biofilm reactors (MBBRs are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  9. Three-dimensional stratification of bacterial biofilm populations in a moving bed biofilm reactor for nitritation-anammox.

    Science.gov (United States)

    Almstrand, Robert; Persson, Frank; Daims, Holger; Ekenberg, Maria; Christensson, Magnus; Wilén, Britt-Marie; Sörensson, Fred; Hermansson, Malte

    2014-01-29

    Moving bed biofilm reactors (MBBRs) are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox) processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB) and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH) to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  10. Discovery of anammox bacteria in terrestrial ecosystems

    OpenAIRE

    Humbert, Sylvia; Aragno, Michel; Zopfi, Jakob

    2011-01-01

    Avant cette étude, le processus anammox (oxydation anaérobie de l’ammonium) était uniquement étudié dans les usines de traitement des eaux usées et dans les milieux aquatiques, sédiments inclus. Cependant, rien n'était connu encore sur la distribution, la diversité, l'abondance et l'activité des bactéries anammox dans les écosystèmes terrestres. Dans cette étude, nous apportons l’évidence, par approche moléculaire, de la présence de bactéries anammox dans les sols de zones humides, les sédime...

  11. Accelerating effect of hydroxylamine and hydrazine on nitrogen removal rate in moving bed biofilm reactor.

    Science.gov (United States)

    Zekker, Ivar; Kroon, Kristel; Rikmann, Ergo; Tenno, Toomas; Tomingas, Martin; Vabamäe, Priit; Vlaeminck, Siegfried E; Tenno, Taavo

    2012-09-01

    In biological nitrogen removal, application of the autotrophic anammox process is gaining ground worldwide. Although this field has been widely researched in last years, some aspects as the accelerating effect of putative intermediates (mainly N₂H₄ and NH₂OH) need more specific investigation. In the current study, experiments in a moving bed biofilm reactor (MBBR) and batch tests were performed to evaluate the optimum concentrations of anammox process intermediates that accelerate the autotrophic nitrogen removal and mitigate a decrease in the anammox bacteria activity using anammox (anaerobic ammonium oxidation) biomass enriched on ring-shaped biofilm carriers. Anammox biomass was previously grown on blank biofilm carriers for 450 days at moderate temperature 26.0 (±0.5) °C by using sludge reject water as seeding material. FISH analysis revealed that anammox microorganisms were located in clusters in the biofilm. With addition of 1.27 and 1.31 mg N L⁻¹ of each NH₂OH and N₂H₄, respectively, into the MBBR total nitrogen (TN) removal efficiency was rapidly restored after inhibitions by NO₂⁻. Various combinations of N₂H₄, NH₂OH, NH₄⁺, and NO₂⁻ were used as batch substrates. The highest total nitrogen (TN) removal rate with the optimum N₂H₄ concentration (4.38 mg N L⁻¹) present in these batches was 5.43 mg N g⁻¹ TSS h⁻¹, whereas equimolar concentrations of N₂H₄ and NH₂OH added together showed lower TN removal rates. Intermediates could be applied in practice to contribute to the recovery of inhibition-damaged wastewater treatment facilities using anammox technology.

  12. Nitrogen removal and spatial distribution of denitrifier and anammox communities in a bioreactor for mine drainage treatment.

    Science.gov (United States)

    Herbert, Roger B; Winbjörk, Harry; Hellman, Maria; Hallin, Sara

    2014-12-01

    Mine drainage water may contain high levels of nitrate (NO3(-)) due to undetonated nitrogen-based explosives. The removal of NO3(-) and nitrite (NO2(-)) in cold climates through the microbial process of denitrification was evaluated using a pilot-scale fixed-bed bioreactor (27 m(3)). Surface water was diverted into the above-ground bioreactor filled with sawdust, crushed rock, and sewage sludge. At hydraulic residence times of ca.15 h and with the addition of acetate, NO3(-) and NO2(-) were removed to below detection levels at a NO3(-) removal rate of 5-10 g N m(-3) (bioreactor material) d(-1). The functional groups contributing to nitrogen removal in the bioreactor were studied by quantifying nirS and nirK present in denitrifying bacteria, nosZI and nosZII genes from the nitrous oxide - reducing community, and a taxa-specific part of the16S rRNA gene for the anammox community. The abundances of nirS and nirK were almost 2 orders of magnitude greater than the anammox specific 16S rRNA gene, indicating that denitrification was the main process involved in nitrogen removal. The spatial distribution of the quantified genes was heterogeneous in the bioreactor, with trends observed in gene abundance as a function of depth, distance from the bioreactor inlet, and along specific flowpaths. There was a significant relationship between the abundance of nirS, nirK, and nosZI genes and depth in the bioreactor, such that the abundance of organisms containing these genes may be controlled by oxygen diffusion and substrate supply in the partially or completely water-saturated material. Among the investigated microbial functional groups, nirS and anammox bacterial 16S rRNA genes exhibited a systematic trend of decreasing and increasing abundance, respectively, with distance from the inlet, which suggested that the functional groups respond differently to changing environmental conditions. The greater abundance of nirK along central flowpaths may indicate that the bioreactor

  13. Suspended sludge and biofilm shaped different anammox communities in two pilot-scale one-stage anammox reactors.

    Science.gov (United States)

    Zheng, Bingyu; Zhang, Liang; Guo, Jianhua; Zhang, Shujun; Yang, Anming; Peng, Yongzhen

    2016-07-01

    The abundance and diversity of anammox bacteria was investigated in two pilot-scale integrated fixed-film activated sludge (IFAS) reactors treating high ammonium wastewater. Reactor A was inoculated with nitrifying sludge, while Reactor B was inoculated with suspended anammox sludge with the dominant anammox bacteria of Candidatus 'Kuenenia'. After 180days' operation, the predominate anammox bacteria was Candidatus 'Brocadia' (65%) in the biofilm, while Candidatus 'Kuenenia' (86%) outcompeted with other anammox bacteria in suspended sludge in Reactor A. Candidatus 'Kuenenia' were dominated in suspended sludge through the entire experiment in Reactor B. In contrast, the predominated species shifted from Candidatus 'Kuenenia' (89%) into Candidatus 'Brocadia' (66%) in the biofilm of Reactor B. This study indicated that Candidatus 'Brocadia' preferred to grow in the biofilm, while Candidatus 'Kuenenia' would dominant over other anammox bacteria in the suspended sludge. Further studies are required to identify the internal factors affecting the distribution of anammox bacteria. PMID:27023382

  14. Aggregate size and architecture determine biomass activity for one-stage partial nitritation and anammox

    DEFF Research Database (Denmark)

    Vlaeminck, S.; Terada, Akihiko; Smets, Barth F.;

    2010-01-01

    In partial nitritation/anammox systems, aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB) remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about this type of granulation so far. In this study, aggreg...

  15. Effect of organic matter strength on anammox for modified greenhouse turtle breeding wastewater treatment.

    Science.gov (United States)

    Chen, Chongjun; Huang, Xiaoxiao; Lei, Chenxiao; Zhang, Tian C; Wu, Weixiang

    2013-11-01

    Anaerobic ammonium-N removal from modified greenhouse turtle breeding wastewater with different chemical oxygen demand (COD) strengths (194.0-577.8 mg L(-1)) at relatively fixed C/N ratios (≈ 2) was investigated using a lab-scale up-flow anaerobic sludge blanket (UASB) anammox reactor. During the entire experiment, the total nitrogen (TN) removal efficiency was about 85% or higher, while the average COD removal efficiency was around 56.5 ± 7.9%. Based on the nitrogen and carbon balance, the nitrogen removal contribution was 79.6 ± 4.2% for anammox, 12.7 ± 3.0% for denitrification+denitritation and 7.7 ± 4.9% for other mechanisms. Denaturing gradient gel electrophoresis (DGGE) analyses revealed that Planctomycete, Proteobacteria and Chloroflexi bacteria were coexisted in the reactor. Anammox was always dominant when the reactor was fed with different COD concentrations, which indicated the stability of the anammox process with the coexistence of the denitrification process in treating greenhouse turtle breeding wastewater.

  16. [Physicochemical and ecological characteristics of the granular sludge during start-up of Anammox reactor].

    Science.gov (United States)

    Song, Yuxia; Xiong, Lei; Chai, Liyuan; Liao, Qi; Tang, Chongjian; Min, Xiaobo; Yang, Zhihui

    2014-12-01

    The anaerobic granular sludge from an Internal Circulation (IC) reactor of a paper mill wastewater treatment plant were seeded in an Anammox upflow anaerobic sludge blanket reactor. After 185 days operation, the reactor was finally started up by increasing the influent ammonium and nitrite concentrations to 224 mg/L and 255 mg/L, respectively, with volumetric nitrogen removal rate increasing to 3.76 kg/(m3·d). The physicochemical characteristics of the cultivated Anammox granules were observed by scanning electron microscope, transmission electron microscope and Fourier Transform infrared spectroscopy (FTIR). Results suggested that during the start-up course, the granular sludge initially disintegrated and then re-aggregated. FTIR spectra results revealed that the Anammox granular sludge contained abundant functional groups, indicating that it may also possess good adsorption properties. The ecological structure of the granular sludge, analyzed by the metagenomic sequencing methods, suggested that the relative abundance of the dominant bacterial community in the seeding sludge, i.e., Proteobacteria, Firmicutes, Bacteroidetes, significantly reduced, while Planctomycetes which contains anaerobic ammonium oxidation bacteria remarkably increased from 1.59% to 23.24% in the Anammox granules. PMID:26016375

  17. [Effect of temperature on stability of nitrogen removal in the ANAMMOX reactor].

    Science.gov (United States)

    Li, Xiang; Huang, Yong; Zheng, Yu-Hui; Yuan, Yi; Li, Da-Peng; Pan, Yang; Zhang, Chun-Lei

    2012-04-01

    The effect of temperature on stability of nitrogen removal efficiency was investigated in an ANANMMOX reactor by measuring the nitrogen removal rate. The results showed that the nitrogen removal rate changed between 1.51 kg x (m3 x d)(-1) and 1.84 kg x (m3 x d)(-1) when the temperature was between 26 degrees C and 37 degrees C. Compared with gradually degrading temperature (nitrogen removal rate variation of amplitude 9.03%), the ladder degrading temperature was more advantageous on the stability of nitrogen removal efficiency. Nitrogen removal rate variation of amplitude was 4.35%. The nitrogen removal rate dropped quickly, when the temperature was below 20 degrees C. Moreover, a large number of NO2(-) -N accumulated in the ANAMMOX process, when temperature is below 15 degrees C in the reactor. A strong relationship between temperature and nitrogen removal rate was found, when the temperature was below 20 degrees C. Based on the effect of temperature on nitrogen removal rate, the strategy about temperature control was proposed to achieve the fast start-up and high efficiency of nitrogen removal under low temperature for the ANANMMOX reactors.

  18. Rate processes in gas phase

    International Nuclear Information System (INIS)

    Reaction-rate theory and experiment are given a critical review from the engineers' point of view. Rates of heavy-particle, collision-induced reaction in gas phase are formulated in terms of the cross sections and activation energies of the reaction. The effect of cross section function shape and of excited state contributions to the reaction both cause the slope of Arrhenius plots to differ from the true activation energy, except at low temperature. The master equations for chemically reacting gases are introduced, and dissociation and ionization reactions are shown to proceed primarily from excited states about kT from the dissociation or ionization limit. Collision-induced vibration, vibration-rotation, and pure rotation transitions are treated, including three-dimensional effects and conservation of energy, which have usually been ignored. The quantum theory of transitions at potential surface crossing is derived, and results are found to be in fair agreement with experiment in spite of some questionable approximations involved

  19. Sustainable operation of submerged Anammox membrane bioreactor with recycling biogas sparging for alleviating membrane fouling.

    Science.gov (United States)

    Li, Ziyin; Xu, Xindi; Xu, Xiaochen; Yang, FengLin; Zhang, ShuShen

    2015-12-01

    A submerged anaerobic ammonium oxidizing (Anammox) membrane bioreactor with recycling biogas sparging for alleviating membrane fouling has been successfully operated for 100d. Based on the batch tests, a recycling biogas sparging rate at 0.2m(3)h(-1) was fixed as an ultimate value for the sustainable operation. The mixed liquor volatile suspended solid (VSS) of the inoculum for the long operation was around 3000mgL(-1). With recycling biogas sparging rate increasing stepwise from 0 to 0.2m(3)h(-1), the reactor reached an influent total nitrogen (TN) up to 1.7gL(-1), a stable TN removal efficiency of 83% and a maximum specific Anammox activity (SAA) of 0.56kg TNkg(-1) VSSd(-1). With recycling biogas sparging rate at 0.2 m(3) h(-1) (corresponding to an aeration intensity of 118m(3)m(-2)h(-1)), the membrane operation circle could prolong by around 20 times compared to that without gas sparging. Furthermore, mechanism of membrane fouling was proposed. And with recycling biogas sparging, the VSS and EPS content increasing rate in cake layer were far less than the ones without biogas sparging. The TN removal performance and sustainable membrane operation of this system showed the appealing potential of the submerged Anammox MBR with recycling biogas sparging in treating high-strength nitrogen-containing wastewaters.

  20. Coexistence of nitrifying, anammox and denitrifying bacteria in a sequencing batch reactor

    Directory of Open Access Journals (Sweden)

    Michela eLangone

    2014-02-01

    Full Text Available Elevated nitrogen removal efficiencies from ammonium-rich wastewaters have been demonstrated by several applications, that combine nitritation and anammox processes. Denitrification will occur simultaneously when organic carbon is also present. In this study, the activity of aerobic ammonia oxidizing, anammox and denitrifying bacteria in a full scale Sequencing Batch Reactor, treating digester supernatants, was studied by means of batch-assays. AOB and anammox activities were maximum at pH of 8.0 and 7.8-8.0, rispectively. Short term effect of nitrite on anammox activity was studied, showing nitrite up to 42 mg/L did not result in inhibition. Both denitrification via nitrate and nitrite were measured. To reduce nitrite-oxidizing activity, high of NH3 – N (1.9-10 mg N-NH3/L and low nitrite (3-8 mg TNN/L are required conditions during the whole SBR cycle.Molecular analysis showed the nitritation-anammox sludge harbored a high microbial diversity, where each microorganism has a specific role. Using ammonia monooxygenase α –subunit (amoA gene as a marker, our analyses suggested different macro- and micro-environments in the reactor strongly affect the AOB community, allowing the development of different AOB species, such as N. europaea/eutropha and N. oligotropha groups, which improve the stability of nitritation process. A specific PCR primer set, used to target the 16S rRNA gene of anammox bacteria, confirmed the presence of the Ca. Brocadia fulgida type, able to grow in precence of organic matter and to tolerate high nitrite concentrations. The diversity of denitrifiers was assessed by using dissimilatory nitrite reductase (nirS gene-based analyses, who showed denitifiers were related to different betaproteobacterial genera, such as Thauera, Pseudomonas, Dechloromonas and Aromatoleum, able to assist in forming microbial aggregates. Concerning possible secondary processes, no n-damo bacteria were found while NOB from the genus of Nitrobacter

  1. Effects of polybrominated diphenyl ethers and plant species on nitrification, denitrification and anammox in mangrove soils.

    Science.gov (United States)

    Chen, Juan; Zhou, Hai Chao; Pan, Ying; Shyla, Farzana Shazia; Tam, Nora Fung-Yee

    2016-05-15

    Little is known about polybrominated diphenyl ethers (PBDEs) and planting affect biogeochemical processes, and their impact on microbial nitrogen (N) transformation in soil. A 12-month microcosm experiment was conducted to understand the effects of a mixture of PBDEs at two contamination levels, 2 and 20 mg kg(-1)dry weight representing low and high soil contamination, respectively, using two mangrove plant species, namely Kandelia obovata (Ko) and Bruguiera gymnorrhiza (Bg), on nitrification, denitrification and anammox in mangrove soils. No significant changes in these N transformation processes were found at month 3 and at a low level of PBDEs in both plant species, suggesting that short-term exposure to 2 mg kg(-1) contamination did not affect microbial N transformation. At month 12, a high level of PBDE contamination significantly decreased the nitrification potential activity and the copy numbers of archaeal amoA and bacterial amoA gene in Ko soil, but such inhibitory effect was not significant in Bg soil. On the contrary, the denitrification-related parameters, including the activities of nitrate reductase and nitrite reductase, potential denitrification activity and copy numbers of nirK, nirS and nosZ gene, were stimulated by a high level of PBDE contamination in both Ko and Bg soils, and the stimulation was higher in the more anaerobic Bg soil. Different from denitrification, a high level of PBDE contamination decreased the copy numbers of anammox bacterial 16S rRNA gene in Bg soil but not in Ko soil; this was possibly related to the lower nitrate concentration in Bg soil that might inhibit the growth of anammox bacteria. These results indicated that the effects of PBDEs on microbial N transformation were plant species-specific, with the nitrifying microorganisms in Ko soil more susceptible to PBDE contamination, while denitrification and anammox in Bg soil were more sensitive. PMID:26901803

  2. The kinetics of nitrogen removal and biogas production in an anammox non-woven membrane reactor.

    Science.gov (United States)

    Ni, Shou-Qing; Lee, Po-Heng; Sung, Shihwu

    2010-08-01

    The anammox non-woven membrane reactor (ANMR) is a novel reactor configuration to culture the slowly growing anammox bacteria. Different mathematical models were used to study the process kinetics of the nitrogen removal in the ANMR. The kinetics of nitrogen gas production of anammox process was first evaluated in this paper. For substrate removal kinetics, the modified Stover-Kincannon model and the Grau second-order model were more applicable to the ANMR than the first-order model and the Monod model. For nitrogen gas production kinetics, the Van der Meer and Heertjes model was more appropriate than the modified Stover-Kincannon model. Model evaluation was carried out by comparing experimental data with predicted values calculated from suitable models. Both model kinetics study and model testing showed that the Grau second-order model and the Van der Meer and Heertjes model seemed to be the best models to describe the nitrogen removal and nitrogen gas production in the ANMR, respectively.

  3. Achieving nitritation and anammox enrichment in a single moving-bed biofilm reactor treating reject water.

    Science.gov (United States)

    Zekker, I; Rikmann, E; Tenno, T; Saluste, A; Tomingas, M; Menert, A; Loorits, L; Lemmiksoo, Vallo; Tenno, T

    2012-01-01

    A biofilm with high nitrifying efficiency was converted into a nitritating and thereafter a nitritating-anammox biofilm in a moving-bed biofilm reactor at 26.5 (+/- 0.5) degrees C by means of a combination of intermittent aeration, low dissolved oxygen concentration, low hydraulic retention time, free ammonia and furthermore, also by elevated HCO3- concentration. Nitrite-oxidizing bacteria (NOB) were more effectively suppressed by an enhanced HCO3- concentration range of 1200-2350 mg/L as opposed to free-ammonia-based process control where NOBs recovered from inhibition; the respective total-nitrogen removal rates were 0.3 kg N/(m3 x d) and 0.2 kg N/(m3 x d). The biofilm modification strategies resulted in a shift in bacterial community as the NOB Nitrobacter spp. were replaced with NOB belonging to the genus Nitrospira spp. and were closely related to Candidatus Nitrospira defluvii. A community of anaerobic ammonium-oxidizing microorganisms -uncultured Planctomycetales bacterium clone P4 (closely related to Candidatus Brocadia fulgida)--was developed.

  4. Heterotrophic denitrification vs. autotrophic anammox – quantifying collateral effects on the oceanic carbon cycle

    Directory of Open Access Journals (Sweden)

    W. Koeve

    2010-08-01

    Full Text Available The conversion of fixed nitrogen to N2 in suboxic waters is estimated to contribute roughly a third to total oceanic losses of fixed nitrogen and is hence understood to be of major importance to global oceanic production and, therefore, to the role of the ocean as a sink of atmospheric CO2. At present heterotrophic denitrification and autotrophic anammox are considered the dominant sinks of fixed nitrogen. Recently, it has been suggested that the trophic nature of pelagic N2-production may have additional, "collateral" effects on the carbon cycle, where heterotrophic denitrification provides a shallow source of CO2 and autotrophic anammox a shallow sink. Here, we analyse the stoichiometries of nitrogen and associated carbon conversions in marine oxygen minimum zones (OMZ focusing on heterotrophic denitrification, autotrophic anammox, and dissimilatory nitrate reduction to nitrite and ammonium in order to test this hypothesis quantitatively. For open ocean OMZs the combined effects of these processes turn out to be clearly heterotrophic, even with high shares of the autotrophic anammox reaction in total N2-production and including various combinations of dissimilatory processes which provide the substrates to anammox. In such systems, the degree of heterotrophy (ΔCO2:ΔN2, varying between 1.7 and 6.5, is a function of the efficiency of nitrogen conversion. On the contrary, in systems like the Black Sea, where suboxic N-conversions are supported by diffusive fluxes of NH4+ originating from neighbouring waters with sulphate reduction, much lower values of ΔCO2:ΔN2 can be found. However, accounting for concomitant diffusive fluxes of CO2, the ratio approaches higher values similar to those computed for open ocean OMZs. Based on this analysis, we question the significance of collateral effects concerning the trophic

  5. Exogenous nitrate attenuates nitrite toxicity to anaerobic ammonium oxidizing (anammox) bacteria.

    Science.gov (United States)

    Li, Guangbin; Vilcherrez, David; Carvajal-Arroyo, Jose Maria; Sierra-Alvarez, Reyes; Field, Jim A

    2016-02-01

    Anaerobic ammonium oxidizing bacteria (anammox) can be severely inhibited by one of its main substrates, nitrite (NO2(-)). At present, there is limited information on the processes by which anammox bacteria are able to tolerate toxic NO2(-). Intracellular consumption or electrochemically driven (transmembrane proton motive force) NO2(-) export are considered the main mechanisms of NO2(-) detoxification. In this work, we evaluated the potential of exogenous nitrate (NO3(-)) on relieving NO2(-) toxicity, putatively facilitated by NarK, a NO3(-)/NO2(-) transporter encoded in the anammox genome. The relative contribution of NO3(-) to NO2(-) detoxification was found to be pH dependent. Exposure of anammox cells to NO2(-) in absence of their electron donating substrate, ammonium (NH4(+)), causes NO2(-) stress. At pH 6.7 and 7.0, the activity of NO2(-) stressed cells was respectively 0 and 27% of the non-stressed control activity (NO2(-) and NH4(+) fed simultaneously). Exogenous NO3(-) addition caused the recovery to 42% and 80% of the control activity at pH 6.7 and 7.0, respectively. The recovery of the activity of NO2(-) stressed cells improved with increasing NO3(-) concentration, the maximum recovery being achieved at 0.85 mM. The NO3(-) pre-incubation time is less significant at pH 7.0 than at pH 6.7 due to a more severe NO2(-) toxicity at lower pH. Additionally, NO3(-) caused almost complete attenuation of NO2(-) toxicity in cells exposed to the proton gradient disruptor carbonyl cyanide m-chlorophenyl hydrazone at pH 7.5, providing evidence that the NO3(-) attenuation is independent of the proton motive force. The absence of a measurable NO3(-) consumption (or NO3(-) dependent N2 production) during the batch tests leaves NO3(-) dependent active transport of NO2(-) as the only plausible explanation for the relief of NO2(-) inhibition. We suggest that anammox cells can use a secondary transport system facilitated by exogenous NO3(-) to alleviate NO2(-) toxicity. PMID

  6. Quantum mechanics of molecular rate processes

    CERN Document Server

    Levine, Raphael D

    1999-01-01

    This survey of applications of the theory of collisions and rate processes to molecular problems explores collisions of molecules with internal structure, generalized Ehrenfest theorem, theory of reactive collisions, and role of symmetry. It also reviews partitioning technique, equivalent potentials and quasibound states, theory of direct reactions, more. 1969 edition.

  7. A new mathematical model for nitrogen gas production with special emphasis on the role of attached growth media in anammox hybrid reactor.

    Science.gov (United States)

    Tomar, Swati; Gupta, Sunil Kumar

    2015-11-01

    The present study emphasised on the development of new mathematical models based on mass balance and stoichiometry of nitrogen removal in anammox hybrid reactor (AHR). The performance of AHR at varying hydraulic retention times (HRTs) and nitrogen loading rates (NLRs) revealed that nitrogen removal efficiency (NRE) increases with increase in HRT and was found optimal (89 %) at HRT of 2 days. Mass balance of nitrogen revealed that major fraction (74.1 %) of input nitrogen is converted into N2 gas followed by 11.2 % utilised in biomass synthesis. Attached growth media (AGM) in AHR contributed to an additional 15.4 % ammonium removal and reduced the sludge washout rate by 29 %. This also enhanced the sludge retention capacity of AHR and thus minimised the formation of nitrate in the treated effluent, which is one of the bottlenecks of anammox process. Process kinetics was also studied using various mathematical models. The mass balance model derived from total nitrogen was found most precise and predicted N2 gas with least error (1.68 ± 4.44 %). Model validation for substrate removal kinetics dictated comparatively higher correlation for Grau second-order model (0.952) than modified Stover-Kincannon model (0.920). The study concluded that owing to features of high biomass retention, less nitrate formation and consistently higher nitrogen removal efficiency, this reactor configuration is techno-economically most efficient and viable. The study opens the door for researchers and scientists for pilot-scale testing of AHR leading to its wide industrial application. PMID:26143610

  8. A new mathematical model for nitrogen gas production with special emphasis on the role of attached growth media in anammox hybrid reactor.

    Science.gov (United States)

    Tomar, Swati; Gupta, Sunil Kumar

    2015-11-01

    The present study emphasised on the development of new mathematical models based on mass balance and stoichiometry of nitrogen removal in anammox hybrid reactor (AHR). The performance of AHR at varying hydraulic retention times (HRTs) and nitrogen loading rates (NLRs) revealed that nitrogen removal efficiency (NRE) increases with increase in HRT and was found optimal (89 %) at HRT of 2 days. Mass balance of nitrogen revealed that major fraction (74.1 %) of input nitrogen is converted into N2 gas followed by 11.2 % utilised in biomass synthesis. Attached growth media (AGM) in AHR contributed to an additional 15.4 % ammonium removal and reduced the sludge washout rate by 29 %. This also enhanced the sludge retention capacity of AHR and thus minimised the formation of nitrate in the treated effluent, which is one of the bottlenecks of anammox process. Process kinetics was also studied using various mathematical models. The mass balance model derived from total nitrogen was found most precise and predicted N2 gas with least error (1.68 ± 4.44 %). Model validation for substrate removal kinetics dictated comparatively higher correlation for Grau second-order model (0.952) than modified Stover-Kincannon model (0.920). The study concluded that owing to features of high biomass retention, less nitrate formation and consistently higher nitrogen removal efficiency, this reactor configuration is techno-economically most efficient and viable. The study opens the door for researchers and scientists for pilot-scale testing of AHR leading to its wide industrial application.

  9. Investigating the role of co-substrate-substrate ratio and filter media on the performance of anammox hybrid reactor treating nitrogen rich wastewater.

    Science.gov (United States)

    Tomar, Swati; Gupta, Sunil Kumar

    2016-03-01

    This study explored the feasibility of using the anammox hybrid reactor (AHR), which combines suspended and attached growth media, for the biodegradation of ammonical nitrogen in wastewater. The study was performed in four laboratory-scale AHRs, inoculated with mixed seed culture (1:1). The anammox process was established by feeding the AHR with synthetic wastewater, containing NH(4)-N and NO(2)-N (1:1), at hydraulic retention time (HRT) of 1 day. The reactors were gradually acclimated to a higher ammonium concentration (1200 mg/l) until the pseudo-steady state was attained. Subsequently, the reactors were operated at various HRTs (0.25-3.0 days) to optimize the HRT and nitrogen loading rate (NLR). The study demonstrated that HRT of 1 day, corresponding to 95.1% of nitrogen removal was optimal. Pearson correlation analysis indicated the strong and positive correlation of HRT and sludge retention time (SRT), whereas the NLR and biomass yield correlated negatively with the nitrogen removal efficiency (NRE). The mass balance of nitrogen showed that a major fraction (79.1%) of the input nitrogen was converted into N2 gas, and 11.25% was utilized in synthesizing the biomass. The filter media in the AHR contributed to an additional 15.4% of ammonium removal and a reduction of 29% in the sludge washout rate. The nitrogen removal kinetics in the AHR followed the modified Stover-Kincannon model, whereas the Lawrence-McCarty model best described the bacterial growth kinetics. The study concludes that the hybrid configuration of the reactor demonstrated promising results and could be suitably applied for industrial applications. PMID:26277220

  10. Investigating the role of co-substrate-substrate ratio and filter media on the performance of anammox hybrid reactor treating nitrogen rich wastewater.

    Science.gov (United States)

    Tomar, Swati; Gupta, Sunil Kumar

    2016-03-01

    This study explored the feasibility of using the anammox hybrid reactor (AHR), which combines suspended and attached growth media, for the biodegradation of ammonical nitrogen in wastewater. The study was performed in four laboratory-scale AHRs, inoculated with mixed seed culture (1:1). The anammox process was established by feeding the AHR with synthetic wastewater, containing NH(4)-N and NO(2)-N (1:1), at hydraulic retention time (HRT) of 1 day. The reactors were gradually acclimated to a higher ammonium concentration (1200 mg/l) until the pseudo-steady state was attained. Subsequently, the reactors were operated at various HRTs (0.25-3.0 days) to optimize the HRT and nitrogen loading rate (NLR). The study demonstrated that HRT of 1 day, corresponding to 95.1% of nitrogen removal was optimal. Pearson correlation analysis indicated the strong and positive correlation of HRT and sludge retention time (SRT), whereas the NLR and biomass yield correlated negatively with the nitrogen removal efficiency (NRE). The mass balance of nitrogen showed that a major fraction (79.1%) of the input nitrogen was converted into N2 gas, and 11.25% was utilized in synthesizing the biomass. The filter media in the AHR contributed to an additional 15.4% of ammonium removal and a reduction of 29% in the sludge washout rate. The nitrogen removal kinetics in the AHR followed the modified Stover-Kincannon model, whereas the Lawrence-McCarty model best described the bacterial growth kinetics. The study concludes that the hybrid configuration of the reactor demonstrated promising results and could be suitably applied for industrial applications.

  11. Nitrification and Anammox with urea as the energy source

    NARCIS (Netherlands)

    Sliekers, A.O.; Haaijer, S.C.M.; Schmid, M.C.; Harhangi, R.H.; Verwegen, K.; Kuenen, J.G.; Jetten, M.S.M.

    2004-01-01

    Urea is present in many ecosystems and can be used as an energy source by chemolithotrophic aerobic ammonia oxidizing bacteria (AOB). Thus the utilization of urea in comparison to ammonia, by AOB as well as anaerobic ammonia oxidizing (Anammox) bacteria was investigated, using enrichments cultures,

  12. Anammox treatment of swine wastewater using immobilized technology

    Science.gov (United States)

    Partial nitrification (PN) coupled with anaerobic oxidation of ammonium (anammox) stands for a totally autotrophic strategy for the removal of nitrogen. This new bioprocess is particularly useful for the treatment of wastewaters with a high ammonium concentration and a low organic load such as lives...

  13. Treatment of anaerobic sludge digester effluents by the CANON process in an air pulsing SBR

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez-Padin, J.R., E-mail: jose.vazquez.padin@usc.es [Department of Chemical Engineering, University of Santiago de Compostela, Lope Gomez de Marzoa, s/n, E-15782 (Spain); Pozo, M.J. [Environmental Department, National Polytechnic School, Ladron de Guevara E11-253, Quito (Ecuador); Jarpa, M. [Environmental Science Center EULA-Chile, University of Concepcion, P.O. Box 160-C, Concepcion (Chile); Figueroa, M.; Franco, A.; Mosquera-Corral, A.; Campos, J.L.; Mendez, R. [Department of Chemical Engineering, University of Santiago de Compostela, Lope Gomez de Marzoa, s/n, E-15782 (Spain)

    2009-07-15

    The CANON (Completely Autotrophic Nitrogen removal Over Nitrite) process was successfully developed in an air pulsing reactor type SBR fed with the supernatant from an anaerobic sludge digester and operated at moderately low temperatures (18-24 {sup o}C). The SBR was started up as a nitrifying reactor, lowering progressively the dissolved oxygen concentration until reaching partial nitrification. Afterwards, an inoculation with sludge containing Anammox biomass was carried out. Nitrogen volumetric removal rates of 0.25 g N L{sup -1} d{sup -1} due to Anammox activity were measured 35 d after inoculation even though the inoculum constituted only 8% (w/w) of the biomass present in the reactor and it was poorly enriched in Anammox bacteria. The maximal nitrogen removal rate was of 0.45 g N L{sup -1} d{sup -1}. By working at a dissolved oxygen concentration of 0.5 mg L{sup -1} in the bulk liquid, nitrogen removal percentages up to 85% were achieved. The reactor presented good biomass retention capacity allowing the accumulation of 4.5 g VSS L{sup -1}. The biomass was composed by ammonia oxidizing bacteria (AOB) forming fluffy structures and granules with an average diameter of 1.6 mm. These granules were composed by Anammox bacteria located in internal anoxic layers surrounded by an external aerobic layer where AOB were placed.

  14. Ladderane Lipids in Anammox Bacteria: Occurence, Biosynthesis and Application as Environmental Markers

    OpenAIRE

    Rattray, J. E.

    2008-01-01

    Ladderane lipids are unusual membrane lipids of anammox bacteria, which contain either three or five cyclobutane rings, and are so far unique in nature. Anammox bacteria are recently identified members of the nitrogen cycle, with the ability to combine ammonium with nitrite to form dinitrogen gas, in waters or sediments containing little or no oxygen. In the natural environment they have been found in many different oxygen poor environments. For the first time, an anammox bacterium from the n...

  15. Hot topics and application trends of the anammox biotechnology: a review by bibliometric analysis

    OpenAIRE

    Zhang, Zuotao; Liu, Sitong

    2014-01-01

    Anammox has been extensively identified as a novel and sustained biotechnology for wastewater treatment. This study was conducted to evaluate the hot topics and application trends of anammox biotechnology by bibliometric analysis. The results show that “Water science and technology” and “Environmental science ecology” are the prevalent journal and category in this field. Many researches about “process” and “inhibition” have been carried out to conquer common challenges of anammox biotechnolog...

  16. Mainstream Partial Nitritation/Anammox Nitrogen Removal Process in the Largest Water Reclamation Plant in Singapore%新加坡最大回用水处理厂污水短程硝化厌氧氨氧化脱氮工艺

    Institute of Scientific and Technical Information of China (English)

    Cao Yeshi; Kwok Bee Hong; Yan Zhou; Yu Liu; He Jianzhong3; Chua Seng Chye; Wah Yuen Long; Yahya Ghani

    2015-01-01

    总结了新加坡樟宜回用水处理厂4次采样的结果,该厂日处理城市污水80万t.在好氧区很好地实现了部分硝化和亚硝酸盐积累,其中好氧氨氧化率平均为72.2%,亚硝酸盐积累率平均为76.0%.在缺氧区氨氮和亚硝酸盐得到了同步去除(厌氧氨氧化).物料衡算结果表明:初沉池的出水总氮的37.5%是通过自养脱氮去除,27.1%是通过传统的硝化/反硝化脱氮去除,其余部分总氮则存在于活性污泥和出水中.微生物和动力学研究表明:短悬浮或游离的厌氧氨氧化菌可存在于污泥龄较短的污水处理系统.最后从出水氮质量浓度、pH、碱度、曝气能耗及反应器容积等方面,将樟宜回用水处理厂的分段进水活性污泥法工艺与新加坡其他3个回用水处理厂的MEL/LE工艺进行了对比分析.%This paper summarizes the results of four sampling programs in Changi Water Reclamation Plant ( WRP) in Singapore, which has a treatment capacity of 800 000 m3/d of municipal wastewater. Partial nitritation (72. 2% of percentage on average) and nitrite shunt ( nitrite accumulation ratio, NAR of 76. 0% on average ) were well established in the aerobic zones. NH4+ removal coupled with NO2-reduction ( Anammox process ) was observed in the anoxic zones. Mass balance showed autotrophic nitrogen removal contributed to 37. 5% removal of the total nitrogen in the primary effluent, while conventional denitritation/denitrification contributed to 27. 1% removal, and the rest was in wasting sludge and final effluent. Microbial and kinetic studies supported the hypothesis that suspension/free cells of Anammox bacteria were able to be retained in such a short SRT process. The comparisons between the process in Changi WRP and the MLE/LE processes in other three WRPs in Singapore with respect to nitrogen concentrations, pH, and alkalinity of the effluent, aeration energy consumption and reactor volume were presented and discussed.

  17. Effects of Inhibiting Acylated Homoserine Lactones (AHLs) on Anammox Activity and Stability of Granules'.

    Science.gov (United States)

    Zhao, Ran; Zhang, Hanmin; Zou, Xiang; Yang, Fenglin

    2016-07-01

    In this study, the effects of AHL-based QS signals on anammox activity and stability of granules' were investigated. Results clearly showed that the vanillin and porcine kidney acylase I could reduce the AHLs in anammox bacteria. Inactivation of AHLs by vanillin and porcine kidney acylase I depressed the nitrogen removal ability of anammox bacteria. A significant inhibition of specific anammox activity was observed when the concentration of vanillin and porcine kidney acylase I increased to 1 g/L. Anammox activity was depressed on enzyme level. Moreover, degradation of AHLs under vanillin and AHL-acylase exposure could result in anammox granules' disintegration. Further research showed that the contents of protein (PN) and polysaccharides (PS) in extracellular polymeric substances were reduced with AHLs blocked, and it further explained the instability and weakening strength of the anammox granules. The results of our investigation provided new insight into the AHL-based QS-regulated anammox activity, leading a potential way to enhance stability of anammox granules. PMID:27061587

  18. Nitrogen removal from sludge dewatering effluent through anaerobic ammonia oxidation process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shao-hui; ZHENG Ping; HUA Yu-mei

    2005-01-01

    Anaerobic ammonia oxidation(Anammox) process is a novel and promising wastewater nitrogen removal process. The feasibility of transition of Anammox from denitrification and the performance of lab-scale Anammox biofilm reactor were investigated with sludge dewatering effluent. The results showed that Anammox process could be successfully started up after cultivation of denitrification biofilm and using it as inoculum. The transition of Anammox from denitrification was accomplished within 85 d. Anammox process was found suitable to remove ammonia from sludge dewatering effluent. The effluent ammonia concentration was detected to be 23.11 mgN/L at HRT of 28 h when influent ammonia concentration was fed 245 mgN/L, which was less than that for the national discharge standard Ⅱ (25 mgN/L) of 243.25 mg NH4+ -N/L and 288.31 mg NO2- -N/L.

  19. The indeterminate rate problem for birth-death processes

    NARCIS (Netherlands)

    Doorn, van Erik A.

    1987-01-01

    A birth-death process is completely determined by its set of rates if and only if this set satisfies a certain condition C, say. If for a set of rates R the condition C is not fulfilled, then the problem arises of characterizing all birth-death processes which have rate set R (the indeterminate rate

  20. Biophysical properties of membrane lipids of anammox bacteria : I. Ladderane phospholipids form highly organized fluid membranes

    NARCIS (Netherlands)

    Boumann, Henry A.; Longo, Marjorie L.; Stroeve, Pieter; Poolman, Bert; Hopmans, Ellen C.; Stuart, Marc C. A.; Damste, Jaap S. Sinninghe; Schouten, Stefan

    2009-01-01

    Anammox bacteria that are capable of anaerobically oxidizing ammonium (anammox) with nitrite to nitrogen gas produce unique membrane phospholipids that comprise hydrocarbon chains with three or five linearly condensed cyclobutane rings. To gain insight into the biophysical properties of these 'ladde

  1. Filters for High Rate Pulse Processing

    OpenAIRE

    Alpert, B. K.; Horansky, R. D.; Bennett, D.A.; Doriese, W. B.; Fowler, J. W.; Hoover, A. S.; Rabin, M. W.; Ullom, J. N.

    2012-01-01

    We introduce a filter-construction method for pulse processing that differs in two respects from that in standard optimal filtering, in which the average pulse shape and noise-power spectral density are combined to create a convolution filter for estimating pulse heights. First, the proposed filters are computed in the time domain, to avoid periodicity artifacts of the discrete Fourier transform, and second, orthogonality constraints are imposed on the filters, to reduce the filtering procedu...

  2. Entropy Rate of Diffusion Processes on Complex Networks

    OpenAIRE

    Gomez-Gardenes, Jesus; Latora, Vito

    2007-01-01

    The concept of entropy rate for a dynamical process on a graph is introduced. We study diffusion processes where the node degrees are used as a local information by the random walkers. We describe analitically and numerically how the degree heterogeneity and correlations affect the diffusion entropy rate. In addition, the entropy rate is used to characterize complex networks from the real world. Our results point out how to design optimal diffusion processes that maximize the entropy for a gi...

  3. Simultaneous Nitrite-Dependent Anaerobic Methane and Ammonium Oxidation Processes

    NARCIS (Netherlands)

    Luesken, F.A.; Sánchez. J.; Van Alen, T.A.; Sanabria, J.; Op den Camp, H.J.; Jetten, M.S.; Kartal, B.

    2011-01-01

    itrite-dependent anaerobic oxidation of methane (n-damo) and ammonium (anammox) are two recently discovered processes in the nitrogen cycle that are catalyzed by n-damo bacteria, including "Candidatus Methylomirabilis oxyfera," and anammox bacteria, respectively. The feasibility of coculturing anamm

  4. ENTROPY PRODUCTION RATE OF THE MINIMAL DIFFUSION PROCESS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The entropy production rate of stationary minimal diffusion processes with smooth coefficients is calculated. As a byproduct, the continuity of paths of the minimal diffusion processes is discussed, and that the point at infinity is absorbing is proved.

  5. Importance of the operating pH in maintaining the stability of anoxic ammonium oxidation (anammox) activity in moving bed biofilm reactors.

    Science.gov (United States)

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2011-07-01

    Two bench-scale parallel moving bed biofilm reactors (MBBR) were operated to assess pH-associated anammox activity changes during long term treatment of anaerobically digested sludge centrate pre-treated in a suspended growth partial nitrification reactor. The pH was maintained at 6.5 in reactor R1, while it was allowed to vary naturally between 7.5 and 8.1 in reactor R2. At high nitrogen loads reactor R2 had a 61% lower volumetric specific nitrogen removal rate than reactor R1. The low pH and the associated low free ammonia (FA) concentrations were found to be critical to stable anammox activity in the MBBR. Nitrite enhanced the nitrogen removal rate in the conditions of low pH, all the way up to the investigated level of 50mg NO(2)-N/L. At low FA levels nitrite concentrations up to 250 mg NO(2)-N/L did not cause inactivation of anammox consortia over a 2-days exposure time.

  6. Importance of the operating pH in maintaining the stability of anoxic ammonium oxidation (anammox) activity in moving bed biofilm reactors.

    Science.gov (United States)

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2011-07-01

    Two bench-scale parallel moving bed biofilm reactors (MBBR) were operated to assess pH-associated anammox activity changes during long term treatment of anaerobically digested sludge centrate pre-treated in a suspended growth partial nitrification reactor. The pH was maintained at 6.5 in reactor R1, while it was allowed to vary naturally between 7.5 and 8.1 in reactor R2. At high nitrogen loads reactor R2 had a 61% lower volumetric specific nitrogen removal rate than reactor R1. The low pH and the associated low free ammonia (FA) concentrations were found to be critical to stable anammox activity in the MBBR. Nitrite enhanced the nitrogen removal rate in the conditions of low pH, all the way up to the investigated level of 50mg NO(2)-N/L. At low FA levels nitrite concentrations up to 250 mg NO(2)-N/L did not cause inactivation of anammox consortia over a 2-days exposure time. PMID:21565492

  7. Rates of N2 production and diversity and abundance of functional genes associated with denitrification and anaerobic ammonium oxidation in the sediment of the Amundsen Sea Polynya, Antarctica

    Science.gov (United States)

    Choi, Ayeon; Cho, Hyeyoun; Kim, Sung-Han; Thamdrup, Bo; Lee, SangHoon; Hyun, Jung-Ho

    2016-01-01

    A combination of molecular microbiological analyses and metabolic rate measurements was conducted to elucidate the diversity and abundance of denitrifying and anaerobic ammonium oxidation (anammox) bacteria and the nitrogen gas (N2) production rates in sediment underlying the highly productive polynya (Stns. 10 and 17) and the sea-ice zone on the outer shelf (Stn. 83) of the Amundsen Sea, Antarctica. Despite the high water column productivity, the N2 production rates by denitrification (0.04-0.31 nmol N cm-3sed. h-1) and anammox (0.13-0.26 nmol N cm-3 sed. h-1) were lower than those measured in other polar regions. In contrast, gene copy number (106-107 copies cm-3 of nirS and nosZ genes targeting denitirifiers and 105-107 copies cm-3 of 16S rRNA genes related to anammox bacteria) of the two bacterial groups at Stn. 17 was similar compared to those of other organic-rich environments. The majority of the nirS sequences were affiliated with Gammaproteobacteria (54% and 61% of the total nirS gene at Stns. 17 and 83, respectively), which were closely related to Pseudomonas aeruginosa. Most nosZ sequences (92% and 72% of the total nosZ genes at Stns. 17 and 83, respectively) were related to the Alphaproteobacteria, which were closely related to Ruegeria pomeroyi and Roseobacter denitrificans. Most (98%) of the sequences related to anammox bacteria were affiliated with Candidatus Scalindua at Stn. 17. Consequently, despite the low metabolic activity, the abundance and composition of most denitrifying and anammox bacteria detected from the ASP were similar to those reported from a variety of marine environments. Our results further imply that increased labile organic matter production resulting from a shift of the phytoplankton community from Phaeocystis to diatoms in response to rapid melting of sea ice stimulates metabolic activities of the denitrifying and anammox bacteria, thereby enhancing the N removal process in the ASP.

  8. Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake

    Science.gov (United States)

    Stoliker, Deborah L.; Repert, Deborah A.; Smith, Richard L.; Song, Bongkeun; LeBlanc, Denis R.; McCobb, Timothy D.; Conaway, Christopher; Hyun, Sung Pil; Koh, Dong-Chan; Moon, Hee Sun; Kent, Douglas B.

    2016-01-01

    The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.

  9. Variability in ESL Essay Rating Processes: The Role of the Rating Scale and Rater Experience

    Science.gov (United States)

    Barkaoui, Khaled

    2010-01-01

    Various factors contribute to variability in English as a second language (ESL) essay scores and rating processes. Most previous research, however, has focused on score variability in relation to task, rater, and essay characteristics. A few studies have examined variability in essay rating processes. The current study used think-aloud protocols…

  10. Developing Anammox for mainstream municipal wastewater treatment

    OpenAIRE

    T Lotti

    2016-01-01

    Conventional wastewater treatment plants (WWTPs), like activated sludge systems, are energy demanding requiring a large electrical energy supply (e.g. 25 kWh PE-1 year-1) which, especially during peak-load periods, may account for an important quote of the grid installed power of the surrounding area. Only across the EU, there are 16000 WWTPs that consume around 10000 GWh year-1 of electricity. Furthermore, the volume of wastewater treated in WWTPs in the EU is increasing with a rate of aroun...

  11. Subexponential loss rate asymptotics for Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang

    We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean time spent at the upper barrier K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive...... asymptotics for the loss rate when K tends to infinity, when the mean of the Lévy process is negative and the positive jumps are subexponential. In the course of this derivation, we achieve a formula, which is a generalization of the celebrated Pollaczeck-Khinchine formula....

  12. Subexponential loss rate asymptotics for Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang

    2011-01-01

    We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean of the local time at K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive asymptotics...... for the loss rate when K tends to infinity, when the mean of the Lévy process is negative and the positive jumps are subexponential. In the course of this derivation, we achieve a formula, which is a generalization of the celebrated Pollaczeck-Khinchine formula....

  13. Markov and semi-Markov processes as a failure rate

    Science.gov (United States)

    Grabski, Franciszek

    2016-06-01

    In this paper the reliability function is defined by the stochastic failure rate process with a non negative and right continuous trajectories. Equations for the conditional reliability functions of an object, under assumption that the failure rate is a semi-Markov process with an at most countable state space are derived. A proper theorem is presented. The linear systems of equations for the appropriate Laplace transforms allow to find the reliability functions for the alternating, the Poisson and the Furry-Yule failure rate processes.

  14. Enhancing simultaneous nitritation and anammox in recirculating biofilters: effects of unsaturated zone depth and alkalinity dissolution of packing materials.

    Science.gov (United States)

    Wen, Jianfeng; Tao, Wendong; Wang, Ziyuan; Pei, Yuansheng

    2013-01-15

    This study investigated effects of unsaturated zone depth on nitrogen removal via simultaneous nitritation and anammox in three vertical flow recirculating biofilters. The biofilters had different depths (25, 40, and 60 cm) of an unsaturated zone and the same depth (35 cm) of a saturated zone. Unsaturated zone depth could be regulated to maintain suitable dissolved oxygen concentrations and enhance entrapment of carbon dioxide for co-occurrence of aerobic ammonia oxidation and anammox in the saturated zones. The biofilters with the larger unsaturated zones had higher ammonium and total inorganic nitrogen removal rates (16.2-33.5 g N/m(3)/d and 4.6-16.7 g N/m(3)/d, respectively) than the biofilter with the smallest unsaturated zone (11.9-18.1 g N/m(3)/d and 4.4-7.9 g N/m(3)/d, respectively). Electric arc furnace slag and marble chips were packed in the unsaturated and saturated zones, respectively, as low-cost materials to supplement alkalinity and buffer pH. Laboratory experiments showed that the maximum alkalinity dissolution efficiency was 513 mg CaCO(3)/kg marble chips and 761 mg CaCO(3)/kg electric arc furnace slag. Marble chips and electric arc furnace slag could increase dairy wastewater pH up to 7 and 9, respectively. The laboratory results are also useful for utilization of furnace slag and marble chips in constructed wetlands.

  15. Role of Rate of Specific Growth Rate in Different Growth Processes: A First Principle Approach

    CERN Document Server

    Biswas, Dibyendu; Patra, Sankar Nayaran

    2015-01-01

    In the present communication, effort is given for the development of a common platform that helps to address several growth processes found in literature. Based on first principle approach, the role of rate of specific growth rate in different growth processes has been considered in an unified manner. It is found that different growth equations can be derived from the same rate equation of specific growth rate. The dependence of growth features of different growth processes on the parameters of the rate equation of specific growth rate has been examined in detail. It is found that competitive environment may increase the saturation level of population size. The exponential growth could also be addressed in terms of two important factors of growth dynamics, as reproduction and competition. These features are, most probably, not reported earlier.

  16. Bio-augmentation for mitigating the impact of transient oxytetracycline shock on anaerobic ammonium oxidation (ANAMMOX) performance.

    Science.gov (United States)

    Jin, Ren-Cun; Zhang, Qian-Qian; Zhang, Zheng-Zhe; Liu, Jia-Hong; Yang, Bi-E; Guo, Li-Xin; Wang, Hui-Zhong

    2014-07-01

    The feasibility of applying bio-augmentation tactics to remit the influence of transient oxytetracycline (OTC) shock on the anaerobic ammonium oxidation (ANAMMOX) process was evaluated. The bio-augmentation was applied together with shock test, with OTC shock concentration of 518 mg L(-1) and 1-h duration. 0.655-2.62 g volatile suspended solid (VSS) sludges were varied to optimize bio-augmentation dosage (BAD), and appropriate bio-augmentation time (BAT) was determined. The validity of the bio-augmentation was indicated by recovery performance and sludge characteristics. The restoring time of 38 h for bio-augmented reactor was shorter than that of non-bio-augmented reactor (45 h), and heme c content was increased respectively from 0.195 ± 0.001, 0.267 ± 0.047, 0.301 ± 0.049, to 0.340 ± 0.053 μmol g(-1) VSS with the BAD of 0.655, 1.31, 1.97, 2.62 g-VSS. The results suggest that bio-augmentation enhances the recovery of ANAMMOX performance following OTC shock and BAT and BAD are key operational factors.

  17. Dissolution rate measurements for resist processing in supercritical carbon dioxide

    Science.gov (United States)

    Pham, Victor Q.; Weibel, Gina L.; Rao, Nagesh G.; Ober, Christopher K.

    2002-07-01

    A dissolution rate monitor (DRM) was successfully constructed to study the behavior of thin photoresist films undergoing the dissolution process in supercritical carbon dioxide (SCCO2). The DRM is based on the principles of interferometry but requires special modifications to the processing vessel to allow for the passage of transmitted and reflected He-Ne laser light. Dissolution rates obtained agree well with independent profilometric measurements of film thickness loss. We found that for block and random copolymers of THPMA-F7MA, dissolution rates vary with film thickness, slowing down considerably towards the silicon surface. This behavior was also observed in TBMA-F7MA random copolymers.

  18. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark;

    2014-01-01

    -stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O......) and nitric oxide (NO) concentrations were monitored and N2O emissions calculated. Significant decreases in N2O emissions were obtained when the frequency of aeration was increased while maintaining a constant air flow rate (from >6 to 1.7% Delta N2O/Delta TN). However, no significant effect on the emissions...... was noted when the duration of aeration was increased while decreasing air flow rate (10.9 +/- 3.2% Delta N2O/Delta TN). The extant ammonium oxidation activity (mgNH(4)(+)-N/gVSS.min) positively correlated with the specific N2O production rate (mgN(2)O-N/gVSS.min) of the systems. Operating under conditions...

  19. Calculations of fission rates for r-process nucleosynthesis

    OpenAIRE

    Panov, I. V.; Kolbe, E.; Pfeiffer, B.; Rauscher, T.; Kratz, K.-L.; Thielemann, F. -K.

    2004-01-01

    Fission plays an important role in the r-process which is responsible not only for the yields of transuranium isotopes, but may have a strong influence on the formation of the majority of heavy nuclei due to fission recycling. We present calculations of beta-delayed and neutron-induced fission rates, taking into account different fission barriers predictions and mass formulae. It is shown that an increase of fission barriers results naturally in a reduction of fission rates, but that neverthe...

  20. Reactive magnetron sputtering : from fundamentals to high deposition rate processes

    OpenAIRE

    Kubart, Tomas

    2013-01-01

    Reactive magnetron sputtering is widely used for synthesis of various compound thin films. The technique is very versatile and scalable. Especially in industry, high productivity is essential and there is a need for processes with high deposition rates. Achieving high deposition rate and true compound stoichiometry of the deposited film is, however, challenging in reactive sputtering. As a consequence of complex interaction between the reactive gas and the sputtered metal, the relation betwee...

  1. Engineering aspects of rate-related processes in food manufacturing.

    Science.gov (United States)

    Adachi, Shuji

    2015-01-01

    Many rate-related phenomena occur in food manufacturing processes. This review addresses four of them, all of which are topics that the author has studied in order to design food manufacturing processes that are favorable from the standpoint of food engineering. They include chromatographic separation through continuous separation with a simulated moving adsorber, lipid oxidation kinetics in emulsions and microencapsulated systems, kinetic analysis and extraction in subcritical water, and water migration in pasta.

  2. Reaction Rate Sensitivity of the gamma-Process Path

    OpenAIRE

    Rauscher, T.

    2004-01-01

    The location of the (gamma,p)/(gamma,n) and (gamma,alpha)/(gamma,n) line at gamma-process temperatures is discussed, using recently published reaction rates based on global Hauser-Feshbach calculations. The results can directly be compared to previously published, classic gamma-process discussions. The nuclei exhibiting the largest sensitivity to uncertainties in nuclear structure and reaction parameters are specified.

  3. Research progress in anammox wastewater treatment system and its actual application%厌氧氨氧化污水处理工艺及其实际应用研究进展

    Institute of Scientific and Technical Information of China (English)

    陈重军; 王建芳; 张海芹; 沈耀良

    2014-01-01

    As a nocelltype of biological nitrogen removal technology, anaerobic ammonium oxidation (anammox) was a process which was driven by anammox organisms, oxidized ammonium to nitrogen gas using nitrite as the electron acceptor and utilize CO2 as carbon source under anoxic conditions. Compared with the traditional nitrification/denitrification process, anammox has great potential for the practical use in removing nitrogen from the wastewater containing high concentration ammonium and low carbon resources, with no requiration of organic carbon resource and lower sludge production. Nowadays, the anammox wastewater treatment system have been successfully applied in removing nitrogen for various wastewater, with remarkable economic and environmental results. Therefore, this paper reviewed the mechanisms, controlling conditions, advantages, functional microbial populations of Sharon-Anammox and Completely autotrophic ammonium removal over nitrite (CANON) process, respectively. Also, the application performance and controlling parameters in the actual wastewater treatment such as landfill leachate, anaerobic digester effluent and piggery wastewater were explained on both of anammox process. The process provided technical support for anammox engineering applications in sewage treatment. In addition, the field scale applications of anammox process were introduced in the later article. However, further researches are needed to understand prospects and problems of anammox process in actual wastewater treatment were discussed. The rapid enrichment of anammox bacteria, inhibitory effects of organic carbon sources and broad applicability of anammox bacteria would be the most popular topic and difficulty in the anammox engineering application. The article has important theoretical and practical significance for the application and promotion of anammox process.%厌氧氨氧化(Anammox)反应是指在厌氧或者缺氧条件下,厌氧氨氧化微生物以NO2--N

  4. Diversity of total and functional microbiome of anammox reactors fed with complex and synthetic nitrogen-rich wastewaters

    DEFF Research Database (Denmark)

    Gülay, Arda; Pellicer i Nàcher, Carles; Mutlu, Ayten Gizem;

    and biodiversity (Parrott 2010), but, not (Harris et al. 2012) in the anammox functional guild diversity (functional diversity term was used based on phylogenetic groups known to harbor the anammox metabolic pathway). Classifying the microbial structure of bioreactors according to substrate complexity using...

  5. ATTITUDE RATE ESTIMATION BY GPS DOPPLER SIGNAL PROCESSING

    Institute of Scientific and Technical Information of China (English)

    He Side; Milos Doroslovacki; Guo Zhenyu; Zhang Yufeng

    2003-01-01

    A method is presented for near-Earth spacecraft or aviation vehicle's attitude rate estimation by using relative Doppler frequency shift of the Global Positioning System (GPS)carrier. It comprises two GPS receiving antennas, a signal processing circuit and an algorithm.The whole system is relatively simple, the cost and wcight, as well as power consumption, are very low.

  6. Relationship between SCR, heart rate and information processing.

    NARCIS (Netherlands)

    Swart, de J.H.; Das-Smaal, E.A.

    1976-01-01

    This study was designed to investigate the relationship between the amount of information processing in concept learning (CL) and autonomic physiological activity as measured by skin conductance response (SCR). Heart rate (HR) was also measured. Two conceptual rules were used: a conjunctive and an i

  7. Hydroxylamine-dependent Anaerobic Ammonium Oxidation (Anammox) by “ Candidatus Brocadia sinica”

    KAUST Repository

    Oshiki, Mamoru

    2016-04-26

    Although metabolic pathways and associated enzymes of anaerobic ammonium oxidation (anammox) of “Ca. Kuenenia stuttgartiensis” have been studied, those of other anammox bacteria are still poorly understood. NO2- reduction to NO is considered to be the first step in the anammox metabolism of “Ca. K. stuttgartiensis”, however, “Ca. Brocadia” lacks the genes that encode canonical NO-forming nitrite reductases (NirS or NirK) in its genome, which is different from “Ca. K. stuttgartiensis”. Here, we studied the anammox metabolism of “Ca. Brocadia sinica”. 15N-tracer experiments demonstrated that “Ca. B. sinica” cells could reduce NO2- to NH2OH, instead of NO, with as yet unidentified nitrite reductase(s). Furthermore, N2H4 synthesis, downstream reaction of NO2- reduction, was investigated using a purified “Ca. B. sinica” hydrazine synthase (Hzs) and intact cells. Both the “Ca. B. sinica” Hzs and cells utilized NH2OH and NH4+, but not NO and NH4+, for N2H4 synthesis and further oxidized N2H4 to N2 gas. Taken together, the metabolic pathway of “Ca. B. sinica” is NH2OH-dependent and different from the one of “Ca. K. stuttgartiensis”, indicating metabolic diversity of anammox bacteria. This article is protected by copyright. All rights reserved.

  8. Calculations of fission rates for r-process nucleosynthesis

    CERN Document Server

    Panov, I V; Pfeiffer, B; Rauscher, T; Kratz, K L; Thielemann, F K

    2005-01-01

    Fission plays an important role in the r-process which is responsible not only for the yields of transuranium isotopes, but may have a strong influence on the formation of the majority of heavy nuclei due to fission recycling. We present calculations of beta-delayed and neutron-induced fission rates, taking into account different fission barriers predictions and mass formulae. It is shown that an increase of fission barriers results naturally in a reduction of fission rates, but that nevertheless fission leads to the termination of the r-process. Furthermore, it is discussed that the probability of triple fission could be high for $A>260$ and have an effect on the formation of the abundances of heavy nuclei. Fission after beta-delayed neutron emission is discussed as well as different aspects of the influence of fission upon r-process calculations.

  9. An operational protocol for facilitating start-up of single-stage autotrophic nitrogen-removing reactors based on process stoichiometry

    DEFF Research Database (Denmark)

    Mutlu, Ayten Gizem; Vangsgaard, Anna Katrine; Sin, Gürkan;

    2013-01-01

    Start-up and operation of single-stage nitritation–anammox sequencing batch reactors (SBRs) for completely autotrophic nitrogen removal can be challenging and far from trivial. In this study, a step-wise procedure is developed based on stoichiometric analysis of the process performance from...... nitrogen species measurements to systematically guide start-up and normal operation efforts (instead of trial and error). The procedure is successfully applied to laboratory-scale SBRs for start-up and maintained operation over an 8-month period. This analysis can serve as a strong decision-making tool to...... take appropriate actions with respect to reactor operation to accelerate start-up or ensure high-rate N removal via the nitritation–anammox pathway....

  10. The rate-limiting process of hydrogen transport in Mo

    Energy Technology Data Exchange (ETDEWEB)

    Ohkoshi, Keishiro; Chikazawa, Yoshitaka; Bandourko, V.; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1996-10-01

    Hydrogen isotope transport characteristics of Mo, whose refractory properties are considered to be suitable as plasma facing material, was investigated by applying 3 keV D{sub 2}{sup +} beam to the membrane specimen. The Arrhenius plot of deuterium permeation probability showed linear increase against the reciprocal temperature and its apparent activation energy was determined as 41.5 kJ/mol. The simultaneous irradiation of 3 keV Ar{sup +} onto backside surface of specimen had little effect on the deuterium permeation rate. According to these results, the rate-limiting process of deuterium transport in Mo was determined. (author)

  11. Effects of process parameters on material removal rate in WEDM

    Directory of Open Access Journals (Sweden)

    H. Singh

    2009-01-01

    Full Text Available Purpose: In this paper, the effects of various process parameters of WEDM like pulse on time (TON, pulse offtime (TOFF, gap voltage (SV, peak current (IP, wire feed (WF and wire tension (WT have been investigatedto reveal their impact on material removal rate of hot die steel (H-11 using one variable at a time approach. Theoptimal set of process parameters has also been predicted to maximize the material removal rate.Design/methodology/approach: The experimental studies were performed on ELECTRONICA SPRINTCUTWEDM machine.Findings: The material removal rate (MRR directly increases with increase in pulse on time (TON and peakcurrent (IP while decreases with increase in pulse off time (TOFF and servo voltage (SV.Practical implications: Wire electrical discharge machining (WEDM is a specialized thermal machiningprocess capable of accurately machining parts which have varying hardness, complex shapes and sharp edgesthat are very difficult to be machined by the traditional machining processes. The practical technology of theWEDM process is based on the conventional EDM sparking phenomenon utilizing the widely accepted noncontacttechnique of material removal.Originality/value: We can say that the wire feed and wire tension are neutral input parameters.

  12. Membrane-bound electron transport systems of an anammox bacterium: A complexome analysis.

    Science.gov (United States)

    de Almeida, Naomi M; Wessels, Hans J C T; de Graaf, Rob M; Ferousi, Christina; Jetten, Mike S M; Keltjens, Jan T; Kartal, Boran

    2016-10-01

    Electron transport, or oxidative phosphorylation, is one of the hallmarks of life. To this end, prokaryotes evolved a vast variety of protein complexes, only a small part of which have been discovered and studied. These protein complexes allow them to occupy virtually every ecological niche on Earth. Here, we applied the method of proteomics-based complexome profiling to get a better understanding of the electron transport systems of the anaerobic ammonium-oxidizing (anammox) bacteria, the N2-producing key players of the global nitrogen cycle. By this method nearly all respiratory complexes that were previously predicted from genome analysis to be involved in energy and cell carbon fixation were validated. More importantly, new and unexpected ones were discovered. We believe that complexome profiling in concert with (meta)genomics offers great opportunities to expand our knowledge on bacterial respiratory processes at a rapid and massive pace, in particular in new and thus far poorly investigated non-model and environmentally-relevant species. PMID:27461995

  13. Signal processing methodologies for an acoustic fetal heart rate monitor

    Science.gov (United States)

    Pretlow, Robert A., III; Stoughton, John W.

    1992-01-01

    Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones within a noise-contaminated signal from a passive acoustic sensor. A linear predictor algorithm is utilized for detection of the heart tone event and additional processing derives heart rate. The linear predictor is adaptively 'trained' in a least mean square error sense on generic fetal heart tones recorded from patients. A real time monitor system is described which outputs to a strip chart recorder for plotting the time history of the fetal heart rate. The system is validated in the context of the fetal nonstress test. Comparisons are made with ultrasonic nonstress tests on a series of patients. Comparative data provides favorable indications of the feasibility of the acoustic monitor for clinical use.

  14. Anammox brings WWTP closer to energy autarky due to increased biogas production and reduced aeration energy for N-removal.

    Science.gov (United States)

    Siegrist, H; Salzgeber, D; Eugster, J; Joss, A

    2008-01-01

    Fifty years ago when only BOD was removed at municipal WWTPs primary clarifiers were designed with 2-3 hours hydraulic retention time (HRT). This changed with the introduction of nitrogen removal in activated sludge treatment that needed more BOD for denitrification. The HRT of primary clarification was reduced to less than one hour for dry weather flow with the consequence that secondary sludge had to be separately thickened and biogas production was reduced. Only recently the ammonia rich digester liquid (15-20% of the inlet ammonia load) could be treated with the very economic autotrophic nitritation/anammox process requiring half of the aeration energy and no organic carbon source compared to nitrification and heterotrophic denitrification. With the introduction of this new innovative digester liquid treatment the situation reverts, allowing us to increase HRT of the primary clarifier to improve biogas production and reduce aeration energy for BOD removal and nitrification at similar overall N-removal. PMID:18309216

  15. Programmable rate modem utilizing digital signal processing techniques

    Science.gov (United States)

    Naveh, Arad

    1992-01-01

    The need for a Programmable Rate Digital Satellite Modem capable of supporting both burst and continuous transmission modes with either Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK) modulation is discussed. The preferred implementation technique is an all digital one which utilizes as much digital signal processing (DSP) as possible. The design trade-offs in each portion of the modulator and demodulator subsystem are outlined.

  16. 北运河沉积物中主要脱氮功能微生物的群落特征%Diversity, abundance and distribution ofnirS-type denitrifiers and Anammox bacteria in sediments of Beiyun River

    Institute of Scientific and Technical Information of China (English)

    鲍林林; 王晓燕; 陈永娟; 张苓荣

    2016-01-01

    Denitrification and anaerobic ammonia oxidation are two main processes for nitrogen removal in nitrogen cycle. The seasonal variation of community diversity and abundance, phylogenetic composition ofnirS-type denitrifiers and Anammox (anaerobic ammonia oxidation) bacteria of sediments in Beiyun River were compared based on PCR (polymerase chain reaction), T-RFLP (terminal restriction fragment length polymorphism), clone and sequencing. The abundance of nirS-type denitrifiers increased from summer to winter while the abundance of Anammox bacteria decreased significantly. What's more, the abundance ofnirS-type denitrifiers was significantly higher than Anammox in fall and winter. Community composition of the two microbial groups varied seasonally and the community diversity ofnirS-type denitrifiers was much higher than Anammox bacteria. Concentrations of nitrogens and organic carbon in the sediments increased significantly from summer to winter. Environmental temperature was significantly correlated with the seasonal changes of abundance and community distribution of the two microbial groups in sediments. Correlation analysis revealed that total nitrogen had a great effect on the abundance ofnirS-type denitrifiers, while C/N was significantly correlated with abundance of Anammox bacteria. NOx? and pH were also the main environmental factors determining the community distribution ofnirS-type denitrifiers and Anammox bacteria in sediments. Phylogenetic analysis revealed that most of the denitrifying microbes belonged to species with relatively high pollution-resistance and efficiency of nitrogen removal. Phylogenetic diversity of nirS-type denitrifiers was much higher than that of Anammox bacteria.nirS-type denitrifiers were grouped into genera Pseudomonas andHalomonas, while Anammox was mainly bacteria belonged toCandidatus Brocadia.%应用分子生物学技术研究北运河沉积物中主要脱氮功能微生物,反硝化细菌和厌氧氨氧化细菌(Anammox)的

  17. Performance of Anammox granular sludge bed reactor started up with nitrifying granular sludge

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ping; LIN Feng-mei; HU Bao-lan; CHEN Jian-song

    2004-01-01

    The anaerobic ammonia oxidation(Anammox) granular sludge bed reactor was started up successfully withnitrifying granular sludge. During the operation, the nitrifying granular sludge was gradually converted into Anammoxgranular sludge with good settling property and high conversion activity. The Anammox reactor worked well with theshortest HRT of 2.43 h. Under the condition that HRT was 6.39 h and influent concentration of ammonia and nitritewas 10 mmol/L, the removal of ammonia and nitrite was 97.17% and 100.00%, respectively. Corresponding

  18. ANAMMOX-UASB 系统处理晚期垃圾渗滤液脱氮性能及其颗粒污泥特性%Characteristics of granular sludge and nitrogen removal performance in ANAMMOX-UASB system fed with mature landfill leachate

    Institute of Scientific and Technical Information of China (English)

    李芸; 张美雪; 熊向阳; 陈刚; 李军; 张彦灼; 宋薇; 王明超

    2016-01-01

    以晚期垃圾渗滤液为研究对象,考察ANAMMOX-UASB系统脱氮性能及ANAMMOX颗粒污泥表观特性和粒径分布变化.结果表明,采用ANAMMOX-UASB系统处理晚期垃圾渗滤液可实现高效脱氮.在稳定期,NH4+-N, NO2--N和TN的平均去除率分别为96%,95%和87%;系统中ANAMMOX颗粒污泥厌氧氨氧化活性良好,仍然是脱氮的主要途径;同时也有部分异养反硝化作用同步脱氮.此外,系统中还存在好氧氨氧化和亚硝氮氧化作用,其活性分别为0.031和0.010 g/( g· d).系统中颗粒污泥颜色由砖红色转变成红褐色,平均粒径由小变大;稳定运行期粒径大于1.5 mm的颗粒污泥为81%;颗粒污泥表层有球菌、杆菌和丝状菌附着.%Taking the mature landfill leachate as the research object, the nitrogen removal performance of the ANAMMOX-UASB (anaerobic ammonia oxidation up-flow anaerobic sludge blanket) system, the ANAMMOX granular sludge characteristics, and the changes of its size distributions were investi-gated.The results show that the ANAMMOX-UASB system can achieve efficient nitrogen removal in mature landfill leachate.At the stable stage, the average removal rates of NH4+-N, NO2--N and TN were 96%, 95%and 87%, respectively.The activity of ANAMMOX granular sludge was very well, and ANAMMOX still was the main way of nitrogen removal, but there was also nitrogen removal by heterotrophic denitrification simultaneously in the system.Moreover, aerobic ammonia oxidation and nitrite oxidation existed in the system, and their activity were 0.031 and 0.010 g/(g· d), respective-ly .The color of granular sludge changed from brick red to red-brown, and the average size of granular sludge changed from small to large.At the stable stage, the proportion of granular sludge size excee-ding 1.5 mm was 81%.There were spherical bacteria, rod-shaped bacteria and filamentous bacteria on the granular sludge surface.

  19. r-Process Lanthanide Production and Heating Rates in Kilonovae

    CERN Document Server

    Lippuner, Jonas

    2015-01-01

    r-Process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the material after nuclear burning ceases, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. (2013, ApJ, 774, 25) and Tanaka & Hotokezaka (2013, ApJ, 775, 113) pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions $Y_e$, initial specific entropies $s$, and expansion timescales $\\tau$. We find that the ejecta is lanthanide-free for $Y_e \\gtrsim 0.22 - 0.30$, depending on $s$ and $\\tau$. The heating rate is insensitive to $s$ and $\\tau$, but certain, larger values of $Y_e$ lead to reduced heating rates, due to individual nuclides dominating the heating. With a...

  20. Anaerobic ammonium-oxidizing (anammox) bacteria and associated activity in fixed-film biofilters of a marine recirculating aquaculture system.

    Science.gov (United States)

    Tal, Yossi; Watts, Joy E M; Schreier, Harold J

    2006-04-01

    Microbial communities in the biological filter and waste sludge compartments of a marine recirculating aquaculture system were examined to determine the presence and activity of anaerobic ammonium-oxidizing (anammox) bacteria. Community DNA was extracted from aerobic and anaerobic fixed-film biofilters and the anaerobic sludge waste collection tank and was analyzed by amplifying 16S rRNA genes by PCR using anammox-selective and universal GC-clamped primers. Separation of amplified PCR products by denaturing gradient gel electrophoresis and sequencing of the different phylotypes revealed a diverse biofilter microbial community. While Planctomycetales were found in all three communities, the anaerobic denitrifying biofilters contained one clone that exhibited high levels of sequence similarity to known anammox bacteria. Fluorescence in situ hybridization studies using an anammox-specific probe confirmed the presence of anammox Planctomycetales in the microbial biofilm from the denitrifying biofilters, and anammox activity was observed in these biofilters, as detected by the ability to simultaneously consume ammonia and nitrite. To our knowledge, this is the first identification of anammox-related sequences in a marine recirculating aquaculture filtration system, and our findings provide a foundation for incorporating this important pathway for complete nitrogen removal in such systems.

  1. Anaerobic ammonium-oxidizing (anammox) bacteria and associated activity in fixed-film biofilters of a marine recirculating aquaculture system.

    Science.gov (United States)

    Tal, Yossi; Watts, Joy E M; Schreier, Harold J

    2006-04-01

    Microbial communities in the biological filter and waste sludge compartments of a marine recirculating aquaculture system were examined to determine the presence and activity of anaerobic ammonium-oxidizing (anammox) bacteria. Community DNA was extracted from aerobic and anaerobic fixed-film biofilters and the anaerobic sludge waste collection tank and was analyzed by amplifying 16S rRNA genes by PCR using anammox-selective and universal GC-clamped primers. Separation of amplified PCR products by denaturing gradient gel electrophoresis and sequencing of the different phylotypes revealed a diverse biofilter microbial community. While Planctomycetales were found in all three communities, the anaerobic denitrifying biofilters contained one clone that exhibited high levels of sequence similarity to known anammox bacteria. Fluorescence in situ hybridization studies using an anammox-specific probe confirmed the presence of anammox Planctomycetales in the microbial biofilm from the denitrifying biofilters, and anammox activity was observed in these biofilters, as detected by the ability to simultaneously consume ammonia and nitrite. To our knowledge, this is the first identification of anammox-related sequences in a marine recirculating aquaculture filtration system, and our findings provide a foundation for incorporating this important pathway for complete nitrogen removal in such systems. PMID:16597996

  2. Predicting online ratings based on the opinion spreading process

    Science.gov (United States)

    He, Xing-Sheng; Zhou, Ming-Yang; Zhuo, Zhao; Fu, Zhong-Qian; Liu, Jian-Guo

    2015-10-01

    Predicting users' online ratings is always a challenge issue and has drawn lots of attention. In this paper, we present a rating prediction method by combining the user opinion spreading process with the collaborative filtering algorithm, where user similarity is defined by measuring the amount of opinion a user transfers to another based on the primitive user-item rating matrix. The proposed method could produce a more precise rating prediction for each unrated user-item pair. In addition, we introduce a tunable parameter λ to regulate the preferential diffusion relevant to the degree of both opinion sender and receiver. The numerical results for Movielens and Netflix data sets show that this algorithm has a better accuracy than the standard user-based collaborative filtering algorithm using Cosine and Pearson correlation without increasing computational complexity. By tuning λ, our method could further boost the prediction accuracy when using Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE) as measurements. In the optimal cases, on Movielens and Netflix data sets, the corresponding algorithmic accuracy (MAE and RMSE) are improved 11.26% and 8.84%, 13.49% and 10.52% compared to the item average method, respectively.

  3. Stellar neutron capture rates - key data for the s process

    Science.gov (United States)

    Käppeler, F.

    2013-12-01

    Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to the He- and C- burning phases of stellar evolution (s process) and to supernova explosions (r and p processes). The s process, which is characterized by low neutron densities, operates in or near the valley of β stability and has produced about half of the elemental abundances between Fe and Bi in the solar system and in the Universe. Because the s abundances are essentially determined by the (n, γ) cross sections along the reaction path, accurate neutron data constitute the key input for s process studies. Important constraints for the physical conditions at the stellar sites can be inferred by comparison of the abundance patterns from current s-process models with solar system material or presolar grains. The experimental methods for the determination of stellar (n, γ) rates are outlined at the example of recent cross section measurements and remaining quests will be discussed with respect to existing laboratory neutron sources and new developments.

  4. Influence of the dose rate in the PVDF degradation processes

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  5. Temperature response of denitrification and anaerobic ammonium oxidation rates and microbial community structure in Arctic fjord sediments.

    Science.gov (United States)

    Canion, Andy; Overholt, Will A; Kostka, Joel E; Huettel, Markus; Lavik, Gaute; Kuypers, Marcel M M

    2014-10-01

    The temperature dependency of denitrification and anaerobic ammonium oxidation (anammox) rates from Arctic fjord sediments was investigated in a temperature gradient block incubator for temperatures ranging from -1 to 40°C. Community structure in intact sediments and slurry incubations was determined using Illumina SSU rRNA gene sequencing. The optimal temperature (Topt ) for denitrification was 25-27°C, whereas anammox rates were optimal at 12-17°C. Both denitrification and anammox exhibited temperature responses consistent with a psychrophilic community, but anammox bacteria may be more specialized for psychrophilic activity. Long-term (1-2 months) warming experiments indicated that temperature increases of 5-10°C above in situ had little effect on the microbial community structure or the temperature response of denitrification and anammox. Increases of 25°C shifted denitrification temperature responses to mesophilic with concurrent community shifts, and anammox activity was eliminated above 25°C. Additions of low molecular weight organic substrates (acetate and lactate) caused increases in denitrification rates, corroborating the hypothesis that the supply of organic substrates is a more dominant control of respiration rates than low temperature. These results suggest that climate-related changes in sinking particulate flux will likely alter rates of N removal more rapidly than warming. PMID:25115991

  6. Presence and diversity of anammox bacteria in cold hydrocarbon-rich seeps and hydrothermal vent sediments of the Guaymas Basin

    NARCIS (Netherlands)

    Russ, L.; Kartal, B.; Op den Camp, H.J.M.; Sollai, M.; Le Bruchec, J.; Caprais, J.-C.; Godfroy, A.; Sinninghe Damsté, J.S.; Jetten, M.S.M.

    2013-01-01

    Hydrothermally active sediments are highly productive, chemosynthetic areas which are characterized by the rapid turnover of particulate organic matter under extreme conditions in which ammonia is liberated. These systems might be suitable habitats for anaerobic ammonium oxidizing (anammox) bacteria

  7. Anaerobic Ammonium-Oxidizing (Anammox) Bacteria and Associated Activity in Fixed-Film Biofilters of a Marine Recirculating Aquaculture System†

    OpenAIRE

    Tal, Yossi; Joy E M Watts; Schreier, Harold J.

    2006-01-01

    Microbial communities in the biological filter and waste sludge compartments of a marine recirculating aquaculture system were examined to determine the presence and activity of anaerobic ammonium-oxidizing (anammox) bacteria. Community DNA was extracted from aerobic and anaerobic fixed-film biofilters and the anaerobic sludge waste collection tank and was analyzed by amplifying 16S rRNA genes by PCR using anammox-selective and universal GC-clamped primers. Separation of amplified PCR product...

  8. Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

    OpenAIRE

    Pitcher, A.; Villanueva, L; Hopmans, E.C.; Schouten, S.; G. J. Reichart; Sinninghe Damsté, J.S.

    2011-01-01

    Ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria have emerged as significant factors in the marine nitrogen cycle and are responsible for the oxidation of ammonium to nitrite and dinitrogen gas, respectively. Potential for an interaction between these groups exists; however, their distributions are rarely determined in tandem. Here we have examined the vertical distribution of AOA and anammox bacteria through the Arabian Sea oxygen minimum zone (OMZ), one of ...

  9. Response of anammox bacteria community structure to nitrogen in paddy soils%稻田厌氧氨氧化菌群落结构对氮肥的响应

    Institute of Scientific and Technical Information of China (English)

    宋亚娜; 吴明基; 林艳

    2013-01-01

    为探明稻田厌氧氨氧化菌多样性及其对氮肥用量的响应状况,利用厌氧氨氧化菌16S rRNA基因特异引物对定位试验稻田土壤DNA进行PCR-DGGE(聚合酶链反应-变性梯度凝胶电泳)并结合DNA克隆测序,研究了氮肥供应量对厌氧氨氧化菌群落结构的影响.DGGE图谱及依据其条带位置和亮度数值计算的多样性指数均显示:高氮处理[N3:225 kg(N)·hm-2]的厌氧氨氧化菌群落结构多样性在表层或根层土壤中均显著(P<0.05)高于中、低氮[N2:150 kg(N)·hm-2; N1:75 kg(N)·hm-2]处理和不施肥对照(CK);同时,高氮处理下表层土壤厌氧氨氧化菌群落多样性指数显著高于根层土壤(P<0.05).冗余分析(RDA)结果表明,表层土壤中厌氧氨氧化菌群落结构组成与不同氮肥水平处理存在显著相关性(P=0.006).此外,本试验获得厌氧氨氧化菌DGGE条带DNA序列18条,登录GenBank并获得登录号.研究表明稻田厌氧氨氧化菌群落结构对高氮水平具有较强的响应,尤其是在表层土壤中.%Anaerobic ammonium oxidizing (anammox) bacteria of phylum Planctomycetes origin have been identified to be responsible for N removal in terrestrial and aquatic environments through combined NFL4+ oxidation and NO2 reduction. Anaerobic ammonium oxidation mediated by anammox bacteria has been noted to be a key process of biogeochemical N cycle in various ecosystems. It was also possible to have anammox processes in flooded paddy fields because of the low oxygen habitat conditions. To investigate the existence of anammox bacteria and the bacteria community diversity response to applied N fertilizer in paddy fields, anammox bacteria community structures in paddy fields were investigated with the aid of denaturing gradient gel electrophoresis and cloning sequencing by assay 16S rRNA gene in the third year of N fertilizer experiment in the field. DGGE images of 16S rRNA gene in surface or root-zone soil showed rich anammox bacteria

  10. PREFACE: International Workshop on Multi-Rate Processes and Hysteresis

    Science.gov (United States)

    Mortell, Michael P.; O'Malley, Robert E.; Pokrovskii, Alexei; Rachinskii, Dmitrii; Sobolev, Vladimir A.

    2008-07-01

    We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can be considered as limit cases of time relaxation processes, or admit an approximation by a differential equation which is singular with respect to a particular parameter. However, the amount of interaction between practitioners of theories of systems with time relaxation and systems with hysteresis (and between the `relaxation' and `hysteresis' research communities) is still low, and cross-fertilization is small. In recent years Ireland has become a home for a series of prestigious International Workshops in Singular Perturbations and Hysteresis: International Workshop on Multi-rate Processes and Hysteresis (University College Cork, Ireland, 3-8 April 2006). Proceedings are published in Journal of Physics: Conference Series, volume 55. See further information at http://euclid.ucc.ie/murphys2008.htm International Workshop on Hysteresis and Multi-scale Asymptotics (University College Cork, Ireland, 17-21 March 2004). Proceedings are published in Journal of Physics: Conference Series, volume 22. See further information at http://euclid.ucc.ie/murphys2006.htm International Workshop on Relaxation Oscillations and Hysteresis (University College Cork, Ireland, 1-6 April 2002). The related collection of invited lectures, was published as a volume Singular Perturbations and Hysteresis, SIAM, Philadelphia, 2005. See further information at http://euclid.ucc.ie/hamsa2004.htm International Workshop on Geometrical Methods of Nonlinear Analysis and Semiconductor Laser Dynamics (University College Cork, Ireland, 5-5 April 2001). A collection of invited papers has been

  11. Nitrogen Loss Processes and Nitrous Oxide Turnover in Oceanic Oxygen Minimum Zones

    Science.gov (United States)

    Ward, B. B.

    2014-12-01

    Nitrogen is an essential element for life and the maintenance of all ecosystems. For many ecosystems, both aquatic and terrestrial, nitrogen is the element most likely to limit the amount and rate of production. But just as ecosystems can suffer from too little nitrogen, they are also sensitive to too much nitrogen, which leads to eutrophication and structural changes in food webs. Thus the processes by which nitrogen is removed are as critical to our understanding of ecosystem function as are those by which it is added. Nitrogen loss processes in the open ocean have been the focus of research and discovery in recent years. Long thought to be dominated by the bacterial respiratory process of denitrification, N loss is now also known to occur by anaerobic ammonium oxidation (anammox). We now understand that the ratio of the two processes is controlled by the quality and quantity of organic matter supplied to the anoxic waters of the ocean's major oxygen deficient zones. Coastal environments are also major sites of N loss but excess N loading from land often ameliorates the direct dependence of anammox and denitrification on organic matter composition. The ratio is important partly because of side products: Denitrification is a significant source and sink for nitrous oxide (N2O), while anammox has no significant contribution to N2O biogeochemistry. With the anthropogenic flux of CFCs at least mostly under control, N2O emissions to the atmosphere are the greatest contribution to ozone destruction, and they also contribute to greenhouse warming. Both anthropogenic and natural sources contribute to N2O emissions, and natural sources are sensitive to anthropogenic forcing. Our direct measurements of N2O production and consumption in the ocean agree with modeling results that have implicated multiple microbial processes and complex physical and biological control of N2O fluxes in the ocean.

  12. Detection limit for rate fluctuations in inhomogeneous Poisson processes

    Science.gov (United States)

    Shintani, Toshiaki; Shinomoto, Shigeru

    2012-04-01

    Estimations of an underlying rate from data points are inevitably disturbed by the irregular occurrence of events. Proper estimation methods are designed to avoid overfitting by discounting the irregular occurrence of data, and to determine a constant rate from irregular data derived from a constant probability distribution. However, it can occur that rapid or small fluctuations in the underlying density are undetectable when the data are sparse. For an estimation method, the maximum degree of undetectable rate fluctuations is uniquely determined as a phase transition, when considering an infinitely long series of events drawn from a fluctuating density. In this study, we analytically examine an optimized histogram and a Bayesian rate estimator with respect to their detectability of rate fluctuation, and determine whether their detectable-undetectable phase transition points are given by an identical formula defining a degree of fluctuation in an underlying rate. In addition, we numerically examine the variational Bayes hidden Markov model in its detectability of rate fluctuation, and determine whether the numerically obtained transition point is comparable to those of the other two methods. Such consistency among these three principled methods suggests the presence of a theoretical limit for detecting rate fluctuations.

  13. Genome-based microbial ecology of anammox granules in a full-scale wastewater treatment system

    OpenAIRE

    Speth, D.R.; Zandt, M.H. in 't; Guerrero Cruz, S.; Dutilh, B.E.; Jetten, M. S. M.

    2016-01-01

    Partial-nitritation anammox (PNA) is a novel wastewater treatment procedure for energy-efficient ammonium removal. Here we use genome-resolved metagenomics to build a genome-based ecological model of the microbial community in a full-scale PNA reactor. Sludge from the bioreactor examined here is used to seed reactors in wastewater treatment plants around the world; however, the role of most of its microbial community in ammonium removal remains unknown. Our analysis yielded 23 near-complete d...

  14. Denitrification exceeds anammox as a nitrogen loss pathway in the Arabian Sea oxygen minimum zone

    Digital Repository Service at National Institute of Oceanography (India)

    Bulow, S.E.; Rich, J.J.; Naik, H.; Pratihary, A.K.; Ward, B.B.

    ��������������������������� ��� � ��� � ��� � ��� � ��� � ��� � � � � Denitrification exceeds Anammox as a nitrogen loss pathway in the Arabian Sea Oxygen Minimum Zone...

  15. Stellar neutron capture rates and the s process

    Directory of Open Access Journals (Sweden)

    Käppeler F.

    2012-02-01

    Full Text Available Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to helium burning in Red Giant stars (s process and to supernova explosions (r and p processes. The s process, which operates in or near the valley of β-stability, has produced about half of the elemental abundances between Fe and Bi. Accurate (n, γ cross sections are the essential input for s process studies, because they determine the abundances produced by that process. Following a brief summary of the neutron capture processes, the focus will be set on the s process in massive stars, where the role of reliable cross section information is particularly important. Eventually, the intriguing aspects of the origin of 60Fe will be addressed. Attempts to determine the stellar cross section of that isotope are pushing experimental possibilities to their limits and present a pertinent challenge for future facilities.

  16. Rate-optimal Bayesian intensity smoothing for inhomogeneous Poisson processes

    NARCIS (Netherlands)

    E. Belitser; P. Serra; H. van Zanten

    2015-01-01

    We apply nonparametric Bayesian methods to study the problem of estimating the intensity function of an inhomogeneous Poisson process. To motivate our results we start by analyzing count data coming from a call center which we model as a Poisson process. This analysis is carried out using a certain

  17. Rate Theory for Correlated Processes: Double Jumps in Adatom Diffusion

    DEFF Research Database (Denmark)

    Jacobsen, J.; Jacobsen, Karsten Wedel; Sethna, J.

    1997-01-01

    We study the rate of activated motion over multiple barriers, in particular the correlated double jump of an adatom diffusing on a missing-row reconstructed platinum (110) surface. We develop a transition path theory, showing that the activation energy is given by the minimum-energy trajectory...... which succeeds in the double jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a root T prefactor for the activated rate of double jumps. Theory and numerical results agree....

  18. Mean level signal crossing rate for an arbitrary stochastic process

    DEFF Research Database (Denmark)

    Yura, Harold T.; Hanson, Steen Grüner

    2010-01-01

    The issue of the mean signal level crossing rate for various probability density functions with primary relevance for optics is discussed based on a new analytical method. This method relies on a unique transformation that transforms the probability distribution under investigation into a normal ...

  19. Structure and composition of biofilm communities in a moving bed biofilm reactor for nitritation-anammox at low temperatures.

    Science.gov (United States)

    Persson, Frank; Sultana, Razia; Suarez, Marco; Hermansson, Malte; Plaza, Elzbieta; Wilén, Britt-Marie

    2014-02-01

    It is a challenge to apply anaerobic ammonium oxidation (anammox) for nitrogen removal from wastewater at low temperatures. Maintenance of anammox- and aerobic ammonia oxidizing bacteria (AOB) and suppression of nitrite oxidizing bacteria (NOB) are key issues. In this work, a nitritation-anammox moving bed biofilm pilot reactor was operated at 19-10°C for 300 d. Nitrogen removal was decreasing, but stable, at 19-13°C. At 10°C removal became unstable. Quantitative PCR, fluorescence in situ hybridization and gene sequencing showed that no major microbial community changes were observed with decreased temperature. Anammox bacteria dominated the biofilm (0.9-1.2 × 10(14) 16S rRNA copies m(-2)). Most anammox bacteria were similar to Brocadia sp. 40, but another smaller Brocadia population was present near the biofilm-water interface, where also the AOB community (Nitrosomonas) was concentrated in thin layers (1.8-5.3 × 10(12) amoA copies m(-2)). NOB (Nitrobacter, Nitrospira) were always present at low concentrations (<1.3 × 10(11) 16S rRNA copies m(-2)).

  20. Radiolytic hydrogen production from process vessels in HB line - production rates compared to evolution rates and discussion of LASL reviews

    Energy Technology Data Exchange (ETDEWEB)

    Bibler, N.E.

    1992-11-12

    Hydrogen production from radiolysis of aqueous solutions can create a safety hazard since hydrogen is flammable. At times this production can be significant, especially in HB line where nitric acid solutions containing high concentrations of Pu-238, an intense alpha emitter, are processed. The hydrogen production rates from these solutions are necessary for safety analyses of these process systems. The methods and conclusions of hydrogen production rate tests are provided in this report.

  1. Computer simulated rate processes in copper vapor lasers

    Science.gov (United States)

    Harstad, K. C.

    1980-01-01

    A computer model for metal vapor lasers has been developed which places emphasis on the change of excited state populations of the lasant through inelastic collisions and radiative interaction. Also included are an energy equation for the pumping electrons and rate equations for laser photon densities. Presented are results of calculations for copper vapor with a neon buffer over a range of conditions. General agreement with experiments was obtained.

  2. Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

    Science.gov (United States)

    Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

    2015-03-01

    In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems.

  3. Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

    Science.gov (United States)

    Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

    2015-03-01

    In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems. PMID:25600011

  4. Rate of imagery processing in two versus three dimensions.

    Science.gov (United States)

    Kerr, N H

    1993-07-01

    A series of five experiments was conducted to test the optimal speed for performing two- and three-dimensional imagery tasks. Subjects were required to keep track of the location of a pathway in an imagined matrix, as the directions of its successive movements were described verbally. Matrices varied in size and in number of spatial dimensions, with two-dimensional matrices drawn on cardboard and three-dimensional ones built from wooden blocks. When subjects were able to dictate the rate of presentation of the terms describing the pathway, they preferred slower rates for three-dimensional than for two-dimensional stimuli. In subsequent experiments, very fast presentation rates had a larger detrimental effect on performance with three-dimensional matrices than with two-dimensional matrices. A comparison of the patterns of performance for subjects who generally scored high with the patterns for those who scored low showed a stronger effect of dimensionality for poor performers, suggesting that individual differences mediate performance on the task. PMID:8350738

  5. Fast optical signal processing in high bit rate OTDM systems

    DEFF Research Database (Denmark)

    Poulsen, Henrik Nørskov; Jepsen, Kim Stokholm; Clausen, Anders;

    1998-01-01

    As all-optical signal processing is maturing, optical time division multiplexing (OTDM) has also gained interest for simple networking in high capacity backbone networks. As an example of a network scenario we show an OTDM bus interconnecting another OTDM bus, a single high capacity user...

  6. High Metal Removal Rate Process for Machining Difficult Materials

    Energy Technology Data Exchange (ETDEWEB)

    Bates, Robert; McConnell, Elizabeth

    2016-06-29

    Machining methods across many industries generally require multiple operations to machine and process advanced materials, features with micron precision, and complex shapes. The resulting multiple machining platforms can significantly affect manufacturing cycle time and the precision of the final parts, with a resultant increase in cost and energy consumption. Ultrafast lasers represent a transformative and disruptive technology that removes material with micron precision and in a single step manufacturing process. Such precision results from athermal ablation without modification or damage to the remaining material which is the key differentiator between ultrafast laser technologies and traditional laser technologies or mechanical processes. Athermal ablation without modification or damage to the material eliminates post-processing or multiple manufacturing steps. Combined with the appropriate technology to control the motion of the work piece, ultrafast lasers are excellent candidates to provide breakthrough machining capability for difficult-to-machine materials. At the project onset in early 2012, the project team recognized that substantial effort was necessary to improve the application of ultrafast laser and precise motion control technologies (for micromachining difficult-to-machine materials) to further the aggregate throughput and yield improvements over conventional machining methods. The project described in this report advanced these leading-edge technologies thru the development and verification of two platforms: a hybrid enhanced laser chassis and a multi-application testbed.

  7. Research progress of high-loaded ANAMMOX reactors%高负荷厌氧氨氧化反应器的研究进展

    Institute of Scientific and Technical Information of China (English)

    姬玉欣; 诸美红; 陈辉; 倪伟敏; 金仁村

    2013-01-01

      剖析了常见的高负荷厌氧氨氧化反应器的构型特点,归纳了颗粒污泥反应器(上流式厌氧污泥床、膨胀颗粒污泥床和气提式反应器)、生物膜反应器和复合式反应器的优缺点。系统总结了高负荷厌氧氨氧化反应器的调控要点,包括操作条件(负荷、回流等)调控、环境条件(pH值、温度、溶解氧等)调控、营养物质(基质比、钙离子浓度、无机碳源等)调控、抑制剂调控和微生物(接种源、优势种、聚集体、生物量和活性等)调控。最后指出,实现高负荷厌氧氨氧化反应器全面应用的关键是突破复杂水质障碍和在低温条件下进行有效调控。%This study analyzed the configuration of some common high-loaded ANAMMOX reactors, and dissected merit and demerit of granular sludge bed reactors,including Granular sludge reactors (upflow anaerobic sludge bed,expanded granular sludge bed and gas-lift reactor),biofilm reactors and hybrid anammox reactors. This paper also summarized detailed process control regulations,including operating conditions (load,reflux),environmental factors(pH,temperature,dissolved oxygen and so on),nutrients (the ratio of substrate,the concentration of Ca2+,inorganic carbon) inhibitors and microorganism (the source of sludge,dominant species,aggregation,biomass and the activity). The key factor of extensive application of the high-loaded ANAMMOX reactors is overcoming the barrier of complex wastewater and regulating reaction conditions at low ambient temperature.

  8. Reconciling Estimates of Earnings Processes in Growth Rates and Levels

    DEFF Research Database (Denmark)

    Daly, Moira; Hryshko, Dmytro; Manovskii, Iourii

    The stochastic process for earnings is the key element of incomplete markets models in modern quantitative macroeconomics. It determines both the equilibrium distributions of endogenous outcomes and the design of optimal policies. Yet, there is no consensus in the literature on the relative...... of earnings spells quantitatively accounts for the full amount of discrepancy in the estimates. Using data from the Panel Study of Income Dynamics, we show that this property of earnings induces a substantial upward bias in the estimate of consumption insurance against permanent shocks....

  9. Exchange Rate Exposure Management: The Benchmarking Process of Industrial Companies

    DEFF Research Database (Denmark)

    Aabo, Tom

    Based on a cross-case study of Danish industrial companies the paper analyzes the benchmarking of the optimal hedging strategy. A stock market approach is pursued but a serious question mark is put on the validity of the obtained information seen from a corporate value-adding point of view...... of practices and strategies that have been established in each company fairly independently over time. The paper argues that hedge benchmarks are useful in their creation process (by forcing a comprehensive analysis) as well as in their final status (by the establishment of a consistent hedging strategy...

  10. Jet rates in the hard scattering process at finite temperature

    CERN Document Server

    Mukherjee, K

    2000-01-01

    We compute the cross-section of the hadronic jets arising from the quark antiquark pair which are produced from a hard photons (of 4-momentum $q$) in the plasma, predominantly consisting of thermalised quarks and gluons. The quark antiquark pair is hard and scattered off the heat bath to form jets, while the gluons being soft get thermalised in the heat bath. The infrared divergences cancel in the observable cross-section to $\\alpha_s$ order, which includes the process of emission and absorption of real gluons. Since the massless quark antiquark pair is hard the Compton scattering processes are absent in the heat bath and it renders an uncancelled collinear divergent piece in the cross-section. We regularize it by eliminating the collinear region from the phase space and write it in terms of jet parameters. The temperature dependent part of the jet cross-section is regular at large ${\\sqrt{q^2}\\over T}$ and vanishes when ${\\sqrt{q^2}\\over T}\\to \\infty$. Since jets carry the thermal signature of the hot plasma...

  11. Informativeness ratings of messages created on an AAC processing prosthesis.

    Science.gov (United States)

    Bartlett, Megan R; Fink, Ruth B; Schwartz, Myrna F; Linebarger, Marcia

    2007-01-01

    BACKGROUND: SentenceShaper() (SSR) is a computer program that supports spoken language production in aphasia by recording and storing the fragments that the user speaks into the microphone, making them available for playback and allowing them to be combined and integrated into larger structures (i.e., sentences and narratives). A prior study that measured utterance length and grammatical complexity in story-plot narratives produced with and without the aid of SentenceShaper demonstrated an "aided effect" in some speakers with aphasia, meaning an advantage for the narratives that were produced with the support of this communication aid (Linebarger, Schwartz, Romania, Kohn, & Stephens, 2000). The present study deviated from Linebarger et al.'s methods in key respects and again showed aided effects of SentenceShaper in persons with aphasia. AIMS: Aims were (1) to demonstrate aided effects in "functional narratives" conveying hypothetical real-life situations from a first person perspective; (2) for the first time, to submit aided and spontaneous speech samples to listener judgements of informativeness; and (3) to produce preliminary evidence on topic-specific carryover from SentenceShaper, i.e., carryover from an aided production to a subsequent unaided production on the same topic. METHODS #ENTITYSTARTX00026; PROCEDURES: Five individuals with chronic aphasia created narratives on two topics, under three conditions: Unaided (U), Aided (SSR), and Post-SSR Unaided (Post-U). The 30 samples (5 participants, 2 topics, 3 conditions) were randomised and judged for informativeness by graduate students in speech-language pathology. The method for rating was Direct Magnitude Estimation (DME). OUTCOMES #ENTITYSTARTX00026; RESULTS: Repeated measures ANOVAs were performed on DME ratings for each participant on each topic. A main effect of Condition was present for four of the five participants, on one or both topics. Planned contrasts revealed that the aided effect (SSR >U) was

  12. Effect of substrate availability on nitrous oxide production by deammonification processes under anoxic conditions.

    Science.gov (United States)

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl-Heinz

    2012-05-01

    Due to its high global warming potential, nitrous oxide (N(2)O) emissions from wastewater treatment processes have recently received a high degree of attention. Nevertheless, there is still a lack of information regarding the microbiological processes leading to N(2)O production. In this study, two lab-scale sequencing batch reactors were operated with deammonification biomass to investigate the role of denitrification and the influence of substrate availability regarding N(2)O formation during the anoxic phase of deammonification. Three different operational phases were established: within the first phase conversion by anammox was favoured and after a transition phase, denitrification activity was promoted. Low nitrous oxide production was observed during stable operation aiming for anammox conversion. Pulsed inflow of the wastewater containing ammonium (NH(4)(+)) and nitrite (NO(2)(-)) led to increased N(2)O production rates. Within the period of denitrification as dominating nitrogen conversion process, the nitrous oxide concentration level was higher during continuous inflow conditions, but the reaction to pulsed inflow was less pronounced. The results indicated that denitrification was responsible for N(2)O formation from the deammonification biomass. Operational settings to achieve suppression of denitrification processes to a large extend were deducted from the results of the experiments. PMID:22296600

  13. 厌氧氨氧化污泥包埋固定化及其脱氮效能%Nitrogen Removal Performance of Immobilized Anammox Sludge

    Institute of Scientific and Technical Information of China (English)

    陈光辉; 李军; 邓海亮; 张彦灼; 郑林雪; 赵白航; 王昌稳; 郑照明

    2015-01-01

    and granule fracture in the 100-day operation, and the total nitrogen ( TN) removal rate still reached 80% when volume loading was 1. 697 kg/( m3·d ) . Meanwhile WPU immobilized granules showed strong capability of retaining sludge and good stability in long-term-run. Through 16S rDNA cloning, it was discovered that the primary ANAMMOX bacteria inside the WPU-immobilized granules were affiliated to Candidatus Brocadia fulgida ( JX243641. 1 ) . As carriers, WPU protected ANAMMOX bacteria and increased biomass. However, they had no effect on bacteria and bacterial community structure.

  14. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    Science.gov (United States)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall, process control via online N2O monitoring was confirmed to be an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. ReferencesWaechter H. et al. (2008) Optics Express, 16: 9239-9244. Wunderlin, P et al. (2013) Environmental Science & Technology 47: 1339-1348.

  15. Enhancement of the rate of radiative processes in the field of a magnetic monopole

    International Nuclear Information System (INIS)

    The spontaneous emission rate for the bound system charge-dyon is calculated. It is shown that the magnetic monopole fields leads to the significant increase of the rate of radiative processes. (author). 14 refs

  16. Effects of intermittent starvation on preservation characteristics of ANAMMOX bacteria%间歇性饥饿对厌氧氨氧化菌混培物保藏特性的影响

    Institute of Scientific and Technical Information of China (English)

    汪彩华; 郑平; 唐崇俭; 陈婷婷

    2013-01-01

    The effects of intermittent starvation on preservation characteristics of anammox bacteria were studied using three different preservation methods, which contained 4℃, 4℃ with addition of substrate ( NO2- -N/NH4+ -N ratio of 1. 32) every ten days and 4℃ with addition of substrate ( NO2- -N/ NH4+ -N ratio of 1.63) every ten days. Results indicated that intermittent starvation was more harmful to anammox bacteria than that of the long-term continuous starvation under anaerobic conditions. Besides, it could be found that the higher concentration of nitrite would have stronger inhibiting effects on the preservation of anammox bacteria. In addition, the anammox bacterial activities were directly correlated with the content of heme c. The color of anammox bacteria could reflect the relative bacterial activities as well as heme c content under the conditions without deliberate color interference. Further, results also showed that the particle structure and the extracellular polymers of anammox bacteria would help to increase the resistance of bacteria to adverse factors. During the 5-month preservations, all the activity decaying rates of the three methods decreased fast initially, and then slowed down to relatively stable values with survival activity percentages of 75. 3% , 70.8% and 62. 7% , respectively.%厌氧条件下,采用4℃、4℃并每隔10 d换1次NO-2-N/NH+4-N浓度比为1.32的基质、4℃并每隔10 d换1次NO-2-N/NH+4-N浓度比为1.63的基质3种方法保藏厌氧氨氧化菌混培物,研究间歇性饥饿对厌氧氨氧化菌混培物保藏特性的影响.结果表明,间歇性饥饿对厌氧氨氧化菌混培物的危害大于长期性饥饿,且亚硝态氮浓度越高危害越大;另厌氧氨氧化菌混培物活性还与血红素c含量有直接相关性,无外界颜色干扰时厌氧氨氧化菌混培物颜色还可直观反映其活性和血红素c含量,且厌氧氨氧化菌混培物的颗粒结构及其富含的胞外多聚物能增强

  17. Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

    NARCIS (Netherlands)

    Pitcher, A.; Villanueva, L.; Hopmans, E.C.; Schouten, S.; Reichart, G.J.; Sinninghe Damsté, J.S.

    2011-01-01

    Ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria have emerged as significant factors in the marine nitrogen cycle and are responsible for the oxidation of ammonium to nitrite and dinitrogen gas, respectively. Potential for an interaction between these groups exists;

  18. Coupling of bacterial nitrification with denitrification and anammox supports N removal in intertidal sediments (Arcachon Bay, France)

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, S.O.; Javanaud, C.; Michotey, V.D.; Guasco, S.; Anschutz, P.; Bonin, P.

    >+/15NO3-) were used to measure oxidation of NH4+ to NO3-/NO2- and its subsequent reduction to N2 via denitrification and/or anammox. We found that denitrification mainly fuelled N loss in both...

  19. Development of Electroactive and Anaerobic Ammonium-Oxidizing (Anammox Biofilms from Digestate in Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Enea Gino Di Domenico

    2015-01-01

    Full Text Available Microbial Fuel cells (MFCs have been proposed for nutrient removal and energy recovery from different wastes. In this study the anaerobic digestate was used to feed H-type MFC reactors, one with a graphite anode preconditioned with Geobacter sulfurreducens and the other with an unconditioned graphite anode. The data demonstrate that the digestate acts as a carbon source, and even in the absence of anode preconditioning, electroactive bacteria colonise the anodic chamber, producing a maximum power density of 172.2 mW/m2. The carbon content was also reduced by up to 60%, while anaerobic ammonium oxidation (anammox bacteria, which were found in the anodic compartment of the reactors, contributed to nitrogen removal from the digestate. Overall, these results demonstrate that MFCs can be used to recover anammox bacteria from natural sources, and it may represent a promising bioremediation unit in anaerobic digestor plants for the simultaneous nitrogen removal and electricity generation using digestate as substrate.

  20. Effects of a strain rate sensitive material on the optimization of an hydroforming process

    OpenAIRE

    Zhang, Cunsheng; Leotoing, Lionel; Guines, Dominique; Ragneau, Eric

    2008-01-01

    The hydroforming process of a T-tube is simulated with the finite element code ABAQUS. The influence of the internal pressure and the axial displacement levels on the final tube quality is evaluated through a "process diagram". Due to the strain rate range observed during the process, the strain rate sensitivity of the material is considered for the determination of the forming limit curves and for simulation of the process. Theoretical and numerical evaluation of the forming limit curves sho...

  1. Presence and diversity of anammox bacteria in cold hydrocarbon-rich seeps and hydrothermal vent sediments of the Guaymas Basin

    Directory of Open Access Journals (Sweden)

    Lina eRuss

    2013-08-01

    Full Text Available Hydrothermally active sediments are highly productive, chemosynthetic areas which are characterized by the rapid turnover of particulate organic matter under extreme conditions in which ammonia is liberated. These systems might be suitable habitats for anaerobic ammonium oxidizing (anammox bacteria but this has not been investigated in detail. Here we report the diversity and abundance of anammox bacteria in sediments that seep cold hydrocarbon-rich fluids and hydrothermal vent areas of the Guaymas Basin in the Cortés Sea using the unique functional anammox marker gene, hydrazine synthase (hzsA. All clones retrieved were closely associated to the ‘Candidatus Scalindua’ genus. Phylogenetic analysis revealed two distinct clusters of hzsA sequences (Ca. Scalindua hzsA cluster I and II. Comparison of individual sequences from both clusters showed that several of these sequences had a similarity as low as 76% on nucleotide level. Based on the analysis of this phylomarker, a very high interspecies diversity within the marine anammox group is apparent. Absolute numbers of anammox bacteria in the sediments samples were determined by amplification of a 257 bp fragment of the hszA gene in a qPCR assay. The results indicate that numbers of anammox bacteria are generally higher in cold hydrocarbon-rich sediments compared to the vent areas and the reference zone. Ladderanes, lipids unique to anammox bacteria were also detected in several of the sediment samples corroborating the hzsA analysis. Due to the high concentrations of reduced sulfur compounds and its potential impact on the cycling of nitrogen we aimed to get an indication about the key players in the oxidation of sulfide in the Guaymas Basin sediments using the alpha subunit of the adenosine-5’-phosphosulfate (APS reductase (aprA. Amplification of the aprA gene revealed a high number of gammaproteobacterial aprA genes covering the two sulfur-oxidizing bacteria aprA lineages as well as

  2. Evidence for rule-based processes in the inverse base-rate effect.

    Science.gov (United States)

    Winman, Anders; Wennerholm, Pia; Juslin, Peter; Shanks, David R

    2005-07-01

    Three studies provide convergent evidence that the inverse base-rate effect (Medin & Edelson, 1988) is mediated by rule-based cognitive processes. Experiment 1 shows that, in contrast to adults, prior to the formal operational stage most children do not exhibit the inverse base-rate effect. Experiments 2 and 3 demonstrate that an adult sample is a mix of participants relying on associative processes who categorize according to the base-rate and participants relying on rule-based processes who exhibit a strong inverse base-rate effect. The distribution of the effect is bimodal, and removing participants independently classified as prone to rule-based processing effectively eliminates the inverse base-rate effect. The implications for current explanations of the inverse base-rate effect are discussed. PMID:16194936

  3. On the hazard rate process for imperfectly monitored multi-unit systems

    Energy Technology Data Exchange (ETDEWEB)

    Barros, A. [Institut des Sciences et Techonologies de l' Information de Troyes (ISTIT-CNRS), Equipe de Modelisation et Surete des Systemes, Universite de Technologie de Troyes (UTT), 12, rue Marie Curie, BP2060, 10010 Troyes cedex (France)]. E-mail: anne.barros@utt.fr; Berenguer, C. [Institut des Sciences et Techonologies de l' Information de Troyes (ISTIT-CNRS), Equipe de Modelisation et Surete des Systemes, Universite de Technologie de Troyes (UTT), 12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Grall, A. [Institut des Sciences et Techonologies de l' Information de Troyes (ISTIT-CNRS), Equipe de Modelisation et Surete des Systemes, Universite de Technologie de Troyes (UTT), 12, rue Marie Curie, BP2060, 10010 Troyes cedex (France)

    2005-12-01

    The aim of this paper is to present a stochastic model to characterize the failure distribution of multi-unit systems when the current units state is imperfectly monitored. The definition of the hazard rate process existing with perfect monitoring is extended to the realistic case where the units failure time are not always detected (non-detection events). The so defined observed hazard rate process gives a better representation of the system behavior than the classical failure rate calculated without any information on the units state and than the hazard rate process based on perfect monitoring information. The quality of this representation is, however, conditioned by the monotony property of the process. This problem is mainly discussed and illustrated on a practical example (two parallel units). The results obtained motivate the use of the observed hazard rate process to characterize the stochastic behavior of the multi-unit systems and to optimize for example preventive maintenance policies.

  4. AUTOMATED SYSTEM OF DATA PROCESSING WITH THE IMPLEMENTATION OF RATING TECHNOLOGY OF TEACHING

    OpenAIRE

    О. И. Дзювина; К. Е. Глинчиков

    2014-01-01

    Rating technology of teaching enables independent and individual work of students, increase their motivation.Purpose: to increase the efficiency of data processing with the implementation of rating technology of teaching.Method: analysis, synthesis,experiment.Results. Developed an automated data processing system for the implementation of rating technology of teaching.Practical implication. Education.Purchase on Elibrary.ru > Buy now

  5. AUTOMATED SYSTEM OF DATA PROCESSING WITH THE IMPLEMENTATION OF RATING TECHNOLOGY OF TEACHING

    Directory of Open Access Journals (Sweden)

    О. И. Дзювина

    2014-01-01

    Full Text Available Rating technology of teaching enables independent and individual work of students, increase their motivation.Purpose: to increase the efficiency of data processing with the implementation of rating technology of teaching.Method: analysis, synthesis,experiment.Results. Developed an automated data processing system for the implementation of rating technology of teaching.Practical implication. Education.Purchase on Elibrary.ru > Buy now

  6. Draft Genome Sequence of Anammox Bacterium "Candidatus Scalindua brodae," Obtained Using Differential Coverage Binning of Sequencing Data from Two Reactor Enrichments

    NARCIS (Netherlands)

    Speth, Daan R; Russ, Lina; Kartal, Boran; Op den Camp, Huub J M; Dutilh, Bas E; Jetten, Mike S M

    2015-01-01

    We present the draft genome of anammox bacterium "Candidatus Scalindua brodae," which at 282 contigs is a major improvement over the highly fragmented genome assembly of related species "Ca. Scalindua profunda" (1,580 contigs) which was previously published.

  7. Properties of Super-Poisson Processes and Super-Random Walks with Spatially Dependent Branching Rates

    Institute of Scientific and Technical Information of China (English)

    Yan Xia REN

    2008-01-01

    The global supports of super-Poisson processes and super-random walks with a branching mechanism ψ(z)=z2 and constant branching rate are known to be noncompact. It turns out that, for any spatially dependent branching rate, this property remains true. However, the asymptotic extinction property for these two kinds of superprocesses depends on the decay rate of the branching-rate function at infinity.

  8. Fermentation process using specific oxygen uptake rates as a process control

    Energy Technology Data Exchange (ETDEWEB)

    Van Hoek, Pim; Aristidou, Aristos; Rush, Brian J.

    2016-08-30

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  9. The Research on Transient Burning Rate of Solid Propellant by Digital Image Processing

    Directory of Open Access Journals (Sweden)

    Xin Peng

    2016-01-01

    Full Text Available In order to obtain the burn rate of the solid propellant that is the important parameter of transient burning, the new method named digital image processing is presented. In the article , the principle of digital image processing is analysed; The burning face of the sample in the each time is located according the image and the coordinates of the burning face is obtained. In experiment the transient burn rate is measured by digital image processing and the accuracy is acceptable.

  10. Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

    Institute of Scientific and Technical Information of China (English)

    Tian Hui; Li Yijie; Zeng Peng

    2014-01-01

    The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene) hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

  11. Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

    Directory of Open Access Journals (Sweden)

    Tian Hui

    2014-12-01

    Full Text Available The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

  12. Seasonal dynamics of anammox bacteria in estuarial sediment of the Mai Po Nature Reserve revealed by analyzing the 16S rRNA and hydrazine oxidoreductase (hzo) genes.

    Science.gov (United States)

    Li, Meng; Cao, Huiluo; Hong, Yi-Guo; Gu, Ji-Dong

    2011-01-01

    The community and population dynamics of anammox bacteria in summer (wet) and winter (dry) seasons in estuarial mudflat sediment of the Mai Po Nature Reserve were investigated by 16S rRNA and hydrazine oxidoreductase (hzo) genes. 16S rRNA phylogenetic diversity showed that sequences related to 'Kuenenia' anammox bacteria were presented in summer but not winter while 'Scalindua' anammox bacteria occurred in both seasons and could be divided into six different clusters. Compared to the 16S rRNA genes, the hzo genes revealed a relatively uniform seasonal diversity, with sequences relating to 'Scalindua', 'Anammoxoglobus', and planctomycete KSU-1 found in both seasons. The seasonal specific bacterial groups and diversity based on the 16S rRNA and hzo genes indicated strong seasonal community structures in estuary sediment of this site. Furthermore, the higher abundance of hzo genes in summer than winter indicates clear seasonal population dynamics. Combining the physicochemical characteristics of estuary sediment in the two seasons and their correlations with anammox bacteria community structure, we proposed the strong seasonal dynamics in estuary sediment of Mai Po to be due to the anthropogenic and terrestrial inputs, especially in summer, which brings in freshwater anammox bacteria, such as 'Kuenenia', interacting with the coastal marine anammox bacteria 'Scalindua'.

  13. Beta decay rates for nuclei with 115 < < 140 for r-process nucleosynthesis

    Indian Academy of Sciences (India)

    Kamales Kar; Soumya Chakravarti; V R Manfredi

    2006-08-01

    For r-process nucleosynthesis the -decay rates for a number of neutron-rich intermediate heavy nuclei are calculated. The model for the -strength function is able to reproduce the observed half-lives quite well.

  14. The un-making of a method: From rating scales to the study of psychological processes

    DEFF Research Database (Denmark)

    Rosenbaum, Philip J.; Valsiner, Jaan

    2011-01-01

    Rating scales are standard instruments in psychology. They force the research participant to provide a numerical estimate of an assumed “degree” of some characteristic along a linear scale. We prove that such numerical estimates are artifacts based on unknown psychological processes that are used...... in the making of a rating. Psychology’s current use of rating scales entails reliance upon unexplored and abbreviated introspection. It superimposes upon the rater the use of real numbers for the subjective construction of the ratings. The axiomatic superimposition of the notion of “degree” of subjective...... in terms of dialogical oppositions. These oppositions can be observed to lead to the moment of subjective synthesis (the rating outcome). Examples are given of the tracing of the process of subjective synthesis from an empirical study using NEO PI items. We claim that reconstruction of the rating task...

  15. Innovative wastewater treatment process with reduced energy consumption and regeneration of nutrients

    DEFF Research Database (Denmark)

    Schmidt, Jens Ejbye; Fitsios, E.; Angelidaki, Irini

    . The suggested process contains the following steps: 1) The organic matter is primarily removed through anaerobic degradation using high-rate reactors. 2) For nitrogen removal. the Anammox process or physico-chemical methods will be applied. 3) For phosphorus removal, bilogical process will be used. 4) On...... for the anaerobic process if digested undiluted. The highest methane potential was found with filtrated sewage, unfiltrated sewage gave biogas potentials, which were 4-6 times lower, depending on the temperature. Size distribution of the granules showed that the biggest granules had the highest hydrolytic activity...... and no substrate limitation was observed for the used granules. Experiment with UASB reactors showed COD removal efficiencies between 49-82 for the toal COD and 25-99 for the soluble COD. No significant differences were observed between reactor performance at 22 and 37 degree C....

  16. Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

    OpenAIRE

    Tian Hui; Li Yijie; Zeng Peng

    2014-01-01

    The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene) hybrid motor have been per...

  17. Relationship between gas-phase chemistries and surface processes in fluorocarbon etch plasmas: A process rate model

    International Nuclear Information System (INIS)

    In a typical plasma tool, both etch and deposition occur simultaneously. Extensive experimental measurements are used to help develop a general model of etch and deposition processes. This model employs reaction probabilities, or surface averaged cross sections, to link the measurable surface processes, etch and deposition, to the flux of various species to the surfaces. Because the cross sections are quantum mechanical in nature, this surface rate model should be applicable to many low temperature plasma processing systems. Further, the parameters that might be important in reaction cross sections are known from quantum mechanics, e.g., species, energy, temperature, and impact angle. Such parameters might vary from system to system, causing the wide processing variability observed in plasma tools. Finally the model is used to compare measurements of ion flux, ion energy, and fluorocarbon radical flux to the measured process rates. It is found that the model appears to be consistent with calculations of gain/loss rates for the various radicals present in the discharge as well as measured etch and deposition rates.

  18. Weak interaction rates for Kr and Sr waiting-point nuclei under rp-process conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sarriguren, P., E-mail: sarriguren@iem.cfmac.csic.e [Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain)

    2009-10-12

    Weak interaction rates are studied in neutron deficient Kr and Sr waiting-point isotopes in ranges of densities and temperatures relevant for the rp process. The nuclear structure is described within a microscopic model (deformed QRPA) that reproduces not only the half-lives but also the Gamow-Teller strength distributions recently measured. The various sensitivities of the decay rates to both density and temperature are discussed. Continuum electron capture is shown to contribute significantly to the weak rates at rp-process conditions.

  19. L2-Algebraic Decay Rate for Transient Birth-Death Processes

    Institute of Scientific and Technical Information of China (English)

    Lijuan CHENG; Yingzhe WANG

    2012-01-01

    This paper is a continuation of the study of the algebraic speed for Markov processes.The authors concentrate on algebraic decay rate for the transient birth-death processes.According to the classification of the boundaries,a series of the sufficient conditions for algebraic decay is presented.To illustrate the power of the results,some examples are included.

  20. Representations for the rate of convergence of birth-death processes

    NARCIS (Netherlands)

    Doorn, van E.A.

    2001-01-01

    We display some representations for the rate of convergence of a birth-death process, which are useful for obtaining upper and lower bounds. The expressions are brought to light by exploiting the spectral representation for the transition probabilities of a birth-death process and results from the t

  1. Bounds and asymptotics for the rate of convergence of birth-death processes

    NARCIS (Netherlands)

    Doorn, van Erik A.; Zeifman, Alexander I.; Panfilova, Tatyana L.

    2008-01-01

    We survey a method initiated by one of us in the 1990's for finding bounds and representations for the rate of convergence of a birth-death process. We also present new results obtained by this method for some specific birth-death processes related to mean-field models and to the $M/M/N/N+R$ service

  2. Representations for the rate of convergence of birth-death processes

    NARCIS (Netherlands)

    Doorn, van Erik A.

    2002-01-01

    We display some representations for the rate of convergence of a birth-death process, which are useful for obtaining upper and lower bounds. The expressions are brought to light by exploiting the spectral representation for the transition probabilities of a birth-death process and results from the t

  3. High production rate of crystallization process in TFA-MOD method for YBCO coated conductors

    International Nuclear Information System (INIS)

    To realize a higher production rate is one of the important issues in the development of the long-tape processing for the YBCO coated conductors by the TFA-MOD process using the reel-to-reel system. Not only scale-up of the furnace and decrease of YBCO thickness with the higher J c value, but higher YBCO growth rates could be effective to achieve a higher traveling rate in this system. It was confirmed that optimization of the process parameters such as high water vapor partial pressure, high diffusion constants due to a low applied total pressure, and a high gas flow rate affect the YBCO growth rate. Consequently, these higher growth rate conditions were simultaneously applied to the reel-to-reel system. As a result, the traveling rate of 1.2 m/h was achieved for fabricating YBCO films in the reel-to-reel system, which is about five times as fast as the previous traveling rate with maintaining high I c value of higher than 200 A/cm-width by controlling above conditions

  4. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    Science.gov (United States)

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

    2016-06-01

    This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  5. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    Directory of Open Access Journals (Sweden)

    Marvin Schmidt

    2016-06-01

    Full Text Available This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  6. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    Science.gov (United States)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation <0.1 <0.5 10 0.6 Normal operation, high NH4+ <0.1 <0.5 100 6.1 High aeration 0.5 to 1.5 up to 50 10 and 50 4.9 NO2- addition (oxic) <0.1 <0.5 to 4 10 5.8 NO2- addition (anoxic) 0 <0.5 to 4 10 3.2 NH2OH addition <0.1 <0.5 10 2.5 Results showed that under normal operating conditions, the N2O isotopic site preference (SP = d15Nα - d15Nβ) was much higher than expected - up to 41‰ - strongly suggesting an unknown N2O production pathway, which is hypothesized to be mediated by anammox activity (Figure 1). A less likely explanation is that the SP of N2O was increased by partial N2O reduction by heterotrophic denitrification. Various experiments were conducted to further investigate N2O formation pathways in the reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall

  7. Analyses of the melt cooling rate in the melt-spinning process

    Directory of Open Access Journals (Sweden)

    B. Karpe

    2012-04-01

    Full Text Available Purpose: Rapid solidification (RS of metallic melts is important for the development of the advance metallic materials, because enables the production of new alloys with superior properties according to conventionally treated alloys. In practice it turned out, that single roll melt spinning process has one of the highest melt cooling rates among all continuous casting processes. But, because very short solidification time and movement of the melt and substrate, melt cooling rate is very difficult to measure with confidence. Primary goal of our work was to determine the limits of cooling rate over the ribbon thickness and to outline, which property or typical feature of the process has the greatest influence on cooling rate of the melt. Design/methodology/approach: On the basis of developed mathematical model, a computer program was made and used for melt cooling rate calculation in the melt-spinning process.Findings: The calculations show that distance from the contact surface in relation to the thermal properties of the melt, chilling wheel material and contact resistance between metal melt and chilling wheel have the greatest influence on melt/ribbon cooling rate. In the case of continuous casting, significant “long term” surface temperature increase may take place, if the wheel is not internally cooled.Research limitations/implications: Influence of the melt physical properties, chill wheel material, contact resistance and cooling mode of the chill wheel on melt cooling rate are outlined.Practical implications: Practical limits of melt cooling rate over ribbon thickness are outlined and directions for the chill wheel cooling system design are indicated.Originality/value: Comparison between cooling rates calculated at various thermal resistance assumptions of particular constituents is outlined. New method for determining contact resistance through variable heat transfer coefficient is introduced which takes into account physical

  8. Co-occurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in subtropical acidic forest soils.

    Science.gov (United States)

    Meng, Han; Wang, Yong-Feng; Chan, Ho-Wang; Wu, Ruo-Nan; Gu, Ji-Dong

    2016-09-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two new processes of recent discoveries linking the microbial nitrogen and carbon cycles. In this study, 16S ribosomal RNA (rRNA) gene of anammox bacteria and pmoA gene of n-damo bacteria were used to investigate their distribution and diversity in natural acidic and re-vegetated forest soils. The 16S rRNA gene sequences retrieved featured at least three species in two genera known anammox bacteria, namely Candidatus Brocadia anammoxidans, Candidatus Brocadia fulgida, and Candidatus Kuenenia stuttgartiensis while the pmoA gene amplified was affiliated with two species of known n-damo bacteria Candidatus Methylomirabilis oxyfera and a newly established Candidatus Methylomirabilis sp. According to the results, the diversity of anammox bacteria in natural forests was lower than in re-vegetated forests, but no significant difference was observed in n-damo community between them. Quantitative real-time PCR showed that both anammox and n-damo bacteria were more abundant in the lower layer (10-20 cm) than the surface layer (0-5 cm). The abundance of anammox bacteria varied from 2.21 × 10(5) to 3.90 × 10(6) gene copies per gram dry soil, and n-damo bacteria quantities were between 1.69 × 10(5) and 5.07 × 10(6) gene copies per gram dry soil in the two different layers. Both anammox and n-damo bacteria are reported for the first time to co-occur in acidic forest soil in this study, providing a more comprehensive information on more defined microbial processes contributing to C and N cycles in the ecosystems. PMID:27178181

  9. Transient kinetics and rate limiting steps for the processive cellobiohydrolase Cel7A

    DEFF Research Database (Denmark)

    Cruys-Bagger, Nicolaj; Hirosuke, Tatsumi; Robin Ren, Guilin;

    2013-01-01

    times of 0.15 - 0.7 s per step at 25 °C, and the rate was highest on amorphous substrate. The cellulose binding module (CBM) was found to raise this rate on crystalline, but not on amorphous substrate. The rapid processive movement signified high intrinsic reactivity, but this parameter had marginal...... mechanistic and regulatory aspects of their heterogeneous catalysis remain poorly understood. Here we address this by applying a deterministic model to real-time kinetic data with high temporal resolution. We used two variants of the cellobiohydrolase Cel7A from H. jecorina, and three types of cellulose...... as substrate. Analysis of the pre-steady state regime allowed delineation rate constants for both fast and slow steps in the enzymatic cycle and assessment of how these constants influenced the rate of hydrolysis at quasi-steady state. Processive movement on the cellulose strand advanced with characteristic...

  10. The role of ratings in the educational process of higher education institutions

    Directory of Open Access Journals (Sweden)

    O.V. Klymenko

    2011-12-01

    Full Text Available In the article investigated the role of the rating system in the educational process of higher education and the problems of its use. Certain basic principles for the implementation of credit-modular system in high school. A comparative analysis of approaches to the rating methodology of control of student performance at the Sumy State University and the Higher School of Economics.

  11. The effects of the bologna process on college enrollment and drop-out rates

    OpenAIRE

    Horstschräer, Julia; Sprietsma, Maresa

    2010-01-01

    This paper estimates the short-term effects of the introduction of the Bachelor degree in the framework of the Bologna Process on college enrollment and drop-out rates. We use variation in the timing of the Bachelor implementation at the department level to identify the effect of the reform based on longitudinal administrative student data from Germany. We find no significant effects on college enrollment or drop-out rates for most subjects.

  12. Theory of molecular rate processes in the presence of intense laser radiation

    Science.gov (United States)

    George, T. F.; Zimmerman, I. H.; Devries, P. L.; Yuan, J.-M.; Lam, K.-S.; Bellum, J. C.; Lee, H.-W.; Slutsky, M. S.; Lin, J.-T.

    1979-01-01

    The present paper deals with the influence of intense laser radiation on gas-phase molecular rate processes. Representations of the radiation field, the particle system, and the interaction involving these two entities are discussed from a general rather than abstract point of view. The theoretical methods applied are outlined, and the formalism employed is illustrated by application to a variety of specific processes. Quantum mechanical and semiclassical treatments of representative atom-atom and atom-diatom collision processes in the presence of a field are examined, and examples of bound-continuum processes and heterogeneous catalysis are discussed within the framework of both quantum-mechanical and semiclassical theories.

  13. In situ annealing and high-rate silicon epitaxy on porous silicon by mesoplasma process

    Science.gov (United States)

    Zhang, Sheng; Lu, Ziyu; Sheng, Jiang; Gao, Pingqi; Yang, Xi; Wu, Sudong; Ye, Jichun; Kambara, Makoto

    2016-05-01

    By a mesoplasma process, a double-layer porous Si is annealed for a few seconds, by which an annealing effect similar to that of a prolonged conventional annealing process is obtained. The basic annealing process is considered to follow the classical sintering theory. However, the surface of the annealed porous Si is rough with large open voids because of H etching. The epitaxial Si films deposited on such a rough surface at a rate of 350 nm/s show a smooth surface with a low defect density compared with those deposited on a polished Si wafer, which clearly demonstrates the advantages of the cluster-assisted mesoplasma process.

  14. Rate-controlling processes in creep of subgrain containing aluminum materials

    Energy Technology Data Exchange (ETDEWEB)

    Sherby, Oleg D. [Department Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States); Ruano, Oscar A. [Department Physical Metallurgy, Centro Nacional de Investigaciones Metalurgicas, CSIC, Av. Gregorio de Amo, 8, 28040 Madrid (Spain)]. E-mail: ruano@cenim.csic.es

    2005-11-25

    The creep behavior of aluminum alloys containing Bi, Zn, Ge, Cu, Fe, Mn and Ti has been investigated. Aluminum containing solutes that diffused faster than aluminum has faster creep rates and lower activation energies for creep than observed in pure aluminum. Solutes that diffused slower than aluminum have slower creep rates and higher activation energies for creep than observed in pure aluminum. A dislocation climb model in the subgrain boundary that involves solute atom diffusion as the rate-controlling creep process is proposed to explain the results.

  15. rp-Process weak-interaction mediated rates of waiting-point nuclei

    CERN Document Server

    Nabi, Jameel-Un

    2012-01-01

    Electron capture and positron decay rates are calculated for neutron-deficient Kr and Sr waiting point nuclei in stellar matter. The calculation is performed within the framework of pn-QRPA model for rp-process conditions. Fine tuning of particle-particle, particle-hole interaction parameters and a proper choice of the deformation parameter resulted in an accurate reproduction of the measured half-lives. The same model parameters were used to calculate stellar rates. Inclusion of measured Gamow-Teller strength distributions finally led to a reliable calculation of weak rates that reproduced the measured half-lives well under limiting conditions. For the rp-process conditions, electron capture and positron decay rates on $^{72}$Kr and $^{76}$Sr are of comparable magnitude whereas electron capture rates on $^{78}$Sr and $^{74}$Kr are 1--2 orders of magnitude bigger than the corresponding positron decay rates. The pn-QRPA calculated electron capture rates on $^{74}$Kr are bigger than previously calculated. The p...

  16. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    Science.gov (United States)

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil.

  17. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    Science.gov (United States)

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil. PMID:16722077

  18. General Purpose Graphics Processing Unit Based High-Rate Rice Decompression and Reed-Solomon Decoding.

    Energy Technology Data Exchange (ETDEWEB)

    Loughry, Thomas A.

    2015-02-01

    As the volume of data acquired by space-based sensors increases, mission data compression/decompression and forward error correction code processing performance must likewise scale. This competency development effort was explored using the General Purpose Graphics Processing Unit (GPGPU) to accomplish high-rate Rice Decompression and high-rate Reed-Solomon (RS) decoding at the satellite mission ground station. Each algorithm was implemented and benchmarked on a single GPGPU. Distributed processing across one to four GPGPUs was also investigated. The results show that the GPGPU has considerable potential for performing satellite communication Data Signal Processing, with three times or better performance improvements and up to ten times reduction in cost over custom hardware, at least in the case of Rice Decompression and Reed-Solomon Decoding.

  19. CHARACTERISTIC DIMENSIONLESS NUMBERS IN MULTI-SCALE AND RATE-DEPENDENT PROCESSES

    Institute of Scientific and Technical Information of China (English)

    Yilong Bai; Mengfen Xia; Haiying Wang; Fujiu Ke

    2003-01-01

    Multi-scale modeling of materials properties and chemical processes has drawn great attention from science and engineering. For these multi-scale and rate-dependent processes, how to characterize their trans-scale formulation is a key point. Three questions should be addressed:● How do multi-sizes affect the problems?● How are length scales coupled with time scales?● How to identify emergence of new structure in process and its effect?For this sake, the macroscopic equations of mechanics and the kinetic equations of the microstructural transformations should form a unified set that be solved simultaneously.As a case study of coupling length and time scales, the trans-scale formulation of wave-induced damage evolution due to mesoscopic nucleation and growth is discussed. In this problem, the trans-scaling could be reduced to two independent dimensionless numbers: the imposed Deborah number De*=(ac*)/(LV*) and the intrinsic Deborah number D* = (nN*c*5)/V* , where a, L, c*, V* and nN* are wave speed, sample size, microcrack size, the rate of microcrack growth and the rate of microcrack nucleation density, respectively. Clearly, the dimensionless number De*=(ac*)/(LV*) includes length and time scales on both meso- and macro- levels and governs the progressive process.Whereas, the intrinsic Deborah number D* indicates the characteristic transition of microdamage to macroscopic rupture since D* is related to the criterion of damage localization, which is a precursor of macroscopic rupture. This case study may highlight the scaling in multi-scale and rate-dependent problems.Then, more generally, we compare some historical examples to see how trans-scale formulations were achieved and what are still open now. The comparison of various mechanisms governing the enhancement of meso-size effects reminds us of the importance of analyzing multi-scale and rate-dependent processes case by case.For multi-scale and rate-dependent processes with chemical reactions and

  20. Reaction rates for the s-process neutron source 22Ne+{\\alpha}

    CERN Document Server

    Longland, Richard; Karakas, Amanda I

    2012-01-01

    The 22Ne({\\alpha},n)25Mg reaction is an important source of neutrons for the s-process. In massive stars responsible for the weak component of the s-process, 22Ne({\\alpha},n)25Mg is the dominant source of neutrons, both during core helium burning and in shell carbon burning. For the main s-process component produced in Asymptotic Giant Branch (AGB) stars, the 13C({\\alpha},n)16O reaction is the dominant source of neutrons operating during the interpulse period, with the 22Ne+{\\alpha} source affecting mainly the s-process branchings during a thermal pulse. Rate uncertainties in the competing 22Ne({\\alpha},n)25Mg and 22Ne({\\alpha},{\\gamma})26Mg reactions result in large variations of s-process nucleosynthesis. Here, we present up-to-date and statistically rigorous 22Ne+{\\alpha} reaction rates using recent experimental results and Monte Carlo sampling. Our new rates are used in post-processing nucleosynthesis calculations both for massive stars and AGB stars. We demonstrate that the nucleosynthesis uncertainties ...

  1. On the time-homogeneous Ornstein–Uhlenbeck process in the foreign exchange rates

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, Regina C.B. da, E-mail: regina@quimica-industrial.com [Department of Mathematics, Instituto Federal de Goiás, Goiânia, Goiás 74055-110 (Brazil); International Center for Condensed Matter Physics, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970, Brasília, Distrito Federal (Brazil); Matsushita, Raul Y. [Department of Statistics, Universidade de Brasília, 70919-970, Brasília, Distrito Federal (Brazil); Castro, Márcio T. de; Figueiredo, Annibal [International Center for Condensed Matter Physics, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970, Brasília, Distrito Federal (Brazil)

    2015-10-02

    Since Gaussianity and stationarity assumptions cannot be fulfilled by financial data, the time-homogeneous Ornstein–Uhlenbeck (THOU) process was introduced as a candidate model to describe time series of financial returns [1]. It is an Ornstein–Uhlenbeck (OU) process in which these assumptions are replaced by linearity and time-homogeneity. We employ the OU and THOU processes to analyze daily foreign exchange rates against the US dollar. We confirm that the OU process does not fit the data, while in most cases the first four cumulants patterns from data can be described by the THOU process. However, there are some exceptions in which the data do not follow linearity or time-homogeneity assumptions. - Highlights: • Gaussianity and stationarity assumptions replaced by linearity and time-homogeneity. • We revisit the time-homogeneous Ornstein–Uhlenbeck (THOU) process. • We employ the THOU process to analyze foreign exchange rates against the US dollar. • The first four cumulants patterns from data can be described by the THOU process.

  2. On the time-homogeneous Ornstein–Uhlenbeck process in the foreign exchange rates

    International Nuclear Information System (INIS)

    Since Gaussianity and stationarity assumptions cannot be fulfilled by financial data, the time-homogeneous Ornstein–Uhlenbeck (THOU) process was introduced as a candidate model to describe time series of financial returns [1]. It is an Ornstein–Uhlenbeck (OU) process in which these assumptions are replaced by linearity and time-homogeneity. We employ the OU and THOU processes to analyze daily foreign exchange rates against the US dollar. We confirm that the OU process does not fit the data, while in most cases the first four cumulants patterns from data can be described by the THOU process. However, there are some exceptions in which the data do not follow linearity or time-homogeneity assumptions. - Highlights: • Gaussianity and stationarity assumptions replaced by linearity and time-homogeneity. • We revisit the time-homogeneous Ornstein–Uhlenbeck (THOU) process. • We employ the THOU process to analyze foreign exchange rates against the US dollar. • The first four cumulants patterns from data can be described by the THOU process

  3. Hierarchical programming language for modal multi-rate real-time stream processing applications

    NARCIS (Netherlands)

    Geuns, Stefan J.; Hausmans, Joost P.H.M.; Bekooij, Marco J.G.

    2014-01-01

    Modal multi-rate stream processing applications with real-time constraints which are executed on multi-core embedded systems often cannot be conveniently specified using current programming languages. An important issue is that sequential programming languages do not allow for convenient programming

  4. Abnormalities in Automatic Processing of Illness-Related Stimuli in Self-Rated Alexithymia.

    Directory of Open Access Journals (Sweden)

    Laura Brandt

    Full Text Available To investigate abnormalities in automatic information processing related to self- and observer-rated alexithymia, especially with regard to somatization, controlling for confounding variables such as depression and affect.89 healthy subjects (60% female, aged 19-71 years (M = 32.1. 58 subjects were additionally rated by an observer.Alexithymia (self-rating: TAS-20, observer rating: OAS; automatic information processing (priming task including verbal [illness-related, negative, positive, neutral] and facial [negative, positive, neutral] stimuli; somatoform symptoms (SOMS-7T; confounders: depression (BDI, affect (PANAS.Higher self-reported alexithymia scores were associated with lower reaction times for negative (r = .19, p < .10 and positive (r = .26, p < .05 verbal primes when the target was illness-related. Self-reported alexithymia was correlated with number (r = .42, p < .01 and intensity of current somatoform symptoms (r = .36, p < .01, but unrelated to observer-rated alexithymia (r = .11, p = .42.Results indicate a faster allocation of attentional resources away from task-irrelevant information towards illness-related stimuli in alexithymia. Considering the close relationship between alexithymia and somatization, these findings are compatible with the theoretical view that alexithymics focus strongly on bodily sensations of emotional arousal. A single observer rating (OAS does not seem to be an adequate alexithymia-measure in community samples.

  5. On diffusion processes with variable drift rates as models for decision making during learning

    International Nuclear Information System (INIS)

    We investigate Ornstein-Uhlenbeck and diffusion processes with variable drift rates as models of evidence accumulation in a visual discrimination task. We derive power-law and exponential drift-rate models and characterize how parameters of these models affect the psychometric function describing performance accuracy as a function of stimulus strength and viewing time. We fit the models to psychophysical data from monkeys learning the task to identify parameters that best capture performance as it improves with training. The most informative parameter was the overall drift rate describing the signal-to-noise ratio of the sensory evidence used to form the decision, which increased steadily with training. In contrast, secondary parameters describing the time course of the drift during motion viewing did not exhibit steady trends. The results indicate that relatively simple versions of the diffusion model can fit behavior over the course of training, thereby giving a quantitative account of learning effects on the underlying decision process

  6. Make It Go Viral! Rate-optimal Control for Resource-Constrained Branching Processes

    CERN Document Server

    Xu, Kuang

    2012-01-01

    We propose a new class of controlled multi-type branching processes with a per-step linear resource constraint, motivated by applications in quantitative marketing, and study the associated growth-rate maximizing control strategies. We show that the optimal growth rate can be achieved by maintaining a single optimal ratio among different population types, for both deterministic and stochastic branching processes. In the special case of a two-type population and with a symmetric revenue structure, the optimal ratio is obtained in closed-form. As a proof of concept, the methodology is applied to the linkage structure of the 2004 US Presidential Election blogosphere, where the optimal growth rate achieves sizable gains over a uniform selection strategy.

  7. Coupling, convergence rates of Markov processes and weak Poincaré inequalities

    Institute of Scientific and Technical Information of China (English)

    王凤雨

    2002-01-01

    Some analytic and probabilistic properties of the weak Poincaré inequality are obtained. In particular, for strong Feller Markov processes the existence of this inequality is equivalent to each of the following: (i)the Liouville property (or the irreducibility); (ii) the existence of successful couplings (or shift-couplings); (iii)the convergence of the Markov process in total variation norm; (iv) the triviality of the tail (or the invariant)σ-field; (v) the convergence of the density. Estimates of the convergence rate in total variation norm of Markov processes are obtained using the weak Poincaré inequality.

  8. New concepts of ammonia removal from digested swine effluents using anammox based deammonification process

    Science.gov (United States)

    Production of biogas from swine manure using anaerobic digesters (AD) is projected to be important in the future. However, surplus nitrogen (N) in AD effluents is difficult to remove using current technology (nitrification/denitrification) because low carbon availability after biogas production. W...

  9. DETERMINATION OF PRINCIPLE COMPONENT AFFETING MATERIAL REMOVAL RATE IN ELECTROCHEMICAL MACHINING PROCESS

    Directory of Open Access Journals (Sweden)

    SURESH H. SUREKAR

    2012-05-01

    Full Text Available Electrochemical Machining process is non- conventional, non-mechanical machining process in which material removal from the workpiece is done by means of Principle of Electrolysis. As in electrolysis in electrochemical machining two electrodes are used of which one is positive (Anode and other is negative (Cathode. Thematerial removal rate in electrochemical machining is determined by Faraday’s Law of Electrolysis and is affected by number of the parameters controllable and non controllable. Each and every parameter is having its own effect on material removal process. Among all the parameters any one is having highest impact on the response or material removal rate and other is having less impact than the first and so on. Optimization of parameters is important in every machining process because the response or result is affected by each parameter. The parameter which has highest impact if optimized and controlled tightly then the response of the process is not deviated to the large extent. Optimization of parameters is done by designing orthogonal array and Taguchi Methodology. Principal Component is determined for getting high material removal rate.

  10. Model-based evaluation of the role of Anammox on nitric oxide and nitrous oxide productions in membrane aerated biofilm reactor

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Smets, Barth F.; Yuan, Zhiguo;

    2013-01-01

    on the total nitrogen (TN) removal and the productions of NO and N2O. The model is applied to evaluate how periodic aeration as a control parameter reduces NO and N2O production but maintains high TN removal in MABR. The simulation results show over 3.5% of the removed TN could be attributed to NO and N2O...... strategies (periodic aeration vs. continuous aeration) reveals that periodic aeration can reduce NO and N2O production while maintaining a high level of nitrogen removal through promoting Anammox growth. Application of periodic aerations with different cycle frequencies to the MABR indicates that an increase......A multispecies one-dimensional biofilm model considering nitric oxide (NO) and nitrous oxide (N2O) productions for membrane aerated biofilm reactor (MABR) that remove nitrogen autotrophically through aerobic ammonia oxidation followed by Anammox is used to study the role of Anammox activity...

  11. Analysis, Synthesis, and Estimation of Fractal-Rate Stochastic Point Processes

    CERN Document Server

    Thurner, S; Feurstein, M C; Heneghan, C; Feichtinger, H G; Teich, M C; Thurner, Stefan; Lowen, Steven B.; Feurstein, Markus C.; Heneghan, Conor; Feichtinger, Hans G.; Teich, Malvin C.

    1997-01-01

    Fractal and fractal-rate stochastic point processes (FSPPs and FRSPPs) provide useful models for describing a broad range of diverse phenomena, including electron transport in amorphous semiconductors, computer-network traffic, and sequences of neuronal action potentials. A particularly useful statistic of these processes is the fractal exponent $\\alpha$, which may be estimated for any FSPP or FRSPP by using a variety of statistical methods. Simulated FSPPs and FRSPPs consistently exhibit bias in this fractal exponent, however, rendering the study and analysis of these processes non-trivial. In this paper, we examine the synthesis and estimation of FRSPPs by carrying out a systematic series of simulations for several different types of FRSPP over a range of design values for $\\alpha$. The discrepancy between the desired and achieved values of $\\alpha$ is shown to arise from finite data size and from the character of the point-process generation mechanism. In the context of point-process simulation, reduction ...

  12. The Non-homogeneous Poisson Process for Fast Radio Burst Rates

    CERN Document Server

    Lawrence, Earl; Law, Casey J; Spolaor, Sarah Burke; Bower, Geoffrey C

    2016-01-01

    This paper presents the non-homogeneous Poisson process (NHPP) for modeling the rate of fast radio bursts (FRBs) and other infrequently observed astronomical events. The NHPP, well-known in statistics, can model changes in the rate as a function of both astronomical features and the details of an observing campaign. This is particularly helpful for rare events like FRBs because the NHPP can combine information across surveys, making the most of all available information. The goal of the paper is two-fold. First, it is intended to be a tutorial on the use of the NHPP. Second, we build an NHPP model that incorporates beam patterns and a power law flux distribution for the rate of FRBs. Using information from 12 surveys including 15 detections, we find an all-sky FRB rate of 586.88 events per sky per day above a flux of 1 Jy (95\\% CI: 271.86, 923.72) and a flux power-law index of 0.91 (95\\% CI: 0.57, 1.25). Our rate is lower than other published rates, but consistent with the rate given in Champion et al. 2016.

  13. Genome-based microbial ecology of anammox granules in a full-scale wastewater treatment system.

    Science.gov (United States)

    Speth, Daan R; In 't Zandt, Michiel H; Guerrero-Cruz, Simon; Dutilh, Bas E; Jetten, Mike S M

    2016-01-01

    Partial-nitritation anammox (PNA) is a novel wastewater treatment procedure for energy-efficient ammonium removal. Here we use genome-resolved metagenomics to build a genome-based ecological model of the microbial community in a full-scale PNA reactor. Sludge from the bioreactor examined here is used to seed reactors in wastewater treatment plants around the world; however, the role of most of its microbial community in ammonium removal remains unknown. Our analysis yielded 23 near-complete draft genomes that together represent the majority of the microbial community. We assign these genomes to distinct anaerobic and aerobic microbial communities. In the aerobic community, nitrifying organisms and heterotrophs predominate. In the anaerobic community, widespread potential for partial denitrification suggests a nitrite loop increases treatment efficiency. Of our genomes, 19 have no previously cultivated or sequenced close relatives and six belong to bacterial phyla without any cultivated members, including the most complete Omnitrophica (formerly OP3) genome to date. PMID:27029554

  14. Shotgun metagenomic data reveals signifcant abundance but low diversity of Candidatus Scalindua marine anammox bacteria in the Arabian Sea oxygen minimum zone

    Directory of Open Access Journals (Sweden)

    laura eVillanueva

    2014-02-01

    Full Text Available Anaerobic ammonium oxidizing (anammox bacteria are responsible for a significant portion of the loss of fixed nitrogen from the oceans, making them important players in the global nitrogen cycle. To date, marine anammox bacteria found in both water columns and sediments worldwide belong almost exclusively to Candidatus Scalindua species. Recently the genome assembly of a marine anammox enrichment culture dominated by Candidatus Scalindua profunda became available and can now be used as a template to study metagenome data obtained from various oxygen minimum zones. Here, we sequenced genomic DNA from suspended particulate matter recovered at the upper (170 m deep and center (600 m area of the oxygen minimum zone in the Arabian Sea by SOLiD and Ion Torrent technology. The genome of Candidatus Scalindua profunda served as a template to collect reads. Based on the mapped reads marine anammox Abundance was estimated to be at least 0.4% in the upper and 1.7% in the center area. Single nucleotide variation (SNV analysis was performed to assess diversity of the Candidatus Scalindua populations. Most highly covered were the two diagnostic anammox genes hydrazine synthase (scal_01318c, hzsA and hydrazine dehydrogenase (scal_03295, hdh, while other genes involved in anammox metabolism (narGH, nirS, amtB, focA and ACS had a lower coverage but could still be assembled and analyzed. The results show that Candidatus Scalindua is abundantly present in the Arabian Sea OMZ, but that the diversity within the ecosystem is relatively low.

  15. Information transfer with rate-modulated Poisson processes: a simple model for nonstationary stochastic resonance.

    Science.gov (United States)

    Goychuk, I

    2001-08-01

    Stochastic resonance in a simple model of information transfer is studied for sensory neurons and ensembles of ion channels. An exact expression for the information gain is obtained for the Poisson process with the signal-modulated spiking rate. This result allows one to generalize the conventional stochastic resonance (SR) problem (with periodic input signal) to the arbitrary signals of finite duration (nonstationary SR). Moreover, in the case of a periodic signal, the rate of information gain is compared with the conventional signal-to-noise ratio. The paper establishes the general nonequivalence between both measures notwithstanding their apparent similarity in the limit of weak signals.

  16. Information transfer with rate-modulated Poisson processes: A simple model for nonstationary stochastic resonance

    Science.gov (United States)

    Goychuk, Igor

    2001-08-01

    Stochastic resonance in a simple model of information transfer is studied for sensory neurons and ensembles of ion channels. An exact expression for the information gain is obtained for the Poisson process with the signal-modulated spiking rate. This result allows one to generalize the conventional stochastic resonance (SR) problem (with periodic input signal) to the arbitrary signals of finite duration (nonstationary SR). Moreover, in the case of a periodic signal, the rate of information gain is compared with the conventional signal-to-noise ratio. The paper establishes the general nonequivalence between both measures notwithstanding their apparent similarity in the limit of weak signals.

  17. Strong Asymmetric Coupling of Two Parallel Exclusion Processes: Effect of Unequal Injection Rates

    Science.gov (United States)

    Xiao, Song; Dong, Peng; Zhang, Yingjie; Liu, Yanna

    2016-03-01

    In this letter, strong asymmetric coupling of two parallel exclusion processes: effect of unequal injection rates will be investigated. It is a generalization of the work of Xiao et al. (Phys. Lett. A 8, 374 (2009)), in which the particles only move on two lanes with rate 1 toward right. We can obtain the diverse phase diagram and density profiles of the system. The vertical cluster mean-field approach and extensively Monte Carlo simulations are used to study the system, and theoretical predictions are in excellent agreement with simulation results.

  18. A single-rate context-dependent learning process underlies rapid adaptation to familiar object dynamics.

    Directory of Open Access Journals (Sweden)

    James N Ingram

    2011-09-01

    Full Text Available Motor learning has been extensively studied using dynamic (force-field perturbations. These induce movement errors that result in adaptive changes to the motor commands. Several state-space models have been developed to explain how trial-by-trial errors drive the progressive adaptation observed in such studies. These models have been applied to adaptation involving novel dynamics, which typically occurs over tens to hundreds of trials, and which appears to be mediated by a dual-rate adaptation process. In contrast, when manipulating objects with familiar dynamics, subjects adapt rapidly within a few trials. Here, we apply state-space models to familiar dynamics, asking whether adaptation is mediated by a single-rate or dual-rate process. Previously, we reported a task in which subjects rotate an object with known dynamics. By presenting the object at different visual orientations, adaptation was shown to be context-specific, with limited generalization to novel orientations. Here we show that a multiple-context state-space model, with a generalization function tuned to visual object orientation, can reproduce the time-course of adaptation and de-adaptation as well as the observed context-dependent behavior. In contrast to the dual-rate process associated with novel dynamics, we show that a single-rate process mediates adaptation to familiar object dynamics. The model predicts that during exposure to the object across multiple orientations, there will be a degree of independence for adaptation and de-adaptation within each context, and that the states associated with all contexts will slowly de-adapt during exposure in one particular context. We confirm these predictions in two new experiments. Results of the current study thus highlight similarities and differences in the processes engaged during exposure to novel versus familiar dynamics. In both cases, adaptation is mediated by multiple context-specific representations. In the case of familiar

  19. Numerical Modeling of Friction Stir Welding Process by Using Rate-dependent Constitutive Model

    Institute of Scientific and Technical Information of China (English)

    Hongwu ZHANG; Zhao ZHANG

    2007-01-01

    Rate-dependent constitutive model was used to simulate the friction stir welding process. The effect of the viscosity coefficient and the process parameters on the material behaviors and the stress distributions around the pin were studied. Results indicate that the stress in front of the pin is larger than that behind the pin. The difference between the radial/circumferential stress in front of the pin and that behind it becomes smaller when the material gets closer to the top surface. This difference increases with increasing the viscosity coefficient and becomes smaller when the welding speed decreases. The variation of the angular velocity does not significantly affect the difference.

  20. Rates of processes with coherent production of different particles and the GSI time anomaly

    Energy Technology Data Exchange (ETDEWEB)

    Giunti, Carlo [INFN, Sezione di Torino, Via P. Giuria 1, I-10125 Torino (Italy)], E-mail: giunti@to.infn.it

    2008-07-17

    With the help of an analogy with a double-slit experiment, it is shown that the standard method of calculation of the rate of an interaction process by adding the rates of production of all the allowed channels, regardless of a possible coherence among them, is correct. The claims that the GSI time anomaly is due to the mixing of neutrinos in the final state of the electron-capture process are refuted. It is shown that the GSI time anomaly may be due to quantum beats due to the existence of two coherent energy levels of the decaying ion with an extremely small energy splitting (about 10{sup -15} eV) and relative probabilities having a ratio of about 1/0008.

  1. Critical value for the contact process with random recovery rates and edge weights on regular tree

    Science.gov (United States)

    Xue, Xiaofeng

    2016-11-01

    In this paper we are concerned with contact processes with random recovery rates and edge weights on rooted regular trees TN. Let ρ and ξ be two nonnegative random variables such that P(ɛ ≤ ξ 0. For each vertex x on TN, ξ(x) is an independent copy of ξ while for each edge e on TN, ρ(e) is an independent copy of ρ. An infected vertex x becomes healthy at rate ξ(x) while an infected vertex y infects an healthy neighbor z at rate proportional to ρ(y , z) . For this model, we prove that the critical value under the annealed measure approximately equals (N E ρ E 1/ξ )-1 as N grows to infinity. Furthermore, we show that the critical value under the quenched measure equals that under the annealed measure when the cluster containing the root formed with edges with positive weights is infinite.

  2. Large-scale calculations of the beta-decay rates and r-process nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Borzov, I.N.; Goriely, S. [Inst. d`Astronomie et d`Astrophysique, Univ. Libre de Bruxelles, Campus Plaine, Bruxelles (Belgium); Pearson, J.M. [Inst. d`Astronomie et d`Astrophysique, Univ. Libre de Bruxelles, Campus Plaine, Bruxelles (Belgium)]|[Lab. de Physique Nucleaire, Univ. de Montreal, Montreal (Canada)

    1998-06-01

    An approximation to a self-consistent model of the ground state and {beta}-decay properties of neutron-rich nuclei is outlined. The structure of the {beta}-strength functions in stable and short-lived nuclei is discussed. The results of large-scale calculations of the {beta}-decay rates for spherical and slightly deformed nuclides of relevance to the r-process are analysed and compared with the results of existing global calculations and recent experimental data. (orig.)

  3. Migration processes and self-rated health among marriage migrants in South Korea

    OpenAIRE

    Chang, HC; Wallace, SP

    2016-01-01

    © 2014 Taylor & Francis Background. Research on migrant health mostly examines labor migrants, with some attention paid to the trauma faced by refugees. Marriage migrants represent an understudied vulnerable population in the migration and health literature. Objectives. Drawing on a Social Determinants of Health (SDH) approach, we use a large Korean national survey and stratified multivariate regressions to examine the link between migration processes and the self-rated health of Korea's thre...

  4. Sensitivity of Type I X-Ray Bursts to rp-Process Reaction Rates

    CERN Document Server

    Amthor, A M; Heger, A; Sakharuk, A; Schatz, H; Smith, K; Galaviz, Daniel; Heger, Alexander; Sakharuk, Alexander; Schatz, Hendrik; Smith, Karl

    2006-01-01

    First steps have been taken in a more comprehensive study of the dependence of observables in Type I X-ray bursts on uncertain (p,gamma) reaction rates along the rp-process path. We use the multizone hydrodynamics code KEPLER which implicitly couples a full nuclear reaction network of more than 1000 isotopes, as needed, to follow structure and evolution of the X-ray burst layer and its ashes. This allows us to incorporate the full rp-process network, including all relevant nuclear reactions, and individually study changes in the X-ray burst light curves when modifying selected key nuclear reaction rates. In this work we considered all possible proton captures to nuclei with 10 < Z < 28 and N <= Z. When varying individual reaction rates within a symmetric full width uncertainty of a factor of 10000, early results for some rates show changes in the burst light curve as large as 10 percent of peak luminosity. This is very large compared to the current sensitivity of X-ray observations. More precise reac...

  5. Video-rate processing in tomographic phase microscopy of biological cells using CUDA.

    Science.gov (United States)

    Dardikman, Gili; Habaza, Mor; Waller, Laura; Shaked, Natan T

    2016-05-30

    We suggest a new implementation for rapid reconstruction of three-dimensional (3-D) refractive index (RI) maps of biological cells acquired by tomographic phase microscopy (TPM). The TPM computational reconstruction process is extremely time consuming, making the analysis of large data sets unreasonably slow and the real-time 3-D visualization of the results impossible. Our implementation uses new phase extraction, phase unwrapping and Fourier slice algorithms, suitable for efficient CPU or GPU implementations. The experimental setup includes an external off-axis interferometric module connected to an inverted microscope illuminated coherently. We used single cell rotation by micro-manipulation to obtain interferometric projections from 73 viewing angles over a 180° angular range. Our parallel algorithms were implemented using Nvidia's CUDA C platform, running on Nvidia's Tesla K20c GPU. This implementation yields, for the first time to our knowledge, a 3-D reconstruction rate higher than video rate of 25 frames per second for 256 × 256-pixel interferograms with 73 different projection angles (64 × 64 × 64 output). This allows us to calculate additional cellular parameters, while still processing faster than video rate. This technique is expected to find uses for real-time 3-D cell visualization and processing, while yielding fast feedback for medical diagnosis and cell sorting. PMID:27410107

  6. Effect of preservative agents on the respiration rate of minimally processed potato (Solanum tuberosum cv. Monalisa).

    Science.gov (United States)

    Petri, E; Arroqui, C; Angós, I; Vírseda, P

    2008-04-01

    The shelf life of minimally processed potatoes (MPP) is limited by enzyme-catalyzed browning reactions, with the increase in respiration being another factor that affects quality retention of this product. Sulfites are commonly used as effective preservative agents in minimally processing potatoes, but ascorbic acid and citric acid are considered natural sulfite substitutes and more accepted by consumers. The aim of this study was to study the effect of combinations of the preservative agents cited above (sodium metabisulfite 0.1% and 0.5%; citric acid 0.1% and 0.5%; ascorbic acid 0.5%) on the respiration rate of MPP (cv. Monalisa) processed at both ambient and refrigerated temperatures. The results have revealed that there is a significant effect of dipping treatment and temperature on respiration rate of MPP. Sodium metabisulfite (SM) reduces respiratory activity up to 0.8 mL/kg/h. The addition of either citric or ascorbic acid enhanced the effect of SM on the reduction of the respiration rate of MPP. The strongest effect (up to 3.3 mL/kg/h) was observed when a combination of all 3 agents at the higher concentrations was employed at a temperature of 18 degrees C.

  7. Analytical Hierarchy Process for Developing a Building Performance-Risk Rating Tool

    Directory of Open Access Journals (Sweden)

    Khalil Natasha

    2016-01-01

    Full Text Available The need to optimize the performance of buildings has increased consequently due to the expansive supply of facilities in higher education building (HEB. Proper performance assessment as a proactive measure may help university building in achieving performance optimization. However, the current maintenance programs or performance evaluation in the HEB is a systemic and cyclic process where maintenance is considered as an operational issue and not as opposed to a strategic issue. Hence, this paper proposed a Building Performance Risk Rating Tool (BPRT as an improved measure for building performance evaluation by addressing the users' risk in health and safety aspects. The BPRT is developed from the result of a rating index using the Analytical Hierarchy Process (AHP method. 12 facilities management (FM experts and practitioners were involved in the rating process. The subjective weightings are analysed using the AHP computer software, the Expert Choice 11. The establishment of the BPRT was introduced as an aid of improvement towards the current performance assessment of HEB by emerging the concept of building performance and risk into a numerical strategic approach

  8. Probing polymer crystallization at processing-relevant cooling rates with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Cavallo, Dario, E-mail: Dario.cavallo@unige.it [University of Genoa, Dept. of Chemistry and Industrial Chemistry, Via Dodecaneso 31, 16146 Genoa (Italy); Portale, Giuseppe [ESRF, Dubble CRG, Netherlands Organization of Scientific Research (NWO), 38043 Grenoble (France); Androsch, René [Martin-Luther-University Halle-Wittenberg, Center of Engineering Sciences, D-06099 Halle/S. (Germany)

    2015-12-17

    Processing of polymeric materials to produce any kind of goods, from films to complex objects, involves application of flow fields on the polymer melt, accompanied or followed by its rapid cooling. Typically, polymers solidify at cooling rates which span over a wide range, from a few to hundreds of °C/s. A novel method to probe polymer crystallization at processing-relevant cooling rates is proposed. Using a custom-built quenching device, thin polymer films are ballistically cooled from the melt at rates between approximately 10 and 200 °C/s. Thanks to highly brilliant synchrotron radiation and to state-of-the-art X-ray detectors, the crystallization process is followed in real-time, recording about 20 wide angle X-ray diffraction patterns per second while monitoring the instantaneous sample temperature. The method is applied to a series of industrially relevant polymers, such as isotactic polypropylene, its copolymers and virgin and nucleated polyamide-6. Their crystallization behaviour during rapid cooling is discussed, with particular attention to the occurrence of polymorphism, which deeply impact material’s properties.

  9. A sensitivity study of s-process: the impact of uncertainties from nuclear reaction rates

    Science.gov (United States)

    Vinyoles, N.; Serenelli, A.

    2016-01-01

    The slow neutron capture process (s-process) is responsible for the production of about half the elements beyond the Fe-peak. The production sites and the conditions under which the different components of s-process occur are relatively well established. A detailed quantitative understanding of s-process nucleosynthesis may yield light in physical processes, e.g. convection and mixing, taking place in the production sites. For this, it is important that the impact of uncertainties in the nuclear physics is well understood. In this work we perform a study of the sensitivity of s-process nucleosynthesis, with particular emphasis in the main component, on the nuclear reaction rates. Our aims are: to quantify the current uncertainties in the production factors of s-process elements originating from nuclear physics and, to identify key nuclear reactions that require more precise experimental determinations. In this work we studied two different production sites in which s-process occurs with very different neutron exposures: 1) a low-mass extremely metal-poor star during the He-core flash (nn reaching up to values of ∼ 1014cm-3); 2) the TP-AGB phase of a M⊙, Z=0.01 model, the typical site of the main s-process component (nn up to 108 — 109cm-3). In the first case, the main variation in the production of s-process elements comes from the neutron poisons and with relative variations around 30%-50%. In the second, the neutron poison are not as important because of the higher metallicity of the star that actually acts as a seed and therefore, the final error of the abundances are much lower around 10%-25%.

  10. New $^{32}$Cl(p,$\\gamma$)$^{33}$Ar reaction rate for astrophysical rp-process calculations

    CERN Document Server

    Schatz, H; Brown, B A; Clément, R; Sakharuk, A A; Sherrill, B M

    2005-01-01

    The $^{32}$Cl(p,$\\gamma$)$^{33}$Ar reaction rate is of potential importance in the rp-process powering type I X-ray bursts. Recently Clement et al. \\cite{CBB04} presented new data on excitation energies for low lying proton unbound states in $^{33}$Ar obtained with a new method developed at the National Superconducting Cyclotron Laboratory. We use their data, together with a direct capture model and a USD shell model calculation to derive a new reaction rate for use in astrophysical model calculations. In particular, we take into account capture on the first excited state in $^{32}$Cl, and also present a realistic estimate of the remaining uncertainties. We find that the $^{32}$Cl(p,$\\gamma$)$^{33}$Ar reaction rate is dominated entirely by capture on the first excited state in $^{32}$Cl over the whole temperature range relevant in X-ray bursts. In the temperature range from 0.2 to 1 GK the rate is up to a factor of 70 larger than the previously recommended rate based on shell model calculations only. The unce...

  11. Effects of electrode immersion depth and remelting rate on electroslag remelting process

    Institute of Scientific and Technical Information of China (English)

    Song Jinchun; Wang Changzhou; Li Song

    2014-01-01

    In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electroslag re-melting process. Studies were carried out to investigate the microscopic and macroscopic effects of electrode immersion depth and melting rate on the potential distribution and heat density in the slag bath,and on the depth and shape of the molten bath. Based on the ifnite element method and the numerical solution method, the effect of the electrode immersion depth on the slag bath heat density was researched; the relationship between the electrode immersion depth and the slag resistance was obtained; and the unsteady-state model of the solidiifcation process of the re-melting ingot was solved using the ifnite difference method. The mathematical model and physical model of the electrode melting process were established and solved; and the corresponding curves between the electrode molten-state and slag-bath physical parameters were obtained. The experimental results veriifed the simulated results studied in this paper.

  12. PRE-Processing for Video Coduing with Rate-Distortion Optimization Decision

    Institute of Scientific and Technical Information of China (English)

    QI Yi; HUANG Yong-gui; QI Hong-gang

    2006-01-01

    This paper proposes an adaptive video pre-processing algorithm for video coding. This algorithm works on the original image before intra- or inter-prediction. It adopts Gaussian filter to remove noise and insignificant features existing in images of video. Detection and restoration of edges are followed to restore the edges which are excessively filtered out in filtered images. Rate-Distortion Optimization (RDO) is employed to decide adaptively whether a processed block or a unprocessed block is coded into bit-streams doe more efficient coding. Our experiment results show that the algorithm achieves good coding performances on both subjective and objective aspects. In addition, the proposed pre-processing algorithm is transparent to decoder, and thus can be compliant with any video coding standards without modifying the decoder.

  13. Corrosion resistance of 2195 aluminum alloy treated by multi-step-heating-rate controlled process

    Institute of Scientific and Technical Information of China (English)

    XU Yue; LIU Yu-feng; GENG Ji-ping

    2006-01-01

    2195 aluminum-lithium alloy was widely applied in the aviation and aerospace industry, but it is highly susceptible to pitting and intergranular corrosion undergoing sever corrosive circumstance and moisture atmosphere. To solve this problem and consequently to prolong its service life, a multi-step-heating-rate(MSRC) process was carried out. Investigations were carried out to find the effect of the MSRC process on the alloys corrosion resistance. It is found that the MSRC process is more favorable for the uniform phase precipitation by comparing the corrosion resistance of samples treated by traditional heat treatments. The potential difference between phases can be reduced and intergranular corrosion is able to be prohibited efficiently. Besides, the rare earth infiltration is beneficial to improving the corrosion resistance. As heating time increases, the corrosion resistance declines gradually,samples treated by artificial aging and solid solution also exhibit a better corrosion resistance.

  14. Effect of longwall face advance rate on spontaneous heating process in the gob area - CFD modelling

    Energy Technology Data Exchange (ETDEWEB)

    Boleslav Taraba; Zdenek Michalec [University of Ostrava, Ostrava (Czech Republic). Dept. of Chemistry

    2011-08-15

    A commercial CFD software programme, FLUENT, was used to study the oxidation process of coal in the mined-out longwall (gob) area. A three-dimensional, single-phase model with a continuously advancing longwall face has been developed. For the model, the gob longwall area was designed on the basis of the actual longwall panel operating in the Ostrava-Karvina Coal Mines (OKD, Czech Republic). The behaviour of the coal to oxygen was modelled using the results arising mainly from the former laboratory-scale experiments with Czech bituminous coals. Basically, the technique of pulse flow calorimetry and measurements at a continuous airflow reactor were applied during the laboratory investigations. In the contribution, the main focus was to understand the effect of the longwall face advancing speed on the oxidation heat production as well as evolution of the gases in the gob area. Simultaneously, the effect of coal crushing in the mined-out area on the spontaneous heating process was examined. Numerical simulations confirmed the existence of a 'favourable' zone for the onset and development of the spontaneous heating process in the gob area. The location and the maximal temperature reached in the 'favourable' zone were found to be significantly affected by the advancing rate of the coalface. The slower the advancing rate is, the higher the maximal temperature and smaller the depth of the 'favourable' zone in the gob area are. When the rate drops to a certain 'critical' value, spontaneous heating turns to flammable combustion of the coal. The value of the 'critical' advancing rate was confirmed to increase if the grain size of the coal left in the gob decreases. Numerical examinations of carbon monoxide concentrations then proved that small incidents of spontaneous heating could occur in the gob area that need not be detected in the airflow of the longwall tail gate. 46 refs., 8 figs., 2 tabs.

  15. Influence of reservoir parameters and steam rate on SAGD process in a reservoir with gas cap

    Energy Technology Data Exchange (ETDEWEB)

    Barillas, J.L.M.; Dutra, T.V.Jr. [Rio Grande do Norte Federal Univ., Natal (Brazil). Dept. of Chemical Engineering; Mata, W. [Rio Grande do Norte Federal Univ., Natal (Brazil). Dept. of Electrical Engineering

    2008-07-01

    The process of steam injection in heavy oil reservoirs involves heating the reservoir to reduce oil viscosity and increase oil-phase mobility. Steam assisted gravity drainage is one of the most promising thermal recovery methods that has been used in countries such as Canada, the United States and Venezuela, but not in Brazil. This study verified if the process could be applied in Brazilian reservoirs. In particular, a reservoir with northeast Brazilian characteristics was studied in a homogeneous model with a gas cap. The STARS software from CMG was used for all cases. The steam requirement was optimized based on an economical study in which a simplified calculation for net present value (NPV) was obtained. The calculation depended on factors such as cumulative oil, steam injected volume, steam/oil cost ratio, net production cost and, oil price and internal return rate. This function made it possible to perform a steam optimization for different systems with maximal NPV. It was determined that optimal steam rate depends on reservoir characteristics. The thickness of the gas cap was found to have little influence on oil recovery. It was concluded that the optimal steam injection rate can be determined for maximal NPV depending on the physical characteristics of the reservoir. 9 refs., 3 tabs., 10 figs.

  16. Coding efficiency of fly motion processing is set by firing rate, not firing precision.

    Directory of Open Access Journals (Sweden)

    Deusdedit Lineu Spavieri

    Full Text Available To comprehend the principles underlying sensory information processing, it is important to understand how the nervous system deals with various sources of perturbation. Here, we analyze how the representation of motion information in the fly's nervous system changes with temperature and luminance. Although these two environmental variables have a considerable impact on the fly's nervous system, they do not impede the fly to behave suitably over a wide range of conditions. We recorded responses from a motion-sensitive neuron, the H1-cell, to a time-varying stimulus at many different combinations of temperature and luminance. We found that the mean firing rate, but not firing precision, changes with temperature, while both were affected by mean luminance. Because we also found that information rate and coding efficiency are mainly set by the mean firing rate, our results suggest that, in the face of environmental perturbations, the coding efficiency is improved by an increase in the mean firing rate, rather than by an increased firing precision.

  17. On the nature of heart rate variability in a breathing normal subject: A stochastic process analysis

    Science.gov (United States)

    Buchner, Teodor; Petelczyc, Monika; Żebrowski, Jan J.; Prejbisz, Aleksander; Kabat, Marek; Januszewicz, Andrzej; Piotrowska, Anna Justyna; Szelenberger, Waldemar

    2009-06-01

    Human heart rate is moderated by the autonomous nervous system acting predominantly through the sinus node (the main cardiac physiological pacemaker). One of the dominant factors that determine the heart rate in physiological conditions is its coupling with the respiratory rhythm. Using the language of stochastic processes, we analyzed both rhythms simultaneously taking the data from polysomnographic recordings of two healthy individuals. Each rhythm was treated as a sum of a deterministic drift term and a diffusion term (Kramers-Moyal expansion). We found that normal heart rate variability may be considered as the result of a bidirectional coupling of two nonlinear oscillators: the heart itself and the respiratory system. On average, the diffusion (noise) component measured is comparable in magnitude to the oscillatory (deterministic) term for both signals investigated. The application of the Kramers-Moyal expansion may be useful for medical diagnostics providing information on the relation between respiration and heart rate variability. This interaction is mediated by the autonomous nervous system, including the baroreflex, and results in a commonly observed phenomenon—respiratory sinus arrhythmia which is typical for normal subjects and often impaired by pathology.

  18. Knowledge on DNA Success Rates to Optimize the DNA Analysis Process: From Crime Scene to Laboratory.

    Science.gov (United States)

    Mapes, Anna A; Kloosterman, Ate D; van Marion, Vincent; de Poot, Christianne J

    2016-07-01

    DNA analysis has become an essential intelligence tool in the criminal justice system for the identification of possible offenders. However, it appears that about half of the processed DNA samples contains too little DNA for analysis. This study looks at DNA success rates within 28 different categories of trace exhibits and relates the DNA concentration to the characteristics of the DNA profile. Data from 2260 analyzed crime samples show that cigarettes, bloodstains, and headwear have relatively high success rates. Cartridge cases, crowbars, and tie-wraps are on the other end of the spectrum. These objective data can assist forensics in their selection process.The DNA success probability shows a positive relation with the DNA concentration. This finding enables the laboratory to set an evidence-based threshold value in the DNA analysis process. For instance, 958 DNA extracts had a concentration value of 6 pg/μL or less. Only 46 of the 958 low-level extracts provided meaningful DNA profiling data. PMID:27364287

  19. Does sample rate introduce an artifact in spectral analysis of continuous processes?

    Directory of Open Access Journals (Sweden)

    Maarten eWijnants

    2013-01-01

    Full Text Available Spectral analysis is a widely used method to estimate 1/f α noise in behavioral and physiological data series. The aim of this paper is to achieve a more solid appreciation for the effects of periodic sampling on the outcomes of spectral analysis. It is shown that spectral analysis is biased by the choice of sample rate because denser sampling comes with lower amplitude fluctuations at the highest frequencies. Here we introduce an analytical strategy that compensates for this effect by focusing on a fixed amount, rather than a fixed percentage of the lowest frequencies in a power spectrum. Using this strategy, estimates of the degree of 1/f α noise become robust against sample rate conversion and more sensitive overall. Altogether, the present contribution may shed new light on known discrepancies in the literature on 1/f α noise, and may provide a means to achieve a more solid framework for 1/f α noise in continuous processes.

  20. Large scale survey of lifetimes and reaction rates for the astrophysical r-process

    Energy Technology Data Exchange (ETDEWEB)

    Erler, Jochen; Reinhard, Paul-Gerhard [Institut fuer Theoretische Physik II, Universitaet Erlangen-Nuernberg (Germany); Loens, Hans Peter; Martinez-Pinedo, Gabriel; Langanke, Karlheinz [Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

    2010-07-01

    We present a large scale survey of lifetimes and reaction rates in the regime of SHE for extremely neutron rich nuclei relevant for the astrophysical r-process. The three competing decay channels spontaneous fission, {alpha}-decay and {beta}-decay are compared. Lifetimes and reaction rates are calculated on the basis of the self-consistent Skyrme-Hartree-Fock model. Where the tunneling probability for spontaneous fission is estimated by the WKB approximation. To get the necessary ingredients for this approximation namely the collective masses and the corrected potential energy surface self-consistent cranking is used. The halflife for {alpha}-decay are calculated from the Q{sub {alpha}} reaction energies using an estimate based on the Viola systematics.

  1. Stellar neutron capture rates – key data for the s process

    Directory of Open Access Journals (Sweden)

    Käppeler F.

    2013-12-01

    Full Text Available Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to the He- and C- burning phases of stellar evolution (s process and to supernova explosions (r and p processes. The s process, which is characterized by low neutron densities, operates in or near the valley of β stability and has produced about half of the elemental abundances between Fe and Bi in the solar system and in the Universe. Because the s abundances are essentially determined by the (n, γ cross sections along the reaction path, accurate neutron data constitute the key input for s process studies. Important constraints for the physical conditions at the stellar sites can be inferred by comparison of the abundance patterns from current s-process models with solar system material or presolar grains. The experimental methods for the determination of stellar (n, γ rates are outlined at the example of recent cross section measurements and remaining quests will be discussed with respect to existing laboratory neutron sources and new developments.

  2. Monitoring granulation rate processes using three PAT tools in a pilot-scale fluidized bed.

    Science.gov (United States)

    Tok, Ai Tee; Goh, Xueping; Ng, Wai Kiong; Tan, Reginald B H

    2008-01-01

    The purpose of this research was to analyze and compare the responses of three Process Analytical Technology (PAT) techniques applied simultaneously to monitor a pilot-scale fluidized bed granulation process. Real-time measurements using focused beam reflectance measurement (Lasentec FBRM) and near-infra red spectroscopy (Bruker NIR) were taken by inserting in-line probes into the fluidized bed. Non-intrusive acoustic emission measurements (Physical Acoustic AE) were performed by attaching piezoelectric sensors on the external wall of the fluidized bed. Powder samples were collected at regular intervals during the granulation process and characterized offline using laser diffraction, scanning electron microscopy, stereo-optical microscopy and loss on drying method. PAT data comprising chord length distribution and chord count (from FBRM), absorption spectra (from NIR) and average signal levels and counts (from AE) were compared with the particle properties measured using offline samples. All three PAT techniques were able to detect the three granulation regimes or rate processes (wetting and nucleation, consolidation and growth, breakage) to varying degrees of sensitivity. Being dependent on optical signals, the sensitivities of the FBRM and NIR techniques were susceptible to fouling on probe windows. The AE technique was sensitive to background fluidizing air flows and external interferences. The sensitivity, strengths and weaknesses of the PAT techniques examined may facilitate the selection of suitable PAT tools for process development and scale-up studies.

  3. Intact polar lipids of Thaumarchaeota and anammox bacteria as indicators of N cycling in the eastern tropical North Pacific oxygen-deficient zone

    Science.gov (United States)

    Sollai, M.; Hopmans, E. C.; Schouten, S.; Keil, R. G.; Sinninghe Damsté, J. S.

    2015-08-01

    In the last decade our understanding of the marine nitrogen cycle has improved considerably thanks to the discovery of two novel groups of microorganisms: ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria. Both groups are important in oxygen-deficient zones (ODZs), where they substantially affect the marine N budget. These two groups of microbes are also well known for producing specific membrane lipids, which can be used as biomarkers to trace their presence in the environment. We investigated the occurrence and distribution of AOA and anammox bacteria in the water column of the eastern tropical North Pacific (ETNP) ODZ, one of the most prominent ODZs worldwide. Suspended particulate matter (SPM) was collected at different depths of the water column in high resolution, at both a coastal and an open-ocean setting. The SPM was analyzed for AOA- and anammox bacteria-specific intact polar lipids (IPLs), i.e., hexose-phosphohexose (HPH)-crenarchaeol and phosphatidylcholine (PC)-monoether ladderane. Comparison with oxygen profiles reveals that both the microbial groups are able to thrive at low (niche segregation of AOA and anammox bacteria in the coastal waters of the ETNP but a partial overlap of the two niches of these microbial species in the open-water setting. The latter distribution suggests the potential for an interaction between the two microbial groups at the open-ocean site, although the nature of this hypothetical interaction (i.e., either competition or cooperation) remains unclear.

  4. Intact polar lipids of Thaumarchaeota and anammox bacteria as indicators of N-cycling in the Eastern Tropical North Pacific oxygen deficient zone

    Science.gov (United States)

    Sollai, M.; Hopmans, E. C.; Schouten, S.; Keil, R. G.; Sinninghe Damsté, J. S.

    2015-03-01

    In the last decade our understanding of the marine nitrogen cycle has improved considerably thanks to the discovery of two novel groups of microorganisms: ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria. Both groups are important in oxygen deficient zones (ODZs), where they substantially affect the marine N-budget. These two groups of microbes are also well known for producing specific membrane lipids, which can be used as biomarkers to trace their presence in the environment. We investigated the occurrence and distribution of AOA and anammox bacteria in the water column of the Eastern Tropical North Pacific (ETNP) ODZ, one of the most prominent ODZs worldwide. Suspended particulate matter (SPM) was collected at different depths of the water column in high resolution, at both a coastal and an open ocean setting. The SPM was analyzed for AOA- and anammox bacteria-specific intact polar lipids (IPLs), i.e. hexose-phosphohexose (HPH)-crenarchaeol and phosphatidylcholine (PC)-monoether ladderane. Comparison with oxygen profiles reveals that both the microbial groups are able to thrive at low (niche segregation of AOA and anammox bacteria in the coastal waters of the ETNP, but a partial overlap of the two niches of these microbial species in the open water setting. The latter distribution suggests the potential for an interaction between the two microbial groups at the open ocean site, either as competition or cooperation.

  5. Intact polar lipids of Thaumarchaeota and anammox bacteria as indicators of N-cycling in the Eastern Tropical North Pacific oxygen deficient zone

    Directory of Open Access Journals (Sweden)

    M. Sollai

    2015-03-01

    Full Text Available In the last decade our understanding of the marine nitrogen cycle has improved considerably thanks to the discovery of two novel groups of microorganisms: ammonia-oxidizing archaea (AOA and anaerobic ammonia-oxidizing (anammox bacteria. Both groups are important in oxygen deficient zones (ODZs, where they substantially affect the marine N-budget. These two groups of microbes are also well known for producing specific membrane lipids, which can be used as biomarkers to trace their presence in the environment. We investigated the occurrence and distribution of AOA and anammox bacteria in the water column of the Eastern Tropical North Pacific (ETNP ODZ, one of the most prominent ODZs worldwide. Suspended particulate matter (SPM was collected at different depths of the water column in high resolution, at both a coastal and an open ocean setting. The SPM was analyzed for AOA- and anammox bacteria-specific intact polar lipids (IPLs, i.e. hexose-phosphohexose (HPH-crenarchaeol and phosphatidylcholine (PC-monoether ladderane. Comparison with oxygen profiles reveals that both the microbial groups are able to thrive at low (<1 μM concentrations of oxygen. Our results indicate a clear niche segregation of AOA and anammox bacteria in the coastal waters of the ETNP, but a partial overlap of the two niches of these microbial species in the open water setting. The latter distribution suggests the potential for an interaction between the two microbial groups at the open ocean site, either as competition or cooperation.

  6. Process for high growth rate and high superconducting properties of REBCO single crystals

    International Nuclear Information System (INIS)

    Process developments for both higher growth rate and superconducting properties are two main objectives of RE1Ba2Cu3O7-δ (REBCO or RE123) single crystal growth. In this paper, we will review several processes for increasing growth rate and achieving higher Tc REBCO superconductors. There are two effective methods to enhance the growth rate. One is to grow single crystals under high oxygen partial pressure, the other is to partially or completely replace Y by RE elements with higher solubilities in the Ba-Cu-O solution, for instance RE=Nd, Sm. Using these methods the growth rate was increased. The unprecendently large REBCO single crystals with the size 25 x 25 mm2 on the a-b plane and up to 20 mm in thickness were obtained. Regarding superconductivity, the critical temperature Tc of about 93 K was achieved from the Y123 single crystals both grown under air and 1 atm oxygen pressure, indicating that Tc is insensitive to the growth atmosphere of the oxygen pressure in the YBCO system. Furthermore, the high Tc of about 95 K NdBCO superconductors with a sharp transition was obtained by using Ba-rich liquid (Ba:Cu ratio=0.75-0.80 of solvent), suggesting that the liquid composition is an important thermodynamic parameter for controlling Tc. Moreover, the partial substitution RE (RE=Nd, Sm) at the Y sites up to 30% shows no obvious reduction of Tc remaining at about 91±1 K. (orig.)

  7. Transesterification of waste cooking oil: Process optimization and conversion rate evaluation

    International Nuclear Information System (INIS)

    Highlights: ► The highest purity of the produced biodiesel determined by gas chromatography was 95%. ► Produced biodiesel samples fell within the requirements of American standard for biodiesel. ► The reaction order is 1st order with a rate constant of 0.01 min-1 in the above point min-1. - Abstract: Biodiesel is a mono-alkyl ester of vegetable oil, animal fat, and recycled cooking oil. It is gaining importance in the quest of finding sustainable fuel as it is compatible with petrodiesel and its synthesis process is becoming more commercially deployable. It is commonly prepared by the transesterification of triglycerides or the esterification of free fatty acid with methanol by stirring and accelerated by the presence of base or acidic catalyst. In this work biodiesel was produced by transesterification of waste cooking oil (WCO) following different process settings with the objective to achieve maximum yield and purity. Due to immiscibility and reaction reversibility, high purity WCO biodiesel of 95% was produced at 12:1 alcohol to oil molar ratio at 1% w/w NaOH catalyst and under continuous mixing of 2 h at 60 °C. Chemical kinetics was determined for the optimal process and found to follow 1st order reaction rate with a rate constant ranges from 0.0035 to 0.0106 min−1. The activation energy was also evaluated by running the experiment at three different temperatures and found to be near 25,496 J/mol. The distillation curve and properties of the resulted fuel was also assessed and were compared plausibly to ASTM biodiesel standards. Furthermore, the emitted soot from a diffusion wick flame was measured via opacity meter and clearly show the advantage of the biodiesel with a nearly an order of magnitude lower.

  8. A General Law of Moment Convergence Rates for Uniform Empirical Process

    Institute of Scientific and Technical Information of China (English)

    Qing Pei ZANG

    2011-01-01

    Let {Xn; n ≥ 1} be a sequence of independent and identically distributed U[0,1]-distributed random variables.Define the uniform empirical process Fn(t)=n-1/2∑ni=1(I{Xi≤t} -t),0 ≤ t ≤ 1,‖Fn‖ =sup0≤t≤1 |Fn(t)|.In this paper,the exact convergence rates of a general law of weighted infinite series of E{‖Fn‖ - εgs(n)}+ are obtained.

  9. Effect of process parameters on growth rate and diameter of nano-porous alumina templates

    Indian Academy of Sciences (India)

    P Chowdhury; K Raghuvaran; M Krishnan; Harish C Barshilia; K S Rajam

    2011-06-01

    Anodic aluminium oxide (AAO) template with hexagonal shaped nano-pores with high aspect ratio was fabricated by two-step anodization processes from high purity aluminium foil. It was observed that pore dimensions were affected by anodizing voltage, electrolyte temperature and the duration of anodization time. The vertical growth rate of the pores (10–250 nm/min) was found to vary exponentially with anodizing voltage; however, it exhibits linear increment with the electrolyte temperature. The measured pore diameter (50–130 nm) shows a linear variation with anodizing voltage. The bottom barrier oxide layer was etched out by pore widening treatment to obtain through holes.

  10. Prediction of leaching rate in heap leaching process by grey dynamic model GDM(1,1)

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-zhi; wu Ai-xiang

    2008-01-01

    The method of developing GM(1,1)model is extended on the basis of grey system theory.Conditions for the transfer function that improve smoothness of original data sequence and decrease the revert error are given.The grey dynamic model is first combined with the transfer function to predict the leaching rate in heap leaching process.The resuhs show that high prediction accuracy call be expected by using the proposed method.This provides a new approach to realize prediction and control of the future behavior of leaching kinetics.

  11. Influence of cooking time and cooling rate on the functionality and microstructure of processed cheese spreads

    Institute of Scientific and Technical Information of China (English)

    LI Xiaodong; WU Han; LIU Huaiwei

    2007-01-01

    The objective of this work was to study the influence of cooking time and cooling rate on functionality and microstructure of processed cheese spreads. When the cooking time was 20 min, the hardness and apparent viscosity were increased, and formed a homogenous, dense, and three-dimensional protein network, and a stronger gel was formed at this time. The slow cooling can increase the hardness and apparent viscosity of products, protein wall was thicker, and network was closer, so products can formed a stronger gel structure. The influence of cooking time on the functional properties was more significant than the influence of rapid cooling.

  12. Influence of process parameters on thermal-rate treatment of ZA42 alloy

    Institute of Scientific and Technical Information of China (English)

    李成栋; 田学雷; 赵梅; 耿浩然

    2002-01-01

    Sand casting process and directional solidification technique combining thermal-rate treatment(TRT) were used. The influence of process parameters on TRT was investigated according to the values of impact toughness. At the same time, the mechanism of TRT was discussed. The results showed that TRT can improve the impact toughness of this alloy, while the hardness is basically constant. The time of heat preservation should not be more than 5min. Different forms of cooling intensification additive have different effects among which the zinc ingot solidified in graphite mold is the best one that can improve impact toughness of samples by more than 80%. With increasing the cooling temperature, the value of α(Al) crystal lattice constant increases. The element Sb has negative effect on TRT.

  13. Effects of Powder Feeding Rate on Interaction between Laser Beam and Powder Streamin Laser Cladding Process

    Institute of Scientific and Technical Information of China (English)

    HUANG Yan-lu; LI Jian-guo; LIANG Gong-ying; SU Jun-yi

    2004-01-01

    A theoretical model was presented to calculate the laser intensity distribution and the particle temperatures at different sites of the workpiece in the laser cladding process. By using this model, the effects of the powder feeding rate on the laser intensity distribution and the particle temperatures were investigated, the calculated results under the condition of different injection angles were also plotted. It is shown that with increasing the injection angle, the laser intensity distributions are similar but the peak value of the laser intensity decreases. Simultaneously, the peak value of the particle temperature increases and the distribution of the particle temperatures gets central symmetrical gradually. These tests results should be considered in model of laser cladding due to their subtle effects on the dynamic processes in laser molten pool.

  14. Coupled physical/biogeochemical modeling including O2-dependent processes in the Eastern Boundary Upwelling Systems: application in the Benguela

    Directory of Open Access Journals (Sweden)

    E. Gutknecht

    2013-06-01

    Full Text Available The Eastern Boundary Upwelling Systems (EBUS contribute to one fifth of the global catches in the ocean. Often associated with Oxygen Minimum Zones (OMZs, EBUS represent key regions for the oceanic nitrogen (N cycle. Important bioavailable N loss due to denitrification and anammox processes as well as greenhouse gas emissions (e.g, N2O occur also in these EBUS. However, their dynamics are currently crudely represented in global models. In the climate change context, improving our capability to properly represent these areas is crucial due to anticipated changes in the winds, productivity, and oxygen content. We developed a biogeochemical model (BioEBUS taking into account the main processes linked with EBUS and associated OMZs. We implemented this model in a 3-D realistic coupled physical/biogeochemical configuration in the Namibian upwelling system (northern Benguela using the high-resolution hydrodynamic ROMS model. We present here a validation using in situ and satellite data as well as diagnostic metrics and sensitivity analyses of key parameters and N2O parameterizations. The impact of parameter values on the OMZ off Namibia, on N loss, and on N2O concentrations and emissions is detailed. The model realistically reproduces the vertical distribution and seasonal cycle of observed oxygen, nitrate, and chlorophyll a concentrations, and the rates of microbial processes (e.g, NH4+ and NO2− oxidation, NO3− reduction, and anammox as well. Based on our sensitivity analyses, biogeochemical parameter values associated with organic matter decomposition, vertical sinking, and nitrification play a key role for the low-oxygen water content, N loss, and N2O concentrations in the OMZ. Moreover, the explicit parameterization of both steps of nitrification, ammonium oxidation to nitrate with nitrite as an explicit intermediate, is necessary to improve the representation of microbial activity linked with the OMZ. The simulated minimum oxygen

  15. Coupled physical/biogeochemical modeling including O2-dependent processes in the Eastern Boundary Upwelling Systems: application in the Benguela

    Directory of Open Access Journals (Sweden)

    A. Paulmier

    2012-10-01

    Full Text Available The Eastern Boundary Upwelling Systems (EBUS contribute to one fifth of the global catches in the ocean. Often associated with Oxygen Minimum Zones (OMZs, EBUS represent key regions for the oceanic nitrogen (N cycle. Important bioavailable N loss due to denitrification and anammox processes as well as greenhouse gas emissions (e.g, N2O occur also in these EBUS. However, their dynamics are currently crudely represented in global models. In the climate change context, improving our capability to properly represent these areas is crucial, due to anticipated changes in the winds, productivity, and oxygen content. We developed a biogeochemical model (BioEBUS taking into account the main processes linked with EBUS and associated OMZs. We implemented this model in a 3-D realistic coupled physical/biogeochemical configuration in the Namibian upwelling system (Northern Benguela using the high-resolution hydrodynamical model ROMS. We present here a validation using in situ and satellite data as well as diagnostic metrics, and sensitivity analyses of key parameters and N2O parameterizations. The impact of parameter values on the OMZ off Namibia, on N loss, and on N2O concentrations and emissions is detailed. The model realistically reproduces the vertical distribution and seasonal cycle of observed oxygen, nitrate and Chl a concentrations, and the rates of microbial processes (e.g. NH4+ and NO2− oxidation, NO3− reduction and anammox as well. Based on our sensitivity analyses, biogeochemical parameter values associated with organic matter decomposition, vertical sinking and nitrification play a key role for the low-oxygen water content, N loss and N2O concentrations in the OMZ. Moreover, the importance of both steps of nitrification, ammonium oxidation to nitrate with nitrite as an explicit intermediate, is highlighted to improve the representation of microbial activity linked with OMZ. The simulated minimum oxygen concentrations are driven by the

  16. Measurement fidelity of heart rate variability signal processing: the devil is in the details.

    Science.gov (United States)

    Jarrin, Denise C; McGrath, Jennifer J; Giovanniello, Sabrina; Poirier, Paul; Lambert, Marie

    2012-10-01

    Heart rate variability (HRV) is a particularly valuable quantitative marker of the flexibility and balance of the autonomic nervous system. Significant advances in software programs to automatically derive HRV have led to its extensive use in psychophysiological research. However, there is a lack of systematic comparisons across software programs used to derive HRV indices. Further, researchers report meager details on important signal processing decisions making synthesis across studies challenging. The aim of the present study was to evaluate the measurement fidelity of time- and frequency-domain HRV indices derived from three predominant signal processing software programs commonly used in clinical and research settings. Triplicate ECG recordings were derived from 20 participants using identical data acquisition hardware. Among the time-domain indices, there was strong to excellent correspondence (ICC(avg)=0.93) for SDNN, SDANN, SDNNi, rMSSD, and pNN50. The frequency-domain indices yielded excellent correspondence (ICC(avg)=0.91) for LF, HF, and LF/HF ratio, except for VLF which exhibited poor correspondence (ICC(avg)=0.19). Stringent user-decisions and technical specifications for nuanced HRV processing details are essential to ensure measurement fidelity across signal processing software programs.

  17. Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

    CERN Document Server

    Ghosh, Arindam

    2016-01-01

    Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. By the time the flow reaches the inner edge, the variation in X-rays needs not reflect the true variation of the rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale also to spread around a mean value. In HMXBs, the size of the viscous Keplerian disk is smaller & thus such a spread could be lower as compared to the LMXBs. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a full knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales when there is an ellipticity in the orbit. We study a few compact binaries using long term RXTE/ASM(1.5-12 keV) & Swift/BAT(15-50keV) data to look for such effects & to infer what the...

  18. [Determination of intrinsic alliin dissolution rates with fiber-optic sensing process analysis].

    Science.gov (United States)

    Geng, Jing; Zhang, Zi-Cheng; Zhang, Hai-Bo; Li, Xin-Xia; Chen, Jian

    2014-10-01

    The apparatus for intrinsic dissolution test recorded in United States Pharmacopeia (USP) integrating with fiber-optic drug dissolution test system (FODT) were used to real-time monitor intrinsic dissolution processes of alliin in four media which were water, solution of HCl with pH 1.2, buffer solution of acetate with pH 4.5, and buffer solution of phosphate with pH 6.8. The intrinsic dissolution rate (IDR) and the similarity factor (f2) of two intrinsic dissolution curves with two apparatuses were calculated. The IDR values of alliin with rotating disk system were 28.1.3, 33.55, 28.38 and 30.95 mg x cm(-2) x min(-1) in four media, respectively. And the IDR values of alliin with stationary disk system were 44.16, 47.07, 45.11 and 51.34 mg x cm(-2) x min(-1), respectively. The similarity factors were 56.42, 50.75, 40.30 and 40.64, respectively. The results showed that the intrinsic alliin dissolution rates were much greater than 1 mg x cm(-2) x min(-1). It inferred that alliin dissolution would not be the rate limiting step to absorption. PMID:25577881

  19. High process yield rates of thermoplastic nanofluidic devices using a hybrid thermal assembly technique.

    Science.gov (United States)

    Uba, Franklin I; Hu, Bo; Weerakoon-Ratnayake, Kumuditha; Oliver-Calixte, Nyote; Soper, Steven A

    2015-02-21

    Over the past decade, thermoplastics have been used as alternative substrates to glass and Si for microfluidic devices because of the diverse and robust fabrication protocols available for thermoplastics that can generate high production rates of the desired structures at low cost and with high replication fidelity, the extensive array of physiochemical properties they possess, and the simple surface activation strategies that can be employed to tune their surface chemistry appropriate for the intended application. While the advantages of polymer microfluidics are currently being realized, the evolution of thermoplastic-based nanofluidic devices is fraught with challenges. One challenge is assembly of the device, which consists of sealing a cover plate to the patterned fluidic substrate. Typically, channel collapse or substrate dissolution occurs during assembly making the device inoperable resulting in low process yield rates. In this work, we report a low temperature hybrid assembly approach for the generation of functional thermoplastic nanofluidic devices with high process yield rates (>90%) and with a short total assembly time (16 min). The approach involves thermally sealing a high T(g) (glass transition temperature) substrate containing the nanofluidic structures to a cover plate possessing a lower T(g). Nanofluidic devices with critical feature sizes ranging between 25-250 nm were fabricated in a thermoplastic substrate (T(g) = 104 °C) and sealed with a cover plate (T(g) = 75 °C) at a temperature significantly below the T(g) of the substrate. Results obtained from sealing tests revealed that the integrity of the nanochannels remained intact after assembly and devices were useful for fluorescence imaging at high signal-to-noise ratios. The functionality of the assembled devices was demonstrated by studying the stretching and translocation dynamics of dsDNA in the enclosed thermoplastic nanofluidic channels.

  20. Comparing OSL and CN techniques for dating fluvial terraces and estimating surface process rates in Pamir

    Science.gov (United States)

    Fuchs, Margret; Gloaguen, Richard; Pohl, Eric; Sulaymonova, Vasila; Merchel, Silke; Rugel, Georg

    2014-05-01

    The quantification of surface process rates is crucial for understanding the topographic evolution of high mountains. Spatial and temporal variations in fluvial incision and basin-wide erosion enable to decipher the role of tectonic and climatic drivers. The Pamir is peculiar in both aspects because of its location at the western end of the India-Asia collision zone, and its position at the edge of two atmospheric circulation systems, the Westerlies and the Indian Summer Monsoon. The architecture of the Panj river network indicates prominent variations across the main tectonic structures of the Pamir. The trunk stream, deflects from the predominantly westward river orientation and cuts across the southern and central Pamir domes before doubling back to the west and leaving the orogen. Optically stimulated luminescence (OSL) dating of fluvial terraces reveals short-term sedimentation along the trunk stream during the last ~25 kyr. The agreement of OSL results to new exposure ages based on the cosmogenic nuclide (CN) 10Be confirms accurate terrace age modelling and treatment of incomplete bleaching. The consistent terrace sedimentation and exposure ages suggest also fast terrace abandonment and rapid onset of incision. Considerable differences in terrace heights reflect high spatial variations of fluvial incision, independent of time interval, change in rock type or catchment increase. Highest rates of (5.9 ± 1.1) mm/yr to (10.0 ± 2.0) mm/yr describe the fluvial dynamic across the Shakhdara Dome and that related to the Darvaz Fault Zone. Lower rates of (3.9 ± 0.6) mm/yr to (4.5 ± 0.7) mm/yr indicate a transient stage north of the Yazgulom Dome. Fluvial incision decreases to rates ranging from (1.7 ± 0.3) mm/yr to (3.9 ± 0.7) mm/yr in graded river reaches associated to southern dome boundaries. The pattern agrees to the interpretation of successive upstream river captures across the southern and central Pamir domes inferred from morphometric analyses of river

  1. Micro-processing of polymers and biological materials using high repetition rate femtosecond laser pulses

    Science.gov (United States)

    Ding, Li

    High repetition rate femtosecond laser micro-processing has been applied to ophthalmological hydrogel polymers and ocular tissues to create novel refractive and diffractive structures. Through the optimization of laser irradiation conditions and material properties, this technology has become feasible for future industrial applications and clinical practices. A femtosecond laser micro-processing workstation has been designed and developed. Different experimental parameters of the workstation such as laser pulse duration, focusing lens, and translational stages have been described and discussed. Diffractive gratings and three-dimensional waveguides have been fabricated and characterized in hydrogel polymers, and refractive index modifications as large as + 0.06 have been observed within the laser-irradiated region. Raman spectroscopic studies have shown that our femtosecond laser micro-processing induces significant thermal accumulation, resulting in a densification of the polymer network and increasing the localized refractive index of polymers within the laser irradiated region. Different kinds of dye chromophores have been doped in hydrogel polymers to enhance the two-photon absorption during femtosecond laser micro-processing. As the result, laser scanning speed can be greatly increased while the large refractive index modifications remain. Femtosecond laser wavelength and pulse energy as well as water and dye concentration of the hydrogels are optimized. Lightly fixed ocular tissues such as corneas and lenses have been micro-processed by focused femtosecond laser pulses, and refractive index modifications without any tissue-breakdown are observed within the stromal layer of the corneas and the cortex of the lenses. Living corneas are doped with Sodium Fluorescein to increase the two-photon absorption during the laser micro-processing, and laser scanning speed can be greatly increased while inducing large refractive index modifications. No evidence of cell death

  2. The rate of food processing in the Oystercatcher : Food intake and energy expenditure constrained by a digestive bottleneck

    NARCIS (Netherlands)

    Kersten, M

    1996-01-01

    1. Whether food intake is determined by the maximum rate at which animals can collect food, or by the rate at which this food can be processed, will strongly affect the organization of their behaviour. We investigated whether the digestive system imposes a constraint on (I) instantaneous rate of foo

  3. Process and technique factors associated with patient ratings of session safety during psychodynamic psychotherapy.

    Science.gov (United States)

    Siegel, Deborah F; Hilsenroth, Mark J

    2013-01-01

    This study investigates the relationships between patient ratings of in-session safety with psychotherapeutic techniques and process. Ninety-four participants received Short-Term Dynamic Psychotherapy (STDP) at a university-based clinic. Patient experiences of therapeutic process were self-assessed early in treatment using the Session Evaluation Questionnaire (SEQ Stiles, 1980). Techniques implemented in session were identified using the Comparative Psychotherapy Process Scale (CPPS: Hilsenroth et al., 2005). Alliance was evaluated with the Combined Alliance Short Form-Patient Version (CASF-P; Hatcher and Barends, 1996). Safety significantly correlated with session depth, smoothness, and positivity. Safety was significantly related to the interaction of psychodynamic-interpersonal and cognitive-behavioral techniques, but to neither individual subscale Safety significantly correlated with CASF-P Total, Confident Collaboration, and Bond. Patient experiences of safety are consistent with exploration and depth of session content. Integration of some CB techniques within a psychodynamic model may facilitate a sense of safety. Safety is notably intertwined with the therapeutic relationship.

  4. Evolution of the fracture process zone in high-strength concrete under different loading rates

    Directory of Open Access Journals (Sweden)

    Cámara M.

    2010-06-01

    Full Text Available For cementitious materials, the inelastic zone around a crack tip is termed as fracture process zone (FPZ and dominated by complicated mechanism, such as microcracking, crack deflection, bridging, crack face friction, crack tip blunting by voids, crack branching, and so on. Due to the length of the FPZ is related with the characteristic length of the cementitious materials, the size, extent and location of the FPZ has been the object of countless research efforts for several decades. For instance, Cedolin et al. [1] have used an optical method based on the moiré interferometry to determine FPZ in concrete. Castro-Montero et al. [2] have applied the method of holographic interferometry to mortar to study the extension of the FPZ. The advantage of the interferometry method is that the complete FPZ can be directly observed on the surface of the sample. Swartz et al. [3] has adopted the dye penetration technique to illustrate the changing patterns observed as the crack progress from the tensile side to the compression side of the beam. Moreover, acoustic emission (AE is also an experimental technique well suited for monitoring fracture process. Haidar et al. [4] and Maji et al. [5] have studied the relation between acoustic emission characteristics and the properties of the FPZ. Compared with the extensive research on properties of the FPZ under quasi-static loading conditions, much less information is available on its dynamic characterization, especially for high-strength concrete (HSC. This paper presents the very recent results of an experimental program aimed at disclosing the loading rate effect on the size and velocity of the (FPZ in HSC. Eighteen three-point bending specimens were conducted under a wide range of loading rates from from 10-4 mm/s to 103 mm/s using either a servo-hydraulic machine or a self-designed drop-weight impact device. The beam dimensions were 100 mm 100 mm in cross section, and 420 mm in length. The initial notch

  5. High-rate dead-time corrections in a general purpose digital pulse processing system

    International Nuclear Information System (INIS)

    The abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform an accurate estimation of the true input counting rate (ICR), a fine pulse height (energy) and shape (peaking time) analysis even at high ICRs. Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obtain both the ICR and energy spectra with high throughput, while the slow analysis is used to obtain high-resolution energy spectra. A complete characterization of the counting capabilities, through both theoretical and experimental approaches, was performed. The dead-time modeling, the throughput curves, the experimental time-interval distributions (TIDs) and the counting uncertainty of the recorded events of both the fast and the slow channels, measured with a planar CdTe (cadmium telluride) detector, will be presented. The throughput formula of a series of two types of dead-times is also derived. The results of dead-time corrections, performed through different methods, will be reported and discussed, pointing out the error on ICR estimation and the simplicity of the procedure. Accurate ICR estimations (nonlinearity < 0.5%) were performed by using the time widths and the TIDs (using 10 ns time bin width) of the detected pulses up to 2

  6. Systematic design of membership functions for fuzzy-logic control: A case study on one-stage partial nitritation/anammox treatment systems.

    Science.gov (United States)

    Boiocchi, Riccardo; Gernaey, Krist V; Sin, Gürkan

    2016-10-01

    A methodology is developed to systematically design the membership functions of fuzzy-logic controllers for multivariable systems. The methodology consists of a systematic derivation of the critical points of the membership functions as a function of predefined control objectives. Several constrained optimization problems corresponding to different qualitative operation states of the system are defined and solved to identify, in a consistent manner, the critical points of the membership functions for the input variables. The consistently identified critical points, together with the linguistic rules, determine the long term reachability of the control objectives by the fuzzy logic controller. The methodology is highlighted using a single-stage side-stream partial nitritation/Anammox reactor as a case study. As a result, a new fuzzy-logic controller for high and stable total nitrogen removal efficiency is designed. Rigorous simulations are carried out to evaluate and benchmark the performance of the controller. The results demonstrate that the novel control strategy is capable of rejecting the long-term influent disturbances, and can achieve a stable and high TN removal efficiency. Additionally, the controller was tested, and showed robustness, against measurement noise levels typical for wastewater sensors. A feedforward-feedback configuration using the present controller would give even better performance. In comparison, a previously developed fuzzy-logic controller using merely expert and intuitive knowledge performed worse. This proved the importance of using a systematic methodology for the derivation of the membership functions for multivariable systems. These results are promising for future applications of the controller in real full-scale plants. Furthermore, the methodology can be used as a tool to help systematically design fuzzy logic control applications for other biological processes. PMID:27390035

  7. Systematic design of membership functions for fuzzy-logic control: A case study on one-stage partial nitritation/anammox treatment systems.

    Science.gov (United States)

    Boiocchi, Riccardo; Gernaey, Krist V; Sin, Gürkan

    2016-10-01

    A methodology is developed to systematically design the membership functions of fuzzy-logic controllers for multivariable systems. The methodology consists of a systematic derivation of the critical points of the membership functions as a function of predefined control objectives. Several constrained optimization problems corresponding to different qualitative operation states of the system are defined and solved to identify, in a consistent manner, the critical points of the membership functions for the input variables. The consistently identified critical points, together with the linguistic rules, determine the long term reachability of the control objectives by the fuzzy logic controller. The methodology is highlighted using a single-stage side-stream partial nitritation/Anammox reactor as a case study. As a result, a new fuzzy-logic controller for high and stable total nitrogen removal efficiency is designed. Rigorous simulations are carried out to evaluate and benchmark the performance of the controller. The results demonstrate that the novel control strategy is capable of rejecting the long-term influent disturbances, and can achieve a stable and high TN removal efficiency. Additionally, the controller was tested, and showed robustness, against measurement noise levels typical for wastewater sensors. A feedforward-feedback configuration using the present controller would give even better performance. In comparison, a previously developed fuzzy-logic controller using merely expert and intuitive knowledge performed worse. This proved the importance of using a systematic methodology for the derivation of the membership functions for multivariable systems. These results are promising for future applications of the controller in real full-scale plants. Furthermore, the methodology can be used as a tool to help systematically design fuzzy logic control applications for other biological processes.

  8. Modeling of organic substrate transformation in the high-rate activated sludge process.

    Science.gov (United States)

    Nogaj, Thomas; Randall, Andrew; Jimenez, Jose; Takacs, Imre; Bott, Charles; Miller, Mark; Murthy, Sudhir; Wett, Bernhard

    2015-01-01

    This study describes the development of a modified activated sludge model No.1 framework to describe the organic substrate transformation in the high-rate activated sludge (HRAS) process. New process mechanisms for dual soluble substrate utilization, production of extracellular polymeric substances (EPS), absorption of soluble substrate (storage), and adsorption of colloidal substrate were included in the modified model. Data from two HRAS pilot plants were investigated to calibrate and to validate the proposed model for HRAS systems. A subdivision of readily biodegradable soluble substrate into a slow and fast fraction were included to allow accurate description of effluent soluble chemical oxygen demand (COD) in HRAS versus longer solids retention time (SRT) systems. The modified model incorporates production of EPS and storage polymers as part of the aerobic growth transformation process on the soluble substrate and transformation processes for flocculation of colloidal COD to particulate COD. The adsorbed organics are then converted through hydrolysis to the slowly biodegradable soluble fraction. Two soluble substrate models were evaluated during this study, i.e., the dual substrate and the diauxic models. Both models used two state variables for biodegradable soluble substrate (SBf and SBs) and a single biomass population. The A-stage pilot typically removed 63% of the soluble substrate (SB) at an SRT <0.13 d and 79% at SRT of 0.23 d. In comparison, the dual substrate model predicted 58% removal at the lower SRT and 78% at the higher SRT, with the diauxic model predicting 32% and 70% removals, respectively. Overall, the dual substrate model provided better results than the diauxic model and therefore it was adopted during this study. The dual substrate model successfully described the higher effluent soluble COD observed in the HRAS systems due to the partial removal of SBs, which is almost completely removed in higher SRT systems.

  9. PREFACE: 6th International Workshop on Multi-Rate Processes and Hysteresis (MURPHYS2012)

    Science.gov (United States)

    Dimian, Mihai; Rachinskii, Dmitrii

    2015-02-01

    The International Workshop on Multi-Rate Processes and Hysteresis (MURPHYS) conference series focuses on multiple scale systems, singular perturbation problems, phase transitions and hysteresis phenomena occurring in physical, biological, chemical, economical, engineering and information systems. The 6th edition was hosted by Stefan cel Mare University in the city of Suceava located in the beautiful multicultural land of Bukovina, Romania, from May 21 to 24, 2012. This continued the series of biennial multidisciplinary conferences organized in Cork, Ireland from 2002 to 2008 and in Pécs, Hungary in 2010. The MURPHYS 2012 Workshop brought together more than 50 researchers in hysteresis and multi-scale phenomena from the United State of America, the United Kingdom, France, Germany, Italy, Ireland, Czech Republic, Hungary, Greece, Ukraine, and Romania. Participants shared and discussed new developments of analytical techniques and numerical methods along with a variety of their applications in various areas, including material sciences, electrical and electronics engineering, mechanical engineering and civil structures, biological and eco-systems, economics and finance. The Workshop was sponsored by the European Social Fund through Sectoral Operational Program Human Resources 2007-2013 (PRO-DOCT) and Stefan cel Mare University, Suceava. The Organizing Committee was co-chaired by Mihai Dimian from Stefan cel Mare University, Suceava (Romania), Amalia Ivanyi from the University of Pecs (Hungary), and Dmitrii Rachinskii from the University College Cork (Ireland). All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing. The Guest Editors wish to place on record their sincere gratitude to Miss Sarah Toms for the assistance she provided

  10. Entropy Production Rate of a One-Dimensional Alpha-Fractional Diffusion Process

    Directory of Open Access Journals (Sweden)

    Yuri Luchko

    2016-02-01

    Full Text Available In this paper, the one-dimensional α-fractional diffusion equation is revisited. This equation is a particular case of the time- and space-fractional diffusion equation with the quotient of the orders of the time- and space-fractional derivatives equal to one-half. First, some integral representations of its fundamental solution including the Mellin-Barnes integral representation are derived. Then a series representation and asymptotics of the fundamental solution are discussed. The fundamental solution is interpreted as a probability density function and its entropy in the Shannon sense is calculated. The entropy production rate of the stochastic process governed by the α-fractional diffusion equation is shown to be equal to one of the conventional diffusion equation.

  11. Dynamic testing at high strain rates of an ultrafine-grained magnesium alloy processed by ECAP

    International Nuclear Information System (INIS)

    A ZK60 magnesium alloy was processed by equal-channel angular pressing (ECAP) at 473 K to produce a grain size of ∼0.8 μm and it was then tested under dynamic conditions at strain rates up to 4.0 x 103 s-1 using a split-Hopkinson bar. The stress-strain curves in dynamic testing exhibited upwards concave curvature suggesting the occurrence of twinning. Examination by transmission electron microscopy showed that dislocation slip played a major role in the flow behavior with dislocation accumulation as the main source of work hardening. An identification of Burgers vectors revealed the extensive presence of prismatic dislocations. Rod-shaped Mg1(Zn,Zr)1 precipitates present in the as-received alloy become fragmented and overaged during ECAP.

  12. Utilization of electromigration in civil and environmental engineering - Processes, transport rates and matrix changes

    DEFF Research Database (Denmark)

    Ottosen, Lisbeth M.; Christensen, Iben Vernegren; Rörig-Dalgaard, Inge;

    2008-01-01

    Electromigration (movement of ions in an applied electric field) is utilized for supply or extraction of ions from various porous materials within both civil and environmental engineering. In civil engineering, most research has been conducted on the removal of chlorides from concrete to hinder...... reinforcement corrosion while in environmental engineering remediation of heavy metal polluted soil is the issue most studied. Never the less, experiments have been conducted with utilization for several other materials and purposes within both engineering fields. Even though there are many topics of common...... interest in the use of electromigration for the two fields, there is no tradition for collaboration. The present paper is a review with the aim of pointing out areas of shared interest. Focus is laid on the purposes of the different processes, transport rates of various ions in different materials...

  13. Ar II Emission Processes and Emission Rate Coefficients in ASTRAL Helicon Plasmas

    Science.gov (United States)

    Boivin, R. F.; Gardner, A.; Kamar, O.; Kesterson, A.; Loch, S.; Munoz, J.; Ballance, C.

    2008-11-01

    Emission processes for Ar II line emission are described for low temperature plasmas (Te ASTRAL helicon plasma source using a 0.33 m monochromator and a CCD camera. ASTRAL produces Ar plasmas with the following parameters: ne = 1E11 -- 1E13 cm-3 and Te = 2 - 10 eV, B-field <= 1.3 kGauss, rf power <= 2 kWatt. RF compensated Langmuir probes are used to measure Te and ne. In this experiment, Ar II transitions are monitored as a function of Te while ne is kept constant. Experimental emission rates are obtained as a function of Te and compared to theoretical predictions. Theoretical predictions make use of the ADAS suite of codes as well as recent R-matrix electron-impact excitation calculations that includes pseudo-states contributions. Our collisional-radiative formalism assumes that the excited levels are in quasi-static equilibrium with the ground and metastable populations.

  14. Regional processes in mangrove ecosystems: Spatial scaling relationships, biomass, and turnover rates following catastrophic disturbance

    Science.gov (United States)

    Ward, G.A.; Smith, T. J.; Whelan, K.R.T.; Doyle, T.W.

    2006-01-01

    Physiological processes and local-scale structural dynamics of mangroves are relatively well studied. Regional-scale processes, however, are not as well understood. Here we provide long-term data on trends in structure and forest turnover at a large scale, following hurricane damage in mangrove ecosystems of South Florida, U.S.A. Twelve mangrove vegetation plots were monitored at periodic intervals, between October 1992 and March 2005. Mangrove forests of this region are defined by a -1.5 scaling relationship between mean stem diameter and stem density, mirroring self-thinning theory for mono-specific stands. This relationship is reflected in tree size frequency scaling exponents which, through time, have exhibited trends toward a community average that is indicative of full spatial resource utilization. These trends, together with an asymptotic standing biomass accumulation, indicate that coastal mangrove ecosystems do adhere to size-structured organizing principles as described for upland tree communities. Regenerative dynamics are different between areas inside and outside of the primary wind-path of Hurricane Andrew which occurred in 1992. Forest dynamic turnover rates, however, are steady through time. This suggests that ecological, more-so than structural factors, control forest productivity. In agreement, the relative mean rate of biomass growth exhibits an inverse relationship with the seasonal range of porewater salinities. The ecosystem average in forest scaling relationships may provide a useful investigative tool of mangrove community biomass relationships, as well as offer a robust indicator of general ecosystem health for use in mangrove forest ecosystem management and restoration. ?? Springer 2006.

  15. Investigation of fatigue crack growth rate of Al 5484 ultrafine grained alloy after ECAP process

    Energy Technology Data Exchange (ETDEWEB)

    Brynk, Tomasz; Rasinski, Marcin; Pakiela, Zbigniew; Kurzydlowski, Krzysztof J. [Faculty of Materials Science and Engineering, Warsaw University of Technology (Poland); Olejnik, Lech [Faculty of Production Engineering, Warsaw University of Technology (Poland)

    2010-05-15

    During the last decade equal-channel angular pressing (ECAP) has emerged as a widely used fabrication route of ultrafine-grained (UFG) metals and alloys. Enhanced mechanical properties of UFG materials produced by severe plastic deformation, with a grain size smaller than 1 {mu}m, have been reported in a large number of publications. However, the higher strength does not imply higher resistance to fatigue both high- and low-cyclic. In fact, due to reduced plasticity, higher fatigue crack propagation rates are reported for UFG materials, particularly in low-amplitude range. The aim of this work was to investigate fatigue crack propagation in samples of Al 5483 alloy subjected to ECAP treatment. Because of small dimensions of the coupons processed by ECAP, non-standard, mini-samples were used in a crack propagation tests. Two test procedures were used to estimate stress intensity factor (K). The first was based on optical measurements of crack length from images recorded during the test. The second method was based on digital image correlation (DIC), which was used to determine K value directly from displacement field near the crack tip. Comparison of these two methods is made and the relationship between the intensity of ECAP process (measured in terms of the number of ECAP passes) and fatigue crack propagation rates proposed. In addition to fatigue resistance, the results of tensile tests carried out with mini-samples are presented. Applicability of such samples in the investigations of the mechanical properties of UFG materials is discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. Utilization of electromigration in civil and environmental engineering--processes, transport rates and matrix changes.

    Science.gov (United States)

    Ottosen, Lisbeth M; Christensen, Iben V; Rorig-Dalgård, Inge; Jensen, Pernille E; Hansen, Henrik K

    2008-07-01

    Electromigration (movement of ions in an applied electric field) is utilized for supply or extraction of ions from various porous materials within both civil and environmental engineering. In civil engineering, most research has been conducted on the removal of chlorides from concrete to hinder reinforcement corrosion while in environmental engineering remediation of heavy metal polluted soil is the issue most studied. Never the less, experiments have been conducted with utilization for several other materials and purposes within both engineering fields. Even though there are many topics of common interest in the use of electromigration for the two fields, there is no tradition for collaboration. The present paper is a review with the aim of pointing out areas of shared interest. Focus is laid on the purposes of the different processes, transport rates of various ions in different materials and on changes in the matrix itself. Desorption and dissolution of the target elements into ionic form is a key issue to most of the processes, and can be the limiting step. The removal rate is generally below 1 cm day(- 1), but it can be much less than 1 mm day(- 1) when desorption is slow and insufficient. Matrix changes occurs under the action of the applied electric field and it includes both physico-chemical and hydrological changes. Some of the solid phases is weathered and new can be formed. Increased fundamental understanding of the effects and side effects, when applying the electric field to a porous material, can lead to improvement of the known technologies and possibly to new applications.

  17. Isotopic Monitoring of N2O Emissions from Wastewater Treatment: Evidence for N2O Production Associated with Anammox Metabolism?

    Science.gov (United States)

    Harris, E. J.; Wunderlin, P.; Joss, A.; Emmenegger, L.; Kipf, M.; Wolf, B.; Mohn, J.

    2015-12-01

    Microbial production is the major source of N2O, the strongest greenhouse gas produced within the nitrogen cycle, and the most important stratospheric ozone destructant released in the 21st century. Wastewater treatment is an important and growing source of N2O, with best estimates predicting N2O emissions from this sector will have increased by >25% by 2020. Novel treatment employing partial nitritation-anammox, rather than traditional nitrification-denitrification, has the potential to achieve a neutral carbon footprint due to increased biogas production - if N2O production accounts for wastewater treatment can be applied to our understanding of N cycling in the natural environment. This study presents the first online isotopic measurements of offgas N2O from a partial-nitritation anammox reactor 1. The measured N2O isotopic composition - in particular the N2O isotopic site preference (SP = δ15Nα - δ15Nβ) - was used to understand N2O production pathways in the reactor. When N2O emissions peaked due to high dissolved oxygen concentrations, low SP showed that N2O was produced primarily via nitrifier denitrification by ammonia oxidizing bacteria (AOBs). N2O production by AOBs via NH2OH oxidation, in contrast, did not appear to be important under any conditions. Over the majority of the one-month measurement period, the measured SP was much higher than expected following our current understanding of N2O production pathways 2. SP reached 41‰ during normal operating conditions and achieved a maximum of 45‰ when nitrite was added under anoxic conditions. These results could be explained by unexpectedly strong heterotrophic N2O reduction despite low dissolved organic matter concentrations, or by an incomplete understanding of isotopic fractionation during N2O production from NH2OH oxidation by AOBs - however the explanation most consistent with all results is a previously unknown N2O production pathway associated with anammox metabolism. Harris et al. (2015

  18. Does sample rate introduce an artifact in spectral analysis of continuous processes?

    Science.gov (United States)

    Wijnants, Maarten L; Cox, R F A; Hasselman, F; Bosman, A M T; Van Orden, Guy

    2012-01-01

    Spectral analysis is a widely used method to estimate 1/f(α) noise in behavioral and physiological data series. The aim of this paper is to achieve a more solid appreciation for the effects of periodic sampling on the outcomes of spectral analysis. It is shown that spectral analysis is biased by the choice of sample rate because denser sampling comes with lower amplitude fluctuations at the highest frequencies. Here we introduce an analytical strategy that compensates for this effect by focusing on a fixed amount, rather than a fixed percentage of the lowest frequencies in a power spectrum. Using this strategy, estimates of the degree of 1/f(α) noise become robust against sample rate conversion and more sensitive overall. Altogether, the present contribution may shed new light on known discrepancies in the psychological literature on 1/f(α) noise, and may provide a means to achieve a more solid framework for 1/f(α) noise in continuous processes. PMID:23346058

  19. Littoral transport rates in the Santa Barbara Littoral Cell: a process-based model analysis

    Science.gov (United States)

    Elias, E. P. L.; Barnard, Patrick L.; Brocatus, John

    2009-01-01

    Identification of the sediment transport patterns and pathways is essential for sustainable coastal zone management of the heavily modified coastline of Santa Barbara and Ventura County (California, USA). A process-based model application, based on Delft3D Online Morphology, is used to investigate the littoral transport potential along the Santa Barbara Littoral Cell (between Point Conception and Mugu Canyon). An advanced optimalization procedure is applied to enable annual sediment transport computations by reducing the ocean wave climate in 10 wave height - direction classes. Modeled littoral transport rates compare well with observed dredging volumes, and erosion or sedimentation hotspots coincide with the modeled divergence and convergence of the transport gradients. Sediment transport rates are strongly dependent on the alongshore variation in wave height due to wave sheltering, diffraction and focusing by the Northern Channel Islands, and the local orientation of the geologically-controlled coastline. Local transport gradients exceed the net eastward littoral transport, and are considered a primary driver for hot-spot erosion.

  20. Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

    Science.gov (United States)

    Ghosh, A.; Chakrabarti, Sandip K.

    2016-09-01

    Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. Hence, by the time the flow reaches the inner edge, the variation in X-rays need not reflect the true variation of the mass supply rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale t_{{visc}} also to spread around a mean value. In high mass X-ray binaries, which are thought to be primarily wind-fed, the size of the viscous Keplerian disk is smaller and thus such a spread could be lower as compared to the low mass X-ray binaries which are primarily fed by Roche lobe overflow. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a detailed knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales, such as when there is an ellipticity in the orbit. We study a few compact binaries using long term All Sky monitor (ASM) data (1.5-12 keV) of Rossi X-ray Timing Explorer (RXTE) and all sky survey data (15-50 keV) of Swift satellites by different methods to look for such smearing effects and to infer what these results can tell us about the viscous processes inside the respective disks. We employ three different methods to seek imprints of periodicity on the X-ray variation and found that in all the cases, the location of the peak in the power density spectra is consistent with the orbital frequencies. Interestingly, in high mass X-ray binaries the peaks are sharp with high rms values, consistent with a small Keplerian disk in a wind fed system. However, in low mass X-ray binaries with larger Keplerian disk component, the peaks are spreaded out with much lower rms values. X-ray reflections, or superhump phenomena which may also cause such X-ray modulations would not be affected by the size of

  1. Study on drying and combustion process in 8rate-CFB incinerator

    Institute of Scientific and Technical Information of China (English)

    LI QingHai; ZHANG YanGuo; CHEN MeiQian; MENG AiHong; CHEN ChangHe

    2009-01-01

    The drying and combustion process in the combined grate and circulating fiuidized bed (grate-CFB)municipal solid waste (MSW) incinerator was investigated experimentally and mathematically. The drying grate bed was simulated by a muffle furnace, which could be controlled at a constant tempera-ture level. The kind of wastes, thickness of waste layer fed and temperature were chosen as the ad-justable parameters to study their effect on the drying process. The experimental results indicated that the hydrophilic wastes were more difficult to be dried than the hydrophobic wastes. The higher the temperature is the easier the waste is to be dried. The thinner waste layer is favorable to drying the waste. The pyrolysis experiment in the furnace showed that the higher temperature level could reduce the conversion rate of carbon to carbon monoxide. The semi-empirical mathematical model that in-cluded the bed material distribution subrnodel, volatile matter release submodel, carbon particle combustion submodel and so on was proposed. A 260 t/d grate-CFB incinerator was modeled and the model predicted bulk density agreed with the measured value from industrial field test. The predicted flue gas (e.g. CO2, CO) concentration deviated slightly from the industrial test data. The parameters and variables used in the model were determined by the experiments or practical field test. This model can be used to design the grate-CFB incinerator and guide its operation.

  2. The Interdependence of Plate Coupling Processes, Subduction Rate, and Asthenospheric Pressure Drop across Subducting Slabs

    Science.gov (United States)

    Royden, L.; Holt, A.; Becker, T. W.

    2015-12-01

    One advantage of analytical models, in which analytic expressions are used for the various components of the subduction system, is the efficient exploration of parameter space and identification of the physical mechanisms controlling a wide breadth of slab kinematics. We show that, despite subtle differences in how plate interfaces and boundary conditions are implemented, results for single subduction from a 3-D semi-analytical model for subduction FAST (Royden & Husson, 2006; Jagoutz et al., 2015) and from the numerical finite-element model CitcomCU (Moresi & Gurnis, 1996, Zhong et al., 2006) are in excellent agreement when plate coupling (via shear stress on the plate interface) takes place in the FAST without the development of topographic relief at the plate boundary. Results from the two models are consistent across a variety of geometries, with fixed upper plate, fixed lower plate, and stress-free plate ends. When the analytical model is modified to include the development of topography above the subduction boundary, subduction rates are greatly increased, indicating a strong sensitivity of subduction to the mode of plate coupling. Rates of subduction also correlate strongly with the asthenospheric pressure drop across the subducting slab, which drives toroidal flow of the asthenosphere around the slab. When the lower plate is fixed, subduction is relatively slow and the pressure drop from below to above the slab is large, inhibiting subduction and slab roll-back. When the upper plate is fixed and when the plate ends are stress-free, subduction rates are approximately 50% faster and the corresponding asthenospheric pressure drop from below to above the slab is small, facilitating rapid subduction. This qualitative correlation between plate coupling processes, asthenospheric pressure drop, and rates of subduction can be extended to systems with more than one subduction zone (Holt et al., 2015 AGU Fall Abstract). Jagoutz, O., Royden, L., Holt, A. & Becker, T. W

  3. Automatic processing of high-rate, high-density multibeam echosounder data

    Science.gov (United States)

    Calder, B. R.; Mayer, L. A.

    2003-06-01

    Multibeam echosounders (MBES) are currently the best way to determine the bathymetry of large regions of the seabed with high accuracy. They are becoming the standard instrument for hydrographic surveying and are also used in geological studies, mineral exploration and scientific investigation of the earth's crustal deformations and life cycle. The significantly increased data density provided by an MBES has significant advantages in accurately delineating the morphology of the seabed, but comes with the attendant disadvantage of having to handle and process a much greater volume of data. Current data processing approaches typically involve (computer aided) human inspection of all data, with time-consuming and subjective assessment of all data points. As data rates increase with each new generation of instrument and required turn-around times decrease, manual approaches become unwieldy and automatic methods of processing essential. We propose a new method for automatically processing MBES data that attempts to address concerns of efficiency, objectivity, robustness and accuracy. The method attributes each sounding with an estimate of vertical and horizontal error, and then uses a model of information propagation to transfer information about the depth from each sounding to its local neighborhood. Embedded in the survey area are estimation nodes that aim to determine the true depth at an absolutely defined location, along with its associated uncertainty. As soon as soundings are made available, the nodes independently assimilate propagated information to form depth hypotheses which are then tracked and updated on-line as more data is gathered. Consequently, we can extract at any time a "current-best" estimate for all nodes, plus co-located uncertainties and other metrics. The method can assimilate data from multiple surveys, multiple instruments or repeated passes of the same instrument in real-time as data is being gathered. The data assimilation scheme is

  4. Effect of aeration regime on N₂O emission from partial nitritation-anammox in a full-scale granular sludge reactor.

    Science.gov (United States)

    Castro-Barros, C M; Daelman, M R J; Mampaey, K E; van Loosdrecht, M C M; Volcke, E I P

    2015-01-01

    N₂O emission from wastewater treatment plants is high of concern due to the strong environmental impact of this greenhouse gas. Good understanding of the factors affecting the emission and formation of this gas is crucial to minimize its impact. This study addressed the investigation of the N₂O emission dynamics in a full-scale one-stage granular sludge reactor performing partial nitritation-anammox (PNA) operated at a N-loading of 1.75 kg NH₄⁺-N m⁻³ d⁻¹. A monitoring campaign was conducted, gathering on-line data of the N₂O concentration in the off-gas of the reactor as well as of the ammonium and nitrite concentrations in the liquid phase. The N₂O formation rate and the liquid N₂O concentration profile were calculated from the gas phase measurements. The mean (gaseous) N₂O-N emission obtained was 2.0% of the total incoming nitrogen during normal reactor operation. During normal operation of the reactor under variable aeration rate, intense aeration resulted in higher N₂O emission and formation than during low aeration periods (mean N₂O formation rate of 0.050 kg N m⁻³ d⁻¹ for high aeration and 0.029 kg N m⁻³ d⁻¹ for low aeration). Accumulation of N₂O in the liquid phase was detected during low aeration periods and was accompanied by a relatively lower ammonium conversion rate, while N₂O stripping was observed once the aeration was increased. During a dedicated experiment, gas recirculation without fresh air addition into the reactor led to the consumption of N₂O, while accumulation of N₂O was not detected. The transition from a prolonged period without fresh air addition and with little recirculation to enhanced aeration with fresh air addition resulted in the highest N₂O formation (0.064 kg N m⁻³ d⁻¹). The results indicate that adequate aeration control may be used to minimize N₂O emissions from PNA reactors.

  5. Influence of the relative deformation rate on tube processing by ultrasonic vibration drawing

    Directory of Open Access Journals (Sweden)

    Susan, M.

    2004-04-01

    Full Text Available After a brief review of the "friction reversion mechanism" during ultrasonic vibration drawing of tubes (UVD, the paper introduces a method to determine the drawing force based on the theorem of total consumed power, in the case of tube processing. The experiments performed on tubes made from 10TiNiCr180 (AISI321 austenitic stainless steel confirm the superiority of UVD technology regarding the diminution of the drawing force, the increase of the plasticity and the improvement of the safety coefficient, tendencies that are enhanced with the decrease of the relative drawing rate. The best results were obtained for the relative drawing rate of 0.12 for which the drawing force decreased with 33 %, plasticity increased with 9 % and safety coefficient with 22 %, as compared to CT.

    Después de un breve resumen del mecanismo de reversión de la fricción al estirado por vibraciones ultrasonoras (EVU, el trabajo propone un método para calcular la fuerza de estirado en base al teorema de la potencia total consumida, en el caso particular de la elaboración de tubos. Los experimentos realizados con tubos de acero inoxidable austenítico 10TiNiCr180 (AISI321 demuestran la superioridad de la tecnología EVU sobre la tecnología clásica (TC, en lo concerniente a la reducción de la fuerza de estirado, el incremento de la plasticidad y la mejora del coeficiente de seguridad, tendencias que se acentúan al diminuirse la velocidad relativa de estirado. Los mejores resultados se han obtenido en el caso de la velocidad relativa de 0,12, para la cual la fuerza de estirado se redujo, aproximadamente, un 33 %; la plasticidad se incrementó en el 9 %; y el coeficiente de seguridad aumentó un 22 % frente a la TC.

  6. Consideration of demand rate in overall equipment effetiveness (OEE on equipment with constant process time

    Directory of Open Access Journals (Sweden)

    Tay C.C.

    2013-06-01

    research should be conducted to test the possibility and to verify the definition of such performance ratio including Takt time on those processes of which its operating time is possibly to be reduced, especially those are not constant and fixed. This piece of research is temporarily done on the process where its operating time is constant from time to time and there is no ideal cycle time possible.Practical implications: The awareness of the overproduction should be emphasized and raised in the intention of pursuing higher OEE value. As the definition proposed such, the process with constant cycle time could even be defined in different performance ratio from time to time regarding to the customer demands and corresponding production rate. These two variables can be adjusted and balanced to increase the OEE value through optimization of average cycle time. Over this, optimization of average cycle time on equipment with constant operating time can be achieved through the optimization of loading number per each processing.Originality/value: The novelty of the paper is the inclusion of customer demand in obtaining OEE value of any particular equipment. Besides that, the equipment without ideal cycle time, which means those processes carried out in constant cycle time are possibly to be evaluated with performance ratio. As consequence of that, the machine utilization and capability used could be quantified and visualized using the performance ratio data of the OEE proposed.

  7. Monitoring Fetal Heart Rate during Pregnancy: Contributions from Advanced Signal Processing and Wearable Technology

    Science.gov (United States)

    Signorini, Maria G.

    2014-01-01

    Monitoring procedures are the basis to evaluate the clinical state of patients and to assess changes in their conditions, thus providing necessary interventions in time. Both these two objectives can be achieved by integrating technological development with methodological tools, thus allowing accurate classification and extraction of useful diagnostic information. The paper is focused on monitoring procedures applied to fetal heart rate variability (FHRV) signals, collected during pregnancy, in order to assess fetal well-being. The use of linear time and frequency techniques as well as the computation of non linear indices can contribute to enhancing the diagnostic power and reliability of fetal monitoring. The paper shows how advanced signal processing approaches can contribute to developing new diagnostic and classification indices. Their usefulness is evaluated by comparing two selected populations: normal fetuses and intra uterine growth restricted (IUGR) fetuses. Results show that the computation of different indices on FHRV signals, either linear and nonlinear, gives helpful indications to describe pathophysiological mechanisms involved in the cardiovascular and neural system controlling the fetal heart. As a further contribution, the paper briefly describes how the introduction of wearable systems for fetal ECG recording could provide new technological solutions improving the quality and usability of prenatal monitoring. PMID:24639886

  8. Biosolids reduction by the oxic-settling-anoxic process: Impact of sludge interchange rate.

    Science.gov (United States)

    Semblante, Galilee U; Hai, Faisal I; Bustamante, Heriberto; Guevara, Nelly; Price, William E; Nghiem, Long D

    2016-06-01

    The impact of sludge interchange rate (SIR) on sludge reduction by oxic-settling-anoxic (OSA) process was investigated. The sludge yield of an OSA system (a sequencing batch reactor, SBR, integrated with external anoxic reactors) was compared to that of a control (an SBR attached to a single-pass aerobic digester). SIR (%) is the percentage by volume of sludge returned from the external reactor into the main bioreactor of the OSA, and was varied from 0% to 22%. OSA achieved greater sludge reduction when fed with unsettled sewage (sCOD=113mg/L) rather than settled sewage (sCOD=60mg/L). The SIR of 11% resulted in the highest OSA performance. At the optimum SIR, higher volatile solids destruction and nitrification/denitrification (i.e., conversion of destroyed volatile solids into inert forms) were observed in the external anoxic and intermittently aerated (i.e., aerobic/anoxic) reactors, respectively. Denitrification in the aerobic/anoxic reactor was inefficient without SIR. Effluent quality and sludge settleability of the main SBR were unaffected by SIR. PMID:26810193

  9. Task Balanced Workflow Scheduling Technique considering Task Processing Rate in Spot Market

    Directory of Open Access Journals (Sweden)

    Daeyong Jung

    2014-01-01

    Full Text Available Recently, the cloud computing is a computing paradigm that constitutes an advanced computing environment that evolved from the distributed computing. And the cloud computing provides acquired computing resources in a pay-as-you-go manner. For example, Amazon EC2 offers the Infrastructure-as-a-Service (IaaS instances in three different ways with different price, reliability, and various performances of instances. Our study is based on the environment using spot instances. Spot instances can significantly decrease costs compared to reserved and on-demand instances. However, spot instances give a more unreliable environment than other instances. In this paper, we propose the workflow scheduling scheme that reduces the out-of-bid situation. Consequently, the total task completion time is decreased. The simulation results reveal that, compared to various instance types, our scheme achieves performance improvements in terms of an average combined metric of 12.76% over workflow scheme without considering the processing rate. However, the cost in our scheme is higher than an instance with low performance and is lower than an instance with high performance.

  10. Comparison of ANAMMOX start-up and its synergistic effect with denitrifying with different seeding sludge sources%不同污泥源条件下ANAMMOX启动及其与反硝化协同脱氮对比

    Institute of Scientific and Technical Information of China (English)

    于德爽; 王晓霞; 李津; 李宁宁; 李伟刚

    2013-01-01

    With the influent water distribution based on the municipal sewage,two ASBRs were started-up simultaneously.With the aerobic nitrification sludge seeded into R1,the mixture of short-cut nitrification and ANAMMOX sludge with the proportion of 2∶1 seeded into R2,the feasibility and differences of ANAMMOX startup in these 2 reactors were studied.The experimental results show that seeding with different sludge sources,these two reactors were both successfully started-up,the starting time of R1was 130 days,R2 was 73 days.During the stable stage,the NH4+-N,NO2--N,TN removal rates in R1 and R2 were 95.30%,91.30%,76.28% and 96.2%,98.3%,90.1%,respectively.The degradation pattern of NO2--N,NO2--N andNO3--N in R1 and R2were similar.The major reaction both in R1 and R2 reactors was ANAMMOX,but the denitrifying reaction offering electron acceptors of NO2--N existed at the same time.After R1 and R2 reached stable,the mature sludge color,shape and microbial composition in these 2 reactors were similar,and the SEM observation showed that most of the bacteria were spherical.%采用城市生活污水配水同时启动两组ASBR,R1接种好氧硝化污泥,R2按2∶1混合接种短程硝化和厌氧氨氧化污泥,研究2个ANAMMOX反应器启动的可行性及其差异.实验结果表明,R1和R2均可成功启动ANAMMOX,R1需130 d,R2仅需73 d;稳定期R1和R2反应器NH4+-N、NO2--N和TN去除率分别达95.30%、91.30%、76.28%和96.2%、98.3%、90.1%,且周期内NH4+-N、NO2--N和NO3--N降解规律相似;R1和R2反应器发生的主要反应为厌氧氨氧化,但同时存在反硝化作用;2组反应器稳定运行后污泥颜色、形态及微生物组成相似,经SEM观察多为球状菌.

  11. Increases in Cognitive and Linguistic Processing Primarily Account for Increases in Speaking Rate with Age

    OpenAIRE

    Nip, Ignatius S. B.; Green, Jordan R.

    2013-01-01

    Age-related increases of speaking rate are not fully understood, but have been attributed to gains in biologic factors and learned skills that support speech production. This study investigated developmental changes in speaking rate and articulatory kinematics of participants aged 4 (N = 7), 7 (N = 10), 10 (N = 9), 13 (N = 7), 16 (N = 9) years and young adults (N = 11) in speaking tasks varying in task demands. Speaking rate increased with age, with decreases in pauses and articulator displac...

  12. A SMOOTH DIFFUSION RATE MODEL OF WOOD DRYING:A SIMULATION TOWARD MORE EFFICIENT PROCESS IN INDUSTRY

    Directory of Open Access Journals (Sweden)

    Edi Cahyono

    2008-01-01

    Full Text Available In this paper we consider modeling of wood drying process in an industry. The process is conducted in a kiln oven. Mathematically, the drying inside the wood is considered as an initial and boundary value problem. The model is a diffusion equation where the diffusion rate depends on the moisture content of the wood. We investigate a smooth diffusion rate and we compare the model with real data from an industry. The model shows a good agreement with the real data. Moreover, the model shows a smoother process of drying, which is more desirable by the timber and lumber industries to improve their current methods of drying.

  13. Can Two Psychotherapy Process Measures Be Dependably Rated Simultaneously? A Generalizability Study

    Science.gov (United States)

    Ulvenes, Pal G.; Berggraf, Lene; Hoffart, Asle; Levy, Raymon A.; Ablon, J. Stuart; McCullough, Leigh; Wampold, Bruce E.

    2012-01-01

    Observer ratings in psychotherapy are a common way of collecting information in psychotherapy research. However, human observers are imperfect instruments, and their ratings may be subject to variability from several sources. One source of variability can be raters' assessing more than 1 instrument at a time. The purpose of this research is to…

  14. Increases in Cognitive and Linguistic Processing Primarily Account for Increases in Speaking Rate with Age

    Science.gov (United States)

    Nip, Ignatius S. B.; Green, Jordan R.

    2013-01-01

    Age-related increases of speaking rate are not fully understood, but have been attributed to gains in biologic factors and learned skills that support speech production. This study investigated developmental changes in speaking rate and articulatory kinematics of participants aged 4 ("N" = 7), 7 ("N" = 10), 10…

  15. Numerical methods for realizing nonstationary Poisson processes with piecewise-constant instantaneous-rate functions

    DEFF Research Database (Denmark)

    Harrod, Steven; Kelton, W. David

    2006-01-01

    with piecewise-constant instantaneous rate functions, a capability that has been implemented in commercial simulation software. They test these algorithms in C programs and make comparisons of accuracy, speed, and variability across disparate rate functions and microprocessor architectures. Choice of optimal...... algorithm could not be predicted without knowledge of microprocessor architecture....

  16. Age of learning affects rate-dependent processing of stops in a second language.

    Science.gov (United States)

    Flege, J E; Schmidt, A M; Wharton, G

    1996-01-01

    The aim of this study was to assess the effect of speaking rate changes on the perception of English stop consonants by four groups of subjects: English and Spanish monolinguals, 'early' Spanish/English bilinguals who learned English in childhood, and 'late' bilinguals who learned English in adulthood. Subjects identified, and then later rated for goodness as exemplars of the English /p/ category, the members of two voice onset time (VOT) continua. The English monolinguals identified a well-defined range of VOT stimuli as English /p/, and stimuli with longer VOT values as 'exaggerated' instances of English /p/. Their goodness ratings increased as VOT increased, then showed a systematic decrease as VOT began to exceed values typical for English /p/. The English monolinguals' goodness ratings also varied systematically as a function of speaking rate, which was simulated in the two continua by varying syllable duration. The Spanish monolinguals, on the other hand, failed to consistently identify any of the stimuli as English /p/. Although speaking rate influenced their goodness ratings, the Spanish monolinguals' rate effects differed significantly from the English monolinguals'. The early bilinguals resembled the English monolinguals, and differed from the Spanish monolinguals to a greater extent than did the late Spanish/English bilinguals. This was taken as support for the hypothesis that early bilinguals are more likely than are late bilinguals to establish new phonetic categories for stop consonants in a second language. PMID:8618957

  17. Signal processing of MEMS gyroscope arrays to improve accuracy using a 1st order Markov for rate signal modeling.

    Science.gov (United States)

    Jiang, Chengyu; Xue, Liang; Chang, Honglong; Yuan, Guangmin; Yuan, Weizheng

    2012-01-01

    This paper presents a signal processing technique to improve angular rate accuracy of the gyroscope by combining the outputs of an array of MEMS gyroscope. A mathematical model for the accuracy improvement was described and a Kalman filter (KF) was designed to obtain optimal rate estimates. Especially, the rate signal was modeled by a first-order Markov process instead of a random walk to improve overall performance. The accuracy of the combined rate signal and affecting factors were analyzed using a steady-state covariance. A system comprising a six-gyroscope array was developed to test the presented KF. Experimental tests proved that the presented model was effective at improving the gyroscope accuracy. The experimental results indicated that six identical gyroscopes with an ARW noise of 6.2 °/√h and a bias drift of 54.14 °/h could be combined into a rate signal with an ARW noise of 1.8 °/√h and a bias drift of 16.3 °/h, while the estimated rate signal by the random walk model has an ARW noise of 2.4 °/√h and a bias drift of 20.6 °/h. It revealed that both models could improve the angular rate accuracy and have a similar performance in static condition. In dynamic condition, the test results showed that the first-order Markov process model could reduce the dynamic errors 20% more than the random walk model.

  18. Sex-specific age-related changes of information processing rate indicators during childhood and adolescence.

    Science.gov (United States)

    Zebec, Mislav S; Budimir, Sanja; Merkas, Marina; Szirovicza, Lajos; Zivicnjak, Miroslav

    2014-06-01

    Despite the relevant findings on non-average information processing rate (IPR) indicators-intelligence relation, and on age-related changes of some of these indicators during aging, the research on sex-specific age-related changes of these indicators during childhood and adolescence are lacking. In a transversal study, 1197 school children (598 girls) aged 8-18 have been individually measured on 5 IPR indicators--two averages (mean_t, median_t) and three non-averages (min_t, max_t, sd_t). The results corroborated the expected non-linear changes of average IPR indicators in the observed developmental period, whereby the sex difference in related developmental patterns was detected: marked age-related decrement in girls ceased at the age of 12, and in boys around the age of 13-14, after which progress in both sexes gradually ceased by the age of 18 and was less pronounced in girls. Generally similar non-linear age-related decrements of non-average indicators were registered, but they showed mutual intensity differences at specific ages and sex difference in developmental patterns was detected, analogously to average indicators. Systematic sex differences in the whole observed period were obtained only in two non-average indicators: girls showed minor sd_t and boys showed minor min_t. In specific age groups, a number of sex differences were obtained that are explainable by two possible mechanisms: earlier maturation in girls and sex bias of the IPR task content. The justifiability of separate, average and non-average, IPR indicators application was corroborated by their distribution form differences, by mutual, predominantly low and medium correlations, by the different intensity of their developmental changes and by their different ability to detect sex differences. For all registered phenomena, the theoretical and/or empirical explanations were offered from the domain of sex specific intellectual, motor and neural development, and it has been shown that non

  19. Exact solutions for the entropy production rate of several irreversible processes.

    Science.gov (United States)

    Ross, John; Vlad, Marcel O

    2005-11-24

    We investigate thermal conduction described by Newton's law of cooling and by Fourier's transport equation and chemical reactions based on mass action kinetics where we detail a simple example of a reaction mechanism with one intermediate. In these cases we derive exact expressions for the entropy production rate and its differential. We show that at a stationary state the entropy production rate is an extremum if and only if the stationary state is a state of thermodynamic equilibrium. These results are exact and independent of any expansions of the entropy production rate. In the case of thermal conduction we compare our exact approach with the conventional approach based on the expansion of the entropy production rate near equilibrium. If we expand the entropy production rate in a series and keep terms up to the third order in the deviation variables and then differentiate, we find out that the entropy production rate is not an extremum at a nonequilibrium steady state. If there is a strict proportionality between fluxes and forces, then the entropy production rate is an extremum at the stationary state even if the stationary state is far away from equilibrium.

  20. Effects of Heating Rate on the Process Parameters of Superplastic Forming for Zr55Cu30Al10Ni5

    Institute of Scientific and Technical Information of China (English)

    YANG Fan; SHI Tielin; LIAO Guanglan

    2014-01-01

    We investigated the effects of heating rate on the process parameters of superplastic forming for Zr55Cu30Al10Ni5 by differential scanning calorimetry. The continuous heating and isothermal annealing analyses suggested that the temperatures of glass transition and onset crystallization are heating rate-dependent in the supercooled liquid region. Then, the time-temperature-transformation diagram under different heating rates indicates that increasing the heating rate can lead to an increase of the incubation time at the same anneal temperature in the supercooled liquid region. Based on the Arrhenius relationship, we discovered that the incubation time increases by 1.08-1.11 times with double increase of the heating rate at the same anneal temperature, and then verified it by the data of literatures and the experimental results. The obtained curve of the max available incubation time reveals that the incubation time at a certain anneal temperature in the supercooled liquid region is not infinite, and will increase with increasing heating rate until this temperature shifts out of the supercooled liquid region because of exceeding critical heating rate. It is concluded that heating rate must be an important processing parameter of superplastic forming for Zr55Cu30Al10Ni5.

  1. Effect of sodium injection rate in reduction process on characteristics of tantalum powders

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The paper presents a research the effect of sodium injection rate in a melt containing potassium tantalum fluoride and a flux on morphology and characteristics of tantalum powders obtained by sodium reduction.

  2. FLUVIAL PROCESSES AND SEDIMENT SCOUR RATE OF THE YELLOW RIVER UNDER ACTION OF UNSTEADY FLOWS

    Institute of Scientific and Technical Information of China (English)

    Yong-Nian XU; Zhi-Yong LIANG; Zhao-Yin WANG

    2001-01-01

    Riverbed scour of the main channel by floods in the Yellow River and its tributaries was investigated, including scour by hyper-concentrated floods. Flood scour usually causes variation of river cross-sections in a way similar to that occured when the sediment inflow is less than the sediment-laden capacity. Scour rate equation for the main channel derived based on the momentum and continuous equations was verified by field data. This equation indicates that unsteady flow scour rate is proportional to the flow density, the velocity of the flood peak, the rising rate of flow discharge per unit width, and so on. The Maximum scour depth after a flood could be predicted by the scour rate equation proposed in this paper.

  3. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal

    OpenAIRE

    Addison, Paul S.

    2016-01-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time–frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine t...

  4. Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

    OpenAIRE

    Yung-Tse Hung; Michel Torrijos; Cata Saady, Noori M.; Rajinikanth Rajagopal; Joseph V. Thanikal

    2013-01-01

    This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB) reactor, hybrid systems etc.; op...

  5. Modeling Nucleation, Growth, and Ostwald Ripening in Crystallization Processes: A Comparison between Population Balance and Kinetic Rate Equation

    OpenAIRE

    Vetter, Thomas; Iggland, Martin; Ochsenbein, David R; Haenseler, Flurin S; Mazzotti, Marco

    2013-01-01

    In this work, we investigate a comprehensive model describing nucleation, growth and Ostwald ripening based on the kinetic rate equation and compare it to commonly used population balance equation models that either describe nucleation and crystal growth or crystal growth and Ostwald ripening. The kinetic rate equation gives a microscopic description of crystallization, i.e., the process is seen as an attachment and detachment of crystals of different sizes to and from each other, thereby cha...

  6. Nonequilibrium thermodynamics transport and rate processes in physical, chemical and biological systems

    CERN Document Server

    Demirel, Yasar

    2014-01-01

    Natural phenomena consist of simultaneously occurring transport processes and chemical reactions. These processes may interact with each other and may lead to self-organized structures, fluctuations, instabilities, and evolutionary systems. Nonequilibrium Thermodynamics, 3rd edition emphasizes the unifying role of thermodynamics in analyzing the natural phenomena. This third edition updates and expands on the first and second editions by focusing on the general balance equations for coupled processes of physical, chemical, and biological systems. The new edition contains a new chapte

  7. Impact of Heating Rate During Exposure of Laser Molten Parts on the Processing Window of PA12 Powder

    Science.gov (United States)

    Drummer, Dietmar; Drexler, Maximilian; Wudy, Katrin

    The additive component manufacturing by selective beam melting of thermoplastic polymer powders can be divided essentially into the following sub-processes: Powder coating, exposure and material consolidation. The mechanical and geometrical properties of a part produced by the selective melting of polymer powders depend toa large extent on these sub-processes. To increase process repeatability basic knowledge about the mutual interactions within the sub-process is of major interest. In the following article the exposure process is focused. Therefore the time dependent energy input into the powder bed is analyzed in its impact on the usable processing window of PA12powder. Thereby parameters like surface temperature, density and strength of molten layers as well as complex body specimens are quantified for varying exposure heating rates. Therefore methods of statistical design of experiments are used. Due to these investigations the derivation of new, the time dependent material behavior of polymers fitting processing strategies is possible.

  8. (n,{gamma}) and (p,{gamma}) rates for s- and p-process nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kaeppeler, F. [Forschungszentrum Karlsruhe, Karlsruhe (Germany)

    1998-06-01

    The late stages of stellar evolution are characterized by a series of nucleosynthesis events. With respect to the heavy elements, these are the s process associated with the helium burning layers in Red Giant stars as well as the r and p processes which occur in supernova explosions. In contrast to the explosive scenarios, the nuclear physics data for s-process studies can be determined in laboratory experiments as illustrated at few recent examples. The application of these techniques to measurements of relevance for the p process are also discussed. (orig.)

  9. Effect of population aging on the international organ donation rates and the effectiveness of the donation process.

    Science.gov (United States)

    Cuende, N; Cuende, J I; Fajardo, J; Huet, J; Alonso, M

    2007-06-01

    This study analyzed the effect of population aging on organ donation for transplants in 43 countries and on the effectiveness of the donation process by comparing the results between Spain and the United States. The percentage of the population aged 65 or over accounted for 33% of the difference in the donation rates between the countries and for 91% of the variation in the rates after age adjustment. However, the level of aging of the Spanish (16.5%) and American (12.3%) populations failed to account for the percentages of deceased donors 65 or over (28% vs. 10%), due to the different age-specific donation rates, much higher in Spain above 50 years. These differences lead to a higher effectiveness of the process in the United States (3.1 transplanted organs per donor vs. 2.5 in Spain), though at lower rates of transplant per million population (73 vs. 87). We conclude that older populations have a greater donation potential as donation rates are strongly associated with population aging. It should therefore be mandatory to adjust donation rates for age before making comparisons. Additionally, effectiveness decreases with older donors, so age should be considered when establishing standards relating to organ donation and effectiveness of the process. PMID:17430401

  10. Building the Method to Determine the Rate of Freezing Water in Penaeus monodon of the Freezing Process

    Directory of Open Access Journals (Sweden)

    Nguyen Tan Dzung

    2012-10-01

    Full Text Available The method of determination the rate of freezing water in Penaeus monodon of freezing process was established on base the equation of energy balance in warming up process Penaeus monodon after freezing to determine specific heat of Penaeus monodon. The result obtained was built the mathematical model (19 to determine the rate of freezing water according to the freezing temperature of Penaeus monodon. The results indicated that when water was completely frozen (ω = 1 or 100%, the optimal freezing temperature of Penaeus monodon was-22.00°C.

  11. Scaling in Rate-Changeable Birth and Death Processes with Random Removals

    Institute of Scientific and Technical Information of China (English)

    KE Jian-Hong; LIN Zhen-Quan; CHEN Xiao-Shuang

    2009-01-01

    We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(t) an aggregate of any size is randomly removed. We then analytically investigate the kinetic evolution of the model by means of the rate equation. The results show that the scaling behavior of the aggregate size distribution is dependent crucially on the net birth rate I(t)-J(t) as well as the birth rate I(t). The aggregate size distribution can approach a standard or modified scaling form in some cases, but it may take a scale-free form in other cases. Moreover, the species can survive finally only if either I(t) - J(t) ≥ P(t) or [J(t) + P(t) - I(t)]t (≌) 0 at t > 1; otherwise, it will become extinct.

  12. Use of Flow Cytometry to Measure Biogeochemical Rates and Processes in the Ocean

    Science.gov (United States)

    Lomas, Michael W.; Bronk, Deborah A.; van den Engh, Ger

    2011-01-01

    An important goal of marine biogeochemists is to quantify the rates at which elements cycle through the ocean's diverse microbial assemblage, as well as to determine how these rates vary in time and space. The traditional view that phytoplankton are producers and bacteria are consumers has been found to be overly simplistic, and environmental metagenomics is discovering new and important microbial metabolisms at an accelerating rate. Many nutritional strategies previously attributed to one microorganism or functional group are also or instead carried out by other groups. To tease apart which organism is doing what will require new analytical approaches. Flow cytometry, when combined with other techniques, has great potential for expanding our understanding of microbial interactions because groups can be distinguished optically, sorted, and then collected for subsequent analyses. Herein, we review the advances in our understanding of marine biogeochemistry that have arisen from the use of flow cytometry.

  13. Collaborative Project: Understanding the Chemical Processes tat Affect Growth rates of Freshly Nucleated Particles

    Energy Technology Data Exchange (ETDEWEB)

    McMurry, Peter [Univ. of Minnesota, Minneapolis, MN (United States); Smuth, James [University Corporation for Atmospheric Research, Irvine, CA (United States)

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate.

  14. Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

    Directory of Open Access Journals (Sweden)

    Yung-Tse Hung

    2013-03-01

    Full Text Available This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB reactor, hybrid systems etc.; operational challenges, mass transfer considerations, energy production estimation, toxicity, modeling, technology assessment and recommendations for successful operation

  15. Single-chamber process development of microcrystalline sicicon solar cells and high-rate deposited intrinsic layers

    OpenAIRE

    Graf, Urs Samuel; Shah, Arvind

    2005-01-01

    The "Micromorph" tandem solar cell concept consisting of an amorphous and a microcrystalline silicon solar cell is considered to be one of the most promising concepts for the next solar cell generation. To translate this concept into action, efficient industrial processes have to be developed. Thereby important issues have to be considered, such as e.g. the development of an economical single-chamber process and the achievement of high deposition rates for intrinsic microcrystalline silicon (...

  16. Diagnostic criteria and adjudication process both determine published event-rates : The ACTION trial experience

    NARCIS (Netherlands)

    Kirwan, Bridget-Anne; Lubsen, Jacobus; de Brouwer, Sophie; Danchin, Nicolas; Battler, Alexander; de Luna, Antonio Bayes; Dunselman, Peter H. J. M.; Glasser, Stephen; Koudstaal, Peter J.; Sutton, George; van Dalen, Frederik J.; Poole-Wilson, Philip A.

    2007-01-01

    Objective: Few trials report event-adjudication procedures in detail. Using data from the ACTION (A Coronary disease Trial Investigating Outcome with Nifedipine GITS) study, we compared the impact on event-rates of an adjudication strategy based on systematic screening of all reported serious advers

  17. The Relationship between Drainage Density, Erosion Rate, and Hilltop Curvature: Implications for Sediment Transport Processes

    Science.gov (United States)

    Clubb, F. J.; Mudd, S. M.; Attal, M.; Milodowski, D. T.; Grieve, S. W. D.

    2015-12-01

    Drainage density is a fundamental landscape metric which describes the extent of the fluvial network. How drainage density varies with erosion rate controls the transit time of water and sediment through catchments, influencing the rate of flood response and biogeochemical cycling. This relationship also has profound implications for landscape response to transient forcing. We extract drainage density for five field sites in the USA with a wide range of climatic and lithological characteristics: Feather River, CA; San Gabriel Mountains, CA; Boulder Creek, CO; Guadalupe Mountains, NM; and Haddington Creek, ID. We find that there is a significant positive relationship between drainage density and erosion rate across every field site. These relationships suggest a non-linear relationship between erosion rates and channel slope with an exponent greater than 1. These results are supported by numerical modeling using the Channel-Hillslope Integrated Landscape Development (CHILD) model. Our modeling results also suggest that non-linear sediment transport fundamentally affects the dominant length scales forming ridges and valleys.

  18. TOC, ATP AND RESPIRATION RATE AS CONTROL PARAMETERS FOR THE ACTIVATED SLUDGE PROCESS

    Science.gov (United States)

    This research was conducted to determine the feasibility of using TOC, ATP and respiration rates as tools for controlling a complete mix activated sludge plant handling a significant amount of industrial waste. Control methodology was centered on using F/M ratio which was determi...

  19. Using a Whole-stream Approach to Quantify Headwater Yedoma DOC Processing Rates in NE Siberia, Russia

    Science.gov (United States)

    Heslop, J.; Walter Anthony, K. M.; Davydova, A.; Davydov, S. P.; Zimov, N.

    2015-12-01

    Climate warming triggers the release of permafrost organic carbon (OC) via permafrost thaw and erosion, exporting large amounts of terrestrial C to aquatic environments and making previously frozen OC from a range of soil depths available for microbial processing. It is estimated 210-476 Pg C is stored in deep, ice-rich loess-dominated soils referred to as yedoma. Yedoma is extensive in NE Siberia and Alaska, where it underlies an area of over 1,000,000 km2 and averages 25 m in thickness. Recent research suggests ancient (Pleistocene-aged) permafrost OC, such as yedoma OC, is rapidly and preferentially utilized by microbial communities in Arctic headwater streams. We utilized a combination of short-term laboratory incubations and a whole-stream approach to examine permafrost-derived dissolved organic carbon (DOC) uptake, processing, and transport rates in a small stream which drains yedoma uplands in Cherskii, NE Siberia. Short-term incubations were conducted on permafrost leachates mixed with stream water to quantify microbial processing rates of permafrost-derived DOC from leachates made with surface (0-15 cm), shallow (70-100 cm), and deep (<2 m) yedoma sediments. In addition, we conducted whole-stream DOC release experiments to quantify permafrost DOC uptake length, rate, and velocity. DOC composition from samples collected during both the incubations and the nutrient-release experiments was characterized using absorbance measurements (SUVA254 and SR) and florescence spectrometry (EEMs) to quantify how DOC composition correlates to and changes with permafrost DOC bioavailability and processing parameters. Preliminary results suggest DOC processing rates may be highest in leachates made from surface sediments, which receive fresh OC input from modern ecosystems, and from deep sediments, which contain ancient, previously immobile OC. Shallow permafrost OC, which experiences degradation from annual freeze-thaw cycles without receiving fresh OC input, may have the

  20. Seasonal variations in ectotherm growth rates: Quantifying growth as an intermittent non steady state compensatory process

    Science.gov (United States)

    Guarini, J.-M.; Chauvaud, Laurent; Cloern, J.E.; Clavier, J.; Coston-Guarini, J.; Patry, Y.

    2011-01-01

    Generally, growth rates of living organisms are considered to be at steady state, varying only under environmental forcing factors. For example, these rates may be described as a function of light for plants or organic food resources for animals and these could be regulated (or not) by temperature or other conditions. But, what are the consequences for an individual's growth (and also for the population growth) if growth rate variations are themselves dynamic and not steady state? For organisms presenting phases of dormancy or long periods of stress, this is a crucial question. A dynamic perspective for quantifying short-term growth was explored using the daily growth record of the scallop Pecten maximus (L.). This species is a good biological model for ectotherm growth because the shell records growth striae daily. Independently, a generic mathematical function representing the dynamics of mean daily growth rate (MDGR) was implemented to simulate a diverse set of growth patterns. Once the function was calibrated with the striae patterns, the growth rate dynamics appeared as a forced damped oscillation during the growth period having a basic periodicity during two transitory phases (mean duration 43. days) and appearing at both growth start and growth end. This phase is most likely due to the internal dynamics of energy transfer within the organism rather than to external forcing factors. After growth restart, the transitory regime represents successive phases of over-growth and regulation. This pattern corresponds to a typical representation of compensatory growth, which from an evolutionary perspective can be interpreted as an adaptive strategy to coping with a fluctuating environment. ?? 2011 Elsevier B.V.

  1. Reliability of the peer-review process for adverse event rating.

    Directory of Open Access Journals (Sweden)

    Alan J Forster

    Full Text Available BACKGROUND: Adverse events are poor patient outcomes caused by medical care. Their identification requires the peer-review of poor outcomes, which may be unreliable. Combining physician ratings might improve the accuracy of adverse event classification. OBJECTIVE: To evaluate the variation in peer-reviewer ratings of adverse outcomes; determine the impact of this variation on estimates of reviewer accuracy; and determine the number of reviewers who judge an adverse event occurred that is required to ensure that the true probability of an adverse event exceeded 50%, 75% or 95%. METHODS: Thirty physicians rated 319 case reports giving details of poor patient outcomes following hospital discharge. They rated whether medical management caused the outcome using a six-point ordinal scale. We conducted latent class analyses to estimate the prevalence of adverse events as well as the sensitivity and specificity of each reviewer. We used this model and Bayesian calculations to determine the probability that an adverse event truly occurred to each patient as function of their number of positive ratings. RESULTS: The overall median score on the 6-point ordinal scale was 3 (IQR 2,4 but the individual rater median score ranged from a minimum of 1 (in four reviewers to a maximum median score of 5. The overall percentage of cases rated as an adverse event was 39.7% (3798/9570. The median kappa for all pair-wise combinations of the 30 reviewers was 0.26 (IQR 0.16, 0.42; Min = -0.07, Max = 0.62. Reviewer sensitivity and specificity for adverse event classification ranged from 0.06 to 0.93 and 0.50 to 0.98, respectively. The estimated prevalence of adverse events using a latent class model with a common sensitivity and specificity for all reviewers (0.64 and 0.83 respectively was 47.6%. For patients to have a 95% chance of truly having an adverse event, at least 3 of 3 reviewers are required to deem the outcome an adverse event. CONCLUSION: Adverse event

  2. A non-permselective membrane reactor for chemical processes normally requiring strict stoichiometric feed rates of reactants

    NARCIS (Netherlands)

    Sloot, H.J.; Versteeg, G.F.; Swaaij, W.P.M. van

    1990-01-01

    A novel type of membrane reactor with separated feeding of the reactants is presented for chemical processes normally requiring strict stoichiometric feed rates of premixed reactants. The reactants are fed in the reactor to the different sides of a porous membrane which is impregnated with a catalys

  3. Integrating Spray Plane-Based Remote Sensing and Rapid Image Processing with Variable-Rate Aerial Application.

    Science.gov (United States)

    A remote sensing and variable rate application system was configured for agricultural aircraft. This combination system has the potential of providing a completely integrated solution for all aspects of aerial site-specific application and includes remote sensing, image processing and georegistratio...

  4. STM study on one-dimensional cluster formation processes of Y rate at C82 and C60 molecules

    International Nuclear Information System (INIS)

    Using scanning tunneling microscopy (STM), we have studied cluster formation processes of fullerene molecules adsorbed on the Cu(111) 1 x 1 surface. We used two endohedral metallofullerenes; Y rate at C82 and Gd rate at C82, and pristine C60. All adsorbed molecules are observed at step edges of the surface, and thus their processes can be treated with a model of one-dimensional cluster formation. When small amounts of molecules are deposited on the surface, we found that the dimer is most abundant among the clusters of Y rate at C82 while monomers are dominant in the cases of Gd rate at C82 and C60. Since Y rate at C82 has an electronic spin while the others do not, we speculated that the preferred dimer formation of Y rate at C82 is owing to an interaction of the spin. Interaction energies among fullerene molecules were estimated based on a statistical analysis of the STM data. (orig.)

  5. Long-term operation performance and variation of substrate tolerance ability in an anammox attached film expanded bed (AAFEB) reactor.

    Science.gov (United States)

    Zhang, Yanlong; Niu, Qigui; Ma, Haiyuan; He, Shilong; Kubota, Kengo; Li, Yu-You

    2016-07-01

    An anammox attached film expanded bed (AAFEB) reactor was operated to study the long-term performance and the variation of substrate tolerance ability. The results indicated that the nitrogen loading potential (NLP) was significantly enhanced from 13.56gN·(L·d)(-)(1) to 20.95gN·(L·d)(-)(1) during the stable operation period. The inhibitory concentration of 10% (IC10) for free ammonia (FA), free nitrous acid (FNA) and SNinf (diluted substrate concentration) increased from 18mg/L, 12μgL(-1) and 370mgNL(-)(1) to 31mg/L, 19μgL(-1) and 670mgNL(-)(1), respectively. However, the substrate shock of 2500mgNL(-)(1) for 24h terribly weakened the treatment performance and substrate tolerance ability of the reactor. The results of batch tests indicated that the existence of lag phase made the AAFEB reactor more vulnerable to substrate variation. The SNinf was accurate to be used to monitor the reactor performance and should be maintained below 320mgNL(-)(1) to ensure the absolute stable operation. PMID:26995619

  6. Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

    Energy Technology Data Exchange (ETDEWEB)

    Smith, James N. [NCAR, Boulder, CO (United States); McMurry, Peter H. [NCAR, Boulder, CO (United States)

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

  7. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal.

    Science.gov (United States)

    Addison, Paul S

    2016-06-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time-frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general. PMID:27382479

  8. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal

    Science.gov (United States)

    2016-01-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time–frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general. PMID:27382479

  9. UTILITY OF THE METHOD T.H.M. (MACHINE - HOUR - RATE PRODUCTION CENTURY PROCESS AUTOMATION

    Directory of Open Access Journals (Sweden)

    Cristina-Otilia, ȚENOVICI

    2014-11-01

    Full Text Available The method T.H.M. (machine - hour - rate gives greater accuracy in the factories or departments, where production is largely by machinery. In the specialty literature, the notion of price - the time - the car is defined as "œa rate calculated by dividing the budgeted or estimated overhead or labour and overhead cost attributable to a machine or group of similar machines by the appropriate number of machine hours. The hours may be the number of hours for which the machine or group is expected to be operated, the number of hours which would relate to normal working for the factory, or full capacity". In a highly mechanised cost centre, majority of the overhead expenses are incurred on account of using the machine, such as, depreciation, power, repairs and maintenance, insurance, etc. This method is currently offering the most equitable basis for absorption of overheads in machine intensive cost centres.

  10. Does sample rate introduce an artifact in spectral analysis of continuous processes?

    OpenAIRE

    Maarten eWijnants; Ralf eCox; Fred eHasselman; Anna eBosman; Guy eVan Orden

    2013-01-01

    Spectral analysis is a widely used method to estimate 1/f α noise in behavioral and physiological data series. The aim of this paper is to achieve a more solid appreciation for the effects of periodic sampling on the outcomes of spectral analysis. It is shown that spectral analysis is biased by the choice of sample rate because denser sampling comes with lower amplitude fluctuations at the highest frequencies. Here we introduce an analytical strategy that compensates for this effect by focusi...

  11. Determination of Rate of Degradation of Iron Plates Due To Rust Using Image Processing -A Review

    Directory of Open Access Journals (Sweden)

    Priyanka Choudhary

    2014-03-01

    Full Text Available Abstract: most of industries and bridges around us make use of iron for manufacturing their products. On the other hand corrosion is a natural process that deteriorates the integrity of iron surface. Therefore, rusting of iron takes place. To avoid unwanted accidents in industries and bridges, it is necessary to detect rusting in earlier stage, so that it can be prevented. Digital image processing for the detection of the rusting provides fast, accurate and objectives results. In this research paper, we have done a systematic review of algorithms that help us to detect the rust area from a metal (iron.it has been found that most of researches are bring their images, processing series in usage for this purpose due to its simplicity in implementing and due to fact the images help capturing the visual inspection process easily and due to the ground teeth. The image processing techniques explored by other peoples based on in-depth analysis, we have also proposed a novel technique to overcome the limitation.

  12. Determination of Rate of Degradation of Iron Plates due to Rust using Image Processing

    Directory of Open Access Journals (Sweden)

    Priyanka Choudhary

    2015-02-01

    Full Text Available Most of industries and bridges around us make use of iron for manufacturing their products. On the other hand corrosion is a natural process that deteriorates the integrity of iron surface. Therefore, rusting of iron takes place. To avoid unwanted accidents in industries and bridges, it is necessary to detect rusting in earlier stage, so that it can be prevented. Digital image processing for the detection of the rusting provides fast, accurate and objectives results. In this research paper, we have done a systematic review of algorithms that help us to detect the rust area from a metal (iron.it has been found that most of researches are bring their images, processing series in usage for this purpose due to its simplicity in implementing and due to fact the images help capturing the visual inspection process easily and due to the ground teeth. The image processing techniques explored by other peoples based on in-depth analysis, we have also proposed a novel technique to overcome the limitation.

  13. The Effects of Power and Feeding Rate on Production of Polyurethane Nanofiber with Electrospinning Process

    Science.gov (United States)

    Öteyaka, Mustafa Ö.; Özel, Emre; Yıldırım, M. Mustafa

    2011-12-01

    Nowadays, nanofiber made of polymers becomes popular on biomaterials research. One of the main reasons to need of nanofiber size is to mimic extracellular matrix (ECM) that play a critical role in proliferation, cell motility and intercellular signaling in vascular graft replacement. In this study polyurethane (PU) is electrospuned for 1 hour to create a scaffold under different conditions. The average diameter of the electrospun nanofibers was determined by analyzing the SEM images using imageJ analysis program. For this purpose, a 3×3 general full factorial in completely randomized design using three levels of two factors; power (W = 20, 22 and 25 Watts) and feeding rate (V = 1.00, 1.25 and 1.50 ml/h) was used to evaluate the response pattern and to determine the combined effect of independent variables. Three replicates were performed. The collected data were analyzed by using ANOVA test. Using α = 0.05, the main effects for power (W) and feeding rate (V) and the power (W)*feeding rate (V) interaction are statistically significant. Based on the statistical results of the experiment, we recommend for finer fiber 22 W and 1.00 ml/h and for less beads a 20 W and 1.50 ml/h to made PU scaffold. SEM analysis confirms a formation of random nanofiber mats.

  14. Signal Processing of MEMS Gyroscope Arrays to Improve Accuracy Using a 1st Order Markov for Rate Signal Modeling

    Science.gov (United States)

    Jiang, Chengyu; Xue, Liang; Chang, Honglong; Yuan, Guangmin; Yuan, Weizheng

    2012-01-01

    This paper presents a signal processing technique to improve angular rate accuracy of the gyroscope by combining the outputs of an array of MEMS gyroscope. A mathematical model for the accuracy improvement was described and a Kalman filter (KF) was designed to obtain optimal rate estimates. Especially, the rate signal was modeled by a first-order Markov process instead of a random walk to improve overall performance. The accuracy of the combined rate signal and affecting factors were analyzed using a steady-state covariance. A system comprising a six-gyroscope array was developed to test the presented KF. Experimental tests proved that the presented model was effective at improving the gyroscope accuracy. The experimental results indicated that six identical gyroscopes with an ARW noise of 6.2 °/√h and a bias drift of 54.14 °/h could be combined into a rate signal with an ARW noise of 1.8 °/√h and a bias drift of 16.3 °/h, while the estimated rate signal by the random walk model has an ARW noise of 2.4 °/√h and a bias drift of 20.6 °/h. It revealed that both models could improve the angular rate accuracy and have a similar performance in static condition. In dynamic condition, the test results showed that the first-order Markov process model could reduce the dynamic errors 20% more than the random walk model. PMID:22438734

  15. Signal Processing of MEMS Gyroscope Arrays to Improve Accuracy Using a 1st Order Markov for Rate Signal Modeling

    Directory of Open Access Journals (Sweden)

    Weizheng Yuan

    2012-02-01

    Full Text Available This paper presents a signal processing technique to improve angular rate accuracy of the gyroscope by combining the outputs of an array of MEMS gyroscope. A mathematical model for the accuracy improvement was described and a Kalman filter (KF was designed to obtain optimal rate estimates. Especially, the rate signal was modeled by a first-order Markov process instead of a random walk to improve overall performance. The accuracy of the combined rate signal and affecting factors were analyzed using a steady-state covariance. A system comprising a six-gyroscope array was developed to test the presented KF. Experimental tests proved that the presented model was effective at improving the gyroscope accuracy. The experimental results indicated that six identical gyroscopes with an ARW noise of 6.2 °/√h and a bias drift of 54.14 °/h could be combined into a rate signal with an ARW noise of 1.8 °/√h and a bias drift of 16.3 °/h, while the estimated rate signal by the random walk model has an ARW noise of 2.4 °/√h and a bias drift of 20.6 °/h. It revealed that both models could improve the angular rate accuracy and have a similar performance in static condition. In dynamic condition, the test results showed that the first-order Markov process model could reduce the dynamic errors 20% more than the random walk model.

  16. Reduction in Repair rate of Welding Processes by Determination & Controlling of Critical KPIVs

    Directory of Open Access Journals (Sweden)

    Faheem Yousaf

    2014-01-01

    Full Text Available Six Sigma is being Implemented all over the World as a successful Quality Improvement Methodology. Many Companies are now days are using Six Sigma as an Approach towards zero defects. This article provides a practical case study regarding the implementation of Six Sigma Project in a Welding Facility and discusses the Statistical Analysis performed for bringing the welding processes in the desired sigma Limits.DMAIC was chosen as potential Six Sigma methodology with the help of findings of this Methodology, Six Sigma Team First Identified the critical Factors affecting the Process Yield and then certain Improvement Measures were taken to improve the Capability of Individual welding Processes and also of Overall Welding Facility.   Cost of Quality was also measured to Validate the Improvement results achieved after Conducting the Six Sigma Project.

  17. Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel

    Directory of Open Access Journals (Sweden)

    Bianchi Eduardo Carlos

    2004-01-01

    Full Text Available New worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. This paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered D2 steel workpieces. Higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. Two different coolant fluids, 5% emulsion and pure oil, were used. The tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. The parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. The surfaces of the workpieces were also examined by scanning electron microscopy (SEM. The results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. The best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.

  18. Perspectives on Applying Metabolomics to Understand Carbon Cycling and Process Rates in Deep-Sea Microorganisms

    Science.gov (United States)

    Vidoudez, C.; Saghatelian, A.; Girguis, P. R.

    2014-12-01

    The metabolisms of deep-sea microorganisms are still poorly characterized. So far, transcriptomics has been the most comprehensive proxy for the whole metabolisms of these organisms, but this approach is limited because it only represents the physiological poise of the cells, and is not linearly correlated to the rates and activity of the metabolic pathways. Using thermodynamics calculations and isotopic analyses can provide constraints on activity, but there are often discrepancies between available energy and calculated active biomass. A further understanding of metabolism both at the species and community level is necessary and metabolomics provides a means of capturing a "snapshot" of cell's metabolite pools, or of following labelled substrates as they move through metabolic pathways. We present our method development and initial results from our studies of the model organism Photobacterium profundum, and the benefits and challenges in meaningfully applying these methods to natural communities. These methods open the way to better understanding deep-sea metabolism on a more comprehensive level, including reserves compounds, alternate and secondary metabolism and potentially new metabolic pathways, and moreover the response of metabolism to changes in experimental conditions and carbon source can be readily followed. These will allow a better understanding of the carbon cycling pathways and their rate in natural communities.

  19. Determination of the Neutron-Capture Rate of 17C for the R-process Nucleosynthesis

    CERN Document Server

    Heine, M; Wu, M -R; Adachi, T; Aksyutina, Y; Alcantara, J; Altstadt, S; Alvarez-Pol, H; Ashwood, N; Aumann, T; Avdeichikov, V; Barr, M; Beceiro-Novo, S; Bemmerer, D; Benlliure, J; Bertulani, C A; Boretzky, K; Borge, M J G; Burgunder, G; Caamano, M; Caesar, C; Casarejos, E; Catford, W; Cederkäll, J; Chakraborty, S; Chartier, M; Chulkov, L V; Cortina-Gil, D; Crespo, R; Pramanik, U Datta; Fernandez, P Diaz; Dillmann, I; Elekes, Z; Enders, J; Ershova, O; Estrade, A; Farinon, F; Fraile, L M; Freer, M; Freudenberger, M; Fynbo, H O U; Galaviz, D; Geissel, H; Gernhäuser, R; Göbel, K; Golubev, P; Diaz, D Gonzalez; Hagdahl, J; Heftrich, T; Heil, M; Heinz, A; Henriques, A; Holl, M; Ickert, G; Ignatov, A; Jakobsson, B; Johansson, H T; Jonson, B; Kalantar-Nayestanaki, N; Kanungo, R; Kelic-Heil, A; Knöbel, R; Kröll, T; Krücken, R; Kurcewicz, J; Kurz, N; Labiche, M; Langer, C; Bleis, T Le; Lemmon, R; Lepyoshkina, O; Lindberg, S; Machado, J; Marganiec, J; Martínez-Pinedo, G; Maroussov, V; Mostazo, M; Movsesyan, A; Najafi, A; Neff, T; Nilsson, T; Nociforo, C; Panin, V; Paschalis, S; Perea, A; Petri, M; Pietri, S; Plag, R; Prochazka, A; Rahaman, A; Rastrepina, G; Reifarth, R; Ribeiro, G; Ricciardi, M V; Rigollet, C; Riisager, K; Röder, M; Rossi, D; del Rio, J Sanchez; Savran, D; Scheit, H; Simon, H; Sorlin, O; Stoica, V; Streicher, B; Taylor, J T; Tengblad, O; Terashima, S; Thies, R; Togano, Y; Uberseder, E; Van de Walle, J; Velho, P; Volkov, V; Wagner, A; Wamers, F; Weick, H; Weigand, M; Wheldon, C; Wilson, G; Wimmer, C; Winfield, J S; Woods, P; Yakorev, D; Zhukov, M V; Zilges, A; Zuber, K

    2016-01-01

    With the R$^{3}$B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of $^{18}$C at a projectile energy around 425~AMeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of $^{17}$C into the ground state of $^{18}$C. Those data have been used to constrain theoretical calculations for transitions populating excited states in $^{18}$C. This allowed to derive the astrophysical cross section $\\sigma^{*}_{\\mathrm{n}\\gamma}$ accounting for the thermal population of $^{17}$C target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures $T_{9}\\leq{}1$~GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of $^{17}$C on the production of second- and thi...

  20. Effect of shrouding CH4 flow rate on flow field and stirring ability of coherent jet in steelmaking process.

    Science.gov (United States)

    Liu, Fuhai; Sun, Dongbai; Zhu, Rong; Su, Rongfang; Wang, Xueyi

    2016-01-01

    Characteristics of flow field and stirring ability of coherent jet with various shrouding CH4 flow rates on the molten bath were studied by combustion experiment and numerical simulation. The axial velocity and total temperature distributions of coherent jet under hot (1700 K) and cold (298 K) ambient condition were analyzed. The Eddy Dissipation Concept model was used in simulation with detail chemical kinetic mechanisms, and the numerical simulation results were agreed well with the combustion experiment in this research. Based on the simulation and experiment results, when the CH4 rate was 230, 207 and 184 Nm(3)/h, their disparity rate of average velocity and total temperature was small than 5 and 6 %, respectively, at high ambient temperature. Hence, the same stirring effect might be achieved by those three kinds of CH4 flow rates in EAF steelmaking process. According to the industrial application research, the best CH4 flow rate is 184 Nm(3)/h, which could stir molten bath well and reduce energy consumption in steelmaking process. PMID:27652186

  1. The combined effects of pre- and post-copulatory processes are masking sexual conflict over mating rate in Gerris buenoi.

    Science.gov (United States)

    Devost, E; Turgeon, J

    2016-01-01

    In polygynandrous animals, post-copulatory processes likely interfere with precopulatory sexual selection. In water striders, sexual conflict over mating rate and post-copulatory processes are well documented, but their combined effect on reproductive success has seldom been investigated. We combine genetic parentage analyses and behavioural observations conducted in a competitive reproductive environment to investigate how pre- and post-copulatory processes influence reproductive success in Gerris buenoi Kirkaldy. Precopulatory struggles had antagonistic effects on male and female reproductive success: efficiently gaining copulations was beneficial for males, whereas efficiently avoiding copulations was profitable for females. Also, high mating rates and an intermediate optimal resistance level of females supported the hypothesis of convenience polyandry. Contrary to formal predictions, high mating rates (i.e. the number of copulations) did not increase reproductive success in males or decrease reproductive success in females. Instead, the reproductive success of both sexes was higher when offspring were produced with several partners and when there were few unnecessary matings. Thus, male and female G. buenoi displayed different interests in reproduction, but post-copulatory processes were masking the effects of copulatory mating success on reproductive success. Given the high mating rates observed, sperm competition could easily counter the effect of mating rates, perhaps in interaction with cryptic female choice and/or fecundity selection. Our study presents a complex but realistic overview of sexual selection forces at work in a model organism for the study of sexual conflict, confirming that insights are gained from investigating all episodes in the reproduction cycle of polygynandrous animals.

  2. Learning control for riser-slug elimination and production-rate optimization for an offshore oil and gas production process

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2014-01-01

    Slugging flow in the offshore oil & gas production attracts lot of attention due to it's limitation of production rate, periodic overload on processing facilities, and even direct cause of emergency shutdown. This work aims at two correlated objectives: (i) Preventing slugging flow; and meanwhile......, (ii) maximizing the production rate at the riser of an offshore production platform, by manipulating a topside choke valve through a learning switching model-free PID controller. The results show good steady-state performance, though a long settling time due to the unknown reference for no slugging...

  3. Dynamic process of trace boron non-equilibrium grain boundary segregation and the effect of cooling rate

    Institute of Scientific and Technical Information of China (English)

    Ping Wu; Xinlai He; Bing Cao; Sen Chen

    2003-01-01

    The dynamic process of non-equilibrium grain boundary segregation of trace boron in Fe-40%Ni alloy during cooling andthe effect of cooling rate were investigated by boron tracking autoradiography technique. The results indicate that during coolingprocess, the amount of segregated boron on grain boundary firstly increases fast, then enters a comparatively even increasing stageand increases rapidly again at the third stage. The details of each stage varied with cooling rate are explained. When thc segregationdevelops to a certain degree, the segregated boron atoms transform fiom solute status to precipitate status.

  4. Insight into the Physical and Dynamical Processes that Control Rapid Increases in Total Flash Rate

    Science.gov (United States)

    Schultz, Christopher J.; Carey, Lawrence D.; Schultz, Elise V.; Blakeslee, Richard J.; Goodman, Steven J.

    2015-01-01

    Rapid increases in total lightning (also termed "lightning jumps") have been observed for many decades. Lightning jumps have been well correlated to severe and hazardous weather occurrence. The main focus of lightning jump work has been on the development of lightning algorithms to be used in real-time assessment of storm intensity. However, in these studies it is typically assumed that the updraft "increases" without direct measurements of the vertical motion, or specification of which updraft characteristic actually increases (e.g., average speed, maximum speed, or convective updraft volume). Therefore, an end-to-end physical and dynamical basis for coupling rapid increases in total flash rate to increases in updraft speed and volume must be understood in order to ultimately relate lightning occurrence to severe storm metrics. Herein, we use polarimetric, multi-Doppler, and lightning mapping array measurements to provide physical context as to why rapid increases in total lightning are closely tied to severe and hazardous weather.

  5. A New Process for Hot Metal Production at Low Fuel Rate - Phase 1 Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Wei-Kao Lu

    2006-02-01

    The project is part of the continuing effort by the North American steel industry to develop a coal-based, cokeless process for hot metal production. The objective of Phase 1 is to determine the feasibility of designing and constructing a pilot scale facility with the capacity of 42,000 mtpy of direct reduced iron (DRI) with 95% metallization. The primary effort is performed by Bricmont, Inc., an international engineering firm, under the supervision of McMaster University. The study focused on the Paired Straight Hearth furnace concept developed previously by McMaster University, The American Iron and Steel Institute and the US Department of Energy.

  6. MODELING COMMERCIAL PROCESSES AND CUSTOMER BEHAVIORS TO ESTIMATE THE DIFFUSION RATE OF NEW PRODUCTS

    Institute of Scientific and Technical Information of China (English)

    Alain BLOCH; Daniel KROB; Ada Suk-Fung NG

    2005-01-01

    This paper presents a generic mathematical model for depicting the diffusion of an innovative product on a given market. Our approach relies on a probabilistic modeling of each customer behavior with respect to the commercial process which is used to promote such a product. We introduce in particular the concept of coherent market that corresponds to a market which can be analyzed in a uniform way within our model. This last notion allows us to recover the classical empirical results that were discovered and widely studied by E.M. Rogers and his school. We explain finally how to use our approach as a support for analytic predictive marketing.

  7. Study of anaerobic ammonium oxidation bacterial community in the aged refuse bioreactor with 16S rRNA gene library technique.

    Science.gov (United States)

    Wang, Chao; Xie, Bing; Han, Lu; Xu, Xiaofan

    2013-10-01

    In order to investigate the anaerobic ammonium-oxidation (Anammox) nitrogen removal pathway of the aged refuse bioreactor treating landfill leachate, a lab-scale bioreactor was established and run for 35 weeks, the performance of the bioreactor and its bacterial community structure of Planctomycetes were analyzed. The results showed that the average TN removal rate of landfill leachate could be reached to 89%. 16S rRNA gene library of Planctomycetes revealed that Anammox sequences accounted for 28.3% of the total Planctomycetes sequences in the bioreactor, and previously recognized Anammox bacterium Candidatus Kuenenia stuttgartiensis was the only detected Anammox species in the reactor. It was also found that Anammox bacteria distributed at different sites of the bioreactor while mostly concentrated in the middle and low-middle part. Results above confirmed that Anammox process could happen in aged refuse bioreactor treating landfill leachate and provided an alternative nitrogen removal pathway in practical landfills.

  8. Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

    Directory of Open Access Journals (Sweden)

    Karcher Patrick

    2005-08-01

    Full Text Available Abstract This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent or form flocs/aggregates (also called granules without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL-1 can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR, packed bed reactor (PBR, fluidized bed reactor (FBR, airlift reactor (ALR, upflow anaerobic sludge blanket (UASB reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes.

  9. Mechanisms of solvent evaporation encapsulation processes: prediction of solvent evaporation rate.

    Science.gov (United States)

    Wang, J; Schwendeman, S P

    1999-10-01

    The mechanism of organic solvent evaporation during microencapsulation and its role during microsphere hardening has been investigated. Evaporation and encapsulation studies were carried out in a jacketed beaker, filled with aqueous hardening solution, which was maintained at constant temperature and constant stirring rate in the turbulent regime. Evaporation of dissolved methylene chloride (MC), ethyl acetate (EA), and acetonitrile (ACN) was examined by the decline in organic solvent concentration in the hardening bath, which was monitored by gas chromatography. The evaporation from the bath followed first-order kinetics under dilute conditions (e.g., MC hardening bath, V(-1/4), and the product of kinematic viscosity and diffusion coefficient, nu(-5/12)D (2/3)), and (2) illustrating that at constant temperature, the tendency of the evaporation system to obey liquid-side transport control follows the same order of increasing Henry's law constant (i.e., MC > EA > ACN). To establish the relationship of evaporation with microsphere hardening, the decline in MC concentration was determined in both the continuous and dispersed polymer phases during microencapsulation. By applying a mass balance with respect to MC in the hardening bath, the cumulative hardening profile of the microspheres was accurately predicted from the interpolating functions of the kinetics of MC loss from the bath with and without polymer added. These results have potential use for microsphere formulation, design of encapsulation apparatus, and scale up of microsphere production. PMID:10514360

  10. Bubble hydrodynamic influence on oxygen transfer rate at presence of cationic and anionic surfactants in electroflotation process

    Institute of Scientific and Technical Information of China (English)

    KOTTI Mariam; KSENTINI Issam; BEN MANSOUR Lassaad

    2013-01-01

    In this work, the effects of the presence of surfactants in the liquid phase and the hydrodynamic regime of the bubble flow on the oxygen transfer rate were investigated in an electroflotation process in batch mode. The volumetric mass transfer coefficient LK a and the oxygenation capacity were evaluated to improve the performances of the electroflotation process in terms of oxygena-tion. In order to evaluate the liquid-side mass transfer coefficient LK , the volumetric mass transfer coefficient LK a was dissociated into LK and the specific interfacial area (a) since the last one was obtained from the gas hold-up and the bubble diameter. The effect of Reynolds number which define the hydrodynamic of the bubble flow has been also studied. Models of LK a and LK have been established to show the effects of the hydrodynamic parameters and liquid phase characteristics on the oxygen transfer rate.

  11. Pulse shaping for all-optical signal processing of ultra-high bit rate serial data signals

    DEFF Research Database (Denmark)

    Palushani, Evarist

    ) between dispersed OTDM data and linearly chirped pump pulses. This resulted in spectral compression, enabling the OTDM tributaries to be converted directly onto a dense wavelength division multiplexing (DWDM) grid. The serial-to-parallel conversion was successfully demonstrated for up to 640-GBd OTDM......The following thesis concerns pulse shaping and optical waveform manipulation for all-optical signal processing of ultra-high bit rate serial data signals, including generation of optical pulses in the femtosecond regime, serial-to-parallel conversion and terabaud coherent optical time division...... record-high serial data rates on a single-wavelength channel. The experimental results demonstrate 5.1- and 10.2-Tbit/s OTDM data signals achieved by 16-ary quadrature amplitude modulation (16-QAM), polarization multiplexing and symbol rates as high as 640 GBd and 1.28 TBd. These signal were transmitted...

  12. Effects of aeration rate on degradation process of oil palm empty fruit bunch with kinetic-dynamic modeling.

    Science.gov (United States)

    Talib, Ahmad Tarmezee; Mokhtar, Mohd Noriznan; Baharuddin, Azhari Samsu; Sulaiman, Alawi

    2014-10-01

    The effect of different aeration rates on the organic matter (OM) degradation during the active phase of oil palm empty fruit bunch (EFB)-rabbit manure co-composting process under constant forced-aeration system has been studied. Four different aeration rates, 0.13 L min(-1) kg(DM)(-1),0.26 L min(-1) kg(DM)(-1),0.49 L min(-1) kg(DM)(-1) and 0.74 L min(-1) kg(DM)(-1) were applied. 0.26 L min(-1) kg(DM)(-1) provided enough oxygen level (10%) for the rest of composting period, showing 40.5% of OM reduction that is better than other aeration rates. A dynamic mathematical model describing OM degradation, based on the ratio between OM content and initial OM content with correction functions of moisture content, free air space, oxygen and temperature has been proposed.

  13. EXCHANGE RATE POLICY AND INFLATION IN THE PROCESS OF CURRENCY INTEGRATION IN SLOVENIA, SLOVAKIA AND ESTONIA WITH THE EUROZONE

    OpenAIRE

    Dorota Zuchowska

    2011-01-01

    Among the Central-Eastern Europe countries which joined the European Union in 2004 only three – the smallest (Slovenia, Slovakia and Estonia) – joined the Eurozone. Within these economies the process of currency integration was diversified in respect to their previously used systems of exchange rate regimes. Also experiences concerning suppressing inflation and meeting the condition of prices stability varied among them. The aim of this article is to answer the question whether the mode of th...

  14. Comparison of glomerular filtration rate measured between anterior and posterior image processing using Gates’ method in an ectopic pelvic kidney

    OpenAIRE

    Li, Na; Li, Baojun; Liang, Wenli; Zhao, Deshan

    2016-01-01

    Objective The aim of this study was to evaluate the difference in measured glomerular filtration rate (GFR) of an ectopic pelvic kidney between anterior and posterior image processing using Gates’ method of renal dynamic imaging. Methods A total of 10 patients were studied retrospectively, with a single ectopic kidney in the pelvic cavity and a contralateral kidney at its normal anatomical position confirmed by ultrasound, computed tomography, renal dynamic imaging, etc. All images of ectopic...

  15. Toward energy-neutral wastewater treatment: a high-rate contact stabilization process to maximally recover sewage organics.

    Science.gov (United States)

    Meerburg, Francis A; Boon, Nico; Van Winckel, Tim; Vercamer, Jensen A R; Nopens, Ingmar; Vlaeminck, Siegfried E

    2015-03-01

    The conventional activated sludge process is widely used for wastewater treatment, but to progress toward energy self-sufficiency, the wastewater treatment scheme needs to radically improve energy balances. We developed a high-rate contact stabilization (HiCS) reactor system at high sludge-specific loading rates (>2 kg bCOD kg(-1)TSS d(-1)) and low sludge retention times (organics than high-rate conventional activated sludge (HiCAS) and the low-rate variants of HiCS and HiCAS. The best HiCS system recovered 36% of the influent chemical energy as methane, due to the combined effects of low production of CO2, high sludge yield, and high methane yield of the produced sludge. The HiCS system imposed a feast-famine cycle and a putative selection pressure on the sludge micro-organisms toward substrate adsorption and storage. Given further optimization, it is a promising process for energy recovery from wastewater.

  16. Features of Heart Rate Variability and Early Postinfarction Remodeling Process in Patients with Recurrent Myocardial Infarction

    Directory of Open Access Journals (Sweden)

    Corina Şerban

    2013-12-01

    Full Text Available The purpose of this study was to evaluate the heart rate variability (HRV level and the features of early post-infarction left ventricular remodeling (PIR in patients with recurrent myocardial infarction (MI, which developed within six months post the initial Q-wave MI (Q-MI. Material and Methods: The study surveyed 105 male patients between 29 and 69 years of age (mean age 52.08±8.5, who underwent a Q-MI and who, for various reasons, have not undergone coronary angiography. All patients underwent echocardiography and the LVM, EDV, ESV and their indexed values, as well as the ejection fraction were determined, including Holter ECG monitoring. In the interim, analysis included the indicators recommended by the standards of measurement, physiological interpretation and clinical use of heart rate variability, such as SDNN, SDANN and RMSSD. The reduction of the total reduction of HRV was taken as SDNN≤100ms, and the marked reduction in HRV - SDNN≤50ms. Results: All the patients were divided into two groups: Group I consisted of patients who, within six months after the initial Q-wave MI, developed fatal or nonfatal reinfarction; Group II included those patients with a favorable course of the disease. The patients in both groups belonged to a somewhat similar age category. By localization of MI, occurrence of AH, as well as the incidence of LV aneurysm, both groups were comparable. However, the Group I patients in acute Q-MI showed significantly more preserved signs of residual myocardial ischemia, which was manifested as early post-infarction angina. The average values of SDNN in patients in Group I were noted to be significantly lower than that in the Group II patients. The same ratio was observed in both groups and also the indicator of SDANN, whereas the mean RMSSD values of the patients of both groups were not significantly different. The percentage of patients with reduced HRV in Group I was 1.8 times higher than that in Group II

  17. Processes and rates of rock fragment displacement on cliffs and scree slopes in an amba landscape, Ethiopia

    Science.gov (United States)

    Nyssen, J.; Poesen, J.; Moeyersons, J.; Deckers, J.; Haile, Mitiku

    2006-11-01

    Distinct rock fragment displacements occur on the ambas, or structurally determined stepped mountains of the Northern Ethiopian Highlands. This paper describes the rock fragment detachment from cliffs by rockfall, quantifies its annual rate, and identifies factors controlling rock fragment movement on the scree slopes. It further presents a conceptual model explaining rock fragment cover at the soil surface in these landscapes. In the May Zegzeg catchment (Dogu'a Tembien district, Tigray), rockfall from cliffs and rock fragment movement on debris slopes by runoff and livestock trampling were monitored over a 4-year period (1998-2001). Rockfall and rock fragment transport mainly induced by livestock trampling appear to be important geomorphic processes. Along a 1500-m long section of the Amba Aradam sandstone cliff, at least 80 t of rocks are detached yearly and fall over a mean vertical distance of 24 m resulting in a mean annual cliff retreat rate of 0.37 mm y - 1 . Yearly unit rock fragment transport rates on scree slopes ranged between 23.1 and 37.9 kg m - 1 y - 1 . This process is virtually stopped when exclosures are established. Corresponding mean rock fragment transport coefficients K are 32-69 kg m - 1 y - 1 on rangeland but only 3.9 kg m - 1 y - 1 in densely vegetated exclosures. A conceptual model indicates that besides rockfall from cliffs and argillipedoturbation, all factors and processes of rock fragment redistribution in the study area are of anthropogenic origin.

  18. A robust and cost-effective integrated process for nitrogen and bio-refractory organics removal from landfill leachate via short-cut nitrification, anaerobic ammonium oxidation in tandem with electrochemical oxidation.

    Science.gov (United States)

    Wu, Li-Na; Liang, Da-Wei; Xu, Ying-Ying; Liu, Ting; Peng, Yong-Zhen; Zhang, Jie

    2016-07-01

    A cost-effective process, consisting of a denitrifying upflow anaerobic sludge blanket (UASB), an oxygen-limited anoxic/aerobic (A/O) process for short-cut nitrification, and an anaerobic reactor (ANR) for anaerobic ammonia oxidation (anammox), followed by an electrochemical oxidation process with a Ti-based SnO2-Sb2O5 anode, was developed to remove organics and nitrogen in a sewage diluted leachate. The final chemical oxygen demand (COD), ammonia nitrogen (NH4(+)-N) and total nitrogen (TN) of 70, 11.3 and 39 (all in mg/L), respectively, were obtained. TN removal in UASB, A/O and ANR were 24.6%, 49.6% and 16.1%, respectively. According to the water quality and molecular biology analysis, a high degree of anammox besides short-cut nitrification and denitrification occurred in A/O. Counting for 16.1% of TN removal in ANR, at least 43.2-49% of TN was removed via anammox. The anammox bacteria in A/O and ANR, were in respective titers of (2.5-5.9)×10(9) and 2.01×10(10)copy numbers/(gSS).

  19. Effects of minimal processing on the respiration rate and quality of rambutan cv. ‘Rong-Rien’

    Directory of Open Access Journals (Sweden)

    Buncha Ooraikul

    2008-04-01

    Full Text Available Respiration rate at 4oC and minimal processing of rambutan cv. ‘Rong-Rien’ were investigated. Rambutan was harvested from Amphur Ban Na San, Surat Thani Province, at the stage when its skin was turning into a combination of red, green and yellow. After harvesting, the fruits were size-graded to 27-30 fruits/kg, hydrocooled to 14oC, packed with ice in Styrofoam boxes and transported to the laboratory at Prince of Songkla University within 6 h. The respiration rate of fresh rambutan fruits was monitored. For minimal processing, the fruits were soaked in warm solution (55oC of 100 ppm sodium hypochlorite for one min and immediately cooled in cold water until their internal temperature reached 14oC. The minimal process included peeling, with and without coring. The peeled and peeled and cored rambutan samples were immersed in a solution of 0.5% citric acid + 0.5% CaCl2 at 4oC for 2 min. The average respiration rates (within 6 h at 4oC of whole fruit, peeled, and peeled and cored rambutan samples were measured and found to be 122, 134 and 143 mg CO2/kg/h, respectively. These findings indicated that a preparation style as peeled rambutan without coring, nylon/LLDPE bag, storage temperature of 4.0±1oC, were suitably applied for processed rambutans. To obtain a longer extended shelf life (>12 days of minimally processed peeled rambutans, further study on food additives, including acidulants and preservative used and gas composition in modified atmosphere packaging (MAP is needed.

  20. High-rate activated sludge system for carbon management--Evaluation of crucial process mechanisms and design parameters.

    Science.gov (United States)

    Jimenez, Jose; Miller, Mark; Bott, Charles; Murthy, Sudhir; De Clippeleir, Haydee; Wett, Bernhard

    2015-12-15

    The high-rate activated sludge (HRAS) process is a technology suitable for the removal and redirection of organics from wastewater to energy generating processes in an efficient manner. A HRAS pilot plant was operated under controlled conditions resulting in concentrating the influent particulate, colloidal, and soluble COD to a waste solids stream with minimal energy input by maximizing sludge production, bacterial storage, and bioflocculation. The impact of important process parameters such as solids retention time (SRT), hydraulic residence time (HRT) and dissolved oxygen (DO) levels on the performance of a HRAS system was demonstrated in a pilot study. The results showed that maximum removal efficiencies of soluble COD were reached at a DO > 0.3 mg O2/L, SRT > 0.5 days and HRT > 15 min which indicates that minimizing the oxidation of the soluble COD in the high-rate activated sludge process is difficult. The study of DO, SRT and HRT exhibited high degree of impact on the colloidal and particulate COD removal. Thus, more attention should be focused on controlling the removal of these COD fractions. Colloidal COD removal plateaued at a DO > 0.7 mg O2/L, SRT > 1.5 days and HRT > 30 min, similar to particulate COD removal. Concurrent increase in extracellular polymers (EPS) production in the reactor and the association of particulate and colloidal material into sludge flocs (bioflocculation) indicated carbon capture by biomass. The SRT impacted the overall mass and energy balance of the high-rate process indicating that at low SRT conditions, lower COD mineralization or loss of COD content occurred. In addition, the lower SRT conditions resulted in higher sludge yields and higher COD content in the WAS.

  1. Entropic formulation for the protein folding process: hydrophobic stability correlates with folding rates

    CERN Document Server

    Molin, J P Dal

    2016-01-01

    We assume that the protein folding process follows two autonomous steps: the conformational search for the native, mainly ruled by the hydrophobic effect; and, the final adjustment stage, which eventually gives stability to the native. Our main tool of investigation is a 3D lattice model provided with a ten-letter alphabet, the stereochemical model. This model was conceived for Monte Carlo (MC) simulations when one keeps in mind the kinetic behavior of protein-like chains in solution. In order to characterize the folding characteristic time ({\\tau}) by two distinct sampling methods, first we present two sets of 10^{3} MC simulations for a fast protein-like sequence. For these sets of folding times, {\\tau} and {\\tau}_{q} were obtained with the application of the standard Metropolis algorithm (MA), and a modified algorithm (M_{q}A). The results for {\\tau}_{q}reveal two things: i) the hydrophobic chain-solvent interactions plus a set of inter-residues steric constraints are enough to emulate the first stage of t...

  2. High-resolution monitoring of bedload transport rates: a benchmark of two approaches (accelerometers and image processing)

    Science.gov (United States)

    Dhont, Blaise; Rousseau, Gauthier; Ancey, Christophe

    2016-04-01

    Experimental and field studies have shown how intermittent bedload transport can be at low flow rates. The development and validation of bedload-transport equations require high-resolution records over long periods of time. Two technologies are considered in the present investigation: image processing and accelerometers mounted on impact plates. The former has been successfully applied to monitor bedload transport in many flume experiments, and the latter has shown encouraging results at different field sites. Calibration is a major issue in both cases, and it is often difficult to assess the precision of the data collected. In our talk, we show how to calibrate and compare the performances of accelerometer and image-processing based techniques in laboratory conditions. The accelerometer is fixed on a perforated steel plate, which is placed vertically at the lower end of the flume. The vibrations due to the particles impacting the plate are recorded with a sampling frequency of 10 kHz. The proxy for bedload transport rate is chosen as the number of peaks above a fixed threshold of the recorded signal. Note that impact plates are usually set in flush with the bed, and to our knowledge, the vertical configuration presented here has not yet been documented. The experimental setup for image processing involves a video-camera that takes top-view images of the particles moving over a white board mounted at the outlet of the flume. Data storage poses an issue, which can be got round by pre-processing the images in real time. The bedload transport rate is estimated based on the number of particles that are identified on the images. The two technologies have the advantages of being cost-effective and demanding limited effort for implementation. They provide high-resolution bedload transport rates over several hours. Estimates of bedload discharge were found to be robust and accurate for low sediment transport rates. At higher rates, the sensors may saturate due the arrival

  3. Modeling two-rate adsorption kinetics: Two-site, two-species, bilayer and rearrangement adsorption processes.

    Science.gov (United States)

    Tripathi, Sumit; Tabor, Rico F

    2016-08-15

    The adsorption kinetics of many systems show apparent two-rate processes, where there appears to be resolved fast and slow adsorption steps. Such non-standard adsorption processes cannot be accounted for by conventional modeling methods, motivating new approaches. In this work, we present four different models that can account for two-rate adsorption and are based upon physically realistic processes - two adsorbing species, two surface sites having different energies, bilayer formation and molecular rearrangement modes. Each model is tested using a range of conditions, and the characteristic behavior is explored and compared. In these models, the effects of mass transport and bulk concentration are also accounted for, making them applicable in systems which are transport-limited or attachment-limited, or intermediate between the two. The applicability of these models is demonstrated by fitting exemplar experimental data for each of the four models, selecting the model on the basis of the known physical behavior of the adsorption kinetics. These models can be applied in a wide range of systems, from stagnant adsorption in large volume water treatment to highly dynamic flow conditions relevant to printing, coating and processing applications. PMID:27209397

  4. Tap density equations of granular powders based on the rate process theory and the free volume concept.

    Science.gov (United States)

    Hao, Tian

    2015-02-28

    The tap density of a granular powder is often linked to the flowability via the Carr index that measures how tight a powder can be packed, under an assumption that more easily packed powders usually flow poorly. Understanding how particles are packed is important for revealing why a powder flows better than others. There are two types of empirical equations that were proposed to fit the experimental data of packing fractions vs. numbers of taps in the literature: the inverse logarithmic and the stretched exponential. Using the rate process theory and the free volume concept under the assumption that particles will obey similar thermodynamic laws during the tapping process if the "granular temperature" is defined in a different way, we obtain the tap density equations, and they are reducible to the two empirical equations currently widely used in literature. Our equations could potentially fit experimental data better with an additional adjustable parameter. The tapping amplitude and frequency, the weight of the granular materials, and the environmental temperature are grouped into this parameter that weighs the pace of the packing process. The current results, in conjunction with our previous findings, may imply that both "dry" (granular) and "wet" (colloidal and polymeric) particle systems are governed by the same physical mechanisms in term of the role of the free volume and how particles behave (a rate controlled process). PMID:25589375

  5. Controlling and monitoring of deammonification process in moving bed biofilm reactor

    OpenAIRE

    Yang, Jingjing

    2012-01-01

    It is considered that partial nitrification combined with anammox, named deammonification, is more environmental friendly compared with conventional nitrification/denitrification due to decrease energy requirement, low emission of CO2 and N2O. Dissolved oxygen (DO) is a significant parameter influencing the nitrogen removal rate and activity of different microorganisms. A proper level of DO concentration is needed to allow ammonium oxidizing bacteria (AOB) to produce a sufficient amount of NO...

  6. High-rate x-ray spectroscopy in mammography with a CdTe detector: A digital pulse processing approach

    Energy Technology Data Exchange (ETDEWEB)

    Abbene, L.; Gerardi, G.; Principato, F.; Del Sordo, S.; Ienzi, R.; Raso, G. [Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy) and INAF/IASF Palermo, Via Ugo La Malfa 153, 90146 Palermo (Italy); Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy); INAF/IASF Palermo, Via Ugo La Malfa 153, 90146 Palermo (Italy); Istituto di Radiologia, Policlinico, 90100 Palermo (Italy); Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy)

    2010-12-15

    Purpose:Direct measurement of mammographic x-ray spectra under clinical conditions is a difficult task due to the high fluence rate of the x-ray beams as well as the limits in the development of high resolution detection systems in a high counting rate environment. In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate x-ray spectroscopy in mammography. Methods: The DPP system performs a digital pile-up inspection and a digital pulse height analysis of the detector signals, digitized through a 14-bit, 100 MHz digitizer, for x-ray spectroscopy even at high photon counting rates. We investigated on the response of the digital detection system both at low (150 cps) and at high photon counting rates (up to 500 kcps) by using monoenergetic x-ray sources and a nonclinical molybdenum anode x-ray tube. Clinical molybdenum x-ray spectrum measurements were also performed by using a pinhole collimator and a custom alignment device. Results: The detection system shows excellent performance up to 512 kcps with an energy resolution of 4.08% FWHM at 22.1 keV. Despite the high photon counting rate (up to 453 kcps), the molybdenum x-ray spectra, measured under clinical conditions, are characterized by a low number of pile-up events. The agreement between the attenuation curves and the half value layer values, obtained from the measured spectra, simulated spectra, and from the exposure values directly measured with an ionization chamber, also shows the accuracy of the measurements. Conclusions: These results make the proposed detection system a very attractive tool for both laboratory research and advanced quality controls in mammography.

  7. The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage.

    Science.gov (United States)

    Ma, Bin; Zhang, Shujun; Zhang, Liang; Yi, Peng; Wang, Junmin; Wang, Shuying; Peng, Yongzhen

    2011-09-01

    The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage was examined in this study. The obtained results showed that total nitrogen (TN) could be efficiently removed by 88.38% when influent TN and chemical oxygen demand (COD) were 45.87 and 44.40 mg/L, respectively. In the first stage, nitritation was instantly achieved by the bioaugmentation strategy, and can be maintained under limited oxygen condition (below 0.2mg/L). The ratio of nitrite to ammonium in the effluent of the nitritation reactor can be controlled at approximate 1.0 by adjusting aeration rate. In the second stage, anammox was realized in the upflow anaerobic sludge blanket (UASB) reactor, where the total nitrogen removal rate was 0.40 kg Nm(-3)d(-1) under limited-substrate condition. Therefore, the organic matter in sewage can be firstly concentrated in biomass which could generate biogas (energy). Then, nitrogen in sewage could be removed in a two-stage autotrophic nitrogen removal process. PMID:21719278

  8. Influence of biogas flow rate on biomass composition during the optimization of biogas upgrading in microalgal-bacterial processes.

    Science.gov (United States)

    Serejo, Mayara L; Posadas, Esther; Boncz, Marc A; Blanco, Saúl; García-Encina, Pedro; Muñoz, Raúl

    2015-03-01

    The influence of biogas flow rate (0, 0.3, 0.6, and 1.2 m(3) m(-2) h(-1)) on the elemental and macromolecular composition of the algal-bacterial biomass produced from biogas upgrading in a 180 L photobioreactor interconnected to a 2.5 L external bubbled absorption column was investigated using diluted anaerobically digested vinasse as cultivation medium. The influence of the external liquid recirculation/biogas ratio (0.5 biogas, was also evaluated. A L/G ratio of 10 was considered optimum to support CO2 and H2S removals of 80% and 100%, respectively, at all biogas flow rates tested. Biomass productivity increased at increasing biogas flow rate, with a maximum of 12 ± 1 g m(-2) d(-1) at 1.2 m(3) m(-2) h(-1), while the C, N, and P biomass content remained constant at 49 ± 2%, 9 ± 0%, and 1 ± 0%, respectively, over the 175 days of experimentation. The high carbohydrate contents (60-76%), inversely correlated to biogas flow rates, would allow the production of ≈100 L of ethanol per 1000 m(3) of biogas upgraded under a biorefinery process approach.

  9. Film Growth Rates and Activation Energies for Core-Shell Nanoparticles Derived from a CVD Based Aerosol Process

    Directory of Open Access Journals (Sweden)

    Frederik Weis

    2015-03-01

    Full Text Available Silica core-shell nanoparticles of about 60–120 nm with a closed outer layer of bismuth or molybdenum oxide of 1–10 nm were synthesized by an integrated chemical vapor synthesis/chemical vapor deposition process at atmospheric pressure. Film growth rates and activation energies were derived from transmission electron microscopy (TEM images for a deposition process based on molybdenum hexacarbonyl and triphenyl bismuth as respective coating precursors. Respective activation energies of 123 ± 10 and 155 ± 10 kJ/mol are in good agreement with the literature and support a deposition mechanism based on surface-induced removal of the precursor ligands. Clean substrate surfaces are thus prerequisite for conformal coatings. Integrated aerosol processes are solvent-free and intrinsically clean. In contrast, commercial silica substrate particles were found to suffer from organic residues which hinder shell formation, and require an additional calcination step to clean the surface prior to coating. Dual layer core-shell structures with molybdenum oxide on bismuth oxide were synthesized with two coating reactors in series and showed similar film growth rates.

  10. Strain rate dependent behaviors of a hot isotropically processed Ti-6Al-4V: Mechanisms and material model

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Xiaohan; Ren, Mingfa; Bu, Fanzi; Chen, Guoqing; Li, Gang [Dalian University of Technology, Dalian (China); Li, Tong [Queensland University of Technology, Brisbane (Australia)

    2016-02-15

    Split-Hopkinson pressure bar (SHPB) was adopted to study the dynamic response of a specifically designed Hot isotropically processed (HIP) Casting Titanium alloy (Ti-6Al-4V). The strain-stress curves were obtained in a range of strain rate (10{sup -3}⁓2.6x10{sup 3}/s) to study the constitutive relationships and the Johnson-Cook model is developed to describe this dynamic constitutive law. It can be found that the static microstructure of this specific HIP casting Ti-6Al-4V is lamellar structure. When the loading increases (strain rate higher than 10{sup 3}/s), this lamellar structure changes to basket weave structure, which further changes the mechanical strength and plasticity.

  11. Increased delignification rate of Dendrocalamus strictus (Roxburgh nees by Schizophyllum commune Fr.; Fr. to reduce chemical consumption during pulping process

    Directory of Open Access Journals (Sweden)

    Vipin Kumar Saini

    2013-08-01

    Full Text Available Pulp and paper industry is traditionally known to be a large contributor to environmental pollution due its largeconsumption of energy and chemicals. To reduce the chemical consumption, rate of delignification was increased bySchizophyllum commune in destructured sample of Dendrocalamus stictus, which was destructured by Impressafiner (compression-cum dewatering process. The extent of delignification was determined and comparison was made between thenon-destructured and destructured samples. The influence of physical parameters like incubation time, moisture level, media,media concentration, pH and temperature were also examined during the study. It was found that rate of delignification wassignificantly 6.43% more in destructured sample than non-destructured sample. Kraft pulping of treated destructured sampleshows 2.59 point reduction in kappa number than untreated non-destructured sample. Thus this paper provides an insight ofthe delignification extent in Dendrocalamus strictus after mechanical operation at varying physical parameters.

  12. Manganese reduction/oxidation reaction on graphene composites as a reversible process for storing enormous energy at a fast rate

    OpenAIRE

    Chen, Yanyi; Xu, Chengjun; Shi, Shan; Li, Jia; Kang, Feiyu; Wei, Chunguang

    2014-01-01

    Oxygen reduction/evolution reaction (ORR/OER) is a basic process for fuel cells or metal air batteries. However, ORR/OER generally requires noble metal catalysts and suffers from low solubility (10-3 molar per liter) of O2, low kinetics rate (10-6 cm2/s) and low reversibility. We report a manganese reduction/oxidation reaction (MRR/MOR) on graphene/MnO2 composites, delivering a high capacity (4200 mAh/g), fast kinetics (0.0024 cm2/s, three orders higher than ORR/OER), high solubility (three o...

  13. Brunovsky Normal Form of Monod Kinetics Models and Growth Rate Control of a Fed-batch Cultivation Process

    Directory of Open Access Journals (Sweden)

    Pavlov Y.

    2007-12-01

    Full Text Available A mathematical methodology that gives assistance to design of fed-batch stabilization and control is presented. The methodology is based both on Utility theory and optimal Control theory. The Utility theory deals with the expressed subjective preferences and allows for the expert preferences to be taken in consideration in complex biotechnological systems as criteria for control and optimization. The Control theory is used for parameters stabilization of a fed-batch cultivation process. The control is written based on information of the growth rate. The simulations show good efficiency of the control laws.

  14. The dynamic network model (DNET): a model for determining salt dissolution rates and incorporating feedback effects in salt dissolution processes

    International Nuclear Information System (INIS)

    For nuclear waste isolation in deep, geologic formations, transport in groundwater appears to be one of the more likely means for radioactive waste to migrate from the repository to the biosphere. With respect to a repository in bedded salt, transport in groundwater would, for most breachment scenarios, have to be preceded by dissolution of all or portions of the salt layers surrounding the repository. The Dynamic Network (DNET) model provides a capability for investigating the rate of salt dissolution with a variety of disruptive events and processes and also provides a capability for investigating the effects of feedback mechanisms such as thermal expansion, subsidence, fracture formation and salt creep

  15. Exact Rates of Convergence of Functional Limit Theorems for Csorgo-Revesz Increments of a Wiener Process

    Institute of Scientific and Technical Information of China (English)

    Wen Sheng WANG

    2002-01-01

    Let {W(t); t ≥ 0} be a standard Wiener process and S be the Strassen set of functions.We investigate the exact rates of convergence to zero (as T →∞) of the variables suP0≤t≤T-aT inff∈ssuP0≤x≤1 |Yt,T(x) - f(x)| and inf0≤t≤T-aT suP0≤x≤1 |Yt,T(x) - f(x)| for any given f ∈ S, whereYt,T(x) = (W(t + xaT) - W(t))(2aT(logTa-1T1 + loglog T))-1/2.We establish a relation between how small the increments are and the functional limit resultsof Csorgo-Revesz increments for a Wiener process. Similar results for partial sums of i.i.d. randomvariables are also given.

  16. An integrated process rate analysis of a regional fine particulate matter episode over Yangtze River Delta in 2010

    Science.gov (United States)

    Li, L.; Huang, C.; Huang, H. Y.; Wang, Y. J.; Yan, R. S.; Zhang, G. F.; Zhou, M.; Lou, S. R.; Tao, S. K.; Wang, H. L.; Qiao, L. P.; Chen, C. H.; Streets, D. G.; Fu, J. S.

    2014-07-01

    A high PM2.5 pollution episode was detected in Shanghai in November 2010. The integrated process rate method, an advanced diagnostic tool, was applied to account for the contribution of different atmospheric processes during the high pollution episode in the Yangtze River Delta region (YRD). The PM2.5 process analysis indicates that the emission of fine particles is the dominant source of high surface PM2.5 concentrations in the major cities of the YRD like Shanghai, Nanjing, and Hangzhou, following horizontal transportation and aerosols. The PM2.5 concentration could be reduced due to vertical advection and diffusion from lower levels to the upper air. The aerosols process such as homogeneous nucleation and condensation producing PM2.5 occurs throughout the PBL layer in urban areas, causing vertical transport from upper levels down to the surface layer. The aerosols process is much more significant in a downwind rural and coastal site like Zhoushan than in the urban areas. The PM2.5 change initiated by both horizontal transport and vertical transport is much stronger at 40-2000 m height than in the surface layer, while the PM2.5 change caused by horizontal diffusion is very small. Dry deposition can significantly reduce concentration of the particulates in the surface level of the atmosphere, and wet deposition can remove the particles in the planetary boundary layer (PBL). The cloud processes can either increase PM2.5 due to the aqueous-phase oxidation of SO2 and NO2 or remove PM2.5 due to cloud scavenging. Solar radiation and humidity are more important to secondary pollution, and they are the significant external factors affecting the chemical reactions among sulfur dioxide, nitrogen oxides, ammonia, volatile compounds and fine particles.

  17. Aerobic N2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process.

    Science.gov (United States)

    Wang, Huoqing; Guan, Yuntao; Pan, Min; Wu, Guangxue

    2016-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas that can be emitted during biological nitrogen removal. N2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600mL/min sequencing batch reactor (SBRL) and 1200mL/min (SBRH). The nitrogen removal percentage was 89% in SBRL and 71% in SBRH, respectively. N2O emission mainly occurred during the aerobic phase, and the N2O emission factor was 10.1% in SBRL and 2.3% in SBRH, respectively. In all batch experiments, the N2O emission potential was high in SBRL compared with SBRH. In SBRL, with increasing aeration rates, the N2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification (SND). By contrast, in SBRH the N2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N2O emission during biological nitrogen removal.

  18. Students' motivational processes and their relationship to teacher ratings in school physical education: a self-determination theory approach.

    Science.gov (United States)

    Standage, Martyn; Duda, Joan L; Ntoumanis, Nikos

    2006-03-01

    In the present study, we used a model of motivation grounded in self-determination theory (Deci & Ryan, 1985, 1991; Ryan & Deci, 2000a, 2000b, 2002) to examine the relationship between physical education (PE) students' motivational processes and ratings of their effort and persistence as provided by their PE teacher. Data were obtained from 394 British secondary school students (204 boys, 189 girls, 1 gender not specified; M age = 11.97 years; SD = .89; range = 11-14 years) who responded to a multisection inventory (tapping autonomy-support, autonomy, competence, relatedness, and self-determined motivation). The students' respective PE teachers subsequently provided ratings reflecting the effort and persistence each student exhibited in their PE classes. The hypothesized relationships among the study variables were examined via structural equation modeling analysis using latent factors. Results of maximum likelihood analysis using the bootstrapping method revealed the proposed model demonstrated a good fit to the data, chi-squared (292) = 632.68, p self-determination. Student-reported levels of self-determined motivation positively predicted teacher ratings of effort and persistence in PE. The findings are discussed with regard to enhancing student motivation in PE settings.

  19. Aerobic N2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process.

    Science.gov (United States)

    Wang, Huoqing; Guan, Yuntao; Pan, Min; Wu, Guangxue

    2016-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas that can be emitted during biological nitrogen removal. N2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600mL/min sequencing batch reactor (SBRL) and 1200mL/min (SBRH). The nitrogen removal percentage was 89% in SBRL and 71% in SBRH, respectively. N2O emission mainly occurred during the aerobic phase, and the N2O emission factor was 10.1% in SBRL and 2.3% in SBRH, respectively. In all batch experiments, the N2O emission potential was high in SBRL compared with SBRH. In SBRL, with increasing aeration rates, the N2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification (SND). By contrast, in SBRH the N2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N2O emission during biological nitrogen removal. PMID:27155411

  20. Bioturbation depths, rates and processes in Massachusetts Bay sediments inferred from modeling of 210Pb and 239 + 240Pu profiles

    Science.gov (United States)

    Crusius, John; Bothner, Michael H.; Sommerfield, Christopher K.

    2004-01-01

    Profiles of 210Pb and 239 + Pu from sediment cores collected throughout Massachusetts Bay (water depths of 36-192 m) are interpreted with the aid of a numerical sediment-mixing model to infer bioturbation depths, rates and processes. The nuclide data suggest extensive bioturbation to depths of 25-35 cm. Roughly half the cores have 210Pb and 239 + 240Pu profiles that decrease monotonically from the surface and are consistent with biodiffusive mixing. Bioturbation rates are reasonably well constrained by these profiles and vary from ~0.7 to ~40 cm2 yr-1. As a result of this extensive reworking, however, sediment ages cannot be accurately determined from these radionuclides and only upper limits on sedimentation rates (of ~0.3 cm yr-1) can be inferred. The other half of the radionuclide profiles are characterized by subsurface maxima in each nuclide, which cannot be reproduced by biodiffusive mixing models. A numerical model is used to demonstrate that mixing caused by organisms that feed at the sediment surface and defecate below the surface can cause the subsurface maxima, as suggested by previous work. The deep penetration depths of excess 210Pb and 239 + 240Pu suggest either that the organisms release material over a range of >15 cm depth or that biodiffusive mixing mediated by other organisms is occurring at depth. Additional constraints from surficial sediment 234Th data suggest that in this half of the cores, the vast majority of the present-day flux of recent, nuclide-bearing material to these core sites is transported over a timescale of a month or more to a depth of a few centimeters below the sediment surface. As a consequence of the complex mixing processes, surface sediments include material spanning a range of ages and will not accurately record recent changes in contaminant deposition.

  1. A user configurable data acquisition and signal processing system for high-rate, high channel count applications

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Arwa, E-mail: arwa.salim@eee.strath.ac.uk [University of Strathclyde, Scotland (United Kingdom); Crockett, Louise [University of Strathclyde, Scotland (United Kingdom); McLean, John; Milne, Peter [D-TACQ Solutions, Scotland (United Kingdom)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The development of a new digital signal processing platform is described. Black-Right-Pointing-Pointer The system will allow users to configure the real-time signal processing through software routines. Black-Right-Pointing-Pointer The architecture of the DRUID system and signal processing elements is described. Black-Right-Pointing-Pointer A prototype of the DRUID system has been developed for the digital chopper-integrator. Black-Right-Pointing-Pointer The results of acquisition on 96 channels at 500 kSamples/s per channel are presented. - Abstract: Real-time signal processing in plasma fusion experiments is required for control and for data reduction as plasma pulse times grow longer. The development time and cost for these high-rate, multichannel signal processing systems can be significant. This paper proposes a new digital signal processing (DSP) platform for the data acquisition system that will allow users to easily customize real-time signal processing systems to meet their individual requirements. The D-TACQ reconfigurable user in-line DSP (DRUID) system carries out the signal processing tasks in hardware co-processors (CPs) implemented in an FPGA, with an embedded microprocessor ({mu}P) for control. In the fully developed platform, users will be able to choose co-processors from a library and configure programmable parameters through the {mu}P to meet their requirements. The DRUID system is implemented on a Spartan 6 FPGA, on the new rear transition module (RTM-T), a field upgrade to existing D-TACQ digitizers. As proof of concept, a multiply-accumulate (MAC) co-processor has been developed, which can be configured as a digital chopper-integrator for long pulse magnetic fusion devices. The DRUID platform allows users to set options for the integrator, such as the number of masking samples. Results from the digital integrator are presented for a data acquisition system with 96 channels simultaneously acquiring data

  2. High-Rate Anaerobic Side-Stream Reactor (ASSR) Processes to Minimize the Production of Excess Sludge.

    Science.gov (United States)

    Park, Chul; Chon, Dong-Hyun

    2015-12-01

    High-rate anaerobic side-stream reactor (ASSR) processes were developed to minimize excess sludge production during wastewater treatment. New ASSRs were operated in 2.5-day solids retention time (SRT), much shorter than 10-day SRT used by the commercial sludge reduction process. The 2.5-day was selected based on literature review and preliminary studies, showing that maximum solublization of key floc components, such as divalent cations, extracellular polymeric substances (EPS), and protease, occur within 2 to 3 days of anaerobic digestion. The laboratory reactor study showed that 2.5-day ASSR systems produced approximately 60 and 20% less sludge than the control (no ASSR) and the 10-day ASSR, respectively. The experimental systems showed acceptable effluent quality, despite minimal sludge wastage. This was possible because sludge EPS were continuously released/degraded and regenerated as sludge underwent recirculation between ASSR and the aerobic basin. The results supported that the activated sludge process incorporating small ASSRs significantly decrease the production of excess sludge during wastewater treatment.

  3. Anaerobic ammonium oxidation for advanced municipal wastewater treatment: is it feasible?

    Institute of Scientific and Technical Information of China (English)

    LI Jie; XIONG Bi-yong; ZHANG Shu-de; YANG Hong; ZHANG Jie

    2005-01-01

    Anaerobic ammonium oxidation(ANAMMOX) is a recently developed process to treat ammonia-rich wastewater. There were numerous articles about the new technology with focus on the ammonium-rich wastewater treatment, but few on advanced municipal wastewater treatment. The paper studied the anaerobic ammonium oxidation(ANAMMOX) process with a down flow anoxic biofilter for nitrogen removal from secondary clarifier effluent of municipal wastewater with low COD/N ratio. The results showed that ANAMMOX process is applicable to advanced wastewater treatment with normal temperature as well as ammonia-rich high temperature wastewater treatment. The results indicated that ammonia removal rate was improved by raising the nitrite concentration, and the reaction rate reached a climax at 118.4 mgN/L of the nitrite nitrogen concentration. If the concentration exceeds 118.4 mgN/L, the ANAMMOX process was significantly inhibited although the ANAMMOX bacteria still showed a relatively high reactivity. The data also indicated that the ratio of NO2- -N:NH4 + -N = 1.3:1 in the influent was appropriate for excellent nitrogen removal. The pH increased gradually along the ANAMMOX biofilter reactor. When the ANAMMOX reaction was ended, the pH was tend to calm. The data suggested that the pH could be used as an indicator to describe the course of ANAMMOX reaction.

  4. Effect of flaxseed supplementation rate and processing on the production, fatty acid profile, and texture of milk, butter, and cheese.

    Science.gov (United States)

    Oeffner, S P; Qu, Y; Just, J; Quezada, N; Ramsing, E; Keller, M; Cherian, G; Goddick, L; Bobe, G

    2013-02-01

    Health and nutrition professionals advise consumers to limit consumption of saturated fatty acids and increase the consumption of foods rich in n-3 fatty acids. Researchers have previously reported that feeding extruded flaxseed, which is high in C18:3n-3, improves the fatty acid profile of milk and dairy products to less saturated fatty acids and to more C18:3n-3. Fat concentrations in milk and butter decreased when cows were fed higher concentrations of extruded flaxseed. The objective of this study was to determine the optimal rate of flaxseed supplementation for improving the fatty acid profile without decreasing production characteristics of milk and dairy products. By using a double 5 × 5 Latin square design, 10 mid- to late-lactation Holstein cows were fed extruded (0, 0.91, 1.81, and 2.72 kg/d) and ground (1.81 kg/d) flaxseed as a top dressing for 2-wk periods each. At the end of each 2-wk treatment period, milk and serum samples were taken. Milk was subsequently manufactured into butter and fresh Mozzarella cheese. Increasing supplementation rates of extruded flaxseed improved the fatty acid profile of milk, butter, and cheese gradually to less saturated and atherogenic fatty acids and to more C18:3n-3 by increasing concentrations of C18:3n-3 in serum. The less saturated fatty acid profile was associated with decreased hardness and adhesiveness of refrigerated butter, which likely cause improved spreadability. Supplementation rates of extruded flaxseed did not affect dry matter intake of the total mixed ration, milk composition, and production of milk, butter, or cheese. Flaxseed processing did not affect production, fatty acid profile of milk, or texture of butter and cheese. Feeding up to 2.72 kg/d of extruded flaxseed to mid- to late-lactation Holstein cows may improve nutritional and functional properties of milk fat without compromising production parameters.

  5. Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA

    Science.gov (United States)

    May, Christine L.; Gresswell, Robert E.

    2003-01-01

    Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low-order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand-replacement fire in unlogged basins in the central Coast Range of Oregon. Debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire. Changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow. The volume of wood and sediment in the channel, and the length of channel with exposed bedrock, were strongly correlated with the time since the previous debris flow. Wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams. In the absence of wood, channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time. With an adequate supply of wood, low-order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain.

  6. Systematic design of membership functions for fuzzy-logic control: A case study on one-stage partial nitritation/anammox treatment systems

    DEFF Research Database (Denmark)

    Boiocchi, Riccardo; Gernaey, Krist; Sin, Gürkan

    2016-01-01

    A methodology is developed to systematically design the membership functions of fuzzy-logic controllers for multivariable systems. The methodology consists of a systematic derivation of the critical points of the membership functions as a function of predefined control objectives. Several...... rules, determine the long term reachability of the control objectives by the fuzzy logic controller. The methodology is highlighted using a single-stage side-stream partial nitritation/Anammox reactor as a case study. As a result, a new fuzzy-logic controller for high and stable total nitrogen removal......, the controller was tested, and showed robustness, against measurement noise levels typical for wastewater sensors. A feedforward-feedback configuration using the present controller would give even better performance. In comparison, a previously developed fuzzy-logic controller using merely expert and intuitive...

  7. XPS study of reductive dissolution of birnessite by oxalate: Rates and mechanistic aspects of dissolution and redox processes

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, D.; Nesbitt, H.W.

    1999-10-01

    Reductive dissolution of synthetic 7{angstrom}-birnessite [MnO{sub 1.7}(OH){sub 0.25} or MnO{sub 1.95}] by Na-oxalate produces a Mn(III) intermediate reaction product (here represented as MnOOH) which subsequently reacts with sorbed (COO){sub 2}{sup {minus}2} to form an unreactive Mn(III)-oxalate surface complex at the solution-mineral interface. X-ray Photoelectron Spectroscopy (XPS) results from Mn2p{sub 3/2}, C1s and O1s spectra of reacted surfaces reveal that initially rapid production of CO{sub 2} results in accumulation of CO{sub 2} at the reaction interface. After about 15 min, the reaction rate decreases to the point where CO{sub 2} desorption keeps pace with accumulation. Surface concentrations of CO{sub 2} suggest that the rate of CO{sub 2} production decreases with time, until after 10 hr of reaction, it is undetectable. Reduction of Mn(IV) to Mn(III) suggests that the MnO{sub 2}-oxalate redox reaction proceeds as a transfer of one electron per metal center. There is no XPS evidence for reduction of Mn(III) from birnessite to Mn(II) in the presence of oxalate. Although this reaction proceeds in presence of arsenite, it is inhibited by oxalate, probably through formation of a strong Mn(III)-oxalate surface complex (either monodentate or bidentate). This hypothesis is consistent with Mn{sup 3+} (aq) stabilization by oxalate in aqueous solutions. Further study using X-ray absorption spectroscopy (XAS) is required for a better understanding of the structure of the surface complexes. Rate of release of soluble Mn(II) to dilute oxalate solutions (5 x 10{sup {minus}4} M) is lower by an order of magnitude than the rate of release to aerated, distilled water at similar pH. Apparently, the process of proton-promoted dissolution of the soluble Mn(II) component of birnessite in distilled water is impeded by the addition of oxalate, probably by formation of a binuclear, bidentate surface complex between Mn(II, III) and adsorbed oxalate ions.

  8. Optical cell tracking analysis using a straight-forward approach to minimize processing time for high frame rate data

    Science.gov (United States)

    Seeto, Wen Jun; Lipke, Elizabeth Ann

    2016-03-01

    Tracking of rolling cells via in vitro experiment is now commonly performed using customized computer programs. In most cases, two critical challenges continue to limit analysis of cell rolling data: long computation times due to the complexity of tracking algorithms and difficulty in accurately correlating a given cell with itself from one frame to the next, which is typically due to errors caused by cells that either come close in proximity to each other or come in contact with each other. In this paper, we have developed a sophisticated, yet simple and highly effective, rolling cell tracking system to address these two critical problems. This optical cell tracking analysis (OCTA) system first employs ImageJ for cell identification in each frame of a cell rolling video. A custom MATLAB code was written to use the geometric and positional information of all cells as the primary parameters for matching each individual cell with itself between consecutive frames and to avoid errors when tracking cells that come within close proximity to one another. Once the cells are matched, rolling velocity can be obtained for further analysis. The use of ImageJ for cell identification eliminates the need for high level MATLAB image processing knowledge. As a result, only fundamental MATLAB syntax is necessary for cell matching. OCTA has been implemented in the tracking of endothelial colony forming cell (ECFC) rolling under shear. The processing time needed to obtain tracked cell data from a 2 min ECFC rolling video recorded at 70 frames per second with a total of over 8000 frames is less than 6 min using a computer with an Intel® Core™ i7 CPU 2.80 GHz (8 CPUs). This cell tracking system benefits cell rolling analysis by substantially reducing the time required for post-acquisition data processing of high frame rate video recordings and preventing tracking errors when individual cells come in close proximity to one another.

  9. [Detection of anaerobic processes and microorganisms in immobilized activated sludge of a wastewater treatment plant with intense aeration].

    Science.gov (United States)

    Litti, Iu V; Nekrasova, V K; Kulikov, N I; Siman'kova, M V; Nozhevnikova, A N

    2013-01-01

    Attached activated sludge from the Krasnaya Polyana (Sochi) wastewater treatment plant was studied after the reconstruction by increased aeration and water recycle, as well as by the installation of a bristle carrier for activated sludge immobilization. The activated sludge biofilms developing under conditions of intense aeration were shown to contain both aerobic and anaerobic microorganisms. Activity of a strictly anaerobic methanogenic community was revealed, which degraded organic compounds to methane, further oxidized by aerobic methanotrophs. Volatile fatty acids, the intermediates of anaerobic degradation of complex organic compounds, were used by both aerobic and anaerobic microorganisms. Anaerobic oxidation of ammonium with nitrite (anammox) and the presence of obligate anammox bacteria were revealed in attached activated sludge biofilms. Simultaneous aerobic and anaerobic degradation of organic contaminants by attached activated sludge provides for high rates of water treatment, stability of the activated sludge under variable environmental conditions, and decreased excess sludge formation. PMID:25509405

  10. A review on regulation methods of nitrite oxidizing bacteria in one-stage anaerobic ammonia oxidation process%一段式厌氧氨氧化工艺亚硝酸盐氧化菌抑制方法研究进展

    Institute of Scientific and Technical Information of China (English)

    谢丽; 殷紫; 尹志轩; 王悦超; 周琪

    2016-01-01

    近年来,厌氧氨氧化工艺(anaerobic ammonium oxidation, Anammox)作为一种新型的脱氮技术,由于其耗能少、效率高而被应用于高氨氮废水的处理中。然而,实际运行的厌氧氨氧化工程中有时会出现亚硝酸盐氧化菌(nitrite oxidizing bacteria, NOB)大量繁殖的情况,导致硝酸盐积累,脱氮效率下降。在一段式 Anammox 反应器中,通过控制某些影响因素,如调节体系中的溶解氧,控制游离氨和游离亚硝酸的浓度,调控碳源浓度以及外加中间产物(N2H4、NO 和 NH2OH)等方式,能够在维持 Anammox 工艺脱氮效率的同时有效抑制 NOB。除了系统地综述一段式 Anammox 工艺中 NOB 抑制手段以外,将进一步讨论实际 Anammox 工程应用中抑制 NOB 大量繁殖行之有效的手段。%In recent years,anaerobic ammonium oxidation (Anammox), a new technology for nitrogen removal, has been used in the treatment of high-strength ammonia wastewater due to its low energy consumption and high treatment efficiency. Whereas, the accumulation of nitrite oxidizing bacteria (NOB) often occurs in full-scale Anammox process, leading to the accumulation of nitrate and deterioration of nitrogen removal effectiveness. In two-stage Anammox processes, NOB accumulation often occurs in partial nitritation stage, the inhibition of which has been discussed in details. While in one-stage Anammox process, NOB accumulation is more common and fatal due to the complexity brought by the coexistence of functional bacteria like ammonium oxidizing bacteria (AOB), NOB, anaerobic ammonia oxidizing bacteria (AnAOB) and denitrifiers. It has been reported that NOB could be effectively suppressed in the one-stage Anammox process by some methods, e.g. regulating dissolved oxygen, altering the free ammonia and free nitrous acid concentration, adjusting carbon source and adding externally intermediate products (N2H4, NO, NH2OH), etc. The regulation methods

  11. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

    Science.gov (United States)

    Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

  12. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

    Directory of Open Access Journals (Sweden)

    Frédéric Gazeau

    Full Text Available Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate. At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

  13. Realization of a digital rate meter as an IIR digital filter by implementing an optimized signal processing algorithm

    Directory of Open Access Journals (Sweden)

    Šaponjić Đorđe

    2009-01-01

    Full Text Available By applying the well known dualism: mean count rate - mean time between successive pulses - the equivalence between an IIR digital filter and a preset count digital rate meter has been demonstrated. By using a bank of four second order IIR filters and an optimized automated algorithm for filter selection, a practical realization of a preset count rate meter giving good tradeoff between statistical fluctuations and speed of response, particularly at low count rates such as background monitoring, is presented. The presented solution is suitable for designing portable count rate meters. The designed prototype is capable of operating up to 3600 pulses per second with an accuracy of over 4% in steady-state and response times of 1 second for the rising edge and 2 seconds for the falling edge of the mean count rate step-change.

  14. The Effects of Bottom Blowing Gas Flow Rate Distribution During the Steelmaking Converter Process on Mixing Efficiency

    Science.gov (United States)

    Chu, Kuan-Yu; Chen, Hsing-Hao; Lai, Po-Han; Wu, Hsuan-Chung; Liu, Yung-Chang; Lin, Chi-Cheng; Lu, Muh-Jung

    2016-04-01

    Featuring the advantages of top-blown and bottom-blown oxygen converters, top and bottom combined blown converters are mainstream devices used in steelmaking converter. This study adopted the FLUENT software to develop a numerical model that simulates 3D multiphase flows of gas (air and argon), liquid steel, and slag. Ten numerical experiments were conducted to analyze the effects that the bottom blowing gas flow rate distribution patterns (uniform, linear fixed total flow rate, linear fixed maximal flow rate, and V-type) and bottom blowing gas flow distribution gradients of combined blown converters exert on slag surface stirring heights, flow field patterns, simulation system dynamic pressures, mixing time, and liquid steel-slag interface velocity. The simulation results indicated that the mixing efficiency was highest for the linear fixed total flow rate, followed by the linear fixed maximal flow rate, V-type, and uniform patterns. The bottom blowing gas flow rate distribution exhibited linear patterns and large gradients, and high bottom blowing total flow rates increased the mixing efficiency substantially. In addition, the results suggested that even when bottom blowing total flow rate was reduced, adopting effective bottom blowing gas flow rate distribution patterns and gradients could improve the mixing efficiency.

  15. 镶拼工艺回缩率在针织服装上的应用%Application of Stitching Process Retraction Rate in Knitted Clothing

    Institute of Scientific and Technical Information of China (English)

    李杰

    2012-01-01

    The process retraction rate of knitted fabric was tested through different stitching process using several kinds of fabrics. The test results indicated that stitching process retraction rate was related with stitching pattern, warp & weft of fabric and fabric type, and also proposed that stitching process retraction rate should be considered in design and production of knitted garments.%采用不同缝型、经纬向缝合,测定了不同针织面料的工艺回缩率。试验结果表明针织服装异料拼接工艺回缩率与缝型、面料经纬向和面料原材料密切相关,针织服装实际设计与生产中应考虑镶拼工艺回缩率因素对成衣的影响。

  16. Start up of deammonification process in one single SBR system.

    Science.gov (United States)

    Li, X; Zen, G; Rosenwinkel, K H; Kunst, S; Weichgrebe, D; Cornelius, A; Yang, Q

    2004-01-01

    A process for autotrophic nitrogen removal named aerobic/anoxic deammonification wherein NH4+ is oxidized by nearly 50% to NO2- and subsequently the ammonia is converted together with the nitrite to molecular nitrogen (N2 gas), has come to full-scale application within the last few years. In this research, sludge from a biological rotation disk located at a landfill leachate plant at Mechernich, Germany, which is capable of performing the deammonification process, was used as seed sludge for acclimating deammonification activities in laboratory scale batch-reactors. In parallel, the same tests were performed with normal activated sludge. Research results indicated that deammonification activities could be obtained from the seeded reactor and also, with limited performance, from normal activated sludge in a single SBR system after several months acclimation. It was also seen that oxygen is an important factor that influences the deammonification from both the acclimatization process and process running. Further results were approved that report an impact of nitrite as a process intermediate on the closely related process of anaerobic ammonia oxidation ("Anammox"). However, limiting concentrations on a bacteria population performing deammonification were found to be different to those reported for a pure Anammox-culture. Also the influence of another intermediate, hydrazine, was tested for speeding up the acclimating process by inducing the deammonification activities and recovering the activities of deammonification from nitrite inhibition. PMID:15536983

  17. On the Primacy of Molecular Processes in Determining Response Rates under Variable-Ratio and Variable-Interval Schedules

    Science.gov (United States)

    Tanno, Takayuki; Sakagami, Takayuki

    2008-01-01

    This study focused on variables that may account for response-rate differences under variable-ratio (VR) and variable-interval (VI) schedules of reinforcement. Four rats were exposed to VR, VI, tandem VI differential- reinforcement-of-high-rate, regulated-probability-interval, and negative-feedback schedules of reinforcement that provided the same…

  18. Effects of Process on Ethanol Lixiviation Rate of Schisandra Chinensis (Turcz.) Baill.%炮制对北五味子醇浸率影响的研究

    Institute of Scientific and Technical Information of China (English)

    李英华; 朱晓慧; 吕秀阳

    2011-01-01

    The study was aimed to investigate the effect of process on ethanol lixiviation rate of Schisandra. The feasibility of ethanol lixiviation rate of Schisandra was evaluated as an index appraising the Schisandra quality of process. Effects of processing time, processing temperature and processing adminiculars adding content to ethanol lixiviation rate of Schisandra were observed. The results showed that different processing adminiculars cause different changing trends of ethanol lixiviation rate of Schisandra. The ethanol lixiviation rate of Schisandra was increased according to the increase of adminicular content when processed by honey. However, the ethanol lixiviation rate of Schisandra was decreased when processed by wine, vinegar or steamed. And the change of adminicular content plays little effect to the ethanol lixiviation rate. The ethanol lixiviation rate of Schisandra was not significantly influenced by the change of process time and temperature. It is concluded that ethanol lixiviation rate of Schisandra attains maximum when process by honey for 6-8 h. The effect of processing temperature to ethanol lixiviation rate of Schisandra was not obvious when processed by vinegar, honey or steamed. The ethanol lixiviation rate of Schisandra attains maximum when processed by wine at 85°C. It is concluded that the lixiviation rate of ethanol was not sensitive to different process factors. Quality appraising system is not suitable to be used in the process of Schisandra.%目的:研究炮制过程对北五味子醇浸率的影响,考察醇浸率作为评价五味子炮制过程控制的辅助参考质量指标的可行性.方法:观察炮制时间、炮制温度、炮制辅料用量改变对五味子醇浸率的影响.结果:不同炮制辅料对醇浸率影响趋势不同,蜜制使五味子的醇浸率增加,且随辅料用量增加逐渐增加.酒制、醋制和蒸制使五味子的醇浸率降低,但辅料用量改变对醇浸率影响较小.炮制时间以及炮

  19. Thermal Rate Coefficients for the Astrochemical Process C + CH$^+$ $\\to$ C$_2^+$ + H by Ring Polymer Molecular Dynamics

    CERN Document Server

    Rampino, Sergio

    2016-01-01

    Thermal rate coefficients for the astrochemical reaction C + CH$^+$ $\\to$ C$_2^+$ + H were computed in the temperature range 20-300 K by using novel rate theory based on ring polymer molecular dynamics (RPMD) on a recently published bond-order based potential energy surface and compared with previous Langevin capture model (LCM) and quasi-classical trajectory (QCT) calculations. Results show that there is a significant discrepancy between the RPMD rate coefficients and the previous theoretical results which can lead to overestimation of the rate coefficients for the title reaction by several orders of magnitude at very low temperatures. We argue that this can be attributed to a very challenging energy profile along the reaction coordinate for the title reaction, not taken into account in extenso by either the LCM or QCT approximation. In the absence of any rigorous quantum mechanical or experimental results, the computed RPMD rate coefficients represent state-of-the-art estimates to be included in astrochemic...

  20. The Effectiveness of Discipline/Judicial Processes on Catholic Campuses as Measured by the Rate of Recidivism

    Science.gov (United States)

    O'Reilly, Frances L.; Evans, Roberta D.

    2007-01-01

    University and college campuses in the United States utilize disciplinary/judicial processes to help address student behavioral problems. These include administrative, majority-peer, and minority-peer processes. This descriptive research was undertaken to find which of these three discipline/judicial processes were the most effective. The…

  1. Measuring water-borne cortisol in Poecilia latipinna:is the process stressful, can stress be minimized and is cortisol correlated with sex steroid release rates?

    Science.gov (United States)

    Gabor, C R; Contreras, A

    2012-09-01

    The stress of water-borne hormone collection process was examined in sailfin mollies Poecilia latipinna. Baseline release rates of the stress hormone cortisol were measured and minimum confinement time for water sampling was evaluated for a standard 60 min v. a 30 min protocol. A 30 min hormone collection period reflects release rates over 60 min. Potential stress response to confinement in the beaker for the water-borne collection process was tested over 4 days. There was no evidence of stress due to the collection methods, as cortisol release rates did not differ significantly across four sequential days of handling for P. latipinna. Males and females did not differ significantly in baseline cortisol release rates. Baseline cortisol release rates from fish immediately after being collected in the field were also not significantly different than those in the 4 day confinement experiment. After exposure to a novel environment, however, P. latipinna mounted a stress response. Stress may also affect sex steroids and behaviour but cortisol release rates were not significantly correlated with sex steroids [11-ketotestosterone (KT), testosterone, or oestradiol], or mating attempts. The correlation between water-borne release rates and plasma steroid levels was validated for both cortisol and KT. Finally, normalizing cortisol release rates using standard length in lieu of mass is viable and accurate. Water-borne hormone assays are a valuable tool for investigating questions concerning the role of hormones in mediating stress responses and reproductive behaviours in P. latipinna and other livebearing fishes.

  2. Distribution and activity of anaerobic ammonium-oxidising bacteria in natural freshwater wetland soils.

    Science.gov (United States)

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu; Cheng, Hai-xiang; Li, Ji; Liu, Xu; Ren, Qian-qi

    2016-04-01

    Anaerobic ammonium oxidation (anammox) process plays a significant role in the marine nitrogen cycle. However, the quantitative importance of this process in nitrogen removal in wetland systems, particularly in natural freshwater wetlands, is still not determined. In the present study, we provided the evidence of the distribution and activity of anammox bacteria in a natural freshwater wetland, located in southeastern China, by using (15)N stable isotope measurements, quantitative PCR assays and 16S rRNA gene clone library analysis. The potential anammox rates measured in this wetland system ranged between 2.5 and 25.5 nmol N2 g(-1) soil day(-1), and up to 20% soil dinitrogen gas production could be attributed to the anammox process. Phylogenetic analysis of 16S rRNA genes showed that anammox bacteria related to Candidatus Brocadia, Candidatus Kuenenia, Candidatus Anammoxoglobus and two novel anammox clusters coexisted in the collected soil cores, with Candidatus Brocadia and Candidatus Kuenenia being the dominant anammox genera. Quantitative PCR of hydrazine synthase genes showed that the abundance of anammox bacteria varied from 2.3 × 10(5) to 2.2 × 10(6) copies g(-1) soil in the examined soil cores. Correlation analyses suggested that the soil ammonium concentration had significant influence on the activity of anammox bacteria. On the basis of (15)N tracing technology, it is estimated that a total loss of 31.1 g N m(-2) per year could be linked the anammox process in the examined wetland. PMID:26621804

  3. MODELING JUMPS IN RETURNS OF FINANCIAL ASSETS AS M4 PROCESSES: MEASURED EXCHANGE RATE EXPOSURE OF ASIAN EQUITY PORTFOLIO

    Institute of Scientific and Technical Information of China (English)

    Djibrilla MOUSSA; Wei ZHANG

    2005-01-01

    Previous work on the exposure of equity markets to exchange rate risk, surprisingly, found stock returns were not significantly affected by exchange rate fluctuations. In this paper, we examine the relation between China, Japan and USA MSCI (Morgan & Stanley Capital International) daily equity index returns and SAFE (State Administration of Foreign Exchange) exchange rate returns of Chinese RMB and Japanese Yen in US dollar. We find a significant relation between Asian foreign equity stock returns and Chinese RMB and Japanese Yen exchange rate returns. This article incorporates foreign exchange values as partial determinants of Asian foreign equity market returns and suggests that currency risk is of hedging concern to investors with implications for portfolio management. We implement our result in portfolio's CaR determination under VaR constraints.

  4. Condition-based maintenance for a system subject to a non-homogeneous wear process with a wear rate transition

    Energy Technology Data Exchange (ETDEWEB)

    Fouladirad, Mitra, E-mail: mitra.fouladirad@utt.f [Universite de Technologie de Troyes, Institut Charles Delaunay, FRE CNRS 2848, 12 rue Marie Curie, 10010 Troyes (France); Grall, Antoine [Universite de Technologie de Troyes, Institut Charles Delaunay, FRE CNRS 2848, 12 rue Marie Curie, 10010 Troyes (France)

    2011-06-15

    The aim of this paper is to propose an adaptive maintenance model for a gradually deteriorating system. The system considered initially deteriorates with a nominal deterioration rate and at an unknown time the system's deterioration rate changes and the new deterioration rate is a time-dependent function. To deal with the transition of mode of deterioration in the framework of the maintenance decision rule an adequate online change detection algorithm is used. The maintenance decision rule is chosen in order to minimise the total maintenance cost including the cost of unavailability. The main result of this paper is to point out the interest of using a detection algorithm and hence the appreciation of a decision rule which takes into account transitions in the deterioration rate.

  5. Distribution of Liquid Flow Rates in the Process of Bubbling with Gas Through Gas-Permeable Inserts

    Science.gov (United States)

    Gizatulin, R. A.; Valuev, D. V.; Dariev, R. S.; Trifonov, V. A.; Borovikov, I. F.

    2016-08-01

    The authors studied the distribution of the vertical components of the rate in the ascending gas-liquid flow when blowing through the bottom nozzle at two levels under three modes of neutral gas supply. It was estimated that under the intensities of gas (nitrogen) of 2 and 4 L/min-t the type of rates distribution in both cross-sections does not differ from the generally accepted one and practically does not depend upon the intensity of gas supply.

  6. The evaluation of music therapy process in the intersubjective perspective: the music therapy rating scale. A pilot study

    OpenAIRE

    Raglio, Alfredo; Traficante,; Oasi,

    2011-01-01

    A Raglio1, D Traficante2, O Oasi31Sospiro Foundation, Cremona, Italy; 2Education Technologies Research Center (CRTI), 3Department of Psychology, Catholic University of the Sacred Heart, Milan, ItalyAbstract: This study presents a tool (Music Therapy Rating Scale [MTRS]) to evaluate the progression of the relationship between the patient and the therapist during music therapy sessions. The rating scale was developed from an intersubjective framework and from an improvisational music therapy te...

  7. Effect of mixing rate and temperature on primary Si phase of hypereutectic Al-20Si alloy during controlled diffusion solidification (CDS) process

    OpenAIRE

    Yuan-dong Li; Xin-long Zhang; Ying Ma

    2015-01-01

    Controlled Diffusion Solidification (CDS) is a promising process relied on mixing two liquid alloys of precisely controlled chemistry and temperature in order to produce a predetermined alloy composition. In this study, the CDS was employed to prepare hypereutectic Al-20%Si (mass fraction) alloy using Al-30%Si and pure Al of different temperatures. The mixing rate was controlled using three small crucibles with a hole of different diameters in their bottom. The effect of mixing rate and tempe...

  8. Process-induced Distortions in CFRP Manufacturing: A bottle-neck for high-rate Production Scenarios

    OpenAIRE

    Kappel, Erik; Stefaniak, Daniel; Hühne, Christian

    2014-01-01

    Undesired process-induced distortions (PID) are an inherent issue in today's CFRP manufacturing scenarios. Distortions are inevitable due to an interaction of composite-specific and process-specific parameters. In academia it is distinguished in three main phenomena Spring-in, Warpage and Forced- interaction while their specific relevance depends on the part shape at hand. As process distortions remain widely unconsidered in current partdevelopment chains, they induce considera...

  9. A nonparametric approach to the estimation of diffusion processes, with an application to a short-term interest rate model

    NARCIS (Netherlands)

    Jiang, GJ; Knight, JL

    1997-01-01

    In this paper, we propose a nonparametric identification and estimation procedure for an Ito diffusion process based on discrete sampling observations. The nonparametric kernel estimator for the diffusion function developed in this paper deals with general Ito diffusion processes and avoids any func

  10. Effect of Pad Surface Micro-Texture on Removal Rate during Interlayer Dielectric Chemical Mechanical Planarization Process

    Science.gov (United States)

    Liao, Xiaoyan; Zhuang, Yun; Borucki, Leonard J.; Cheng, Jiang; Theng, Siannie; Ashizawa, Toranosuke; Philipossian, Ara

    2013-01-01

    The effect of pad surface micro-texture on removal rate in interlayer dielectric chemical mechanical planarization was investigated. Blanket 200-mm oxide wafers were polished on a Dow® IC1000TM K-groove pad conditioned at two different conditioning forces. The coefficient of friction increased slightly (by 7%) while removal rate increased dramatically (by 65%) when conditioning force was increased from 26.7 to 44.5 N. Pad surface micro-texture analysis results showed that pad surface contact area decreased dramatically (by 71%) at the conditioning force of 44.5 N, leading to a sharp increase in the local contact pressure and resulting in a significantly higher removal rate.

  11. Increasing silver leaching rate from leaching-resistant zinc residues by thiourea leaching method with pressurized preoxidation process

    Institute of Scientific and Technical Information of China (English)

    胡天觉; 曾光明; 黄国和; 袁兴中; 李建兵

    2003-01-01

    As for the leaching-resistant zinc residues, the silver leaching rate can be over 98% through the processof pressurized preoxidation and thiourea leaching. Compared with the method of extracting the silver directly fromthe leaching-resistant zinc residues, the silver leaching rate is greatly improved. The optimum preoxidation condi-tions are: particle size range 40 - 60 μm, oxygen partial pressure 106 Pa, temperature 80 - 90 ℃, pH= 1.0, andleaching time 5 h. After pretreatment, the time of thiourea leaching silver is shortened to 1.5 h, and the thioureaconsumption is reduced greatly. The oxidation mechanism and the thiourea leaching kinetics were also explored.

  12. Educational Attainment as Process: Using Hierarchical Discrete-Time Event History Analysis to Model Rate of Progress

    Science.gov (United States)

    Bahr, Peter Riley

    2009-01-01

    Variables that address student enrollment patterns (e.g., persistence, enrollment inconsistency, completed credit hours, course credit load, course completion rate, procrastination) constitute a longstanding fixture of analytical strategies in educational research, particularly research that focuses on explaining variation in academic outcomes.…

  13. Calculation method of rate and area of sedimentation, by non-conventional mathematical process of data treatment

    International Nuclear Information System (INIS)

    The used methods for calculating the rate and area of sedimentation are based in techniques of graphical resolution. The solution of the problem by a mathematical resolution, using computational methods, is more fast and more accuracy. The comparison between the results from this methods and the conventional method is shown. (E.G.)

  14. Effect of SF6 flow rate on the etched surface profile and bottom grass formation in deep reactive ion etching process

    International Nuclear Information System (INIS)

    While deep reactive ion etching (DRIE) has proven to be a boon for silicon micromachining applications, certain factors still exist which affect the satisfactory performance of DRIE. Some of the process limitations include bottom grass formation, RIE lag, loading and notching effects and aspect ratio dependent etching. This paper presents the effect of SF6 flow rate and etching/passivation cycle time on the etched shape profile and bottom grass formation. Rectangular trenches of varying widths are etched using Alcatel etching system. Critical DRIE process parameters, such as SF6 flow rate and ratio of etching and passivation cycle time, are varied to explore the dependence of etched shape profile on these parameters. It is found that low SF6 flow rate, i.e. 250 sccm, results in relatively smooth bottom surface. As SF6 flow rate is increased, bottom surface roughness increases and grass forms on the bottom of etched trenches. Shape of etched surface profile was found to be changed from positive profile to negative profile, when the SF6 flow rate was increased. Ratio of etching/passivation cycle was also found to be critical for prevention of bottom grass formation. DRIE process parameters were optimised to get smooth and vertical sidewalls

  15. Effect of rolling on fatigue crack growth rate of Wire and Arc Additive Manufacture (WAAM) processed Titanium

    OpenAIRE

    Qiu, Xundong

    2013-01-01

    Titanium (Ti) alloys have been commonly used in the aerospace industry, not only because they have a high strength-to-weight ratio (comparing to the steels) but also their satisfactory corrosion resistance. Furthermore, they can be assembled with the carbon fibre composite parts. However, conventional manufacturing methods cause high material scrap rate and require lots of machining to obtain the final shape and size, which increases both the manufacturing time and cost. In ...

  16. A Stringent Limit on the Mass Production Rate of $r$-Process Elements in the Milky Way

    CERN Document Server

    Macias, Phillip

    2016-01-01

    We analyze data from several studies of metal-poor stars in the Milky Way, focusing on both strong (Eu) and weak (Sr) $r$-process elements. Because these elements were injected in an explosion, we calculate the mass swept up when the blast wave first becomes radiative, yielding a lower limit for the dilution of such elements and hence a lower limit on the ejecta mass which is incorporated into the next generation of stars. Our study demonstrates that in order to explain the largest enhancements in [Eu/Fe] observed in stars at low [Fe/H] metallicities, individual $r$-process production events must synthesize a minimum of $10^{-3.5} M_{\\odot}$ of $r$-process material. We also show that if the site of Mg production is the same as that of Eu, individual injection events must synthesize up to $ \\sim 10^{-3} M_{\\odot}$ of $r$-process material. On the other hand, demanding that Sr traces Mg production results in $r$-process masses per event of $\\sim 10^{-5} M_{\\odot}$. This suggests that the astrophysical sites resp...

  17. Growing Chlorella vulgaris in Photobioreactor by Continuous Process Using Concentrated Desalination: Effect of Dilution Rate on Biochemical Composition

    Directory of Open Access Journals (Sweden)

    Ângelo Paggi Matos

    2014-01-01

    Full Text Available Desalination wastewater, which contains large amount of salt waste, might lead to severely environmental pollution. This study evaluated the effect of dilution rate (0.1≤D≤0.3 day−1 on microalgal biomass productivity, lipid content, and fatty acid profile under steady-state condition of Chlorella vulgaris supplemented with concentrated desalination. Continuous culture was conducted for 55 days. Results show that the biomass productivity (Px varied from 57 to 126 mg L−1 d−1 (dry mass when the dilution rate ranged from 0.1 to 0.3 day−1. At lowest dilution rate (D=0.1 day−1, the continuous culture regime ensured the highest values of maximum biomass concentration (Xm=570±20 mL−1 and protein content (52%. Biomass lipid content was an increasing function of D. The most abundant fatty acids were the palmitic (25.3±0.6% at D=0.1 day−1 and the gamma-linolenic acid (23.5±0.1% at D=0.3 day−1 ones. These fatty acids present 14 to 18 carbons in the carbon chain, being mainly saturated and polyunsaturated, respectively. Overall, the results show that continuous culture is a powerful tool to investigate the cell growth kinetics and physiological behaviors of the algae growing on desalination wastewater.

  18. The astrophysical r-process and its dependence on properties of nuclei far from stability: Beta strength functions and neutron capture rates

    International Nuclear Information System (INIS)

    The question of the astrophysical site of the rapid neutron capture (r-) process which is believed to be responsible for the production of the heavy elements in the universe has been a problem in astrophysics for more than two decades. The solution of this problem is not only dependent on the development of realistic astrophysical supernova models, i.e. correct treatment of the hydrodynamics of gravitational collapse and supernova explosion and the equation of state of hot and dense matter, but is shown in this paper to be very sensitive also to 'standard' nuclear physics properties of nuclei far from stability such as beta decay properties and neutron capture rates. For both of the latter, strongly oversimplifying assumptions, not applying the development in nuclear physics during the last decade, have been made in almost all r-process calculations performed up to now. A critical discussion of the state of the art of such calculations seems therefore to be indicated. In this paper procedures are described which allow one to obtain: 1) β-decay properties (decay rates, β-delayed neutron emissions and fission rates); 2) neutron capture rates for neutron-rich nuclei considerably improved over what has been used up to now. The beta strength functions are calculated for approx. equal to6000 nuclei between beta stability line and neutron drip line. By hydrodynamical supernova explosion calculations using realistic stellar models it is shown that as a consequence of the improved β-rates explosive He burning is a convincing alternative site to the 'classical' r-process whose existence still is questionable. The new β-rates will be important also for the investigation of further astrophysical sites producing heavy elements such as the r(n)-processes in explosive C or Ne burning. (orig.)

  19. The effect of temperature and strain rate on elongation to failure in nanostructured Al-0.2wt% Zr alloy fabricated by ARB process

    Directory of Open Access Journals (Sweden)

    Hanieh Solouki

    2015-12-01

    Full Text Available A nano/ultra-fine grain Al-0.2wt% Zr alloy was produced by accumulated roll bonding (ARB processafter 10 cycles. The fraction of high angle grain boundaries increased from 8% to 65.4% during 10passes during ARB process. This alloy was subjected to tensile test at different temperatures (523,573and 623 K and strain rates (0.1 and 0.01 s-1. The optimum condition of temperature and strain rate of623k and 0.01s-1 was achieved for maximum elongation to failure, leading to 100% elongation,although maximum elongation was achieved at higher strain rate and maximum chosen temperature.In fracture surfaces after the test, dimples in higher temperature were deeper, bigger, and longer thanlow temperature. Because of presenting the superplasticity character at elevated temperature andhigher strain rate, there was no evidence of necking after failure.

  20. Investigation on the Effect of Nozzle Number on the Recirculation Rate and Mixing Time in the RH Process Using VOF + DPM Model

    Science.gov (United States)

    Ling, Haitao; Li, Fei; Zhang, Lifeng; Conejo, Alberto N.

    2016-06-01

    A mathematical model has been developed to explain the effect of the number of nozzles on recirculation flow rate in the RH process. Experimental data from water modeling were employed to validate the mathematical model. The experimental data included the velocity fields measured with a particle image velocimetry technique and mixing time. The multiphase model volume of fluid was employed to allow a more realistic representation of the free surface in the vacuum chamber while injected argon bubbles were treated as discrete phase particles and modeled using the discrete phase model. Interfacial forces between bubbles and liquid phase were considered, including the lift force. The simulations carried out with the mathematical model involved changes in the gas flow rate from 12 to 36 L/min and a number of nozzles from 4 to 8. The results indicated a logarithmic increment in the recirculation rate as the gas flow rate increased and also corresponded with an exponential decrease in mixing time. The plume area and liquid velocities resulting from individual nozzles were computed. A maximum optimum recirculation rate was defined based on a mechanism proposed to explain the effect of gas flow rate and the number of nozzles on the recirculation rate.

  1. Estimation of soil redistribution rates due to snow cover related processes in a mountainous area (Valle d'Aosta, NW Italy

    Directory of Open Access Journals (Sweden)

    E. Ceaglio

    2011-09-01

    Full Text Available Mountain areas are widely affected by soil erosion, which is commonly linked to runoff processes. Also winter processes, like snow gliding and full-depth avalanches, may be important factors that can enhance soil erosion, however the role and importance of snow movements as agents of soil redistribution are not well understood yet. The aim of this study is to provide information on the relative importance of snow related soil erosion processes in comparison to runoff processes. In the study area, which is an avalanche path characterized by intense snow movements and soil erosion, soil redistribution rates were quantified with two methods: (i by field measurements of sediment yield in an avalanche deposition area during 2009 and 2010 winter seasons; (ii by Caesium-137 method, which supplies the cumulative net soil loss/gain since 1986, including winter and summer soil erosion processes. The soil erosion rates estimated from the sediment yield at the avalanche deposit area (3.2 and 20.8 Mg ha−1 event−1 is comparable to the yearly erosion rates (averaged since 1986 estimated with the Cs-137 method (8.8–13.4 Mg ha−1 yr−1. The soil accumulation rate estimated with data from the avalanche deposition area (28.2 and 160.7 Mg ha−1 event−1 is even more intense than the yearly deposition rates estimated with Cs-137 (8.9–12.6 Mg ha−1 yr−1. This might be due to the high relevance of the two investigated avalanche events and/or to the discrepancy between the long-term (since 1986 signal of the Cs-137 method compared to rates of 2009 and 2010. Even though the comparability is limited by the different time scale of the applied methods, both methods yielded similar magnitudes of soil redistribution rates indicating that soil erosion due to snow movements is the main driving force of soil redistribution in the area. Therefore winter processes have to be

  2. Processes and rate of retreat of the clay and sandstone sea cliffs of the northern Boulonnais (France)

    Science.gov (United States)

    Pierre, Guillaume

    2006-01-01

    Retreat of the clay and sandstone cliffs of the northern Boulonnais (France) has been quantified using stereophotogrammetry. The low retreat rate of this coastal strip — 0.08 m/yr between 1939 and 2003 — is far less than that encountered on chalk and clay-chalk cliffs of either side of the Channel, and even less than a previous estimate of 0.17 m/yr regularly quoted in management studies. The retreat rate is closely related to shore platform morphology and dynamics. The shore platform presents 1) a steeply sloping ramp due to the accumulation of flat calcareous megaclasts that reduce marine erosion; 2) upstanding bare platform surfaces, related to tectonic deformation; and 3) thick platform-beaches trapped in troughs. In all three cases, the reflective behaviour of the nearshore protects the cliff foot from the incoming waves. Two critical eroding segments are the result of changes in the platform sedimentary budget. Around Cran Poulet, and between Plage de la Sirène and Pointe de la Courte Dune, the retreat rate is up to 0.25 and 0.15 m/yr, respectively. At Cran Poulet, recession has been facilitated by the extraction of pebble for more than half a century, whereas erosion of the beach at la Sirène is probably linked to severe erosion of the coastline in the adjacent Wissant Bay. Mass movements on the cliff face are essentially shallow-seated translational slides along with small debris falls and mudflows. The instability of the Argiles de Châtillon is greatly diminished by their sandy and silty texture and by the presence of interstratified solid shelly limestone beds that allow steep slopes to develop in rather weak material. The 'vertical erosion antecedent' is the erosional mode of the cliff, and its reduced efficiency explains the slow recession of the cliff. This study will help to determine the long term evolution of the Boulonnais coast.

  3. On the entropy rate and mutual information rate of Markov modulated Poisson process%马尔科夫调制泊松点过程的熵率和相互信息率∗

    Institute of Scientific and Technical Information of China (English)

    吕绍川

    2015-01-01

    显示地导出了一类连续时间参数隐马尔科夫模型-马尔科夫调制泊松点过程(MMPP)的熵率和相互信息率。模拟研究表明这类隐马尔科夫模型参数的最大似然估计的精度和效与观测过程和隐过程之间的相互信息率密切相关。一般地,相互信息率可作为 MMPP 中各个混合分量广义距离(或差别性)的一个度量。%The Entropy rate and mutual information rate of a hidden Markov model,the Markov modulated Poisson process (MMPP),are explicitly derived.Simulation studies suggest that the accuracy and efficiency of Maximum Likelihood Estimation (MLE)of this class of models are closely associated with mutual information rate between observed point process and latent Markov chain.

  4. New determination of the 13C(a, n)16O reaction rate and its influence on the s-process nucleosynthesis in AGB stars

    CERN Document Server

    Guo, B; Lugaro, M; Buntain, J; Pang, D Y; Li, Y J; Su, J; Yan, S Q; Bai, X X; Chen, Y S; Fan, Q W; Jin, S J; Karakas, A I; Li, E T; Li, Z C; Lian, G; Liu, J C; Liu, X; Shi, J R; Shu, N C; Wang, B X; Wang, Y B; Zeng, S; Liu, W P

    2012-01-01

    We present a new measurement of the $\\alpha$-spectroscopic factor ($S_\\alpha$) and the asymptotic normalization coefficient (ANC) for the 6.356 MeV 1/2$^+$ subthreshold state of $^{17}$O through the $^{13}$C($^{11}$B, $^{7}$Li)$^{17}$O transfer reaction and we determine the $\\alpha$-width of this state. This is believed to have a strong effect on the rate of the $^{13}$C($\\alpha$, $n$)$^{16}$O reaction, the main neutron source for {\\it slow} neutron captures (the $s$-process) in asymptotic giant branch (AGB) stars. Based on the new width we derive the astrophysical S-factor and the stellar rate of the $^{13}$C($\\alpha$, $n$)$^{16}$O reaction. At a temperature of 100 MK our rate is roughly two times larger than that by \\citet{cau88} and two times smaller than that recommended by the NACRE compilation. We use the new rate and different rates available in the literature as input in simulations of AGB stars to study their influence on the abundances of selected $s$-process elements and isotopic ratios. There are ...

  5. Effect of pressure-drop rate on the isolation of cananga oil using instantaneous controlled pressure-drop process

    OpenAIRE

    Kristiawan, Magdalena

    2008-01-01

    The isolation of Indonesian cananga oil was carried out by a new process, instantaneous controlled pressure drop (DIC). Dry cananga flowers (Cananga odorata Hook. fil. et Thomson, forma macrophylla) were exposed for a short time to saturated steam and then the pressure was abruptly decreased to a vacuum level (about 5 kPa). This abrupt pressure drop provokes auto-vaporization of the superheated volatile compounds, expansion and breaking of the cell walls and instantaneous cooling. In this ...

  6. Impact of Fungicide Mancozeb at Different Application Rates on Soil Microbial Populations, Soil Biological Processes, and Enzyme Activities in Soil

    Directory of Open Access Journals (Sweden)

    Abhishek Walia

    2014-01-01

    Full Text Available The use of fungicides is the continuous exercise particularly in orchard crops where fungal diseases, such as white root rot, have the potential to destroy horticultural crops rendering them unsaleable. In view of above problem, the present study examines the effect of different concentrations of mancozeb (0–2000 ppm at different incubation periods for their harmful side effects on various microbiological processes, soil microflora, and soil enzymes in alluvial soil (pH 6.8 collected from apple orchards of Shimla in Himachal Pradesh (India. Low concentrations of mancozeb were found to be deleterious towards fungal and actinomycetes population while higher concentrations (1000 and 2000 ppm were found to be detrimental to soil bacteria. Mancozeb impaired the process of ammonification and nitrification. Similar results were observed for nitrifying and ammonifying bacteria. Phosphorus solubilization was increased by higher concentration of mancozeb, that is, 250 ppm and above. In unamended soil, microbial biomass carbon and carbon mineralization were adversely affected by mancozeb. Soil enzymes, that is, amylase, invertase, and phosphatase showed adverse and disruptive effect when mancozeb used was above 10 ppm in unamended soil. These results conclude that, to lessen the harmful effects in soil biological processes caused by this fungicide, addition of higher amount of nitrogen based fertilizers is required.

  7. Aging kinetics of levoglucosan orientational glass as a rate dispersion process and consequences for the heterogeneous dynamics view

    Science.gov (United States)

    Righetti, Maria Cristina; Tombari, Elpidio; Johari, G. P.

    2016-08-01

    Aging kinetics of a glass is currently modeled in terms of slowing of its α-relaxation dynamics, whose features are interpreted in terms of dynamic heterogeneity, i.e., formation and decay of spatially and temporally distinct nm-size regions. To test the merits of this view, we studied the calorimetric effects of aging an orientational glass of levoglucosan crystal in which such regions would not form in the same way as they form in liquids, and persist in structural glasses, because there is no liquid-like molecular diffusion in the crystal. By measuring the heat capacity, Cp, we determined the change in the enthalpy, H, and the entropy, S, during two aging-protocols: (a) keeping the samples isothermally at temperature, Ta, and measuring the changes after different aging times, ta, and (b) keeping the samples at different Tas and measuring the changes after the same ta. A model-free analysis of the data shows that as ta is increased (procedure (a)), H and S decrease according to a dispersive rate kinetics, and as Ta is increased (procedure (b)), H and S first increase, reach a local maximum at a certain Ta, and then decrease. Even though there is no translational diffusion to produce (liquid-like) free volume, and no translational-rotational decoupling, the aging features are indistinguishable from those of structural glasses. We also find that the Kohlrausch parameter, originally fitted to the glass-aging data, decreases with decrease in Ta, which is incompatible with the current use of the aging data for estimating the α-relaxation time. We argue that the vibrational state of a glass is naturally incompatible with its configurational state, and both change on aging until they are compatible, in the equilibrium liquid. So, dipolar fluctuations seen as the α-relaxation would not be the same motions that cause aging. We suggest that aging kinetics is intrinsically dispersive with its own characteristic rate constant and it does not yield the α-relaxation rate

  8. The application of stochastic processes in exchange rate forecasting : benchmark test for the EUR/USD and the USD/TRY

    OpenAIRE

    Gözgör, Giray

    2013-01-01

    This paper investigates the short-time exchange rate predictability in a developed and in an emerging market, and for this purpose we consider the Euro/United States Dollar (EUR/USD) and the United States Dollar/Turkish Lira (USD/TRY) exchange rates. We apply the benchmark test and compare the results of daily out-of-sample forecasting by Brownian Motion (BM), Geometric Brownian. Motion (GBM), Ornstein-Uhlenbeck Mean-reversion (OUM), Jump Diffusion (JD) stochastic processes, Vector Autoregres...

  9. Trophic position and metabolic rate predict the long-term decay process of radioactive cesium in fish: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Hideyuki Doi

    Full Text Available Understanding the long-term behavior of radionuclides in organisms is important for estimating possible associated risks to human beings and ecosystems. As radioactive cesium (¹³⁷Cs can be accumulated in organisms and has a long physical half-life, it is very important to understand its long-term decay in organisms; however, the underlying mechanisms determining the decay process are little known. We performed a meta-analysis to collect published data on the long-term ¹³⁷Cs decay process in fish species to estimate biological (metabolic rate and ecological (trophic position, habitat, and diet type influences on this process. From the linear mixed models, we found that 1 trophic position could predict the day of maximum ¹³⁷Cs activity concentration in fish; and 2 the metabolic rate of the fish species and environmental water temperature could predict ecological half-lives and decay rates for fish species. These findings revealed that ecological and biological traits are important to predict the long-term decay process of ¹³⁷Cs activity concentration in fish.

  10. Impact toughness and microstructure relationship in niobium- and vanadium-microalloyed steels processed with varied cooling rates to similar yield strength

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, S. [Center for Structural and Functional Materials and Department of Chemical Engineering, University of Louisiana at Lafayette, LA 70504-4130 (United States); Misra, R.D.K. [Center for Structural and Functional Materials and Department of Chemical Engineering, University of Louisiana at Lafayette, LA 70504-4130 (United States)]. E-mail: dmisra@louisiana.edu; Mannering, T. [Nucor-Yamato Steel, P.O. Box 1228, 5929 East State Highway 18, Blytheville, AR 72316 (United States); Panda, D. [Nucor-Yamato Steel, P.O. Box 1228, 5929 East State Highway 18, Blytheville, AR 72316 (United States); Jansto, S.G. [Reference Metals, 1000 Old Pond Road, Bridgeville, PA 15017 (United States)

    2006-11-15

    We describe here the relationship between microstructure and impact toughness behavior as a function of cooling rate for industrially processed Nb- and V-microalloyed steels of almost similar yield strength ({approx}60 ksi). Both Nb- and V-microalloyed steels exhibited increase in toughness with increase in cooling rates during processing. However, Nb-microalloyed steels were characterized by relatively higher toughness than the V-microalloyed steels under identical processing conditions. The microstructure of Nb- and V-microalloyed steels processed at conventional cooling rate, primarily consisted of polygonal ferrite-pearlite microconstituents, while Nb-microalloyed steels besides polygonal ferrite and pearlite contained significant fraction of degenerated pearlite. The microstructure of Nb- and V-microalloyed steels processed at relatively higher cooling rate contained degenerated pearlite and lath-type (acicular) ferrite in addition to the primary ferrite-pearlite constituents. The fraction of degenerated pearlite was higher in Nb-microalloyed steels than in the V-microalloyed steels. In both Nb- and V-microalloyed steels the precipitation characteristics were similar with precipitation occurring at grain boundaries, dislocations, and in the ferrite matrix. Fine-scale ({approx}5-10 nm) precipitation was observed in the ferrite matrix of both the steels. The selected area diffraction (SAD) pattern analysis revealed that these fine precipitates were MC type of niobium and vanadium carbides in the respective steels and followed Baker-Nutting orientation relationship with the ferrite matrix. The microstructural studies suggest that the increase in toughness of Nb-microalloyed steels is attributed to higher fraction of degenerated pearlite in the steel.

  11. Impact toughness and microstructure relationship in niobium- and vanadium-microalloyed steels processed with varied cooling rates to similar yield strength

    International Nuclear Information System (INIS)

    We describe here the relationship between microstructure and impact toughness behavior as a function of cooling rate for industrially processed Nb- and V-microalloyed steels of almost similar yield strength (∼60 ksi). Both Nb- and V-microalloyed steels exhibited increase in toughness with increase in cooling rates during processing. However, Nb-microalloyed steels were characterized by relatively higher toughness than the V-microalloyed steels under identical processing conditions. The microstructure of Nb- and V-microalloyed steels processed at conventional cooling rate, primarily consisted of polygonal ferrite-pearlite microconstituents, while Nb-microalloyed steels besides polygonal ferrite and pearlite contained significant fraction of degenerated pearlite. The microstructure of Nb- and V-microalloyed steels processed at relatively higher cooling rate contained degenerated pearlite and lath-type (acicular) ferrite in addition to the primary ferrite-pearlite constituents. The fraction of degenerated pearlite was higher in Nb-microalloyed steels than in the V-microalloyed steels. In both Nb- and V-microalloyed steels the precipitation characteristics were similar with precipitation occurring at grain boundaries, dislocations, and in the ferrite matrix. Fine-scale (∼5-10 nm) precipitation was observed in the ferrite matrix of both the steels. The selected area diffraction (SAD) pattern analysis revealed that these fine precipitates were MC type of niobium and vanadium carbides in the respective steels and followed Baker-Nutting orientation relationship with the ferrite matrix. The microstructural studies suggest that the increase in toughness of Nb-microalloyed steels is attributed to higher fraction of degenerated pearlite in the steel

  12. Use of glucose consumption rate (GCR) as a tool to monitor and control animal cell production processes in packed-bed bioreactors.

    Science.gov (United States)

    Meuwly, F; Papp, F; Ruffieux, P-A; Bernard, A R; Kadouri, A; von Stockar, U

    2006-03-01

    For animal cell cultures growing in packed-bed bioreactors where cell number cannot be determined directly, there is a clear need to use indirect methods that are not based on cell counts in order to monitor and control the process. One option is to use the glucose consumption rate (GCR) of the culture as an indirect measure to monitor the process in bioreactors. This study was done on a packed-bed bioreactor process using recombinant CHO cells cultured on Fibra-Cel disk carriers in perfusion mode at high cell densities. A key step in the process is the switch of the process from the cell growth phase to the production phase triggered by a reduction of the temperature. In this system, we have used a GCR value of 300 g of glucose per kilogram of disks per day as a criterion for the switch. This paper will present results obtained in routine operations for the monitoring and control of an industrial process at pilot-scale. The process operated with this GCR-based strategy yielded consistent, reproducible process performance across numerous bioreactor runs performed on multiple production sites. PMID:16153735

  13. Participation of Electron Transfer Process in Rate-Limiting Step of Aromatic Hydroxylation Reactions by Compound I Models of Heme Enzymes.

    Science.gov (United States)

    Asaka, Maaya; Fujii, Hiroshi

    2016-07-01

    Hydroxylation reactions of aromatic rings are key reactions in various biological and chemical processes. In spite of their significance, no consensus mechanism has been established. Here we performed Marcus plot analysis for aromatic hydroxylation reactions with oxoiron(IV) porphyrin π-cation radical complexes (compound I). Although many recent studies support the mechanism involving direct electrophilic attack of compound I, the slopes of the Marcus plots indicate a significant contribution of an electron transfer process in the rate-limiting step, leading us to propose a new reaction mechanism in which the electron transfer process between an aromatic compound and compound I is in equilibrium in a solvent cage and coupled with the subsequent bond formation process. PMID:27327623

  14. Rate-based modelling of combined SO2 removal and NH3 recycling integrated with an aqueous NH3-based CO2 capture process

    International Nuclear Information System (INIS)

    Highlights: • A rigorous, rate-based model for an NH3–CO2–SO2–H2O system was developed. • Model predictions are in good agreement with pilot plant results. • >99.9% of SO2 was captured and >99.9% of slipped ammonia was reused. • The process is highly adaptable to the variations of SO2/NH3 level, temperatures. - Abstract: To reduce the costs of controlling emissions from coal-fired power stations, we propose an advanced and effective process of combined SO2 removal and NH3 recycling, which can be integrated with the aqueous NH3-based CO2 capture process to simultaneously achieve SO2 and CO2 removal, NH3 recycling and flue gas cooling in one process. A rigorous, rate-based model for an NH3–CO2–SO2–H2O system was developed and used to simulate the proposed process. The model was thermodynamically and kinetically validated by experimental results from the open literature and pilot-plant trials, respectively. Under typical flue gas conditions, the proposed process has SO2 removal and NH3 reuse efficiencies of >99.9%. The process is strongly adaptable to different scenarios such as high SO2 levels in flue gas, high NH3 levels from the CO2 absorber and high flue gas temperatures, and has a low energy requirement. Because the process simplifies flue gas desulphurisation and resolves the problems of NH3 loss and SO2 removal, it could significantly reduce the cost of CO2 and SO2 capture by aqueous NH3

  15. Modelling nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

    Science.gov (United States)

    Mashifane, T. B.; Vichi, M.; Waldron, H. N.; Machu, E.; Garçonc, V.

    2016-08-01

    Understanding nitrite dynamics in oxygen minimum zones (OMZs) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations may occur below detection limits in some regions. Nitrite concentrations are key to understanding intermediate nitrogen processes and their implication for nitrogen loss in OMZs. A coupled physical-biogeochemical model is applied in the Benguela OMZ to study nitrite dynamics and its associated feedback processes. Simulated results show occurrence of primary and secondary nitrite maxima in the Benguela shelf waters. The primary nitrite maxima in the Benguela are attributed to nitrification and nitrate assimilation as they occur in association with the nitracline. Secondary nitrite maxima accumulate in the Angola-Benguela Front (ABF) OMZ and are attributed to denitrification. The secondary nitrite maxima are consumed by anaerobic ammonium oxidation (anammox) off Walvis Bay. Nitrite maxima are restricted to the shelf off Walvis Bay and advected offshore in the ABF region. Interchanges between the poleward South Atlantic Central Water (SACW) and the equatorward, well-aerated Eastern South Atlantic Central Water (ESACW) drive the seasonality of nitrogen processes in the Benguela. Subsequent nitrite reduction in the Benguela OMZ leads to nitrous oxide production, with high concentrations occurring in the ABF region as a result of nitrification and denitrification. Off Walvis Bay, nitrous oxide production is low since nitrite is consumed by anammox. Nitrous oxide production occurs in thermocline, intermediate and deeper water masses in the ABF region. High N fluxes in the Benguela are attributed to nitrification as compared to anammox and denitrification. Results from this study demonstrate the role of intermediate nitrogen species in nitrogen feedback

  16. Rates of uniform convergence for empirical processes of strictly stationaryβ-mixing sequences indexed by an unbounded class of functions

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Dixin张涤新

    2002-01-01

    Assume that {Xn} is a strictly stationary β-mixing random sequence with the β-mixing coefficient βk = O(k-r), 0 2 or p > 4, uniform convergence rates of empirical processes of strictly stationary β-mixing random sequence over the index classes can reach O((nr/(l+r)/logn)-1/2) or O((nr/(1+r)/ log n)-3/4) and that the Central Limit Theorem does not always hold for the empirical processes.``

  17. Influence Of Temperature On The Rate Of Copper Recovery From The Slag Of The Flash Direct-To-Blister Process By A Solid Carbon Reducer

    Directory of Open Access Journals (Sweden)

    Madej P.

    2015-09-01

    Full Text Available The aim of the work was to investigate the influence of temperature on the rate of copper removal from the obtained slag from the flash direct-to-blister process by means of a carbon reducer. The slag used in this work was taken from the direct-to-blister Outokumpu flash furnace at the smelter in Głogów, and graphite penetrators were used as the slag reducers. The experiment was carried out at 1573 K, 1623 K and 1673 K. It was found that the rate of the de-coppering process of the “Głogów” slag increased with the increase of temperature.

  18. Level Crossing Rate and Average Fade Duration of the Double Nakagami-m Random Process and Application in MIMO Keyhole Fading Channels

    CERN Document Server

    Zlatanov, Nikola; Karagiannidis, George K; 10.1109/LCOMM.2008.081058

    2009-01-01

    We present novel exact expressions and accurate closed-form approximations for the level crossing rate (LCR) and the average fade duration (AFD) of the double Nakagami-m random process. These results are then used to study the second order statistics of multiple input multiple output (MIMO) keyhole fading channels with space-time block coding. Numerical and computer simulation examples validate the accuracy of the presented mathematical analysis and show the tightness of the proposed approximations.

  19. Analysis and Improvement of Ladle Automatic Opening Rate of VD process%影响VD工艺钢包自开率的分析及改进

    Institute of Scientific and Technical Information of China (English)

    代刚; 储晓明

    2015-01-01

    In order to solve problem of reducing to almost zero from nearly 100%ladle automatic opening rate due to change of EAF-LF-CCM production process to be EAF-LF-VD-CCM production process at EAF plant of Jiangsu Steel Group, the reason of reducing of ladle automatic opening rate was analyzed, and the corresponding improvement was made focusing on the reason of influencing on ladle automatic opening rate which made the ladle automatic opening rate increased to 89%and stable.%为了解决江苏苏钢集团电炉厂生产工艺过程由EAF-LF-CCM变为EAF-LF-VD-CCM后钢包自开率由近100%降至几乎为零的问题,分析了钢包自开率降低的原因,针对影响钢包自开率原因进行相关改进,使钢包自开率提高到89%以上并稳定.

  20. Utility of birefringence changes due to collagen thermal denaturation rate process analysis: vessel wall temperature estimation for new short term heating balloon angioplasty

    Science.gov (United States)

    Kaneko, Kenji; Shimazaki, Natsumi; Gotoh, Maya; Nakatani, Eriko; Arai, Tsunenori

    2007-02-01

    Our photo thermal reaction heating architecture balloon realizes less than 10 s short term heating that can soften vessel wall collagen without damaging surrounding tissue thermally. New thermal balloon angioplasty, photo-thermo dynamic balloon angioplasty (PTDBA) has experimentally shown sufficient opening with 2 atm low pressure dilation and prevention of chronic phase restenosis and acute phase thrombus in vivo. Even though PTDBA has high therapeutic potential, the most efficient heating condition is still under study, because relationship of treatment and thermal dose to vessel wall is not clarified yet. To study and set the most efficient heating condition, we have been working on establishment of temperature history estimation method from our previous experimental results. Heating target of PTDBA, collagen, thermally denatures following rate process. Denaturation is able to be quantified with measured collagen birefringence value. To express the denaturation with equation of rate process, the following ex vivo experiments were performed. Porcine extracted carotid artery was soaked in two different temperature saline baths to enforce constant temperature heating. Higher temperature bath was set to 40 to 80 degree Celsius and soaking duration was 5 to 40 s. Samples were observed by a polarizing microscope and a scanning electron microscope. The birefringence was measured by polarizing microscopic system using Brace-Koehler compensator 1/30 wavelength. The measured birefringence showed temperature dependency and quite fit with the rate process equation. We think vessel wall temperature is able to be estimated using the birefringence changes due to thermal denaturation.