WorldWideScience

Sample records for modeling steam sterilization

  1. Steam sterilization of air turbine dental handpieces.

    Science.gov (United States)

    Edwardsson, S; Svensäter, G; Birkhed, D

    1983-12-01

    The efficacy of autoclaving high-speed dental handpieces was tested in two types of downward displacement steam sterilizers (instrument autoclaves), commonly used in the dentist's office. Eight series of experiments were performed with various sterilization schedules. Lubrication oils with or without antimicrobial agent were used in four of the series. Each handpiece was inoculated with 1 ml of a suspension containing equal amounts of saliva and spores of Bacillus stearothermophilus (approx. 10(6) spores/ml). Neither sterilization at 120-124 degrees C for 20 min nor at 134-136 degrees C for 10 min resulted in complete inactivation of the spores in series in which the instruments were tested without oil or with oil containing no antimicrobial agent. However, when the handpieces were lubricated with oil containing isopropanol and formaldehyde and the schedule 134-136 degrees C/10 min was used, no growth was observed. The results indicate that instrument autoclaves with built-in programs of 120-124 degrees C/20 min and 134-136 degrees C/10 min could have insufficient capacity to sterilize lubricated or unlubricated dental handpieces. The use of oils containing an antimicrobial agent can overcome this problem.

  2. Immediate use steam sterilization: it's all about the process.

    Science.gov (United States)

    Nania, Paula

    2013-07-01

    Proper reprocessing of surgical instrumentation assists in infection prevention efforts. Immediate use steam sterilization, previously known as flash sterilization, is an effective method of sterilization if it is performed according to manufacturers' validated instructions. Items that undergo immediate use steam sterilization are subject to the same cleaning and decontamination requirements that apply to preparing items for terminal sterilization, and manufacturers' instructions for use must be strictly followed. In 2009, The Joint Commission revised its position statement on flash sterilization and emphasized that three critical steps of reprocessing must be followed to ensure sterility (ie, cleaning and decontamination, sterilization, aseptic transfer) and that complete documentation must be available for each immediate use steam sterilization cycle so that the device is traceable to the patient if problems arise. Copyright © 2013 AORN, Inc. Published by Elsevier Inc. All rights reserved.

  3. Decontamination of laboratory microbiological waste by steam sterilization.

    OpenAIRE

    1982-01-01

    A steam sterilizer (autoclave) was tested to determine the operating parameters that affected sterilization of microbiological waste. Tests involved standardized loads (5, 10 ad 15 lb [ca. 2.27, 4.54, and 6.80 kg, respectively]) contaminated petri plates in autoclave bags placed in polypropylene or stainless steel containers. Thermal and biological data were obtained by using a digital potentiometer and a biological indicator containing spores of Bacillus stearothermophilus, respectively. The...

  4. Validation of low-temperature steam with formaldehyde sterilization for endoscopes, using validation device.

    Science.gov (United States)

    Kanemitsu, Keiji; Ogawa, Akihisa; Hatori, Tsuruo; Imasaka, Takayuki; Kunishima, Hiroyuki; Inden, Ken; Hatta, Masumitsu; Nakamura, Ichiro; Hirayama, Yoshihiro; Kaku, Mitsuo

    2005-12-01

    Validation of sterilization is an important step before clinical use of medical equipment. Adequate validation of sterilization of the endoscope has not been reported. One reason for this is the lack of suitable devices for validation. The VDES (validation device for endoscope sterilization; Olympus prototype model, Olympus, Tokyo, Japan) was designed in two types (type A and type B) and resembles gastroscopes and duodenoscopes, respectively. Each type consists of inner and outer tubing and a central capsule containing a biological indicator. The device was designed to examine the effectiveness of low-temperature sterilizers, such as ethylene oxide gas, hydrogen peroxide gas plasma, and low-temperature steam with formaldehyde (LTSF) sterilizer. The aim of this study was to validate the sterilization of GI endoscopes by the LTSF sterilizer. Sterilization was assessed using both types of VDES after a 60-min application of LTSF. Culture of the biological indicator confirmed the complete eradication of the bacteria in a total of 10 experiments with each type of VDES after LTSF sterilization. Our results confirm that the LTSF sterilizer may sterilize endoscopes currently distributed by Olympus. Commercialization of VDES will make it possible to evaluate the reliability of sterilization when it is set in the sterilization device with endoscopes.

  5. Microbiological evaluation of the steam sterilization of assembled laparoscopic instruments

    Directory of Open Access Journals (Sweden)

    Tamara Carolina de Camargo

    Full Text Available ABSTRACT Objective: assess the safety of steam sterilization of assembled laparoscopic instruments with challenge contamination. Method: a laboratory experimental study, using as test samples trocars and laparoscopic graspers. Geobacillus stearothermophillus ATCC-7953 was used, with a microbial population of 106UFC/Filter paper substrate, removed from the biological indicator. Three of them were introduced into each instrument at the time of assembly, and sterilized at pressurized saturated steam, 134oC for 5 minutes. After sterilization, the instrument was disassembled and each filter paper substrate was inoculated in soybean casein culture and incubated at 56oC for 21 days. In case of absence of growth, they were subjected to heat shock of 80oC, for 20 minutes and re-incubated for 72 hours. Sample size: 185 graspers and 185 trocars, with 95% power. We paired the experiments with comparative negative control groups (5 graspers and 5 trocars with challenge contamination, sterilized disassembled and positive control (30 filter paper supports, unsterilized, subject to the same incubation procedures. Results: there was no microbial growth in experimental and negative control. The results of the positive control were satisfactory. Conclusion: this study provided strong scientific evidence to support the safety of steam sterilizing of the assembled laparoscopic instrument.

  6. Baby bottle steam sterilizers for disinfecting home nebulizers inoculated with non-tuberculous mycobacteria.

    Science.gov (United States)

    Towle, D; Callan, D A; Lamprea, C; Murray, T S

    2016-03-01

    Non-tuberculous mycobacteria (NTMb), present in environmental water sources, can contribute to respiratory infection in patients with chronic pulmonary disease. Contaminated nebulizers are a potential source of respiratory infection. Treatment with baby bottle steam sterilizers disinfects home nebulizers inoculated with bacterial pathogens but whether this method works for disinfection of NTMb is unclear. Baby bottle steam sterilization was compared with vigorous water washing for disinfecting home nebulizers inoculated with NTMb mixed with cystic fibrosis sputum. No NTMb was recovered from any nebulizers after steam treatment whereas viable NTMb grew after water washing, demonstrating that steam sterilization effectively disinfects NTMb-inoculated nebulizers.

  7. The effect of steam sterilization on recombinant spider silk particles.

    Science.gov (United States)

    Lucke, Matthias; Winter, Gerhard; Engert, Julia

    2015-03-15

    In this work, the recombinant spider silk protein eADF4(C16) was used to fabricate particles in the submicron range using a micromixing method. Furthermore, particles in the micrometer range were produced using an ultrasonic atomizer system. Both particle species were manufactured by an all-aqueous process. The submicroparticles were 332 nm in average diameter, whereas 6.70 μm was the median size of the microparticles. Both particle groups showed a spherical shape and exhibited high β-sheet content in secondary structure. Submicro- and microparticles were subsequently steam sterilized and investigated with respect to particle size, secondary structure and thermal stability. Sterilization temperature and time were increased to assess the thermal stability of eADF4(C16) particles. Actually, particles remained stable and their properties did not change even after autoclaving at 134°C. Both, the untreated and the autoclaved submicroparticles showed no overt cytotoxicity on human dermal fibroblasts after incubation for 72 h. The eADF4(C16) particles were already loaded with proteins and small molecules in previous studies. With that, we can provide a highly promising parenteral drug delivery system based on a defined polypeptide carrier, manufactured with an all-aqueous process and being fully sterilizable. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. [On the importance of the steam trap to the efficient sterilization of solutions in stored blood bottles by saturated steam under pressure (author's transl)].

    Science.gov (United States)

    Schreiber, M; Göbel, M

    1979-01-01

    Biological tests with soil samples were performed to fix the sterilization time for a new steam sterilizer. These tests yielded repeatedly positive spore findings despite modifications of the conditions of sterilization. Having excluded a series of possible sources of trouble, the authors stated that the quality of the steam was the assignable cause. After restoration of the functionality of the steam traps, the biological tests yielded negative results also under normal conditions of sterilization.

  9. Degradation of 316L stainless steel sternal wire by steam sterilization.

    Science.gov (United States)

    Shih, Chun-Che; Su, Yea-Yang; Chen, Lung-Ching; Shih, Chun-Ming; Lin, Shing-Jong

    2010-06-01

    Sterilization is an important step prior to the implantation of medical devices inside the human body. In this work we studied the influence of steam sterilization cycles on the oxide film properties of stainless steel sternal wire. Characterization techniques such as open- circuit potential, potentiodynamic measurement, electrochemical impedance spectroscopy, cathodic stripping, transmission electron microscopy, atomic force microscopy and scanning electron microscopy were employed to investigate the cycles of steam sterilization on the corrosion behavior of sternal wire. The results showed that the oxide properties are a function of the number of steam sterilization cycles and deteriorate as the number of cycles increases. Steam sterilization might damage the implant integrity and heavy metals could be released to the surrounding tissues due to deterioration of the oxide film.

  10. Influences of the steam sterilization on the properties of calcium phosphate porous bioceramics.

    Science.gov (United States)

    Li, Xiangfeng; Guo, Bo; Xiao, Yumei; Yuan, Tun; Fan, Yujiang; Zhang, Xingdong

    2016-01-01

    The influences of steam sterilization on the physicochemical properties of calcium phosphate (Ca-P) porous bioceramics, including β-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP) and hydroxyapatite (HA) are investigated. After being steam sterilized in an autoclave (121 °C for 40 min), the porous bioceramics are dried and characterized. The steam sterilization has no obvious effects on the phase composition, thermal stability, pH value and dissolubility of β-TCP porous bioceramic, but changes its morphology and mechanical strength. Meanwhile, the steam sterilization leads to the significant changes of the morphology, phase composition, pH value and dissolubility of BCP porous bioceramic. The increase of dissolubility and mechanical strength, the decrease of pH value of the immersed solution and partial oriented growth of crystals are also observed in HA porous bioceramic after steam sterilization. These results indicate that the steam sterilization can result in different influences on the physicochemical properties of β-TCP, BCP and HA porous bioceramics, thus the application of the steam sterilization on the three kinds of Ca-P porous bioceramics should be considered carefully based on the above changed properties.

  11. Decontamination of laboratory microbiological waste by steam sterilization.

    Science.gov (United States)

    Rutala, W A; Stiegel, M M; Sarubbi, F A

    1982-01-01

    A steam sterilizer (autoclave) was tested to determine the operating parameters that affected sterilization of microbiological waste. Tests involved standardized loads (5, 10 ad 15 lb [ca. 2.27, 4.54, and 6.80 kg, respectively]) contaminated petri plates in autoclave bags placed in polypropylene or stainless steel containers. Thermal and biological data were obtained by using a digital potentiometer and a biological indicator containing spores of Bacillus stearothermophilus, respectively. The transfer of heat was more efficient when smaller loads of microbiological waste were tested and stainless steel rather than polypropylene containers were used. A single bag with the sides rolled down to expose the top layer of petri plates allowed heat to pass better than did a single bag with the top constricted by a twist-tie. The presence of water in the autoclave bag did not significantly improve heat-up time in stainless steel or polypropylene containers. The results of biological tests substantiated the temperature data. When 10 or 15 lb of microbiological waste was exposed to various test conditions, the only condition that ensured the destruction of B. stearothermophilus involved the use of a stainless steel container (with or without water) for 90 min. Autoclaving for 45 min resulted in the destruction of bacteria included in 10 lb (136 +/- 3 plates) or 15 lb (205 +/- 6 plates) of microbiological waste when stainless steel containers with or without water or polypropylene containers with water used, whereas 60 min was required to kill all bacteria if polypropylene containers without water were used. PMID:7103486

  12. Microbiological evaluation of the steam sterilization of assembled laparoscopic instruments.

    Science.gov (United States)

    Camargo, Tamara Carolina de; Graziano, Kazuko Uchikawa; Almeida, Alda Graciele Claudio Dos Santos; Suzuki, Karina; Silva, Cely Barreto da; Pinto, Flávia Morais Gomes

    2016-11-21

    assess the safety of steam sterilization of assembled laparoscopic instruments with challenge contamination. a laboratory experimental study, using as test samples trocars and laparoscopic graspers. Geobacillus stearothermophillus ATCC-7953 was used, with a microbial population of 106UFC/Filter paper substrate, removed from the biological indicator. Three of them were introduced into each instrument at the time of assembly, and sterilized at pressurized saturated steam, 134oC for 5 minutes. After sterilization, the instrument was disassembled and each filter paper substrate was inoculated in soybean casein culture and incubated at 56oC for 21 days. In case of absence of growth, they were subjected to heat shock of 80oC, for 20 minutes and re-incubated for 72 hours. Sample size: 185 graspers and 185 trocars, with 95% power. We paired the experiments with comparative negative control groups (5 graspers and 5 trocars with challenge contamination, sterilized disassembled) and positive control (30 filter paper supports, unsterilized), subject to the same incubation procedures. there was no microbial growth in experimental and negative control. The results of the positive control were satisfactory. this study provided strong scientific evidence to support the safety of steam sterilizing of the assembled laparoscopic instrument. avaliar a segurança da esterilização a vapor, do instrumental laparoscópico montado com desafio da contaminação. estudo experimental laboratorial, cujo corpo de prova foram trocarte e pinça laparoscópica. Utilizou-se esporos Geobacillus stearothermophillus ATCC-7953, com população microbiana de 106UFC/suporte de papel filtro, removidos do indicador biológico. Três deles foram introduzidos no interior de cada instrumento, no momento da montagem, sendo esterilizados a vapor saturado sob pressão, 134oC por 5 minutos. Depois da esterilização, o instrumental foi desmontado, e cada suporte de papel filtro foi inoculado em meio de cultura

  13. Comparison of steam sterilization conditions efficiency in the treatment of Infectious Health Care Waste.

    Science.gov (United States)

    Maamari, Olivia; Mouaffak, Lara; Kamel, Ramza; Brandam, Cedric; Lteif, Roger; Salameh, Dominique

    2016-03-01

    Many studies show that the treatment of Infectious Health Care Waste (IHCW) in steam sterilization devices at usual operating standards does not allow for proper treatment of Infectious Health Care Waste (IHCW). Including a grinding component before sterilization allows better waste sterilization, but any hard metal object in the waste can damage the shredder. The first objective of the study is to verify that efficient IHCW treatment can occur at standard operating parameters defined by the contact time-temperature couple in steam treatment systems without a pre-mixing/fragmenting or pre-shredding step. The second objective is to establish scientifically whether the standard operation conditions for a steam treatment system including a step of pre-mixing/fragmenting were sufficient to destroy the bacterial spores in IHCW known to be the most difficult to treat. Results show that for efficient sterilization of dialysis cartridges in a pilot 60L steam treatment system, the process would require more than 20 min at 144°C without a pre-mixing/fragmenting step. In a 720L steam treatment system including pre-mixing/fragmenting paddles, only 10 min at 144°C are required to sterilize IHCW proved to be sterilization challenges such as dialysis cartridges and diapers in normal conditions of rolling.

  14. Evaluation of steam sterilization conditions for [{sup 18}F]fludeoxyglucose

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Priscilla F.; Nascimento, Leonardo T.; Valente, Eduardo S.; Silva, Juliana B.; Silveira, Marina B.; Ferreira, Soraya Z., E-mail: somafe@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Unidade de Pesquisa e Producao de Radiofarmacos

    2011-07-01

    [{sup 18}F]Flu deoxyglucose ({sup 18}FDG) is the most commonly used radiopharmaceutical for positron emission tomography. Sterile filtration of the final product into sterile vials using 0.22 {mu}m filter membrane is usually adopted for {sup 18}FDG. However, Good Manufacturing Practice (GMP) guidelines recommend heat sterilization as the method of choice to ensure sterility of pharmaceutical preparations. The aim of this study was to essay different steam sterilization conditions in order to choose the best one for {sup 18}FDG. Three different sterilization conditions were essayed. The first one at 121 deg C for 15 minutes, the second one at 135 deg C for 3.5 minutes and the third one at 133 deg C for 2 minutes. {sup 18}FDG pH-formulation was kept around 6.0. At the end of autoclave cycles, {sup 18}FDG sterility was evaluated by direct inoculation of {sup 18}FDG in culture media and radiochemical purity was determined by TLC and HPLC. Results demonstrated that all essayed conditions were able to ensure {sup 18}FDG sterility, but caused a decrease in radiochemical purity of {sup 18}FDG. Autoclave cycle at 133 deg C for 2 minutes was the best essayed condition for {sup 18}FDG terminal sterilization, once it provided the greater radiochemical purity value and took less time. {sup 18}FDG was able to meet specifications after autoclave cycles, what supports the application of steam sterilization in routine {sup 18}FDG production, in compliance with GMP. (author)

  15. Long-term elastic durability of polymer matrix composite materials after repeated steam sterilization.

    Science.gov (United States)

    Chong, Alexander C M; Fischer, Gustav; Dart, Bradley R; Wooley, Paul H

    2015-11-01

    We compared the durability of 3 different selected composite materials that underwent repeated steam sterilization with the durability of traditional metal materials. Composite materials Tepex, CFR-PPS (carbon-fiber-reinforced polyphenylene sulfide), and HTN-53 (Zytel HTN53G50HSLR NC010) were evaluated for durability and water retention after repeated steam sterilization. These composites were compared with stainless steel and aluminum. The structural properties of these materials were measured (short-beam load-to-failure and cyclic compression loading tests) before, during, and after repeated steam sterilization. The relative radiographic density of these materials was also compared. There was no significant difference in the moisture retention of these composite materials before and after repeated sterilization. The composite materials were significantly more radiolucent than the metals. For all the composite materials, load to failure deteriorated after repeated sterilization. The cyclic compression loading tests showed HTN-53 had the poorest performance, with complete failure after 400 cycles of repeated sterilization. CFR-PPS performed slightly better, with 33% failure at final testing. Tepex had no failures at final testing. Although HTN-53 has shown promise in other orthopedic applications, its performance after repeated sterilization was relatively poor. Tepex showed the most potential for durability after repeated sterilization. Further study is needed to identify specific applications for these materials in the orthopedic industry.

  16. Dimensional stability of a polyvinylsiloxane impression material following ethylene oxide and steam autoclave sterilization.

    Science.gov (United States)

    Holtan, J R; Olin, P S; Rudney, J D

    1991-04-01

    Polyvinlsiloxane impressions were made from a stainless steel master die machined to stimulate five full veneer crown preparations symmetrically placed in an arch form. Three groups of 10 impressions each were made. Treatment groups were sterilized using an ethylene oxide gas and a conventional steam autoclave. Casts were poured and intrapreparation, height, and diameter measurements were made using a stereomicroscope, a digital electronic caliper, and a 1-inch travel dial indicator. Analysis of dimensional changes for the two groups showed that casts made from impressions sterilized by ethylene oxide are acceptable for use in the construction of fixed or removable prostheses. Casts made from impressions sterilized in a steam autoclave can be used for the fabrication of diagnostic casts and some transitional prostheses, but not for routine construction of crowns or fixed partial dentures.

  17. Steam sterilization and automatic dispensing of [{sup 18}F]fludeoxyglucose (FDG) for injection

    Energy Technology Data Exchange (ETDEWEB)

    Karwath, Pascal [Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany) and MC-Pharma GmbH (MCP), Bonn (Germany)]. E-mail: p.karwath@uni-bonn.de; Sartor, Johannes [MC-Pharma GmbH (MCP), Bonn (Germany); Gries, Wolfgang [MC-Pharma GmbH (MCP), Bonn (Germany); Wodarski, Christine [MC-Pharma GmbH (MCP), Bonn (Germany); Dittmar, Claus [MC-Pharma GmbH (MCP), Bonn (Germany); Biersack, Hans J. [Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Guhlke, Stefan [Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany) and MC-Pharma GmbH (MCP), Bonn (Germany)]. E-mail: stefan.guhlke@ukb.uni-bonn.de

    2005-04-01

    For the purpose of implementing steam sterilization of 2-[{sup 18}F]FDG (FDG) in the final container into routine production, we have validated and established a fully automated dispensing and sterilization system, thereby considerably reducing the radiation burden to the personnel. Methods: The commercially available system combines aseptic dispensing of the product solution under a miniaturized laminar flow unit with subsequent steam sterilization, realized by heating of the product in the final containers by an autoclave included in the dispensing unit, thus incorporating current pharmaceutical manufacturing standards for the production of parental radiopharmaceuticals. The efficiency of the used sterilization cycle, the stability of FDG under the conditions of sterilization and the stability of the final product towards radiolysis was investigated with respect to various pH-formulations. Results: The system was found to be fully valid for filling of vials in a laminar flow class A (US-class 100) environment and for sterilization of FDG in the final container. The pH for sterilizing FDG solutions must be slightly acidic to avoid decomposition. A pH of 5.5 appears to be optimal and gives FDG of very high radiochemical purity ({approx}99%). In addition, radiolysis of FDG in solutions of high activity concentration was significantly lower at pH 5.5 than at neutral pH. Conclusion: Terminal sterilization enables the production of FDG in full compliance with GMP-regulations even in Class C or D (US class 10,000 or 100,000) laboratories.

  18. Parametric study for horizontal steam generator modelling

    Energy Technology Data Exchange (ETDEWEB)

    Ovtcharova, I. [Energoproekt, Sofia (Bulgaria)

    1995-12-31

    In the presentation some of the calculated results of horizontal steam generator PGV - 440 modelling with RELAP5/Mod3 are described. Two nodalization schemes have been used with different components in the steam dome. A study of parameters variation on the steam generator work and calculated results is made in cases with separator and branch.

  19. The effect of steam sterilization on the accuracy of spring-style mechanical torque devices for dental implants

    Directory of Open Access Journals (Sweden)

    Mahshid M

    2012-07-01

    Full Text Available Minoo Mahshid,1 Aboulfazl Saboury,1 Ali Fayaz,1 Seyed Jalil Sadr,1 Friedrich Lampert,2 Maziar Mir2,31Department of Prosthodontics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 2Department of Conservative Dentistry, Aachen RWTH Hospital, Aachen, Germany; 3Beckman Laser Institute, UCI, Irvine, CA, USABackground: Mechanical torque devices (MTDs are one of the most commonly recommended devices used to deliver optimal torque to the screw of dental implants. Recently, high variability has been reported about the accuracy of spring-style mechanical torque devices (S-S MTDs. Joint stability and survival rate of fixed implant supported prosthesis depends on the accuracy of these devices. Currently, there is limited information on the steam sterilization influence on the accuracy of MTDs. The purpose of this study was to assess the effect of steam sterilization on the accuracy (±10% of the target torque of spring-style mechanical torque devices for dental implants.Materials and methods: Fifteen new S-S MTDs and their appropriate drivers from three different manufacturers (Nobel Biocare, Straumann [ITI], and Biomet 3i [3i] were selected. Peak torque of devices (5 in each subgroup was measured before and after autoclaving using a Tohnichi torque gauge. Descriptive statistical analysis was used and a repeated-measures ANOVA with type of device as a between-subject comparison was performed to assess the difference in accuracy among the three groups of spring-style mechanical torque devices after sterilization. A Bonferroni post hoc test was used to assess pairwise comparisons.Results: Before steam sterilization, all the tested devices stayed within 10% of their target values. After 100 sterilization cycles, results didn't show any significant difference between raw and absolute error values in the Nobel Biocare and ITI devices; however the results demonstrated an increase of error values in the 3i group (P < 0.05. Raw error

  20. Sterilization.

    Science.gov (United States)

    Peterson, Herbert B

    2008-01-01

    Worldwide, sterilization (tubal sterilization and vasectomy) is used by more people than any other method of contraception. All techniques of tubal sterilization in widespread use in the United States have low risks of surgical complications. Although tubal sterilization is highly effective, the risk of pregnancy varies by age and method of occlusion. Pregnancies can occur many years after the procedure, and when they do, the risk of ectopic gestation is high. There is now strong evidence against the existence of a post-tubal ligation syndrome of menstrual abnormalities. Although women who have undergone tubal sterilization are more likely than other women to undergo hysterectomy subsequently, there is no known biologic basis for this relationship. Although sterilization is intended to be permanent, expressions of regret and requests for reversal are not uncommon and are much more likely to occur among women sterilized at young ages. Tubal sterilization has little or no effect on sexual function for most women. Vasectomy is less likely than tubal sterilization to result in serious complications. Minor complications, however, are not uncommon. Vasectomy does not increase the risk of heart disease, and available evidence argues against an increase in the risk of prostate cancer, testicular cancer, or overall mortality. Whether a postvasectomy pain syndrome exists remains controversial. Although the long-term effectiveness of vasectomy is less well-studied than that for tubal sterilization, it seems likely to be at least as effective. Intrauterine devices and progestin implants are long-acting, highly effective alternatives to sterilization.

  1. THE EFFECTS OF DIFFERENT STEAM-STERILIZATION PROGRAMS ON MATERIAL PROPERTIES OF POLY(L-LACTIDE)

    NARCIS (Netherlands)

    ROZEMA, FR; BOS, RRM; BOERING, G; VANASTEN, JAAM; NIJENHUIS, AJ; PENNINGS, AJ

    1991-01-01

    As-polymerized poly(L-lactide) test rods were sterilized by seven different specially designed computer-operated autoclaving programs. As a control, common hospital sterilization was performed. In all cases, the molecular weight decreased after sterilization. A short time high-temperature

  2. Sterilization.

    Science.gov (United States)

    Rioux, M H

    1979-05-01

    The history of sterilization in North America has included enactment of laws in 37 U. S. states and 2 Canadian provinces allowing the procedure to be performed to eliminate undesirable, genetically-transmitted traits. These eugenic laws applied to any of the following categories of persons: mentally regarded, mentally ill, epileptic, criminal, alcoholic, or poor people. Pressure from geneticists, lawyers, and others concerned with the implications of such laws, led to their repeal in many places. Noneugenic and nontherapeutic sterilization is today a recognized medical practice. Legally, such procedures must meet the following criteria: 1) informed consent; 2) individual benefit; and 3) performance with reasonable care and skill. If these criteria are met, doctors are protected from legal liability. The most legal, social, and ethical ambiguities arise in cases where nontherapeutic sterilization is performed on individuals unable to give consent, e.g., minors or mentally handicapped persons.

  3. Computer modeling of a convective steam superheater

    Science.gov (United States)

    Trojan, Marcin

    2015-03-01

    Superheater is for generating superheated steam from the saturated steam from the evaporator outlet. In the case of pulverized coal fired boiler, a relatively small amount of ash causes problems with ash fouling on the heating surfaces, including the superheaters. In the convection pass of the boiler, the flue gas temperature is lower and ash deposits can be loose or sintered. Ash fouling not only reduces heat transfer from the flue gas to the steam, but also is the cause of a higher pressure drop on the flue gas flow path. In the case the pressure drop is greater than the power consumed by the fan increases. If the superheater surfaces are covered with ash than the steam temperature at the outlet of the superheater stages falls, and the flow rates of the water injected into attemperator should be reduced. There is also an increase in flue gas temperature after the different stages of the superheater. Consequently, this leads to a reduction in boiler efficiency. The paper presents the results of computational fluid dynamics simulations of the first stage superheater of both the boiler OP-210M using the commercial software. The temperature distributions of the steam and flue gas along the way they flow together with temperature of the tube walls and temperature of the ash deposits will be determined. The calculated steam temperature is compared with measurement results. Knowledge of these temperatures is of great practical importance because it allows to choose the grade of steel for a given superheater stage. Using the developed model of the superheater to determine its degree of ash fouling in the on-line mode one can control the activation frequency of steam sootblowers.

  4. Computer modeling of a convective steam superheater

    Directory of Open Access Journals (Sweden)

    Trojan Marcin

    2015-03-01

    Full Text Available Superheater is for generating superheated steam from the saturated steam from the evaporator outlet. In the case of pulverized coal fired boiler, a relatively small amount of ash causes problems with ash fouling on the heating surfaces, including the superheaters. In the convection pass of the boiler, the flue gas temperature is lower and ash deposits can be loose or sintered. Ash fouling not only reduces heat transfer from the flue gas to the steam, but also is the cause of a higher pressure drop on the flue gas flow path. In the case the pressure drop is greater than the power consumed by the fan increases. If the superheater surfaces are covered with ash than the steam temperature at the outlet of the superheater stages falls, and the flow rates of the water injected into attemperator should be reduced. There is also an increase in flue gas temperature after the different stages of the superheater. Consequently, this leads to a reduction in boiler efficiency. The paper presents the results of computational fluid dynamics simulations of the first stage superheater of both the boiler OP-210M using the commercial software. The temperature distributions of the steam and flue gas along the way they flow together with temperature of the tube walls and temperature of the ash deposits will be determined. The calculated steam temperature is compared with measurement results. Knowledge of these temperatures is of great practical importance because it allows to choose the grade of steel for a given superheater stage. Using the developed model of the superheater to determine its degree of ash fouling in the on-line mode one can control the activation frequency of steam sootblowers.

  5. Steam sterilization effect on the accuracy of friction-style mechanical torque limiting devices

    Directory of Open Access Journals (Sweden)

    Seyed Jalil Sadr

    2014-01-01

    Clinical Implication: Within the limitation of this study the torque output of each individual device deviated in varying degrees from target torque values. However, the majority of the new frictional-style devices tested in this study, delivered fairly consistent torque output within 10% of their preset target values after sterilization. Astra Tech devices were the only one showing more than 10% difference from their torque values in 5% of the measurements. Combined effects of sterilization and aging still needs to be determined.

  6. An Improved Steam Injection Model with the Consideration of Steam Override

    Directory of Open Access Journals (Sweden)

    He Congge

    2017-01-01

    Full Text Available The great difference in density between steam and liquid during wet steam injection always results in steam override, that is, steam gathers on the top of the pay zone. In this article, the equation for steam override coefficient was firstly established based on van Lookeren’s steam override theory and then radius of steam zone and hot fluid zone were derived according to a more realistic temperature distribution and an energy balance in the pay zone. On this basis, the equation for the reservoir heat efficiency with the consideration of steam override was developed. Next, predicted results of the new model were compared with these of another analytical model and CMG STARS (a mature commercial reservoir numerical simulator to verify the accuracy of the new mathematical model. Finally, based on the validated model, we analyzed the effects of injection rate, steam quality and reservoir thickness on the reservoir heat efficiency. The results show that the new model can be simplified to the classic model (Marx-Langenheim model under the condition of the steam override being not taken into account, which means the Marx-Langenheim model is corresponding to a special case of this new model. The new model is much closer to the actual situation compared to the Marx-Langenheim model because of considering steam override. Moreover, with the help of the new model, it is found that the reservoir heat efficiency is not much affected by injection rate and steam quality but significantly influenced by reservoir thickness, and to ensure that the reservoir can be heated effectively, the reservoir thickness should not be too small.

  7. Modeling the suppression of sea lamprey populations by the release of sterile males or sterile females

    Science.gov (United States)

    Klassen, Waldemar; Adams, Jean V.; Twohey, Michael B.

    2004-01-01

    The suppressive effects of trapping adult sea lampreys, Petromyzon marinus Linnaeus, and releasing sterile males (SMRT) or females (SFRT) into a closed system were expressed in deterministic models. Suppression was modeled as a function of the proportion of the population removed by trapping, the number of sterile animals released, the reproductive rate and sex ratio of the population, and (for the SFRT) the rate of polygyny. Releasing sterile males reduced populations more quickly than did the release of sterile females. For a population in which 30% are trapped, sterile animals are initially released at ratio of 10 sterile to 1 fertile animal, 5 adult progeny are produced per fertile mating, 60% are male, and males mate with an average of 1.65 females, the initial population is reduced 87% by SMRT and 68% by SFRT in one generation. The extent of suppression achieved is most sensitive to changes in the initial sterile release ratio. Given the current status of sea lamprey populations and trapping operations in the Great Lakes, the sterile-male-release technique has the best chance for success on a lake-wide basis if implemented in Lake Michigan. The effectiveness of the sterile-female-release technique should be investigated in a controlled study. Advancing trapping technology should be a high priority in the near term, and artificial rearing of sea lampreys to the adult stage should be a high priority in the long term. The diligent pursuit of sea lamprey suppression over a period of several decades can be expected to yield great benefits.

  8. Study on mathematical model of steam coal blending

    Institute of Scientific and Technical Information of China (English)

    高洪阁; 李白英; 刘泽常; 尹增德

    2002-01-01

    It is necessary to set up a new mathematical model of steam coal blending instead of the old model. Indexes such as moisture content, ash content, volatile matter, sulfur content and heating value in the new mathematical model have linear relation. The new mathematical model can also predict ash-fusion temperature precisely by considering coal ash ratio in steam coal blending, therefore it is possible to obtain linear relation of ash-fusion temperature between single coal and steam coal blending. The new mathematical model can improve precision of steam coal blending and perfect the old mathematical model of steam coal blending.

  9. Modelling the horizontal steam generator with APROS

    Energy Technology Data Exchange (ETDEWEB)

    Ylijoki, J. [VTT Energy, Espoo (Finland); Palsinajaervi, C.; Porkholm, K. [IVO International Ltd, Vantaa (Finland)

    1995-12-31

    In this paper the capability of the five- and six-equation models of the simulation code APROS to simulate the behaviour of the horizontal steam generator is discussed. Different nodalizations are used in the modelling and the results of the stationary state runs are compared. Exactly the same nodalizations have been created for the five- and six-equation models. The main simulation results studied in this paper are void fraction and mass flow distributions in the secondary side of the steam generator. It was found that quite a large number of simulation volumes is required to simulate the distributions with a reasonable accuracy. The simulation results of the different models are presented and their validity is discussed. (orig.). 4 refs.

  10. Crosslinked agarose encapsulated sorbents resistant to steam sterilization. Preparation and mechanical properties

    NARCIS (Netherlands)

    Koning, de Henk W.M.; Chamuleau, Rob A.F.M.; Bantjes, Adriaan

    1983-01-01

    The application of agarose in hemoperfusion is hampered by the lack of a suitable sterilization method. A technique has been developed for the crosslinking of agarose encapsulated sorbents by the reaction with 1,3-dichloro-2-propanol (DCP) under strong alkaline conditions. A twofold molar excess of

  11. Study of the influence of sporulation conditions on heat resistance of Geobacillus stearothermophilus used in the development of biological indicators for steam sterilization.

    Science.gov (United States)

    Guizelini, Belquis P; Vandenberghe, Luciana P S; Sella, Sandra Regina B R; Soccol, Carlos Ricardo

    2012-12-01

    Biological indicators are important tools in infection control via sterilization process monitoring. The use of a standardized spore crop with a well-defined heat resistance will guarantee the quality of a biological indicator. Ambient factors during sporulation can affect spore characteristics and properties, including heat resistance. The aim of this study is to evaluate the main sporulation factors responsible for heat resistance in Geobacillus stearothermophilus, a useful biological indicator for steam sterilization. A sequence of a three-step optimization of variables (initial pH, nutrient concentration, tryptone, peptone, beef extract, yeast extract, manganese sulfate, magnesium sulfate, calcium chloride and potassium phosphate) was carried out to screen those that have a significant influence on heat resistance of produced spores. The variable exerting greatest influence on G. stearothermophilus heat resistance during sporulation was found to be the initial pH. Lower nutrient concentration and alkaline pH around 8.5 tended to enhance decimal reduction time at 121 °C (D(121°C)). A central composite design enabled a fourfold enhancement in heat resistance, and the model obtained accurately describes positive pH and negative manganese sulfate concentration influence on spore heat resistance.

  12. Phenomenological study of extended seesaw model for light sterile neutrino

    CERN Document Server

    Nath, Newton; Goswami, Srubabati; Gupta, Shivani

    2016-01-01

    We study the zero textures of the Yukawa matrices in the minimal extended type-I seesaw (MES) model which can give rise to $\\sim$ eV scale sterile neutrinos. In this model, three right handed neutrinos and one extra singlet $S$ are added to generate a light sterile neutrino. The light neutrino mass matrix for the active neutrinos, $ m_{\

  13. Influence of sterilization on the mineralization of titanium implants induced by incubation in various biological model fluids.

    Science.gov (United States)

    Serro, A P; Saramago, B

    2003-11-01

    The aim of this work was to investigate the effect of the sterilization processes on the mineralization of titanium implants induced by incubation in various biological model fluids. Titanium samples were submitted to the following sterilization processes used for implant materials: steam autoclaving, glow discharge Ar plasma treatment and gamma-irradiation. The modification of the treated surfaces was evaluated by contact angle determinations, X-ray photoelectron spectroscopy (XPS), laser profilometry and X-ray diffraction. The most significant modifications were detected on the wettability: while the samples treated with Ar plasma became highly hydrophilic (water contact angle approximately 0 degrees), gamma-irradiation and steam sterilization induced an increase in the hydrophobicity. After being sterilized, the samples were incubated for one week in three biological model fluids: Hanks' Balanced Salt Solution, Kokubo's simulated body fluid (SBF) and a fluid, designated by SBF0, with the same composition of SBF but without buffer TRIS. The level of mineralization of the incubated Ti samples, assessed by dynamic contact angle analysis, scanning electron microscopy, electron dispersive spectroscopy and XPS, indicated that the early stages of mineralization are essentially independent of the sterilization method. In contrast, the incubating fluid plays a determinant role, SBFO being the most efficient medium for biomineralization of titanium.

  14. Sterilization Effect Survey of Downward-discharged Pressure steam sterilizar%下排气压力蒸汽灭菌器灭菌效果的综合监测

    Institute of Scientific and Technical Information of China (English)

    刘红萍; 王凤茹

    2002-01-01

    The downward - discharged pressure, steam sterilizor was surveyed 60 times from July 1996 to February 1997. The majormeans included 121°C centigrade pressed- steam sterilization chemical indicator card 3M adhesive plaster, stationary point thermometer,themophilic lipobacillus spore bacteria card and process.

  15. Numerical modeling of secondary side thermohydraulics of horizontal steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Melikhov, V.I.; Melikhov, O.I.; Nigmatulin, B.I. [Research and Engineering Centre of LWR Nuclear Plants Safety, Moscow (Russian Federation)

    1995-12-31

    A mathematical model for the transient three-dimensional secondary side thermal hydraulics of the horizontal steam generator has been developed. The calculations of the steam generator PGV-1000 and PGV-4 nominal regimes and comparison of numerical and experimental results have been carried out. 7 refs.

  16. Modelling of a Coil Steam Generator for CSP applications

    DEFF Research Database (Denmark)

    Pelagotti, Leonardo; Sørensen, Kim; Condra, Thomas Joseph;

    2014-01-01

    The project investigates a new design for a CSP plant steam generation system, the Coil Steam Generator (CSG). This system allows faster start-ups and therefore higher daily energy production from the Sun. An analytical thermodynamic simulation model of the evaporator and a mechanical analysis...

  17. Comparison of numerical simulation and experimental data for steam-in-place sterilization

    Science.gov (United States)

    Young, Jack H.; Lasher, William C.

    1993-01-01

    A complex problem involving convective flow of a binary mixture containing a condensable vapor and noncondensable gas in a partially enclosed chamber was modelled and results compared to transient experimental values. The finite element model successfully predicted transport processes in dead-ended tubes with inside diameters of 0.4 to 1.0 cm. When buoyancy driven convective flow was dominant, temperature and mixture compositions agreed with experimental data. Data from 0.4 cm tubes indicate diffusion to be the primary air removal method in small diameter tubes and the diffusivity value in the model to be too large.

  18. Modeling steam pressure under martian lava flows

    Science.gov (United States)

    Dundas, Colin M.; Keszthelyi, Laszlo P.

    2013-01-01

    Rootless cones on Mars are a valuable indicator of past interactions between lava and water. However, the details of the lava–water interactions are not fully understood, limiting the ability to use these features to infer new information about past water on Mars. We have developed a model for the pressurization of a dry layer of porous regolith by melting and boiling ground ice in the shallow subsurface. This model builds on previous models of lava cooling and melting of subsurface ice. We find that for reasonable regolith properties and ice depths of decimeters, explosive pressures can be reached. However, the energy stored within such lags is insufficient to excavate thick flows unless they draw steam from a broader region than the local eruption site. These results indicate that lag pressurization can drive rootless cone formation under favorable circumstances, but in other instances molten fuel–coolant interactions are probably required. We use the model results to consider a range of scenarios for rootless cone formation in Athabasca Valles. Pressure buildup by melting and boiling ice under a desiccated lag is possible in some locations, consistent with the expected distribution of ice implanted from atmospheric water vapor. However, it is uncertain whether such ice has existed in the vicinity of Athabasca Valles in recent history. Plausible alternative sources include surface snow or an aqueous flood shortly before the emplacement of the lava flow.

  19. Modelling of Steam Generating Paraboloidal dish Solar Thermal Power System

    Energy Technology Data Exchange (ETDEWEB)

    Siangsukone, P.; Lovegrove, K.

    2006-07-01

    The Australian National University (ANU) has a 400m2 Paraboloidal dish solar concentrator system, informally named the Big Dish that produces superheated steam via a receiver mounted monotube boiler connected to 50kWe steam engine for electricity generation. This paper describes an investigation of the system and its components modelled using the TRNYSYS transient system simulation package. The system was modelled in the context of performance assessment for multiple dishes, central generation Rankine cycle power plants. Five new custom components; paraboloidal dish collector, steam cavity receiver, steam line or feedwater line, steam engine, and pressure drop calculator, were developed for the TRNSYS deck file constructed for this study. Validation tests were performed by comparing with the latest experimental results measured with a 1-minute time step and good agreement, with errors less than 10%, has been found. (Author)

  20. 压力蒸汽灭菌后湿包分析及防控措施%Analysis and control measures of wet pack after pressure steam sterilization

    Institute of Scientific and Technical Information of China (English)

    顾运珠

    2015-01-01

    Objective To analyze and take measures to control the occurrence of wet bag after the pulse vacuum sterilization.Methods By steam quality, pressure cooker loading, overweight package management, packaging material requirements, ensure the drying time, the cooling 30min, personnel management and other measures.Results There was no wet bag after the pressure steam sterilization.Conclusion The establishment of scientific quality standards and operational procedures, to do a good job training, to ensure the quality of sterilization.%目的:通过分析脉动真空灭菌后湿包及采取措施,防控湿包的发生。方法通过蒸汽质量、压力锅装载摆放、超重包管理、包装材料要求、保证干燥时间、出锅后冷却30min、人员管理等措施。结果压力蒸汽灭菌后未发生湿包。结论建立科学的工作质量标准和操作规程,做好人员培训,保证灭菌质量。

  1. Modelling and analysis of impulsive releases of sterile mosquitoes.

    Science.gov (United States)

    Huang, Mingzhan; Song, Xinyu; Li, Jia

    2017-12-01

    To study the impact of releasing sterile mosquitoes on mosquito-borne disease transmissions, we propose two mathematical models with impulsive releases of sterile mosquitoes. We consider periodic impulsive releases in the first model and obtain the existence, uniqueness, and globally stability of a wild-mosquito-eradication periodic solution. We also establish thresholds for the control of the wild mosquito population by selecting the release rate and the release period. In the second model, the impulsive releases are determined by the closely monitored wild mosquito density, or the state feedback. We prove the existence of an order one periodic solution and find a relatively small attraction region, which ensures the wild mosquito population is under control. We provide numerical analysis which shows that a smaller release rate and more frequent releases are more efficient in controlling the wild mosquito population for the periodic releases, but an early release of sterile mosquitoes is more effective for the state feedback releases.

  2. Mathematical model in controlling dengue transmission with sterile mosquito strategies

    Science.gov (United States)

    Aldila, D.; Nuraini, N.; Soewono, E.

    2015-09-01

    In this article, we propose a mathematical model for controlling dengue disease transmission with sterile mosquito techniques (SIT). Sterile male introduced from lab in to habitat to compete with wild male mosquito for mating with female mosquito. Our aim is to displace gradually the natural mosquito from the habitat. Mathematical model analysis for steady states and the basic reproductive ratio are performed analytically. Numerical simulation are shown in some different scenarios. We find that SIT intervention is potential to controlling dengue spread among humans population

  3. A three-dimensional laboratory steam injection model allowing in situ saturation measurements. [Comparing steam injection and steam foam injection with nitrogen and without nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Demiral, B.M.R.; Pettit, P.A.; Castanier, L.M.; Brigham, W.E.

    1992-08-01

    The CT imaging technique together with temperature and pressure measurements were used to follow the steam propagation during steam and steam foam injection experiments in a three dimensional laboratory steam injection model. The advantages and disadvantages of different geometries were examined to find out which could best represent radial and gravity override flows and also fit the dimensions of the scanning field of the CT scanner. During experiments, steam was injected continuously at a constant rate into the water saturated model and CT scans were taken at six different cross sections of the model. Pressure and temperature data were collected with time at three different levels in the model. During steam injection experiments, the saturations obtained by CT matched well with the temperature data. That is, the steam override as observed by temperature data was also clearly seen on the CT pictures. During the runs where foam was present, the saturation distributions obtained from CT pictures showed a piston like displacement. However, the temperature distributions were different depending on the type of steam foam process used. The results clearly show that the pressure/temperature data alone are not sufficient to study steam foam in the presence of non-condensible gas.

  4. Numerical investigation of mass transfer in the flow path of the experimental model of the PGV-1500 steam generator's steam receiving section with two steam nozzles

    Science.gov (United States)

    Golibrodo, L. A.; Krutikov, A. A.; Nadinskii, Yu. N.; Nikolaeva, A. V.; Skibin, A. P.; Sotskov, V. V.

    2014-10-01

    The hydrodynamics of working medium in the steam volume model implemented in the experimental setup constructed at the Leipunskii Institute for Physics and Power Engineering was simulated for verifying the procedure of calculating the velocity field in the steam space of steam generators used as part of the reactor plants constructed on the basis of water-cooled water-moderated power-generating reactors (VVER). The numerical calculation was implemented in the environment of the STAR-CCM+ software system with its cross verification in the STAR-CD and ANSYS CFX software systems. The performed numerical investigation served as a basis for substantiating the selection of the computation code and parameters for constructing the computer model of the steam receiving device of the PGV-1500 steam generator experimental model, such as the quantization scheme, turbulence model, and mesh model.

  5. Mechanisms Underlying Mammalian Hybrid Sterility in Two Feline Interspecies Models.

    Science.gov (United States)

    Davis, Brian W; Seabury, Christopher M; Brashear, Wesley A; Li, Gang; Roelke-Parker, Melody; Murphy, William J

    2015-10-01

    The phenomenon of male sterility in interspecies hybrids has been observed for over a century, however, few genes influencing this recurrent phenotype have been identified. Genetic investigations have been primarily limited to a small number of model organisms, thus limiting our understanding of the underlying molecular basis of this well-documented "rule of speciation." We utilized two interspecies hybrid cat breeds in a genome-wide association study employing the Illumina 63 K single-nucleotide polymorphism array. Collectively, we identified eight autosomal genes/gene regions underlying associations with hybrid male sterility (HMS) involved in the function of the blood-testis barrier, gamete structural development, and transcriptional regulation. We also identified several candidate hybrid sterility regions on the X chromosome, with most residing in close proximity to complex duplicated regions. Differential gene expression analyses revealed significant chromosome-wide upregulation of X chromosome transcripts in testes of sterile hybrids, which were enriched for genes involved in chromatin regulation of gene expression. Our expression results parallel those reported in Mus hybrids, supporting the "Large X-Effect" in mammalian HMS and the potential epigenetic basis for this phenomenon. These results support the value of the interspecies feline model as a powerful tool for comparison to rodent models of HMS, demonstrating unique aspects and potential commonalities that underpin mammalian reproductive isolation.

  6. Five-component propagation model for steam explosion analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.; Moriyama, Kiyofumi; Park, H.S.; Maruyama, Yu; Sugimoto, Jun [Severe Accident Research Laboratory, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    1999-07-01

    A five-field simulation code JASMINE-pro has been developed at JAERI for the calculation of the propagation and explosion phase of steam explosions. The basic equations and the constitutive relationships specifically utilized in the propagation models in the code are introduced in this paper. Some calculations simulating the KROTOS 1D and 2D steam explosion experiments are also stated in the paper to show the present capability of the code. (author)

  7. Steam separator modeling for various nuclear reactor transients

    Energy Technology Data Exchange (ETDEWEB)

    Paik, C Y; Mullen, G; Knoess, C; Griffith, P

    1987-06-01

    In a pressurized water reactor steam generator, a moisture separator is used to separate steam and liquid and to insure that essentially dry steam is supplied to the turbine. During a steam line break or combined steam line break plus tube rupture, a number of phenomena can occur in the separator which have no counterparts during steady-state operation. How the separator will perform under these circumstances is important for two reasons, it affects the carry-over of radioactive iodine and the water inventory in the secondary side. This study has as its goal the development of a simple separator model which can be applied to a variety of steam generator for off-design conditions. Experiments were performed using air and water on three different types of centrifugal separators: a cyclone as a generic separator, a Combustion Engineering type stationary swirl vane separator, and a Westinghouse type separator. The cyclone separator system has three stages of separation: first the cyclone, then a gravity separator, and finally a chevron plate separator. The other systems have only a centrifugal separator to isolate the effect of the primary separator. Experiments were also done in MIT blowdown rig, with and without a separator, using steam and water. The separators appear to perform well at flow rates well above the design values as long as the downcomer water level is not high. High downcomer water level rather than high flow rates appear to be the primary cause of degraded performance. Appreciable carry-over from the separator section of a steam generator occurs when the drain lines from three stages of separation are unable to carry off the liquid flow. Failure scenarios of the separator for extreme range of conditions from the quasi-steady state transient to the fast transients are presented. A general model structure and simple separator models are provided.

  8. Modeling of Steam Distillation Mechanism during Steam Injection Process Using Artificial Intelligence

    Science.gov (United States)

    Ahadi, Arash; Kharrat, Riyaz

    2014-01-01

    Steam distillation as one of the important mechanisms has a great role in oil recovery in thermal methods and so it is important to simulate this process experimentally and theoretically. In this work, the simulation of steam distillation is performed on sixteen sets of crude oil data found in the literature. Artificial intelligence (AI) tools such as artificial neural network (ANN) and also adaptive neurofuzzy interference system (ANFIS) are used in this study as effective methods to simulate the distillate recoveries of these sets of data. Thirteen sets of data were used to train the models and three sets were used to test the models. The developed models are highly compatible with respect to input oil properties and can predict the distillate yield with minimum entry. For showing the performance of the proposed models, simulation of steam distillation is also done using modified Peng-Robinson equation of state. Comparison between the calculated distillates by ANFIS and neural network models and also equation of state-based method indicates that the errors of the ANFIS model for training data and test data sets are lower than those of other methods. PMID:24883365

  9. Modeling of steam distillation mechanism during steam injection process using artificial intelligence.

    Science.gov (United States)

    Daryasafar, Amin; Ahadi, Arash; Kharrat, Riyaz

    2014-01-01

    Steam distillation as one of the important mechanisms has a great role in oil recovery in thermal methods and so it is important to simulate this process experimentally and theoretically. In this work, the simulation of steam distillation is performed on sixteen sets of crude oil data found in the literature. Artificial intelligence (AI) tools such as artificial neural network (ANN) and also adaptive neurofuzzy interference system (ANFIS) are used in this study as effective methods to simulate the distillate recoveries of these sets of data. Thirteen sets of data were used to train the models and three sets were used to test the models. The developed models are highly compatible with respect to input oil properties and can predict the distillate yield with minimum entry. For showing the performance of the proposed models, simulation of steam distillation is also done using modified Peng-Robinson equation of state. Comparison between the calculated distillates by ANFIS and neural network models and also equation of state-based method indicates that the errors of the ANFIS model for training data and test data sets are lower than those of other methods.

  10. A model for liquid film in steam turbine

    Science.gov (United States)

    Simon, Amelie; Marcelet, Meryem; Herard, Jean-Marc; Dorey, Jean-Marc; Lance, Michel

    2015-11-01

    Wetness in steam turbines induces losses and erosion. Drops are created due to the fast expansion of the steam (homogeneous nucleation) and the impurities in the steam (heterogeneous nucleation). The droplets grow and some among them settle on the blade leading to a thin liquid film. This film may then be atomized into coarse water drops which crash on the following blades. The liquid film configuration is a thin film on a curved surface, created by the drop deposit and under high steam friction. In steam turbines, the liquid film is subject to high rotational effect (rotor) and/or to negative gravity. Moreover, due to interfacial instabilities, some drops are torn off from the film. The retained approach is an integral formulation of the Navier-Stokes equation (or shallow water equation) with specific terms. The derivation of these equations requires some closure laws for the convection contributions, the Coriolis terms and for terms related to the additional mass coming from the drops deposit. Once chosen, mathematical and mechanical analyses are performed (hyperbolicity, entropy, galilean and rotational invariance). A two-dimensional code has been developed based on finite volume method to simulate numerically this liquid film model for steam turbines.

  11. Mathematical modelling of steam generator and design of temperature regulator

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanovic, S.S. [EE Institute Nikola Tesla, Belgrade (Yugoslavia)

    1999-07-01

    The paper considers mathematical modelling of once-through power station boiler and numerical algorithm for simulation of the model. Fast and numerically stable algorithm based on the linearisation of model equations and on the simultaneous solving of differential and algebraic equations is proposed. The paper also presents the design of steam temperature regulator by using the method of projective controls. Dynamic behaviour of the system closed with optimal linear quadratic regulator is taken as the reference system. The desired proprieties of the reference system are retained and solutions for superheated steam temperature regulator are determined. (author)

  12. The influence of chemical indicator in pressure steam sterilizing package on sterilization effect monitoring%压力蒸汽灭菌包内化学指示物对灭菌监测效果的影响

    Institute of Scientific and Technical Information of China (English)

    姚卓娅; 孙晶玉; 叶伟超; 李海娟

    2015-01-01

    Objective:To explore the accuracy of chemical indicator in pressure steam sterilizing package on monitoring of sterilization effect in sterilization process. Methods:In accordance with the original implementation of Industry Standards of Disinfection and supply Center issued by Ministry of Health on December 1, 2009, we strengthened the management of the whole process of sterilization using the questionnaire survey method, experimental method and random sampling method. We compared the monitoring effect of chemical indicator in sterilization process of different manufacturers commonly used in Chinese hospitals. At the same time, we analyzed the causes of nonconformities, implemented the improvement measures, and improved the package chemical indicator's accuracy of monitoring sterilization effect. Results:The effect of sterilization monitoring were associated with production manufacturer defect, packaging materials with poor permeability, direct contact of chemical indicator with the metal utensils, too large package, too full loading before sterilization, unsatisfactory steam quality, sterilizer operation mistake, and failure operation. Conclusion:The sterilization effects of package chemical indicator were inlfuenced by many factors. The managers should take the initiative to strengthen the sterilization process details management, properly select qualiifed package chemical indicator according to the different risks level, structure of operation objects, different material, and provide accurate and valuable monitoring results for sterilization package to ensure the quality of sterile objects, medical safety, and a comprehensive high quality nursing service.%目的:探讨压力蒸汽灭菌包内化学指示物在经过灭菌过程后所提供的灭菌监测效果的准确性。方法:按照原卫生部2009年12月1日实施的“医院消毒供应中心行业标准”,加强灭菌全流程管理,采用问卷调查法、实验法与随机抽样法相结合

  13. Physical and statistical models for steam generator clogging diagnosis

    CERN Document Server

    Girard, Sylvain

    2014-01-01

    Clogging of steam generators in nuclear power plants is a highly sensitive issue in terms of performance and safety and this book proposes a completely novel methodology for diagnosing this phenomenon. It demonstrates real-life industrial applications of this approach to French steam generators and applies the approach to operational data gathered from French nuclear power plants. The book presents a detailed review of in situ diagnosis techniques and assesses existing methodologies for clogging diagnosis, whilst examining their limitations. It also addresses numerical modelling of the dynamic

  14. Modeling and Optimization of the Steam Turbine Network of an Ethylene Plant

    Institute of Scientific and Technical Information of China (English)

    LI Zeqiu; ZHAO Liang; DU Wenli; QIAN Feng

    2013-01-01

    In this paper,we developed a hybrid model for the steam turbines of a utility system,which combines an improved neural network model with the thermodynamic model.Then,a nonlinear programming (NLP) model of the steam turbine network is formulated by utilizing the developed steam turbine models to minimize the total steam cost for the whole steam turbine network.Finally,this model is applied to optimize the steam turbine network of an ethylene plant.The obtained results demonstrate that this hybrid model can accurately estimate and evaluate the performance of steam turbines,and the significant cost savings can be made by optimizing the steam turbine network operation at no capital cost.

  15. A simplified model of decontamination by BWR steam suppression pools

    Energy Technology Data Exchange (ETDEWEB)

    Powers, D.A.

    1997-05-01

    Phenomena that can decontaminate aerosol-laden gases sparging through steam suppression pools of boiling water reactors during reactor accidents are described. Uncertainties in aerosol properties, aerosol behavior within gas bubbles, and bubble behavior in plumes affect predictions of decontamination by steam suppression pools. Uncertainties in the boundary and initial conditions that are dictated by the progression of severe reactor accidents and that will affect predictions of decontamination by steam suppression pools are discussed. Ten parameters that characterize boundary and initial condition uncertainties, nine parameters that characterize aerosol property and behavior uncertainties, and eleven parameters that characterize uncertainties in the behavior of bubbles in steam suppression pools are identified. Ranges for the values of these parameters and subjective probability distributions for parametric values within the ranges are defined. These uncertain parameters are used in Monte Carlo uncertainty analyses to develop uncertainty distributions for the decontamination that can be achieved by steam suppression pools and the size distribution of aerosols that do emerge from such pools. A simplified model of decontamination by steam suppression pools is developed by correlating features of the uncertainty distributions for total decontamination factor, DF(total), mean size of emerging aerosol particles, d{sub p}, and the standard deviation of the emerging aerosol size distribution, {sigma}, with pool depth, H. Correlations of the median values of the uncertainty distributions are suggested as the best estimate of decontamination by suppression pools. Correlations of the 10 percentile and 90 percentile values of the uncertainty distributions characterize the uncertainty in the best estimates. 295 refs., 121 figs., 113 tabs.

  16. Modelling 3D Steam Turbine Flow Using Thermodynamic Properties of Steam Iapws-95

    Directory of Open Access Journals (Sweden)

    Rusanow A.V.

    2016-01-01

    Full Text Available An approach to approximate equations of state for water and steam (IAPWS-95 for the calculation of three-dimensional flows of steam in turbomachinery in a range of operation of the present and future steam turbines is described. Test calculations of three-dimensional viscous flow in an LP steam turbine using various equations of state (perfect gas, Van der Waals equation, equation of state for water and steam IAPWS-95 are made. The comparison of numerical results with experimental data is also presented.

  17. Sterile particles from the flavor gauge model of masses

    Science.gov (United States)

    Smetana, Adam

    2013-04-01

    Our motivation is to study a dynamics which has the ambition to underlie models of the electroweak symmetry breaking via the condensation of known fermions. The right-handed neutrinos and the seesaw mechanism are necessary ingredients for viability of this scenario. The existence of right-handed neutrinos follows from theoretical consistence of a model based on dynamical flavor gauge symmetry breaking. The model is defined by a particular flavor representation setting of electroweakly charged fermions. Only finite number of versions of the model exists. They differ by the number and the flavor structure of the right-handed neutrino sector. We choose for inspection one of them, the non-minimal version with right-handed neutrinos in one sextet and four anti-triplet flavor representations. We show that a Majorana pairing of the sextet right-handed neutrinos is responsible for the flavor symmetry breaking and for the seesaw pattern of the neutrino mass matrix. The dynamically generated neutrino mass matrix spontaneously breaks the lepton number and the chiral sterility symmetry of the right-handed neutrino sector. As a result, a spectrum of majorons, neutrino composites, manifests. We study main characteristics of both massive sterile neutrinos and majorons.

  18. Computer modeling of a three-dimensional steam injection experiment

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, S.; Castanier, L.M. [Stanford Univ., CA (United States). Petroleum Research Inst.

    1993-08-01

    The experimental results and CT scans obtained during a steam-flooding experiment with the SUPRI 3-D steam injection laboratory model are compared with the results obtained from a numerical simulator for the same experiment. Simulation studies were carried out using the STARS (Steam and Additives Reservoir Simulator) compositional simulator. The saturation and temperature distributions obtained and heat-loss rates measured in the experimental model at different stages of steam-flooding were compared with those calculated from the numerical simulator. There is a fairly good agreement between the experimental results and the simulator output. However, the experimental scans show a greater degree of gravity override than that obtained with the simulator for the same heat-loss rates. Symmetric sides of the experimental 5-spot show asymmetric heat-loss rates contrary to theory and simulator results. Some utility programs have been written for extracting, processing and outputting the required grid data from the STARS simulator. These are general in nature and can be useful for other STARS users.

  19. An experimental study of a VVER reactor's steam generator model operating in the condensing mode

    Science.gov (United States)

    Morozov, A. V.; Remizov, O. V.

    2012-05-01

    Results obtained from an experimental study of a VVER reactor's steam generator model operating in the condensing mode are presented. The obtained empirical dependence for calculating the power of heat exchangers operating in the steam condensation mode is presented.

  20. Modelling studies of horizontal steam generator PGV-1000 with Cathare

    Energy Technology Data Exchange (ETDEWEB)

    Karppinen, I. [VTT Energy, Espoo (Finland)

    1995-12-31

    To perform thermal-hydraulic studies applied to nuclear power plants equipped with VVER, a program of qualification and assessment of the CATHARE computer code is in progress at the Institute of Protection and Nuclear Safety (IPSN). In this paper studies of modelling horizontal steam generator of VVER-1000 with the CATHARE computer code are presented. Steady state results are compared with measured data from the fifth unit of Novovoronezh nuclear power plant. (orig.). 10 refs.

  1. A Risk-Based Approach to Variable Load Configuration Validation in Steam Sterilization: Application of PDA Technical Report 1 Load Equivalence Topic.

    Science.gov (United States)

    Pavell, Anthony; Hughes, Keith A

    2010-01-01

    This article describes a method for achieving the load equivalence model, described in Parenteral Drug Association Technical Report 1, using a mass-based approach. The item and load bracketing approach allows for mixed equipment load size variation for operational flexibility along with decreased time to introduce new items to the operation. The article discusses the utilization of approximately 67 items/components (Table IV) identified for routine sterilization with varying quantities required weekly. The items were assessed for worst-case identification using four temperature-related criteria. The criteria were used to provide a data-based identification of worst-case items, and/or item equivalence, to carry forward into cycle validation using a variable load pattern. The mass approach to maximum load determination was used to bracket routine production use and allows for variable loading patterns. The result of the item mapping and load bracketing data is "a proven acceptable range" of sterilizing conditions including loading configuration and location. The application of these approaches, while initially more time/test-intensive than alternate approaches, provides a method of cycle validation with long-term benefit of ease of ongoing qualification, minimizing time and requirements for new equipment qualification for similar loads/use, and for rapid and rigorous assessment of new items for sterilization.

  2. Pest persistence and eradication conditions in a deterministic model for sterile insect release.

    Science.gov (United States)

    Gordillo, Luis F

    2015-01-01

    The release of sterile insects is an environment friendly pest control method used in integrated pest management programmes. Difference or differential equations based on Knipling's model often provide satisfactory qualitative descriptions of pest populations subject to sterile release at relatively high densities with large mating encounter rates, but fail otherwise. In this paper, I derive and explore numerically deterministic population models that include sterile release together with scarce mating encounters in the particular case of species with long lifespan and multiple matings. The differential equations account separately the effects of mating failure due to sterile male release and the frequency of mating encounters. When insects spatial spread is incorporated through diffusion terms, computations reveal the possibility of steady pest persistence in finite size patches. In the presence of density dependence regulation, it is observed that sterile release might contribute to induce sudden suppression of the pest population.

  3. Computational Fluid Dynamic Model of Steam Ingestion into a Transonic Compressor

    Science.gov (United States)

    2009-06-01

    DYNAMIC MODEL OF STEAM INGESTION INTO A TRANSONIC COMPRESSOR by Collin R. Hedges June 2009 Thesis Advisor: Anthony J. Gannon Second...TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Computational Fluid Dynamic Model of Steam Ingestion into a Transonic Compressor 6...flight deck. When ingested into jet engines, this steam may increase the engines’ susceptibility to stall. The serpentine air inlet ducts and single

  4. Mathematical modeling of control system for the experimental steam generator

    Directory of Open Access Journals (Sweden)

    Podlasek Szymon

    2016-01-01

    Full Text Available A steam generator is an essential unit of each cogeneration system using steam machines. Currently one of the cheapest ways of the steam generation can be application of old steam generators came from army surplus store. They have relatively simple construction and in case of not so exploited units – quite good general conditions, and functionality of mechanical components. By contrast, electrical components and control systems (mostly based on relay automatics are definitely obsolete. It is not possible to use such units with cooperation of steam bus or with steam engines. In particular, there is no possibility for automatically adjustment of the pressure and the temperature of the generated steam supplying steam engines. Such adjustment is necessary in case of variation of a generator load. The paper is devoted to description of improvement of an exemplary unit together with construction of the measurement-control system based on a PLC. The aim was to enable for communication between the steam generator and controllers of the steam bus and steam engines in order to construction of a complete, fully autonomic and maintenance-free microcogeneration system.

  5. Mathematical modeling of control system for the experimental steam generator

    Science.gov (United States)

    Podlasek, Szymon; Lalik, Krzysztof; Filipowicz, Mariusz; Sornek, Krzysztof; Kupski, Robert; Raś, Anita

    2016-03-01

    A steam generator is an essential unit of each cogeneration system using steam machines. Currently one of the cheapest ways of the steam generation can be application of old steam generators came from army surplus store. They have relatively simple construction and in case of not so exploited units - quite good general conditions, and functionality of mechanical components. By contrast, electrical components and control systems (mostly based on relay automatics) are definitely obsolete. It is not possible to use such units with cooperation of steam bus or with steam engines. In particular, there is no possibility for automatically adjustment of the pressure and the temperature of the generated steam supplying steam engines. Such adjustment is necessary in case of variation of a generator load. The paper is devoted to description of improvement of an exemplary unit together with construction of the measurement-control system based on a PLC. The aim was to enable for communication between the steam generator and controllers of the steam bus and steam engines in order to construction of a complete, fully autonomic and maintenance-free microcogeneration system.

  6. Computerized operating cost model for industrial steam generation

    Energy Technology Data Exchange (ETDEWEB)

    Powers, T.D.

    1983-02-01

    Pending EPA regulations, establishing revised emission levels for industrial boilers are perceived to have an effect on the relative costs of steam production technologies. To aid in the comparison of competitive boiler technologies, the Steam Cost Code was developed which provides levelized steam costs reflecting the effects of a number of key steam cost parameters. The Steam Cost Code is a user interactive FORTRAN program designed to operate on a VAX computer system. The program requires the user to input a number of variables describing the design characteristics, capital costs, and operating conditions for a specific boiler system. Part of the input to the Steam Cost Code is the capital cost of the steam production system. The capital cost is obtained from a program called INDCEPT, developed by Oak Ridge National Laboratory under Department of Energy, Morgantown Energy Technology Center sponsorship.

  7. Cosmology with self-interacting sterile neutrinos and dark matter - A pseudoscalar model

    CERN Document Server

    Archidiacono, Maria; Hansen, Rasmus Sloth; Tram, Thomas

    2014-01-01

    Short baseline neutrino oscillation experiments have shown hints of the existence of additional sterile neutrinos in the eV mass range. Such sterile neutrinos are incompatible with cosmology because they suppress structure formation unless they can be prevented from thermalising in the early Universe. Here we present a novel scenario in which both sterile neutrinos and dark matter are coupled to a new, light pseudoscalar. This can prevent thermalisation of sterile neutrinos and make dark matter sufficiently self-interacting to have an impact on galactic dynamics and possibly resolve some of the known problems with the standard cold dark matter scenario. Our model singles out a dimensionless coupling strength for both sterile neutrinos and dark matter in the range $g_s \\sim g_d \\sim 10^{-5}$ and predicts a dark matter particle mass in the MeV range.

  8. Modeling local chemistry in PWR steam generator crevices

    Energy Technology Data Exchange (ETDEWEB)

    Millett, P.J. [EPRI, Palo Alto, CA (United States)

    1997-02-01

    Over the past two decades steam generator corrosion damage has been a major cost impact to PWR owners. Crevices and occluded regions create thermal-hydraulic conditions where aggressive impurities can become highly concentrated, promoting localized corrosion of the tubing and support structure materials. The type of corrosion varies depending on the local conditions, with stress corrosion cracking being the phenomenon of most current concern. A major goal of the EPRI research in this area has been to develop models of the concentration process and resulting crevice chemistry conditions. These models may then be used to predict crevice chemistry based on knowledge of bulk chemistry, thereby allowing the operator to control corrosion damage. Rigorous deterministic models have not yet been developed; however, empirical approaches have shown promise and are reflected in current versions of the industry-developed secondary water chemistry guidelines.

  9. A three-dimensional laboratory steam injection model allowing in situ saturation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Demiral, B.M.R.; Pettit, P.A.; Castanier, L.M.; Brigham, W.E.

    1992-08-01

    The CT imaging technique together with temperature and pressure measurements were used to follow the steam propagation during steam and steam foam injection experiments in a three dimensional laboratory steam injection model. The advantages and disadvantages of different geometries were examined to find out which could best represent radial and gravity override flows and also fit the dimensions of the scanning field of the CT scanner. During experiments, steam was injected continuously at a constant rate into the water saturated model and CT scans were taken at six different cross sections of the model. Pressure and temperature data were collected with time at three different levels in the model. During steam injection experiments, the saturations obtained by CT matched well with the temperature data. That is, the steam override as observed by temperature data was also clearly seen on the CT pictures. During the runs where foam was present, the saturation distributions obtained from CT pictures showed a piston like displacement. However, the temperature distributions were different depending on the type of steam foam process used. The results clearly show that the pressure/temperature data alone are not sufficient to study steam foam in the presence of non-condensible gas.

  10. Modelling the effects of the sterile insect technique applied to Eldana saccharina Walker in sugarcane

    Directory of Open Access Journals (Sweden)

    L Potgieter

    2012-12-01

    Full Text Available A mathematical model is formulated for the population dynamics of an Eldana saccharina Walker infestation of sugarcane under the influence of partially sterile released insects. The model describes the population growth of and interaction between normal and sterile E.saccharina moths in a temporally variable, but spatially homogeneous environment. The model consists of a deterministic system of difference equations subject to strictly positive initial data. The primary objective of this model is to determine suitable parameters in terms of which the above population growth and interaction may be quantified and according to which E.saccharina infestation levels and the associated sugarcane damage may be measured. Although many models have been formulated in the past describing the sterile insect technique, few of these models describe the technique for Lepidopteran species with more than one life stage and where F1-sterility is relevant. In addition, none of these models consider the technique when fully sterile females and partially sterile males are being released. The model formulated is also the first to describe the technique applied specifically to E.saccharina, and to consider the economic viability of applying the technique to this species. Pertinent decision support is provided to farm managers in terms of the best timing for releases, release ratios and release frequencies.

  11. Prognostics for Steam Generator Tube Rupture using Markov Chain model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gibeom; Heo, Gyunyoung [Kyung Hee University, Yongin (Korea, Republic of); Kim, Hyeonmin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    This paper will describe the prognostics method for evaluating and forecasting the ageing effect and demonstrate the procedure of prognostics for the Steam Generator Tube Rupture (SGTR) accident. Authors will propose the data-driven method so called MCMC (Markov Chain Monte Carlo) which is preferred to the physical-model method in terms of flexibility and availability. Degradation data is represented as growth of burst probability over time. Markov chain model is performed based on transition probability of state. And the state must be discrete variable. Therefore, burst probability that is continuous variable have to be changed into discrete variable to apply Markov chain model to the degradation data. The Markov chain model which is one of prognostics methods was described and the pilot demonstration for a SGTR accident was performed as a case study. The Markov chain model is strong since it is possible to be performed without physical models as long as enough data are available. However, in the case of the discrete Markov chain used in this study, there must be loss of information while the given data is discretized and assigned to the finite number of states. In this process, original information might not be reflected on prediction sufficiently. This should be noted as the limitation of discrete models. Now we will be studying on other prognostics methods such as GPM (General Path Model) which is also data-driven method as well as the particle filer which belongs to physical-model method and conducting comparison analysis.

  12. A reaction-diffusion model of the Darien Gap Sterile Insect Release Method

    Science.gov (United States)

    Alford, John G.

    2015-05-01

    The Sterile Insect Release Method (SIRM) is used as a biological control for invasive insect species. SIRM involves introducing large quantities of sterilized male insects into a wild population of invading insects. A fertile/sterile mating produces offspring that are not viable and the wild insect population will eventually be eradicated. A U.S. government program maintains a permanent sterile fly barrier zone in the Darien Gap between Panama and Columbia to control the screwworm fly (Cochliomyia Hominivorax), an insect that feeds off of living tissue in mammals and has devastating effects on livestock. This barrier zone is maintained by regular releases of massive quantities of sterilized male screwworm flies from aircraft. We analyze a reaction-diffusion model of the Darien Gap barrier zone. Simulations of the model equations yield two types of spatially inhomogeneous steady-state solutions representing a sterile fly barrier that does not prevent invasion and a barrier that does prevent invasion. We investigate steady-state solutions using both phase plane methods and monotone iteration methods and describe how barrier width and the sterile fly release rate affects steady-state behavior.

  13. Mathematical Modeling of Ultra-Superheated Steam Gasification

    Science.gov (United States)

    Xin, Fen

    Pure steam gasification has been of interest in hydrogen production, but with the challenge of supplying heat for endothermic reactions. Traditional solutions included either combusting feedstocks at the price of decreasing carbon conversion ratio, or using costly heating apparatus. Therefore, a distributed gasifier with an Ultra-Superheated-Steam (USS) generator was invented, satisfying the heat requirement and avoiding carbon combustion in steam gasification. This project developed the first version of the Ultra-Superheated-Steam-Fluidization-Model (USSFM V1.0) for the USS gasifier. A stand-alone equilibrium combustion model was firstly developed to calculate the USS mixture, which was the input to the USSFM V1.0. Model development of the USSFM V1.0 included assumptions, governing equations, boundary conditions, supporting equations and iterative schemes of guessed values. There were three nested loops in the dense bed and one loop in the freeboard. The USSFM V1.0 included one main routine and twenty-four subroutines. The USSFM V1.0 was validated with experimental data from the Enercon USS gasifier. The calculated USS mixture had a trace of oxygen, validating the initial expectation of creating an oxygen-free environment in the gasifier. Simulations showed that the USS mixture could satisfy the gasification heat requirement without partial carbon combustion. The USSFM V1.0 had good predictions on the H2% in all tests, and on other variables at a level of the lower oxygen feed. Provided with higher oxygen feed, the USSFM V1.0 simulated hotter temperatures, higher CO% and lower CO2%. Errors were explained by assumptions of equilibrium combustion, adiabatic reactors, reaction kinetics, etc. By investigating specific modeling data, gas-particle convective heat transfers were found to be critical in energy balance equations of both emulsion gas and particles, while bubble size controlled both the mass and energy balance equations of bubble gas. Parametric study

  14. Effect of cross-section models on the validity of sterile neutrino mixing limits

    CERN Document Server

    Stowell, Patrick; Cartwright, Susan

    2015-01-01

    Charged-Current Quasi-Elastic (CCQE) neutrino scattering is the signal channel for sterile neutrino oscillation experiments. Recent cross-section measurements have made it clear that the current understanding of this channel in the few-GeV region is incomplete, and several sophisticated theoretical models have been proposed to tackle this issue, although it is not clear which model best describes the global dataset. In this paper we argue that the current uncertainty surrounding CCQE cross-sections is a serious problem for experiments seeking to produce sterile neutrino limits. We perform a sterile neutrino analysis with published MINERvA data as an illustrative example. We highlight the need for caution in interpreting sterile neutrino limits given the context of incomplete cross-section model information.

  15. The Wheel Model of STEAM Education Based on Traditional Korean Scientific Contents

    Science.gov (United States)

    Kim, Pyoung Won

    2016-01-01

    The Korean STEAM education pursues a convergent human resources education, but there are shortcomings associated with it due to the fact that it excludes the Humanities in its curriculum. This study embodies the accomplishments from the design and field application of the STEAM education model that has added Humanities fields (history, geography,…

  16. A mathematical model for wild and sterile species in competition: immigration

    Science.gov (United States)

    Flores, J. C.

    2003-10-01

    We consider a mathematical model of eradication by competition between wild and sterile species when immigration is present. We discuss the case with constant and random immigration flux. In the first case, there is a threshold of eradication Mc related to the number M of sterile individuals. This threshold is evaluated analytically and depends on the niche capacity for instance . Under this threshold ( MCeratitis capitata) eradication and frontiers control program carried out in different regions of the world by the corresponding agricultural services.

  17. Effect of dry heat and steam sterilization on load-deflection characteristics of β-titanium wires: An in vitro study

    Directory of Open Access Journals (Sweden)

    Shiva Alavi

    2012-01-01

    Conclusion: It appears dry heat sterilization increases stiffness of RES, BETA, CNA and HONE but autoclave sterilization did not have any effect on load-deflection characteristics of most of the β-titanium wires tested, indicating that clinicians who want to provide maximum safety for their patients can autoclave TMAL, RES and CNA before applying them.

  18. 高压蒸汽灭菌法对两种末端切断钳影响的比较%Effect of high-pressure steam sterilization on two kinds of orthodontic distal end cutters

    Institute of Scientific and Technical Information of China (English)

    王婧; 曹帅; 王璞; 张凯亮; 曹宝成

    2013-01-01

    背景:虽然蒸汽灭菌法是口腔临床常用的一种消毒方法,但其是否会对消毒器械产生更明显的影响学术界一直存在着争议。  目的:对比分析高压蒸汽灭菌后两种常用正畸用末端切断钳剪切力值及腐蚀程度的变化,以明确高压蒸汽灭菌法对两种品牌末端切断钳的影响。  方法:取天天、3M牌末端切断钳各15把,均随机分为3组,分别进行高压蒸汽灭菌,高压蒸汽灭菌联合口外剪切,高压蒸汽灭菌联合口内剪切。测量经0,20,40,60次消毒后末端切断钳的剪切力,拍摄金相片并对两种切断钳钳喙进行X射线能谱分析。  结果与结论:随着消毒次数增加,6组切断钳的剪切力值均随之增大,天天末端切断钳3组剪切力的增大程度明显大于对应的3M末端切断钳3组(P OBJECTIVE:To investigate the effect of autoclave on two kinds of orthodontic distal end cutters by comparing shearing force and corrosion after sterilization. METHODS:Tiantian (n=15) and 3M (n=15) distal end cutters commonly used in orthodontic treatment were chosen for testing and divided into three groups, respectively. Three groups for each kind of cutter were treated with high-pressure steam sterilization, steam sterilization+extraoral shear, and steam sterilization+intraoral shear, respectively. The shearing force and metal ography of the distal end cutters were recorded after 0, 20, 40, and 60 cycles of sterilization. An energy dispersive spectrometer was used to scan the surfaces of the working edges of the distal end cutters after 60 cycles. RESULTS AND CONCLUSION:It was found that with an increase in the number of sterilization cycles, the shear force and extent of corrosion increased in al six groups of distal end cutters, but the situation was worse for Tiantian cutters than for 3M cutters. It was found that the difference of shear force between the Tiantian autoclave group and 3M autoclave

  19. Kinetic model on coke oven gas with steam reforming

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-yuan; ZHOU Jie-min; YAN Hong-jie

    2008-01-01

    The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio ofH2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%.

  20. A nonlinear dynamic model of a once-through, helical-coil steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Abdalla, M.A. [Oak Ridge Inst. for Science and Education, TN (United States)

    1993-07-01

    A dynamic model of a once-through, helical-coil steam generator is presented. The model simulates the advanced liquid metal reactor superheated cycle steam generator with a four-region, moving-boundary, drift-flux model. The model is described by a set of nonlinear differential equations derived from the fundamental equations of conversation of mass, energy, and momentum. Sample results of steady-state and transient calculations are presented.

  1. An optimization model for the operations of steam production in industrial boilers

    OpenAIRE

    Rocco,Cleber Damião; Morabito, Reinaldo

    2012-01-01

    In this study, a mixed integer linear programming model is presented to support some of the key decisions in the steam production system with industrial boilers. The model approaches the fuel management decisions (fuel replenishment and its inventory control), boiler operational decisions (start-up, warm-up, and shutdown operations), and which boiler should produce steam. The model adjustments and its validation were carried out through a case study in a large food industry. In face of the go...

  2. 2 232 case reports of pressure steam sterilization for orthopedic surgical instruments%运用压力蒸汽灭菌法灭菌骨科手术器械2232例报道

    Institute of Scientific and Technical Information of China (English)

    周玉英

    2014-01-01

    目的:运用压力蒸汽灭菌法灭菌,确保骨科手术器械灭菌质量,加强医院供应室灭菌质量管理,预防医院感染的发生。方法:采用回顾性分析方法对2232件骨科手术器械进行物理、化学、生物监测,严格控制发放标准。结果:2232件骨科手术器械,经物理监测、化学监测、快速生物监测均合格,但2件出现棉包布有破洞,2件出现无纺布高温炼成破洞,5件出现湿包,3件出现清洗质量不合格。结论:骨科手术器械大多为植入物,系为高度危险性物品,必须严格把握灭菌质量,细化过程管理,保证患者安全。%Objective:To use pressure steam sterilization in order to ensure the quality of orthopedic surgical instruments steri-lization, strengthen quality management of hospital supply room sterilization and prevent the occurrence of hospital infections. Meth-ods:2232 pieces of orthopedic surgical instruments were monitored physically, chemically and biologically by applying pressure steam sterilization, and the provision standard was controlled strictly. Results: 2232 pieces of orthopedic surgical instruments were qualified through the physical, chemical and rapid biological monitoring, however, the cotton cloth of 2 pieces had holes, non-woven fabric of 2 pieces had be heated into holes, 5 pieces had wet bags, and the cleaning quality of 3 pieces was not qualified. Conclusions: Most or-thopedic surgical instruments are implantable, as well as highly dangerous goods. Therefore, it must strictly grasp the quality of sterili-zation and refine process management so as to ensure the safety of patients.

  3. Monitoring Methods and Application of the Effects of High Pressure Steam Sterilization in Supply Room%浅谈供应室高压蒸汽灭菌效果监测的方法及运用

    Institute of Scientific and Technical Information of China (English)

    于桦

    2011-01-01

    Objective To analyze the effects of various monitoring method of daily high pressure steam sterilization in supply room and offer technology reference for clinic to control the hospital infection. Methods The principle of every monitoring means and condition of real use were compared and analyzed to find out the advantages and disadvantages of the methods.Results Every monitor means has its own strong points and supplements each other to complete quality monitoring for sterilization goods together. Conclusion Comprehensively applying various monitoring measures to effectively quality control of sterilization goods is the key to control the hospital infection. [Chinese Medical Equipment Journal,2011 ,32 (7) : 107-108]%目的:对供应室日常高压灭菌效果的各种监测方法进行分析,为临床控制医院感染提供技术参考.方法:对各项监测手段的原理及实际运用情况进行对比分析,找出优缺点.结果:各项监测方法各有所长,相辅相成共同完成对灭菌物品的质量监测.结论:综合运用各项监测手段进行灭菌物品的质量控制,是确保医院内感染得到有效控制的关键.

  4. keV sterile neutrino Dark Matter in gauge extensions of the Standard Model

    CERN Document Server

    Bezrukov, F; Lindner, M

    2009-01-01

    It is known, that a keV scale sterile neutrino is a good Warm Dark Matter (WDM) candidate. We study how this possibility could be realised in the context of gauge extensions of the Standard Model (SM). The naive expectation leads to large thermal overproduction of sterile neutrinos in this setup. However, we find that it is possible to use out-of-equilibrium decay of the other right-handed neutrinos of the model to dilute the present density of the keV sterile neutrinos and achieve the observed DM density. We present the universal requirements that should be satisfied by the gauge extensions of the SM, containing right-handed neutrinos, to be viable models of WDM, and provide a simple example in the context of the Left-Right symmetric model.

  5. Development and validation of a CFD-based steam reformer model

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen; Dahlqvist, Mathis; Saksager, Anders

    2006-01-01

    of the ethanol steam reformer.  Based on the model predictions, a detailed investigation of the processes controlling the hydrogen production rates is presented. It was found that efficient heat transfer from the flue gas to the endothermic steam reforming reactions is critical and represents a limiting factor...... a detailed mechanism for the reforming reactions. Heat exchange between the flue gas and reformate streams through the reformer reactor walls was also included as a conjugate heat transfer process.  From a review of published models for the catalytic steam reforming of ethanol and preliminary predictions...

  6. Modeling a Helical-coil Steam Generator in RELAP5-3D for the Next Generation Nuclear Plant

    Energy Technology Data Exchange (ETDEWEB)

    Nathan V. Hoffer; Piyush Sabharwall; Nolan A. Anderson

    2011-01-01

    Options for the primary heat transport loop heat exchangers for the Next Generation Nuclear Plant are currently being evaluated. A helical-coil steam generator is one heat exchanger design under consideration. Safety is an integral part of the helical-coil steam generator evaluation. Transient analysis plays a key role in evaluation of the steam generators safety. Using RELAP5-3D to model the helical-coil steam generator, a loss of pressure in the primary side of the steam generator is simulated. This report details the development of the steam generator model, the loss of pressure transient, and the response of the steam generator primary and secondary systems to the loss of primary pressure. Back ground on High Temperature Gas-cooled reactors, steam generators, the Next Generation Nuclear Plant is provided to increase the readers understanding of the material presented.

  7. Modeling of soluble impurities distribution in the steam generator secondary water

    Energy Technology Data Exchange (ETDEWEB)

    Matal, O.; Simo, T. [Energovyzkum s.r.o., Brno (Switzerland); Kucak, L.; Urban, F. [Slovak Technical Univ., Bratislava (Slovakia)

    1997-12-31

    A model was developed to compute concentration of impurities in the WWER 440 steam generator (SG) secondary water along the tube bundle. Calculated values were verified by concentration values obtained from secondary water sample chemical analysis. (orig.). 2 refs.

  8. Internal steam reforming in solid oxide fuel cells: Status and opportunities of kinetic studies and their impact on modelling

    DEFF Research Database (Denmark)

    Mogensen, David; Grunwaldt, J.-D.; Hendriksen, Peter Vang;

    2011-01-01

    of such a system require SOFC models that include accurate description of the steam reforming rate. The objective of this article is to review the reported kinetic expressions for the steam reforming reaction. Extensive work has been performed on traditional catalysts for steam reforming. Because of differences...

  9. NUMERICAL SIMULATION OF WET STEAM CONDENSING FLOW WITH AN EULERIAN/EULERIAN MODEL

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Wet steam condensing flow in low-pressure steam turbine leads to efficiency losses and blade erosions.In order to investigate this problem by numerical approach, an Eulerian/Eulerian model has been developed, in which the wet steam is regarded as mixture comprising two coupled systems: the vapor phase and the liquid phase.These two systems are both described by conservation equations.High resolution TVD scheme is employed to capture condensing phenomena in wet steam flow.This model has been validated by numerical simulations of condensing flows in 1D and 2D nozzles.Compared with experimental data, a good agreement is observed.This Eulerian/Eulerian model can be extended to 3D calculation of condensing flow.

  10. Testing sterile neutrino extensions of the Standard Model at future lepton colliders

    CERN Document Server

    Antusch, Stefan

    2015-01-01

    Extending the Standard Model (SM) with sterile ('right-handed') neutrinos is one of the best motivated ways to account for the observed neutrino masses. We discuss the expected sensitivity of future lepton collider experiments for probing such extensions. An interesting testable scenario is given by 'symmetry protected seesaw models', which theoretically allow for sterile neutrino masses around the electroweak scale with up to order one mixings with the light (SM) neutrinos. In addition to indirect tests, e.g. via electroweak precision observables, sterile neutrinos with masses around the electroweak scale can also be probed by direct searches, e.g. via sterile neutrino decays at the Z pole, deviations from the SM cross section for four lepton final states at and beyond the WW threshold and via Higgs boson decays. We study the present bounds on sterile neutrino properties from LEP and LHC as well as the expected sensitivities of possible future lepton colliders such as ILC, CEPC and FCC-ee (TLEP).

  11. Direct-Steam Linear Fresnel Performance Model for NREL's System Advisor Model

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, M. J.; Zhu, G.

    2012-09-01

    This paper presents the technical formulation and demonstrated model performance results of a new direct-steam-generation (DSG) model in NREL's System Advisor Model (SAM). The model predicts the annual electricity production of a wide range of system configurations within the DSG Linear Fresnel technology by modeling hourly performance of the plant in detail. The quasi-steady-state formulation allows users to investigate energy and mass flows, operating temperatures, and pressure drops for geometries and solar field configurations of interest. The model includes tools for heat loss calculation using either empirical polynomial heat loss curves as a function of steam temperature, ambient temperature, and wind velocity, or a detailed evacuated tube receiver heat loss model. Thermal losses are evaluated using a computationally efficient nodal approach, where the solar field and headers are discretized into multiple nodes where heat losses, thermal inertia, steam conditions (including pressure, temperature, enthalpy, etc.) are individually evaluated during each time step of the simulation. This paper discusses the mathematical formulation for the solar field model and describes how the solar field is integrated with the other subsystem models, including the power cycle and optional auxiliary fossil system. Model results are also presented to demonstrate plant behavior in the various operating modes.

  12. Surgery, sterilization and sterility.

    Science.gov (United States)

    Green, V W

    1993-03-01

    The history of sterilization was not linked from the first with surgery. Surgery came first, fully 600 years before the principles of asepsis and anesthesia were even introduced in the middle of the 1800s. Also in the 1800s, the beginnings of thermal sterilization were being developed in the food industry. The basic principles of antisepsis and prevention of wound suppuration, including the destruction of germs on instruments, dressings, the hands of the surgeon and his assistants, and everything else in contact with the wound were clearly elucidated by Lister in the 1870s and remain the inviolate principles of surgical asepsis today. In general, the marriage between the surgeons and the sterilizers was a successful one; the major handicap to eternal bliss and harmony, however, was an incompatibility between the partners. As in many marriages, the partners made unwarranted demands upon each other, and became frustrated when these demands were unfulfilled. The field of surgical sterilization and surgical safety is less confused by technical inconsistencies than it is by semantic nightmares, such that we will never reach a universal definition of sterility. However, we do not really need a universal definition of sterility. Rather we should learn how to translate sterility tests in terms of the real world infections hazards.

  13. Production-log base model for carbonate permeability distribution and steam flood optimization

    Energy Technology Data Exchange (ETDEWEB)

    Ahamed, S.F.; Choudhry, M.A.; Abdulbaqi, J.B. [Kuwait Gulf Oil Co. (Kuwait)

    2008-10-15

    This paper presented a model for the effective management of primary and thermal oil recovery operations in the Wafra Field in Kuwait, where a small huff and puff project was carried out in 1998 to determine if steam injection was a feasible recovery option for the field. The Eocene heavy oil reservoirs of the Wafra Field are carbonate rock admixtures with gypsum and anhydrite. They are the shallowest of the field's productive horizons and exhibit a high degree of fluid flow heterogeneity. The assessment of vertical and lateral permeability variation is a key factor for success of the reservoir development plan. Steam injection began in 2006 in a small scale test (SST) to determine if the innovative technology could produce steam from effluent water and to test the viability of steam injection in carbonate reservoirs. Following the success of the SST, a large scale pilot (LSP) is schedule to start in 2009. It can be used for completion strategies of injectors and producers in steam injection. The model showed that the productivity of the Eocene wells could be correlated with common available logs to develop a log based-permeability model. A series of cross plots for the perforated intervals of high and low productivity wells were constructed to develop a relationship between well productivity and location of log parameters on the plots. A relationship between rock quality, productivity and conventional log parameters was established. It was concluded that the vertical permeability and interwell continuity in the Eocene wells can be used to optimize new well placement for horizontal and vertical infill drilling. The model is also an effective tool to predict the steam injectivity profile to understand the anomalies related to temperature-depth distribution. The model can be used to improve the efficiency of formation heating by optimizing the steam flood process and steam pattern well completion. 16 refs.

  14. Modeling of an once through helical coil steam generator of a superheated cycle for sizing analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeon Sik; Sim, Yoon Sub; Kim, Eui Kwang [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    A thermal sizing code, named as HSGSA (Helical coil Steam Generator Sizing Analyzer), for a sodium heated helical coil steam generator is developed for KALIMER (Korea Advanced LIquid MEtal Reactor) design. The theoretical modeling of the shell and tube sides is described and relevant correlations are presented. For assessment of HSGSA, a reference plant design case is compared to the calculational outputs from HSGSA simulation. 9 refs., 6 figs. (Author)

  15. Steam-oil displacement and the principles of calculation through modelling

    Energy Technology Data Exchange (ETDEWEB)

    Durdevic, V.; Nedeljkovic, V.

    1982-06-01

    When steam is injected into oil reservoirs, both the reservoir rock and fluid are heated. The viscosity of the heated oil is reduced and its mobility in the porous medium is increased. Before application of this method, steam injection simulation models are made, followed by pilot tests. Nafta-Gas is preparing and engineering a study for the application of this enhanced oil recovery method.

  16. Modeling, Simulation and Optimization of Hydrogen Production Process from Glycerol using Steam Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeongpil; Cho, Sunghyun; Kim, Tae-Ok; Shin, Dongil [Myongji University, Yongin (Korea, Republic of); Lee, Seunghwan [JNK Heaters, Seoul (Korea, Republic of); Moon, Dong Ju [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-12-15

    For improved sustainability of the biorefinery industry, biorefinery-byproduct glycerol is being investigated as an alternate source for hydrogen production. This research designs and optimizes a hydrogen-production process for small hydrogen stations using steam reforming of purified glycerol as the main reaction, replacing existing processes relying on steam methane reforming. Modeling, simulation and optimization using a commercial process simulator are performed for the proposed hydrogen production process from glycerol. The mixture of glycerol and steam are used for making syngas in the reforming process. Then hydrogen are produced from carbon monoxide and steam through the water-gas shift reaction. Finally, hydrogen is separated from carbon dioxide using PSA. This study shows higher yield than former U.S.. DOE and Linde studies. Economic evaluations are performed for optimal planning of constructing domestic hydrogen energy infrastructure based on the proposed glycerol-based hydrogen station.

  17. Steam turbine governor modeling and parameters testing for power system simulation

    Institute of Scientific and Technical Information of China (English)

    Ying LI; Chufeng PENG; Zenghui YANG

    2009-01-01

    The theoretical modeling, parameters test and model correction for a steam turbine (ST) governor are discussed. A set of ST Governor system model for power system simulation is created based on this research. A power system simulation for an actual power grid accident is conducted using this new model and the comparison between the simulation and actual data show that the results are satisfactory.

  18. Preparatory selection of sterilization regime for canned Natural Atlantic Mackerel with oil based on developed mathematical models of the process

    Directory of Open Access Journals (Sweden)

    Maslov A. A.

    2016-12-01

    Full Text Available Definition of preparatory parameters for sterilization regime of canned "Natural Atlantic Mackerel with Oil" is the aim of current study. PRSC software developed at the department of automation and computer engineering is used for preparatory selection. To determine the parameters of process model, in laboratory autoclave AVK-30M the pre-trial process of sterilization and cooling in water with backpressure of canned "Natural Atlantic Mackerel with Oil" in can N 3 has been performed. Gathering information about the temperature in the autoclave sterilization chamber and the can with product has been carried out using Ellab TrackSense PRO loggers. Due to the obtained information three transfer functions for the product model have been identified: in the least heated area of autoclave, the average heated and the most heated. In PRSC programme temporary temperature dependences in the sterilization chamber have been built using this information. The model of sterilization process of canned "Natural Atlantic Mackerel with Oil" has been received after the pre-trial process. Then in the automatic mode the sterilization regime of canned "Natural Atlantic Mackerel with Oil" has been selected using the value of actual effect close to normative sterilizing effect (5.9 conditional minutes. Furthermore, in this study step-mode sterilization of canned "Natural Atlantic Mackerel with Oil" has been selected. Utilization of step-mode sterilization with the maximum temperature equal to 125 °C in the sterilization chamber allows reduce process duration by 10 %. However, the application of this regime in practice requires additional research. Using the described approach based on the developed mathematical models of the process allows receive optimal step and variable canned food sterilization regimes with high energy efficiency and product quality.

  19. Linear parameter-varying modeling and control of the steam temperature in a Canadian SCWR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Peiwei, E-mail: sunpeiwei@mail.xjtu.edu.cn; Zhang, Jianmin; Su, Guanghui

    2017-03-15

    Highlights: • Nonlinearity of Canadian SCWR is analyzed based on step responses and Nyquist plots. • LPV model is derived through Jacobian linearization and curve fitting. • An output feedback H{sub ∞} controller is synthesized for the steam temperature. • The control performance is evaluated by step disturbances and wide range operation. • The controller can stabilize the system and reject the reactor power disturbance. - Abstract: The Canadian direct-cycle Supercritical Water-cooled Reactor (SCWR) is a pressure-tube type SCWR under development in Canada. The dynamics of the steam temperature have a high degree of nonlinearity and are highly sensitive to reactor power disturbances. Traditional gain scheduling control cannot theoretically guarantee stability for all operating regions. The control performance can also be deteriorated when the controllers are switched. In this paper, a linear parameter-varying (LPV) strategy is proposed to solve such problems. Jacobian linearization and curve fitting are applied to derive the LPV model, which is verified using a nonlinear dynamic model and determined to be sufficiently accurate for control studies. An output feedback H{sub ∞} controller is synthesized to stabilize the steam temperature system and reject reactor power disturbances. The LPV steam temperature controller is implemented using a nonlinear dynamic model, and step changes in the setpoints and typical load patterns are carried out in the testing process. It is demonstrated through numerical simulation that the LPV controller not only stabilizes the steam temperature under different disturbances but also efficiently rejects reactor power disturbances and suppresses the steam temperature variation at different power levels. The LPV approach is effective in solving control problems of the steam temperature in the Canadian SCWR.

  20. Phenomena of wet pack after pulsing vacuum steam sterilization:analysis and countermeasures%脉动真空压力蒸汽灭菌湿包原因分析及对策

    Institute of Scientific and Technical Information of China (English)

    徐月美; 陈宜华; 金翠萍; 陈蓉美

    2014-01-01

    Objectve We will analyze the reason of wet pack appeared after pulsing vacuum steam sterilization.In order to bring forward the methods and countermeasures of control to reduce the appearance of wet pack.Methods For the basic nursing pack packed by cotton or non-woven or non-woven+crepe paper or paper-plastic bag,the similar specialized instrument,the same size of operating room surgical apparatus pack and operating room cloth pack,the foreign apparatus,we will take types of classified loading and mixed loading according to the different kinds of sterilization package,choose the fabric process taking addvantage of the two sterilization in the department,run a sterilization cycle according to the normal operating procedure of pulsing vacuum steam sterilization,observe the position,amount and variety of wet pack according to the different pan time and cooling-down time. We will choose 2 batch-totally 8 batch and contiously monitor 7 days everday.Results There were 32 wet packs appeared among the 56 batch-totally 2660 sterilization packages.Different materials have a variety of phenomena of wet pack.The first one is paper-plastic bag ,next is non-woven,then the third is non-woven+crepe paper,and the last is cotton.The material,size and weight could effect on the appearance of wet pack.The metallic apparatus is easier than mercery.The larger volume and the more weight,the easier of wet pack appeared.Different loading and cooling-down methods have an influence on wet pack.The mixed loading is easier than the classified loading.All of wet pack have all kinds of position.The lowest is easier than the two floors above it.And the sterilization package closing to the lining of sterilization is easier to the wet pack appeared. The shorter cooling-down time,the easier.Conclusion Strengthen the control of sterilized supply center and standard operation proceduce,such as drying equipment items,package,sterilization and unload,could effectively control the appearance of wet pack

  1. Modelling horizontal steam generator with ATHLET. Verification of different nodalization schemes and implementation of verified constitutive equations

    Energy Technology Data Exchange (ETDEWEB)

    Beliaev, J.; Trunov, N.; Tschekin, I. [OKB Gidropress (Russian Federation); Luther, W. [GRS Garching (Germany); Spolitak, S. [RNC-KI (Russian Federation)

    1995-12-31

    Currently the ATHLET code is widely applied for modelling of several Power Plants of WWER type with horizontal steam generators. A main drawback of all these applications is the insufficient verification of the models for the steam generator. This paper presents the nodalization schemes for the secondary side of the steam generator, the results of stationary calculations, and preliminary comparisons to experimental data. The consideration of circulation in the water inventory of the secondary side is proved to be necessary. (orig.). 3 refs.

  2. Towards microbiological quality assurance in radiation sterilization processing: a limiting case model

    Energy Technology Data Exchange (ETDEWEB)

    Doolan, P.T. (Becton Dickinson and Co., Parasmus, NJ (USA)); Dwyer, J.; Fitch, F.R. (Manchester Univ. (UK). Inst. of Science and Technology); Dwyer, V.M. (York Univ. (UK). Dept. of Physics); Halls, N.A. (Becton Dickinson and Co., Dun Laoghaire (Ireland)); Tallentire, A. (Manchester Univ. (UK). Dept. of Pharmacy)

    1985-03-01

    A Limiting Case Model has been developed which describes the dependence on radiation dose of the proportion of items, in a population of items subjected to irradiation, which are contaminated by one or more organisms. This model is independent of the initial distribution of numbers of micro-organisms on items and represents a conservative approach to estimation of the proportions of non-sterile items in an irradiated population of items.

  3. Application of a single-fluid model for the steam condensing flow prediction

    Science.gov (United States)

    Smołka, K.; Dykas, S.; Majkut, M.; Strozik, M.

    2016-10-01

    One of the results of many years of research conducted in the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology are computational algorithms for modelling steam flows with a non-equilibrium condensation process. In parallel with theoretical and numerical research, works were also started on experimental testing of the steam condensing flow. This paper presents a comparison of calculations of a flow field modelled by means of a single-fluid model using both an in-house CFD code and the commercial Ansys CFX v16.2 software package. The calculation results are compared to inhouse experimental testing.

  4. Exergy Analysis of a Subcritical Reheat Steam Power Plant with Regression Modeling and Optimization

    Directory of Open Access Journals (Sweden)

    MUHIB ALI RAJPER

    2016-07-01

    Full Text Available In this paper, exergy analysis of a 210 MW SPP (Steam Power Plant is performed. Firstly, the plant is modeled and validated, followed by a parametric study to show the effects of various operating parameters on the performance parameters. The net power output, energy efficiency, and exergy efficiency are taken as the performance parameters, while the condenser pressure, main steam pressure, bled steam pressures, main steam temperature, and reheat steam temperature isnominated as the operating parameters. Moreover, multiple polynomial regression models are developed to correlate each performance parameter with the operating parameters. The performance is then optimizedby using Direct-searchmethod. According to the results, the net power output, energy efficiency, and exergy efficiency are calculated as 186.5 MW, 31.37 and 30.41%, respectively under normal operating conditions as a base case. The condenser is a major contributor towards the energy loss, followed by the boiler, whereas the highest irreversibilities occur in the boiler and turbine. According to the parametric study, variation in the operating parameters greatly influences the performance parameters. The regression models have appeared to be a good estimator of the performance parameters. The optimum net power output, energy efficiency and exergy efficiency are obtained as 227.6 MW, 37.4 and 36.4, respectively, which have been calculated along with optimal values of selected operating parameters.

  5. Modelling of 4D seismic data for the monitoring of the steam chamber growth during SAGD process

    Energy Technology Data Exchange (ETDEWEB)

    Lerat, O.; Adjemian, F.; Auvinet, A.; Baroni, A.; Bemer, E.; Eschard, R.; Etienne, G.; Renard, G.; Servant, G. [IFP, Lyon (France); Michel, L.; Rodriguez, S.; Aubin, F. [CGG Veritas, Calgary, AB (Canada); Euzen, T. [IFP Technologies Canada Inc., Calgary, AB (Canada)

    2009-07-01

    Reservoir heterogeneities influence the performance of heavy-oil production by the steam-assisted gravity drainage (SAGD) process. This paper reported on a study that evaluated the impact of reservoir heterogeneities on the steam chamber growth in a heavy oil field of the Canadian Athabasca McMurray Formation. The study involved three steps: (1) the construction of an initial static model, (2) the simulation of the thermal production of heavy oil with two coupled fluid-flow and geomechanical models, and (3) the production of synthetic seismic maps at different steps of steam injection. Two periods of SAGD production were studied in detail, notably the early times of steam injection and later on when the steam chamber developed laterally and vertically towards the top of the reservoir. The objective was to improve the interpretation of 4D seismic data in steam-assisted production at an early stage by understanding how the steam would be distributed along the injection well in the first few weeks or months of steam injection. The study was based on a fully integrated approach that involved geology, geophysics, reservoir and geomechanics. The study revealed that for long periods of production, the reservoir-scale heterogeneities can impact the production by a limitation of the steam chamber growth upwards. However, paths and drains in the upper part of the reservoir could allow the steam to propagate in low-pay areas or in thief zones. 11 refs., 18 figs.

  6. 中低温蒸汽处理对鲜切胡萝卜片减菌效果及其品质的影响%Effect of steam sterilization treatments on the quality of fresh-cut carrot slices

    Institute of Scientific and Technical Information of China (English)

    周明晖; 刘书来; 丁玉庭

    2012-01-01

    To explore the effects of steam sterilization treatments on the quality of vegetables,fresh-cut carrot slices were treated by steam with different temperature(50~100℃).The results showed that,with the increase of temperature and time of steam,the amount of microorganisms,moisture,carotenoids,firmness and color of the fresh-cut carrot slices decreased significantly(P0.05).When the low temperature steam(50~70℃) was used for 600s,the amount of microorganisms decreased more than 3lg(cfu/g),with moisture loss below 5% and carotenoids retention above 85%.In addition,it had little effects on the firmness and color of samples.While the moderate temperature steam(80~100℃) and the traditional boiling water blanching had more harmful effects on the carrot slices'quality.It can be concluded that low temperature steam treatments can reduce the amount of microorganisms of fresh-cut carrot slices and keep their quality as much as possible.%以鲜切胡萝卜片为研究对象,采用中低温蒸汽(50~100℃)进行减菌处理,分析了蒸汽处理过程中鲜切胡萝卜片品质指标的变化。结果表明,鲜切胡萝卜片的菌落总数、水分、类胡萝卜素、硬度、色泽等指标均随处理温度及时间的增加而显著减少(P〈0.05)。采用低温蒸汽(50~70℃)处理600s,对胡萝卜片的减菌效果明显,且失水率小于5%,类胡萝卜素保留高于85%,对蔬菜的硬度和色泽影响较小。而经中温蒸汽(80~100℃)及传统的沸水热烫处理后的胡萝卜片,其品质质地明显降低。因此,低温蒸汽减菌处理能有效降低胡萝卜片中的菌落总数,并可最大程度保护其品质质地。

  7. Slow Steaming in Maritime Transportation: Fundamentals, Trade-offs, and Decision Models

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.; Kontovas, Christos A.

    2015-01-01

    burned. The purpose of this chapter is to examine the practice of slow steaming from various angles. In that context, a taxonomy of models is presented, some fundamentals are outlined, the main trade-offs are analysed, and some decision models are presented. Some examples are finally presented so...

  8. Dynamic Modeling of Steam Condenser and Design of PI Controller Based on Grey Wolf Optimizer

    Directory of Open Access Journals (Sweden)

    Shu-Xia Li

    2015-01-01

    Full Text Available Shell-and-tube condenser is a heat exchanger for cooling steam with high temperature and pressure, which is one of the main kinds of heat exchange equipment in thermal, nuclear, and marine power plant. Based on the lumped parameter modeling method, the dynamic mathematical model of the simplified steam condenser is established. Then, the pressure PI control system of steam condenser based on the Matlab/Simulink simulation platform is designed. In order to obtain better performance, a new metaheuristic intelligent algorithm, grey wolf optimizer (GWO, is used to realize the fine-tuning of PI controller parameters. On the other hand, the Z-N engineering tuning method, genetic algorithm, and particle swarm algorithm are adopted for tuning PI controller parameters and compared with GWO algorithm. Simulation results show that GWO algorithm has better control performance than other four algorithms.

  9. Light Sterile Neutrino and Dark Matter in Left-Right Symmetric Models Without Higgs Bidoublet

    CERN Document Server

    Borah, Debasish

    2016-01-01

    We present a class of left-right symmetric models where Dirac as well as Majorana mass terms of neutrinos can arise at one-loop level in a scotogenic fashion: with dark matter particles going inside the loop. We show the possibility of naturally light right handed neutrinos that can have interesting implications at neutrinoless double beta decay experiments as well as cosmology. Apart from a stable dark matter candidate stabilised by a remnant $Z_2$ symmetry, one can also have a long lived keV sterile neutrino dark matter in these models. This class of models can have very different collider signatures compared to the conventional left-right models.

  10. Mathematical modelling of methane steam reforming in a membrane reactor: an isothermal model

    Energy Technology Data Exchange (ETDEWEB)

    Assaf, E.M. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Dept. de Fisico-Quimica; Jesus, C.D.F.; Assaf, J.M. [Sao Carlos Univ., SP (Brazil). Dept. de Engenharia Quimica

    1998-06-01

    A mathematical modelling of one-dimensional, stationary and isothermic membrane reactor for methane steam reforming was developed to compare the maximum yield for methane conversion in this reactor with that in a conventional fixed-bed reactor. Fick`s first law was used to describe the mechanism of hydrogen permeation. The variables studied include: reaction temperature, hydrogen feed flow rate and membrane thickness. The results show that the membrane reactor presents a higher methane conversion yield than the conventional fixed-bed reactor. (author) 16 refs., 5 figs., 1 tab.; e-mail: eassaf at iqsc.sc.usp.br; mansur at power.ufscar.br

  11. MATHEMATICAL MODELLING OF METHANE STEAM REFORMING IN A MEMBRANE REACTOR: AN ISOTHERMIC MODEL

    Directory of Open Access Journals (Sweden)

    E.M. ASSAF

    1998-06-01

    Full Text Available A mathematical modelling of one-dimensional, stationary and isothermic membrane reactor for methane steam reforming was developed to compare the maximum yield for methane conversion in this reactor with that in a conventional fixed-bed reactor. Fick's first law was used to describe the mechanism of hydrogen permeation. The variables studied include: reaction temperature, hydrogen feed flow rate and membrane thickness. The results show that the membrane reactor presents a higher methane conversion yield than the conventional fixed-bed reactor.

  12. Modeling and simulation of an isothermal reactor for methanol steam reforming

    Directory of Open Access Journals (Sweden)

    Raphael Menechini Neto

    2014-04-01

    Full Text Available Due to growing electricity demand, cheap renewable energy sources are needed. Fuel cells are an interesting alternative for generating electricity since they use hydrogen as their main fuel and release only water and heat to the environment. Although fuel cells show great flexibility in size and operating temperature (some models even operate at low temperatures, the technology has the drawback for hydrogen transportation and storage. However, hydrogen may be produced from methanol steam reforming obtained from renewable sources such as biomass. The use of methanol as raw material in hydrogen production process by steam reforming is highly interesting owing to the fact that alcohol has the best hydrogen carbon-1 ratio (4:1 and may be processed at low temperatures and atmospheric pressures. They are features which are desirable for its use in autonomous fuel cells. Current research develops a mathematical model of an isothermal methanol steam reforming reactor and validates it against experimental data from the literature. The mathematical model was solved numerically by MATLAB® and the comparison of its predictions for different experimental conditions indicated that the developed model and the methodology for its numerical solution were adequate. Further, a preliminary analysis was undertaken on methanol steam reforming reactor project for autonomous fuel cell.

  13. A MATHEMATICAL MODEL OF THE ROASTING CHESTNUTS PROCESS BY SUPERHEATED STEAM

    Directory of Open Access Journals (Sweden)

    A. N. Ostrikov

    2013-01-01

    Full Text Available The mathematic modeling for chestnuts roasting process by superheated steam is conducted. Diffusion and thermal diffusion coefficients are used for process description. Initial conditions and boundary conditions of the third kind for thermal conductivity and mass transfer equations are set.

  14. An original combined multiphase model of the steam-explosion premixing phase

    OpenAIRE

    Leskovar, Matjaž; Mavko, Borut

    2015-01-01

    In multiphase flow, different distributions can occur that cannot be adequately modeled with just free-surface models or with just multiphase models. Such a distribution of phases occurs for example, in isothermal steam-explosion premixing experiments, where dispersed spheres penetrate the water and the water-air surface remains sharp. A common practice when modeling isothermal premixing experiments is to treat all three phases involved - the water, the air and the spheres phase - equally, wi...

  15. Satellite galaxies in semi-analytic models of galaxy formation with sterile neutrino dark matter

    CERN Document Server

    Lovell, Mark R; Boyarsky, Alexey; Cole, Shaun; Frenk, Carlos S; Gonzalez-Perez, Violeta; Kennedy, Rachel; Ruchayskiy, Oleg; Smith, Alex

    2015-01-01

    The sterile neutrino is a viable dark matter candidate that can be produced in the early Universe via non-equilibrium processes, and would therefore possess a highly non-thermal spectrum of primordial velocities. In this paper we analyse the process of structure formation with this class of dark matter particles. To this end we construct primordial dark matter power spectra as a function of the lepton asymmetry, $L_6$, that is present in the primordial plasma and leads to resonant sterile neutrino production. We compare these power spectra with those of thermally produced dark matter particles and show that resonantly produced sterile neutrinos are much colder than their thermal relic counterparts. We also demonstrate that the shape of these power spectra are not determined by the free-streaming scale alone. We then use the power spectra as an input for semi-analytic models of galaxy formation in order to predict the number of luminous satellite galaxies in a Milky Way-like halo. By assuming that the mass of ...

  16. An Isothermal Steam Expander for an Industrial Steam Supplying System

    Directory of Open Access Journals (Sweden)

    Chen-Kuang Lin

    2015-01-01

    Full Text Available Steam is an essential medium used in the industrial process. To ensure steam quality, small and middle scale boilers are often adopted. However, because a higher steam pressure (compared to the necessary steam pressure is generated, the boiler’s steam pressure will be reduced via a pressure regulator before the steam is directed through the process. Unfortunately, pressure is somewhat wasted during the reducing process. Therefore, in order to promote energy efficiency, a pressure regulator is replaced by a steam expander. With this steam expander, the pressure will be transformed into mechanical energy and extracted during the expansion process. A new type of isothermal steam expander for an industrial steam supplying system will be presented in the paper. The isothermal steam expander will improve the energy efficiency of a traditional steam expander by replacing the isentropic process with an isothermal expansion process. With this, steam condensation will decrease, energy will increase, and steam quality will be improved. Moreover, the mathematical model of the isothermal steam expander will be established by using the Schmidt theory, the same principle used to analyze Stirling engines. Consequently, by verifying the correctness of the theoretical model for the isothermal steam expander using experimental data, a prototype of 100 c.c. isothermal steam expander is constructed.

  17. Multifactorial modelling of high-temperature treatment of timber in the saturated water steam medium

    Science.gov (United States)

    Prosvirnikov, D. B.; Safin, R. G.; Ziatdinova, D. F.; Timerbaev, N. F.; Lashkov, V. A.

    2016-04-01

    The paper analyses experimental data obtained in studies of high-temperature treatment of softwood and hardwood in an environment of saturated water steam. Data were processed in the Curve Expert software for the purpose of statistical modelling of processes and phenomena occurring during this process. The multifactorial modelling resulted in the empirical dependences, allowing determining the main parameters of this type of hydrothermal treatment with high accuracy.

  18. Sterile neutrino in a minimal three-generation see-saw model

    Indian Academy of Sciences (India)

    Biswajoy Brahmachari; Sandhya Choubey; Rabindra N Mohapatra

    2003-02-01

    We investigate symmetries in Dirac and Majorana mass matrices of neutrinos in a three-generation scenario. We show that if we invoke e + - × 2R symmetry, one combination of right-handed neutrino states remains massless which can be interpreted as a sterile neutrino. Next we consider a (2) × (1)Y × (1)R gauge model and show how higher-dimensional operators can induce mixing between left- and right-handed states which explains solar, atmospheric and LSND experimental results.

  19. Kinetic models comparison for steam gasification of coal/biomass blend chars.

    Science.gov (United States)

    Xu, Chaofen; Hu, Song; Xiang, Jun; Yang, Haiping; Sun, Lushi; Su, Sheng; Wang, Baowen; Chen, Qindong; He, Limo

    2014-11-01

    The non-isothermal thermogravimetric method (TGA) was applied to different chars produced from lignite (LN), sawdust (SD) and their blends at the different mass ratios in order to investigate their thermal reactivity under steam atmosphere. Through TGA analysis, it was determined that the most prominent interaction between sawdust and lignite occurred at the mass ratio of sawdust/lignite as 1:4, but with further dose of more sawdust into its blends with lignite, the positive interaction deteriorated due to the agglomeration and deactivation of the alkali mineral involved in sawdust at high steam gasification temperature. Through systematic comparison, it could be observed that the random pore model was the most suitable among the three gas-solid reaction models adopted in this research. Finally, rational kinetic parameters were reached from these gas-solid reaction models, which provided a basis for design and operation of the realistic system of co-gasification of lignite and sawdust in this research.

  20. A unified model for prediction of CSOR in steam-based bitumen recovery

    Energy Technology Data Exchange (ETDEWEB)

    Edmunds, N.; Peterson, J. [Laricina Energy Ltd., Calgary, AB (Canada)

    2007-07-01

    A model was used to estimate the cumulative steam-oil ratio (CSOR) of steam assisted gravity drainage (SAGD) processes in high-permeability reservoirs. The aim of the model was to correlate the CSOR performance of current SAGD projects against single reservoir variables, and was designed for use in evaluations and economic analyses. The model assumed that depletion was gravity driven, and that produced oil from the steam zone was uniformly reduced to residual oil saturation. An empirical constant was used to account for heat stored below the chamber as a factor of the overburden transient losses. CSOR was predicted as a function of time. Model parameters were tested at EnCana's Foster Creek McMurray project and at Canadian Natural Resources' Primrose Grand Rapids site, while CSS data were obtained from the Cold Lake Clearwater project. The model was then used to compare SAGD and CSS projects. Results showed that vertical-radial geometry was thermally inefficient when compared to the horizontal trough used in SAGD operations. Vertical CSS methods also made inefficient use of the gravity potential of oil, due to the radial inflow constriction in the near-wellbore region. It was concluded that horizontal drainage geometry was able to sustain higher production rates at higher bottom hole viscosities.10 refs., 2 tabs., 9 figs.

  1. Improved Sterilization of Sensitive Biomaterials with Supercritical Carbon Dioxide at Low Temperature.

    Directory of Open Access Journals (Sweden)

    Anne Bernhardt

    Full Text Available The development of bio-resorbable implant materials is rapidly going on. Sterilization of those materials is inevitable to assure the hygienic requirements for critical medical devices according to the medical device directive (MDD, 93/42/EG. Biopolymer-containing biomaterials are often highly sensitive towards classical sterilization procedures like steam, ethylene oxide treatment or gamma irradiation. Supercritical CO₂ (scCO₂ treatment is a promising strategy for the terminal sterilization of sensitive biomaterials at low temperature. In combination with low amounts of additives scCO₂ treatment effectively inactivates microorganisms including bacterial spores. We established a scCO₂ sterilization procedure under addition of 0.25% water, 0.15% hydrogen peroxide and 0.5% acetic anhydride. The procedure was successfully tested for the inactivation of a wide panel of microorganisms including endospores of different bacterial species, vegetative cells of gram positive and negative bacteria including mycobacteria, fungi including yeast, and bacteriophages. For robust testing of the sterilization effect with regard to later application of implant materials sterilization all microorganisms were embedded in alginate/agarose cylinders that were used as Process Challenge Devices (PCD. These PCD served as surrogate models for bioresorbable 3D scaffolds. Furthermore, the impact of scCO₂ sterilization on mechanical properties of polysaccharide-based hydrogels and collagen-based scaffolds was analyzed. The procedure was shown to be less compromising on mechanical and rheological properties compared to established low-temperature sterilization methods like gamma irradiation and ethylene oxide exposure as well as conventional steam sterilization. Cytocompatibility of alginate gels and scaffolds from mineralized collagen was compared after sterilization with ethylene oxide, gamma irradiation, steam sterilization and scCO₂ treatment. Human

  2. Modeling a high output marine steam generator feedwater control system which uses parallel turbine-driven feed pumps

    Institute of Scientific and Technical Information of China (English)

    QIU Zhi-qiang; ZOU Hai; SUN Jian-hua

    2008-01-01

    Parallel turbine-driven feedwater pumps are needed when ships travel at high speed. In order to study marine steam generator feedwater control systems which use parallel turbine-driven feed pumps,a mathematical model of marine steam generator feedwater control system was developed which includes mathematical models of two steam generators and parallel turbine-driven feed pumps as well as mathematical models of feedwater pipes and feed regulating valves. The operating condition points of the parallel turbine-driven feed pumps were calculated by the Chebyshev curve fit method. A water level controller for the steam generator and a rotary speed controller for the turbine-driven feed pumps were also included in the model. The accuracy of the mathematical models and their controllers was verified by comparing their results with those from a simulator.

  3. A Generalized and Simple Numerical Model to Compute the Feed Water Preheating System for Steam Power Plants

    Directory of Open Access Journals (Sweden)

    Ioana Opriș

    2017-02-01

    Full Text Available A general and simple numerical model is presented to calculate the uncontrolled steam flows extracted from a turbine to preheat the feed-water of a steam generator. For a user-defined technological scheme, a set of clear rules is given to complete the elements of the augmented matrix of the linear system that solves the problem. The model avoids writing of the heat balance equations for each heat exchanger. The steam extractions to the heaters are determined as related to the flow rate at the condenser. A numerical example is given to show the results.

  4. Light sterile neutrino and dark matter in left-right symmetric models without a Higgs bidoublet

    Science.gov (United States)

    Borah, Debasish

    2016-10-01

    We present a class of left-right symmetric models where Dirac as well as Majorana mass terms of neutrinos can arise at the one-loop level in a scotogenic fashion: with dark matter particles going inside the loop. We show the possibility of naturally light right-handed neutrinos that can have interesting implications for neutrinoless double beta decay experiments as well as cosmology. Apart from a stable dark matter candidate stabilized by a remnant Z2 symmetry, one can also have a long-lived keV sterile neutrino dark matter in these models. This class of models can have very different collider signatures compared to the conventional left-right models.

  5. Solar tower power plant using a particle-heated steam generator: Modeling and parametric study

    Science.gov (United States)

    Krüger, Michael; Bartsch, Philipp; Pointner, Harald; Zunft, Stefan

    2016-05-01

    Within the framework of the project HiTExStor II, a system model for the entire power plant consisting of volumetric air receiver, air-sand heat exchanger, sand storage system, steam generator and water-steam cycle was implemented in software "Ebsilon Professional". As a steam generator, the two technologies fluidized bed cooler and moving bed heat exchangers were considered. Physical models for the non-conventional power plant components as air- sand heat exchanger, fluidized bed coolers and moving bed heat exchanger had to be created and implemented in the simulation environment. Using the simulation model for the power plant, the individual components and subassemblies have been designed and the operating parameters were optimized in extensive parametric studies in terms of the essential degrees of freedom. The annual net electricity output for different systems was determined in annual performance calculations at a selected location (Huelva, Spain) using the optimized values for the studied parameters. The solution with moderate regenerative feed water heating has been found the most advantageous. Furthermore, the system with moving bed heat exchanger prevails over the system with fluidized bed cooler due to a 6 % higher net electricity yield.

  6. Experimental characterization and modeling of an ethanol steam reformer

    DEFF Research Database (Denmark)

    Mandø, Matthias; Bovo, Mirko; Nielsen, Mads Pagh

    2006-01-01

    (ethanol, bio-diesel etc.) represents sustainable sources of hydrogen for micro Combined Heat and Power (CHP) production as well as Auxiliary Power Units (APUs). The system was experimentally characterized and theoretically modelled using a 1-dimensional system model implemented in MATLAB/Simulink...

  7. Development of a numerical hydraulic model of the Los Azufres steam pipeline network

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Gutierrez, Alfonso; Martinez-Estrella, Juan Ignacio; Hernandez-Ochoa, Abel Felipe; Verma, Mahendra P. [Instituto de Investigaciones Electricas, Ave. Reforma 113, Col. Palmira, 62490 Cuernavaca, Mor. (Mexico); Mendoza-Covarrubias, Alfredo; Ruiz-Lemus, Alejandro [Comision Federal de Electricidad, Campo Geotermico Los Azufres, Campamento Agua Fria, Mich. (Mexico)

    2009-09-15

    The development and documentation of a hydraulic model of the steam pipeline network at the Los Azufres geothermal field is presented, as well as the results obtained using one- and two-phase numerical simulators. Flow simulations were performed to determine pressure and heat losses, flow directions and velocities in that network. Computed well pressures agree within {+-}10% with measured values, except in three of the 41 wells in the system where the differences are between 10% and 13%. Computed and measured steam flow rates entering the Los Azufres geothermal power plants agree within 10%, with the exception of one that showed a 26.7% difference. This is most likely due to a mismatch between the reported and actual flow rates delivered by the pipeline network. The computed results are considered highly satisfactory given the complexity of the Los Azufres network. (author)

  8. A spatial model with pulsed releases to compare strategies for the sterile insect technique applied to the mosquito Aedes aegypti.

    Science.gov (United States)

    Oléron Evans, Thomas P; Bishop, Steven R

    2014-08-01

    We present a simple mathematical model to replicate the key features of the sterile insect technique (SIT) for controlling pest species, with particular reference to the mosquito Aedes aegypti, the main vector of dengue fever. The model differs from the majority of those studied previously in that it is simultaneously spatially explicit and involves pulsed, rather than continuous, sterile insect releases. The spatially uniform equilibria of the model are identified and analysed. Simulations are performed to analyse the impact of varying the number of release sites, the interval between pulsed releases and the overall volume of sterile insect releases on the effectiveness of SIT programmes. Results show that, given a fixed volume of available sterile insects, increasing the number of release sites and the frequency of releases increases the effectiveness of SIT programmes. It is also observed that programmes may become completely ineffective if the interval between pulsed releases is greater that a certain threshold value and that, beyond a certain point, increasing the overall volume of sterile insects released does not improve the effectiveness of SIT. It is also noted that insect dispersal drives a rapid recolonisation of areas in which the species has been eradicated and we argue that understanding the density dependent mortality of released insects is necessary to develop efficient, cost-effective SIT programmes.

  9. Improved Sterilization of Sensitive Biomaterials with Supercritical Carbon Dioxide at Low Temperature: e0129205

    National Research Council Canada - National Science Library

    Anne Bernhardt; Markus Wehrl; Birgit Paul; Thomas Hochmuth; Matthias Schumacher; Kathleen Schütz; Michael Gelinsky

    2015-01-01

    ... sterilization procedures like steam, ethylene oxide treatment or gamma irradiation. Supercritical CO2 (scCO2) treatment is a promising strategy for the terminal sterilization of sensitive biomaterials at low temperature...

  10. An Analytical Model for Simulating Heavy-Oil Recovery by Cyclic Steam Injection Using Horizontal Wells, SUPRI TR-118

    Energy Technology Data Exchange (ETDEWEB)

    Diwan, Utpal; Kovscek, Anthony R.

    1999-08-09

    In this investigation, existing analytical models for cyclic steam injection and oil recovery are reviewed and a new model is proposed that is applicable to horizontal wells. A new flow equation is developed for oil production during cyclic steaming of horizontal wells. The model accounts for the gravity-drainage of oil along the steam-oil interface and through the steam zone. Oil viscosity, effective permeability, geometry of the heated zone, porosity, mobile oil saturation, and thermal diffusivity of the reservoir influence the flow rate of oil in the model. The change in reservoir temperature with time is also modeled, and it results in the expected decline in oil production rate during the production cycle as the reservoir cools. Wherever appropriate, correlations and incorporated to minimize data requirements. A limited comparison to numerical simulation results agrees well, indicating that essential physics are successfully captured. Cyclic steaming appears to be a systematic met hod for heating a cold reservoir provided that a relatively uniform distribution of steam is obtained along the horizontal well during injection. A sensitivity analysis shows that the process is robust over the range of expected physical parameters.

  11. Application of the thermal-hydraulic codes in VVER-440 steam generators modelling

    Energy Technology Data Exchange (ETDEWEB)

    Matejovic, P.; Vranca, L.; Vaclav, E. [Nuclear Power Plant Research Inst. VUJE (Slovakia)

    1995-12-31

    Performances with the CATHARE2 V1.3U and RELAP5/MOD3.0 application to the VVER-440 SG modelling during normal conditions and during transient with secondary water lowering are described. Similar recirculation model was chosen for both codes. In the CATHARE calculation, no special measures were taken with the aim to optimize artificially flow rate distribution coefficients for the junction between SG riser and steam dome. Contrary to RELAP code, the CATHARE code is able to predict reasonable the secondary swell level in nominal conditions. Both codes are able to model properly natural phase separation on the SG water level. 6 refs.

  12. Mercury release during autoclave sterilization of amalgam.

    Science.gov (United States)

    Parsell, D E; Karns, L; Buchanan, W T; Johnson, R B

    1996-05-01

    Natural teeth are an invaluable teaching tool for preclinical instruction in operative dentistry and endodontic techniques. Cavity preparation in teeth containing amalgam restorations is a realistic simulation of an often experienced clinical situation. As various pathogens are contained in saliva, teeth must be disinfected before use by students. The purpose of this study is to indirectly evaluate whether mercury vapor is released from amalgam restorations in such teeth during steam autoclave sterilization. Mercury vapor detection, sample mass changes and x-ray fluorescence data were collected from experimental steam autoclave sterilization of amalgam samples sealed in autoclave bags. All of the data showed evidence of mercury vapor generation coincident to steam autoclave sterilization. Mercury vapor levels within the room where amalgam was exposed to steam autoclave sterilization reached levels that constitute an unnecessary health risk to dental personnel. The volume of amalgam tested simulated that contained in 175 amalgam restored teeth. Initial venting of the autoclave chamber produced mercury vapor concentrations significantly in excess of OSHA vapor concentration ceiling levels. Thus, the use of a steam autoclave for sterilization of amalgam containing teeth for use in preclinical laboratory exercises may be harmful to personnel involved.

  13. BASICS OF STERILE COMPOUNDING: Sterilization Methods in Sterile Product Manufacturing.

    Science.gov (United States)

    Akers, Michael J

    2015-01-01

    Sterilization methods to produce sterile preparations include heat, gas, radiation, and filtration. This article focuses on heat, gas, and radiation sterilization, plus a brief introduction to bright-light sterilization. Microbiology basics and microbial death kinetics, key to understanding why these sterilization methods work, will also be briefly discussed. Filtration sterilization will be covered in a separate article.

  14. 贵州省149所医院小型压力蒸汽灭菌器现况调查与分析%Investigation and analysis of current situation of small steam sterilizers in 149 hospitals of Guizhou province

    Institute of Scientific and Technical Information of China (English)

    徐艳; 杨怀; 牟霞; 王萍; 陈京; 孙云婷; 张满

    2015-01-01

    目的:调查医院小型压力蒸汽灭菌器使用现况,分析存在问题,为贵州省卫生行政部门加强消毒灭菌管理提供依据。方法2013年3月贵州省医院感染管理培训基地集中培训后发放调查表,对贵州省二级(含二级)以上医院小型压力蒸汽灭菌器使用现况进行调查。结果共调查149所医院,89所医院配置158台小型压力蒸汽灭菌器,二级医院110台、三级医院48台;其中B型83台、S型11台、N型64台,N型中46台分布于检验科,主要用于医疗废物及试验用品的灭菌,18台分布于口腔科、五官科、手术室、眼科、消毒供应中心,主要用于器械灭菌及紧急器械灭菌;灭菌物品过程监控调查显示,二级与三级医院每锅物理监测执行率分别为98.94%、97.87%,每包化学监测执行率分别为87.76%、86.96%,每周一次生物监测执行率分别为87.50%、97.67%;二级医院与三级医院使用小型压力蒸汽灭菌器科室建立灭菌物品清洗质量监测执行率分别为72.97%与74.19%,建立灭菌质控登记本执行率分别为83.64%与81.25%。结论贵州省医院临床科室忽视小型压力蒸汽灭菌器类型,错误选择灭菌负载范围,需要不断加强监管、正确选择并使用小型压力蒸汽灭菌器,实现临床器械集中处理。%OBJECTIVE To investigate the current status of small steam sterilizers and analyze the existing problems so as to provide guidance for the disinfection and sterilization by the health administrative departments in Guizhou province .METHODS The questionnaires were assigned to investigate the current status of use of small steam sterilizers in two‐level and two‐level above hospitals of Guizhou province after the centralized training was conducted in Guizhou province nosocomial infection management training base in Mar ,2013 .RESULTS A total of 149 hospitals were investigated ,of

  15. Fluid-Structure Interaction Effects Modeling for the Modal Analysis of a Steam Generator Tube Bundle

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, J.F. [DCNS Prop, Serv Tech et Sci, F-44620 La Montagne, (France); Broc, D. [CEA Saclay, Serv Etud Mecan et Sism, F-91191 Gif Sur Yvette, (France)

    2009-07-01

    Seismic analysis of steam generator is of paramount importance in the safety assessment of nuclear installations. These analyses require, in particular, the calculation of frequency, mode shape, and effective modal mass of the system Eigenmodes. As fluid-structure interaction effects can significantly affect the dynamic behavior of immersed structures, the numerical modeling of the steam generator has to take into account FSI. A complete modeling of heat exchangers (including pressure vessel, tubes, and fluid) is not accessible to the engineer for industrial design studies. In the past decades, homogenization methods have been studied and developed in order to model tubes and fluid through an equivalent continuous media, thus avoiding the tedious task to mesh all structure and fluid sub-domains within the tube bundle. Few of these methods have nonetheless been implemented in industrial finite element codes. In a previous paper (Sigrist, 2007, 'Fluid-Structure Interaction Effects Modeling for the Modal Analysis of a Nuclear Pressure Vessel', J. Pressure Vessel Technol., 123, p. 1-6), a homogenization method has been applied to an industrial case for the modal analysis of a nuclear rector with internal structures and coupling effects modeling. The present paper aims at investigating the extension of the proposed method for the dynamic analysis of tube bundles with fluid-structure interaction modeling. The homogenization method is compared with the classical coupled method in terms of eigenfrequencies, Eigenmodes, and effective modal masses. (authors)

  16. Sterile neutrinos at LBNE

    CERN Document Server

    Hollander, David

    2014-01-01

    In this paper we examine the sensitivity of the Long Baseline Neutrino Oscillation Experiment to the inclusion of two new sterile neutrino flavors with masses in the eV range. We implement a modified Casas-Ibarra parametrization which can accommodate medium scale mass eigenstates and introduces a new complex mixing angle. We explore the new mixing angle parameter space and demonstrate how LBNE can be used to either provide evidence for or rule out a particular model of sterile neutrinos. Certain three-flavor CP-violation scenarios cannot be distinguished from the sterile neutrinos. Constraints from the Daya Bay reactor experiment are used to help lift this degeneracy.

  17. Model-Free Coordinated Control for MHTGR-Based Nuclear Steam Supply Systems

    Directory of Open Access Journals (Sweden)

    Zhe Dong

    2016-01-01

    Full Text Available The modular high temperature gas-cooled reactor (MHTGR is a typical small modular reactor (SMR that offers simpler, standardized and safer modular design by being factory built, requiring smaller initial capital investment, and having a shorter construction period. Thanks to its small size, the MHTGRs could be beneficial in providing electric power to remote areas that are deficient in transmission or distribution and in generating local power for large population centers. Based on the multi-modular operation scheme, the inherent safety feature of the MHTGRs can be applicable to large nuclear plants of any desired power rating. The MHTGR-based nuclear steam supplying system (NSSS is constituted by an MHTGR, a side-by-side arranged helical-coil once-through steam generator (OTSG and some connecting pipes. Due to the side-by-side arrangement, there is a tight coupling effect between the MHTGR and OTSG. Moreover, there always exists the parameter perturbation of the NSSSs. Thus, it is meaningful to study the model-free coordinated control of MHTGR-based NSSSs for safe, stable, robust and efficient operation. In this paper, a new model-free coordinated control strategy that regulates the nuclear power, MHTGR outlet helium temperature and OTSG outlet overheated steam temperature by properly adjusting the control rod position, helium flowrate and feed-water flowrate is established for the MHTGR-based NSSSs. Sufficient conditions for the globally asymptotic closed-loop stability is given. Finally, numerical simulation results in the cases of large range power decrease and increase illustrate the satisfactory performance of this newly-developed model-free coordinated NSSS control law.

  18. Simulation modeling of nuclear steam generator water level process--a case study

    Science.gov (United States)

    Zhao; Ou; Du

    2000-01-01

    Simulation modeling of the nuclear steam generator (SG) water level process in Qinshan Nuclear Power Plant (QNPP) is described in this paper. A practical methodology was adopted so that the model is both simple and accurate for control engineering implementation. The structure of the model is in the form of a transfer function, which was determined based on first-principles analysis and expert experience. The parameters of the model were obtained by taking advantage of the recorded historical response curves under the existing closed-loop control system. The results of process dimensional data verification and experimental tests demonstrate that the simulation model depicts the main dynamic characteristics of the SG water level process and is in accordance with the field recorded response curves. The model has been successfully applied to the design and test of an advanced digital feedwater control system in QNPP.

  19. Modelling of methanol-to-hydrogen steam reforming with a heat flux distributed along a microchannel

    Science.gov (United States)

    Kuznetsov, V. V.; Kozlov, S. P.

    2008-09-01

    The flow of reacting mixture of methanol and steam in a 2D microslot was studied numerically at activation of the reactions on the channel wall. This modelling was carried out in the framework of Navier — Stokes equations for a laminar flow of multicomponent compressible gas. Correlations between thermal, diffusion, and physical-chemical processes were studied under the conditions of intense endothermic reaction and external heat supply distributed along the channel. It is shown that not only the amount of heat supplied to the reaction zone is essential, but also the mode of heat supply along the channel length is important, which allows optimization of the compact reactor for hydrogen production.

  20. Sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, J. [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics, Johannes Gutenberg University, 55099 Mainz (Germany); Machado, P. A. N., E-mail: pedro.machado@uam.es [Departamento de Física Teórica, Universidad Autónoma de Madrid, Cantoblanco E-28049 Madrid (Spain); Instituto de Física Teórica UAM/CSIC, Calle Nicolás Cabrera 13-15, Cantoblanco E-28049 Madrid (Spain); Maltoni, M. [Instituto de Física Teórica UAM/CSIC, Calle Nicolás Cabrera 13-15, Cantoblanco E-28049 Madrid (Spain); Schwetz, T. [Institute for Nuclear Physics, Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021 Karlsruhe (Germany)

    2016-06-21

    We characterize statistically the indications of a presence of one or more light sterile neutrinos from MiniBooNE and LSND data, together with the reactor and gallium anomalies, in the global context. The compatibility of the aforementioned signals with null results from solar, atmospheric, reactor, and accelerator experiments is evaluated. We conclude that a severe tension is present in the global fit, and therefore the addition of eV-scale sterile neutrinos does not satisfactorily explain the anomalies.

  1. Probability of detection model for the non-destructive inspection of steam generator tubes of PWRs

    Science.gov (United States)

    Yusa, N.

    2017-06-01

    This study proposes a probability of detection (POD) model to discuss the capability of non-destructive testing methods for the detection of stress corrosion cracks appearing in the steam generator tubes of pressurized water reactors. Three-dimensional finite element simulations were conducted to evaluate eddy current signals due to stress corrosion cracks. The simulations consider an absolute type pancake probe and model a stress corrosion crack as a region with a certain electrical conductivity inside to account for eddy currents flowing across a flaw. The probabilistic nature of a non-destructive test is simulated by varying the electrical conductivity of the modelled stress corrosion cracking. A two-dimensional POD model, which provides the POD as a function of the depth and length of a flaw, is presented together with a conventional POD model characterizing a flaw using a single parameter. The effect of the number of the samples on the PODs is also discussed.

  2. Evaluation of disinfection and sterilization of reusable angioscopes with the duck hepatitis B model

    National Research Council Canada - National Science Library

    Chaufour, Xavier; Deva, Anand K; Vickery, Karen; Zou, Jean; Kumaradeva, Priya; White, Geoff H; Cossart, Yvonne E

    1999-01-01

    .... The samples were collected immediately after drying (control), after flushing with 5 mL of water, after glutaraldehyde disinfection for 5, 10, and 20 minutes, and after ethylene oxide gas sterilization...

  3. Modeling of indirect carbon fuel cell systems with steam and dry gasification

    Science.gov (United States)

    Ong, Katherine M.; Ghoniem, Ahmed F.

    2016-05-01

    An indirect carbon fuel cell (ICFC) system that couples coal gasification to a solid oxide fuel cell (SOFC) is a promising candidate for high efficiency stationary power. This study couples an equilibrium gasifier model to a detailed 1D MEA model to study the theoretical performance of an ICFC system run on steam or carbon dioxide. Results show that the fuel cell in the ICFC system is capable of power densities greater than 1.0 W cm-2 with H2O recycle, and power densities ranging from 0.2 to 0.4 W cm-2 with CO2 recycle. This result indicates that the ICFC system performs better with steam than with CO2 gasification as a result of the faster electro-oxidation kinetics of H2 relative to CO. The ICFC system is then shown to reach higher current densities and efficiencies than a thermally decoupled gasifier + fuel cell (G + FC) system because it does not include combustion losses associated with autothermal gasification. 55-60% efficiency is predicted for the ICFC system coupled to a bottoming cycle, making this technology competitive with other state-of-the-art stationary power candidates.

  4. Lepton number violating processes in the minimal 3-3-1 model with sterile neutrinos

    CERN Document Server

    Machado, A C B; Pleitez, V

    2016-01-01

    We consider a given numerical solution for the real part of the unitary matrices which diagonalize the charged lepton mass matrices in the minimal 3-3-1 model with sterile neutrinos, and we study its phenomenological consequences in various processes involving flavor number violating interactions. In the allowed leptonic tree level decays $l_i\\to l_jl_kl_k$, where $l_i=\\mu,\\tau$, $l_{j,k}=e,\\mu$, we found that in particular the channel $\\mu\\to eee$ impose a lower mass limit on the vector doubly charged bilepton of $4.58$ TeV and that the scalar contributions are negligible in this kind of processes. We also test the matrices solution in the tree level Higgs reaction $h^0\\to l_il_j$ and in the one-loop decays $l_i\\to l_j\\gamma$, and found that in the loop processes the virtual interactions of the exotic particles with leptons provide signals much larger than in the standard model, but still quite smaller than the experimental upper limits.

  5. Perspectives of the global steam coal market: the COALMOD-World model; Perspektiven des globalen Kesselkohlemarktes. Das COALMOD-World-Modell

    Energy Technology Data Exchange (ETDEWEB)

    Haftendorn, Clemens; Holz, Franziska; Winke, Tim; Hirschhausen, Christian von [Deutsches Institut fuer Wirtschaftsforschung, Berlin (Germany). Abt. Energie, Verkehr und Umwelt

    2012-03-15

    The global steam coal market has undergone drastic change over the past ten years due to growing demand, flexibilisation of trade conditions and intensified stock exchange trading. An equilibrium model called COALMOD-World is now available for simulating the national and global steam coal market over several periods and analysing future market developments. For this purpose the model maps the international seaborne steam coal trade as well as the relevant national markets. It calculates annual market equilibria, thus permitting regionally specific forecasts on trade coal quantities and prices up the year 2030.

  6. Using MiniBooNE NCEL and CCQE cross section results to constrain 3+1 sterile neutrino models

    CERN Document Server

    Wilkinson, Callum; Thompson, Lee

    2014-01-01

    The MiniBooNE NCEL and CCQE cross-section measurements (neutrino running) are used to set limits in the $\\Delta m^{2}-\\sin^{2}\\vartheta_{\\mu s}$ plane for a 3+1 sterile neutrino model with a mass splitting $0.1 \\leq \\Delta m^{2} \\leq 10.0$ eV$^{2}$. GENIE is used, with a relativistic Fermi gas model, to relate $E_{\

  7. Thermal-hydraulic characteristics of a Westinghouse Model 51 steam generator. Volume 2. Appendix A, numerical results. Interim report. [CALIPSOS code numerical data

    Energy Technology Data Exchange (ETDEWEB)

    Fanselau, R.W.; Thakkar, J.G.; Hiestand, J.W.; Cassell, D.

    1981-03-01

    The Comparative Thermal-Hydraulic Evaluation of Steam Generators program represents an analytical investigation of the thermal-hydraulic characteristics of four PWR steam generators. The analytical tool utilized in this investigation is the CALIPSOS code, a three-dimensional flow distribution code. This report presents the steady state thermal-hydraulic characteristics on the secondary side of a Westinghouse Model 51 steam generator. Details of the CALIPSOS model with accompanying assumptions, operating parameters, and transport correlations are identified. Comprehensive graphical and numerical results are presented to facilitate the desired comparison with other steam generators analyzed by the same flow distribution code.

  8. Modeling Creep-Fatigue-Environment Interactions in Steam Turbine Rotor Materials for Advanced Ultra-supercritical Coal Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen [General Electric Global Research, Niskayuna, NY (United States)

    2014-04-01

    The goal of this project is to model creep-fatigue-environment interactions in steam turbine rotor materials for advanced ultra-supercritical (A-USC) coal power Alloy 282 plants, to develop and demonstrate computational algorithms for alloy property predictions, and to determine and model key mechanisms that contribute to the damages caused by creep-fatigue-environment interactions.

  9. Resonantly produced 7 keV sterile neutrino dark matter models and the properties of Milky Way satellites.

    Science.gov (United States)

    Abazajian, Kevork N

    2014-04-25

    Sterile neutrinos produced through a resonant Shi-Fuller mechanism are arguably the simplest model for a dark matter interpretation of the origin of the recent unidentified x-ray line seen toward a number of objects harboring dark matter. Here, I calculate the exact parameters required in this mechanism to produce the signal. The suppression of small-scale structure predicted by these models is consistent with Local Group and high-z galaxy count constraints. Very significantly, the parameters necessary in these models to produce the full dark matter density fulfill previously determined requirements to successfully match the Milky Way Galaxy's total satellite abundance, the satellites' radial distribution, and their mass density profile, or the "too-big-to-fail problem." I also discuss how further precision determinations of the detailed properties of the candidate sterile neutrino dark matter can probe the nature of the quark-hadron transition, which takes place during the dark matter production.

  10. Multi-scale modeling of the heat and mass transfer in a monolithic methane steam-reformer for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo, Luis Evelio Garcia; Oliveira, Amir Antonio Martins [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica], e-mail: evelio@labcet.ufsc.br, e-mail: amirol@emc.ufsc.br

    2006-07-01

    Here we present a heat and mass transfer analysis for the catalytic methane steam-reforming in a porous monolithic reactor. Thermodynamic analysis provides the bounds for temperature, pressure and steam-methane molar ration for optimum operation. However, the reactor operation is also constrained by chemical kinetics and heat and mass transfer limitations. Porous wash coated monoliths have been used for a long time in the automotive industry as catalytic converters for destruction of gas and particulate pollutants. Here we analyze the modeling issues related to a multi-scale porous structure and develop a model able to assess the advantages and drawbacks of using a monolith as support for a catalyst layer for steam-reforming. (author)

  11. Degradation of chitosan-based materials after different sterilization treatments

    Science.gov (United States)

    San Juan, A.; Montembault, A.; Gillet, D.; Say, J. P.; Rouif, S.; Bouet, T.; Royaud, I.; David, L.

    2012-02-01

    Biopolymers have received in recent years an increasing interest for their potential applications in the field of biomedical engineering. Among the natural polymers that have been experimented, chitosan is probably the most promising in view of its exceptional biological properties. Several techniques may be employed to sterilize chitosan-based materials. The aim of our study was to compare the effect of common sterilization treatments on the degradation of chitosan-based materials in various physical states: solutions, hydrogels and solid flakes. Four sterilization methods were compared: gamma irradiation, beta irradiation, exposure to ethylene oxide and saturated water steam sterilization (autoclaving). Exposure to gamma or beta irradiation was shown to induce an important degradation of chitosan, regardless of its physical state. The chemical structure of chitosan flakes was preserved after ethylene oxide sterilization, but this technique has a limited use for materials in the dry state. Saturated water steam sterilization of chitosan solutions led to an important depolymerization. Nevertheless, steam sterilization of chitosan flakes bagged or dispersed in water was found to preserve better the molecular weight of the polymer. Hence, the sterilization of chitosan flakes dispersed in water would represent an alternative step for the preparation of sterilized chitosan solutions. Alternatively, autoclaving chitosan physical hydrogels did not significantly modify the macromolecular structure of the polymer. Thus, this method is one of the most convenient procedures for the sterilization of physical chitosan hydrogels after their preparation.

  12. Modeling of Spray System Operation under Hydrogen and Steam Emissions in NPP Containment during Severe Accident

    Directory of Open Access Journals (Sweden)

    Vadim E. Seleznev

    2011-01-01

    Full Text Available The paper describes one of the variants of mathematical models of a fluid dynamics process inside the containment, which occurs in the conditions of operation of spray systems in severe accidents at nuclear power plant. The source of emergency emissions in this case is the leak of the coolant or rupture at full cross-section of the main circulating pipeline in a reactor building. Leak or rupture characteristics define the localization and the temporal law of functioning of a source of emergency emission (or accrued operating of warmed up hydrogen and steam in the containment. Operation of this source at the course of analyzed accident models should be described by the assignment of the relevant Dirichlet boundary conditions. Functioning of the passive autocatalytic recombiners of hydrogen is described in the form of the complex Newton boundary conditions.

  13. Freeze-in production of sterile neutrino dark matter in U(1){sub B−L} model

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Anirban; Gupta, Aritra [Harish-Chandra Research Institute,Chhatnag Road, Jhunsi, Allahabad 211 019 (India)

    2016-09-27

    With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1){sub B−L} model. The U(1){sub B−L} model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W{sup ±} decay can also be a dominant production mode of the sterile neutrino DM. To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1){sub B−L} model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.

  14. K-FIX(GT): A computer program for modeling the expansion phase of steam explosions within complex three dimensional cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hyder, M.L. [Westinghouse Savannah River Co., Aiken, SC (United States); Farawila, Y.M.; Abdel-Khalik, S.I.; Halvorson, P.J. [Georgia Inst. of Tech., Atlanta, GA (US)

    1992-05-01

    In the development of the Severe Accident Analysis Program for the Savannah River production reactors, it was recognized that certain accidents have the potential for causing damaging steam explosions. The massive SRS reactor buildings are likely to withstand any imaginable steam explosion. However, reactor components and building structures including hatches, ventilation ducts, etc., could be at risk if such an explosion occurred. No tools were available to estimate the effects of such explosions on actual structures. To meet this need, the Savannah River Laboratory contracted with the Georgia Institute of Technology Research Institute for development of a computer-based calculational tool for estimating the effects of steam explosions. The goal for this study was to develop a computer code that could be used parametrically to predict the effects of various steam explosions on their surroundings. This would be able to predict whether a steam explosion of a given magnitude would be likely to fail a particular structure. This would require, of course, that the magnitude of the explosion be specified through some combination of judgment and calculation. The requested code, identified as the K-FIX(GT) code, was developed and delivered by the contractor, along with extensive documentation. The several individual reports that constitute the documentation are each being issued as a separate WSRC report. Documentation includes several model calculations, and representation of these in graphic form. This report gives detailed instructions for the use of the code, including identification of all input parameters required.

  15. K-FIX(GT): A computer program for modeling the expansion phase of steam explosions within complex three dimensional cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hyder, M.L. [Westinghouse Savannah River Co., Aiken, SC (United States); Farawila, Y.M.; Abdel-Khalik, S.I.; Halvorson, P.J. [Georgia Inst. of Tech., Atlanta, GA (US)

    1992-05-01

    In the development of the Severe Accident Analysis Program for the Savannah River production reactors, it was recognized that certain accidents have the potential for causing damaging steam explosions. The massive SRS reactor buildings are likely to withstand any imaginable steam explosion. However, reactor components and building structures including hatches, ventilation ducts, etc., could be at risk if such an explosion occurred. No tools were available to estimate the effects of such explosions on actual structures. To meet this need, the Savannah River Laboratory contracted with the Georgia Institute of Technology Research Institute for development of a computer-based calculational tool for estimating the effects of steam explosions. The goal for this study was to develop a computer code that could be used parametrically to predict the effects of various steam explosions on their surroundings. This would be able to predict whether a steam explosion of a given magnitude would be likely to fail a particular structure. This would require, of course, that the magnitude of the explosion be specified through some combination of judgment and calculation. The requested code, identified as the K-FIX(GT) code, was developed and delivered by the contractor, along with extensive documentation. The several individual reports that constitute the documentation are each being issued as a separate WSRC report. Documentation includes several model calculations, and representation of these in graphic form. This report gives detailed instructions for the use of the code, including identification of all input parameters required.

  16. Tubal Sterilization

    Science.gov (United States)

    ... at any time. Postpartum sterilization can take place right after a woman gives birth, if it was a cesarean delivery (C-section). It can also be performed within hours or days of a vaginal ... occur. Contact your doctor right away if you:develop a feverbleed from an ...

  17. Design and modelling of an innovative three-stage thermal storage system for direct steam generation CSP plants

    Science.gov (United States)

    Garcia, Pierre; Vuillerme, Valéry; Olcese, Marco; El Mourchid, Nadim

    2016-05-01

    Thermal Energy Storage systems (TES) for a Direct Steam Generation (DSG) solar plant feature preferably three stages in series including a latent heat storage module so that steam can be recovered with a limited temperature loss. The storage system designed within the Alsolen Sup project is characterized by an innovative combination of sensible and latent modules. A dynamic model of this three-stage storage has been developed and applied to size the storage system of the Alsolen Sup® plant demonstrator at CEA Cadarache. Results of this simulation show that this promising concept is an efficient way to store heat in DSG solar plants.

  18. Computational Fluid Dynamics Modeling of Steam Condensation on Nuclear Containment Wall Surfaces Based on Semiempirical Generalized Correlations

    Directory of Open Access Journals (Sweden)

    Pavan K. Sharma

    2012-01-01

    Full Text Available In water-cooled nuclear power reactors, significant quantities of steam and hydrogen could be produced within the primary containment following the postulated design basis accidents (DBA or beyond design basis accidents (BDBA. For accurate calculation of the temperature/pressure rise and hydrogen transport calculation in nuclear reactor containment due to such scenarios, wall condensation heat transfer coefficient (HTC is used. In the present work, the adaptation of a commercial CFD code with the implementation of models for steam condensation on wall surfaces in presence of noncondensable gases is explained. Steam condensation has been modeled using the empirical average HTC, which was originally developed to be used for “lumped-parameter” (volume-averaged modeling of steam condensation in the presence of noncondensable gases. The present paper suggests a generalized HTC based on curve fitting of most of the reported semiempirical condensation models, which are valid for specific wall conditions. The present methodology has been validated against limited reported experimental data from the COPAIN experimental facility. This is the first step towards the CFD-based generalized analysis procedure for condensation modeling applicable for containment wall surfaces that is being evolved further for specific wall surfaces within the multicompartment containment atmosphere.

  19. Freeze-in Production of Sterile Neutrino Dark Matter in U(1)$_{\\rm B-L}$ Model

    CERN Document Server

    Biswas, Anirban

    2016-01-01

    With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to touch the neutrino floor. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1)$_{\\rm B-L}$ model. The U(1)$_{\\rm B-L}$ model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that $W^\\pm$ decay can also be a dominant production mode of the sterile neutrino DM. To ...

  20. Steam sterilization of previously-assembled laparoscopic instruments Esterilización por vapor de los instrumentos laparoscópicos previamente armados Esterilização pelo vapor dos instrumentos laparoscópicos previamente montados

    Directory of Open Access Journals (Sweden)

    Tamara Carolina de Camargo

    2008-01-01

    Full Text Available Video-laparoscopy represents one of the greatest surgical advances in the recent past. Reprocessable laparoscopic instruments are complex devices that, if completely disassembled for sterilization, would cause problems for the surgical teams at the moment of their use in the surgery. The method of choice for the sterilization of this equipment is saturated steam under pressure. The goal of this review was to describe the state-of-the-art in the search for safe results in autoclaving the previously-assembled reprocessable laparoscopic instruments, since they are difficult to assemble at the moment of surgery. The PUBMED database was consulted, using controlled and free keywords, as well as their combinations, without time or language restrictions. The study investigating the exact issue of this research found contamination in both assembled (1/24 and disassembled (1/30 instruments, demonstrating equivalent risks. In view of the results and considering the lack of studies, a new experimental laboratory study is recommended, using a contamination challenge.El video-laparoscopía representa uno de los mayores avances en el área de la cirugía en los últimos tiempos. Los instrumentos laparoscópicos reprocesables son artículos complejos, que si son esterilizados totalmente desarmados ocasionan trastornos a los equipos quirúrgicos en el momento de su utilización en el campo operatorio. El método de elección para la esterilización de esos instrumentos es el vapor saturado bajo presión. El objetivo de esta revisión fue describir el estado del arte en búsqueda de los resultados de la seguridad en el autoclavado del instrumental laparoscópico reprocesable, previamente armado, teniendo presente las dificultades de su montaje en el momento de la cirugía. Se consultó la base de datos PUBMED, usando vocablos controlados, libres y la combinación de ambos, sin restricción de tiempo e idioma. Fueron localizados apenas dos artículos que

  1. Sterilization of heparinized cuprophan hemodialysis membranes

    NARCIS (Netherlands)

    ten Hoopen, Hermina W.M.; Hinrichs, W.L.J.; Hinrichs, W.L.J.; Engbers, G.H.M.; Feijen, Jan

    1996-01-01

    The effects of sterilization of dry heparinized Cuprophan hemodialysis membranes by means of ethylene oxide (EtO) exposure, gamma irradiation, or steam on the anticoagulant activity and chemical characteristics of immobilized heparin and the permeability of the membrane were investigated.

  2. Analysis based on the diffusion model for saturation silica gel with water vapor at conservation units steam circuit TPP

    Science.gov (United States)

    Goldaev, Sergey; Khushvaktov, Alisher

    2015-01-01

    A quantitative analysis of the diffusion model dehumidifying air in the steam circuit of TPP, with a layer of silica gel. Showed that such an approximation, supplemented the experimental value of the coefficient of free diffusion identified by the developed method gives reliable values for the concentration of water vapor absorption over time.

  3. Catalytic activity of phosphorus and steam modified HZSM-5 and the theoretical selection of phosphorus grafting model

    Institute of Scientific and Technical Information of China (English)

    Renqing Lü; Zuogang Cao; Xinhai Liu

    2008-01-01

    The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phospho-rus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified HZSM-5 zeolites have been investigated. The X-ray diffraction (XRD) results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption (TPD) of ammonia. The oxidation state of phosphorus shown by XPS is +5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type Ⅰ and type Ⅳ, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum.

  4. Biomass Steam Gasification with In-Situ CO2 Capture for Enriched Hydrogen Gas Production: A Reaction Kinetics Modelling Approach

    Directory of Open Access Journals (Sweden)

    Mohamed Ibrahim Abdul Mutalib

    2010-08-01

    Full Text Available Due to energy and environmental issues, hydrogen has become a more attractive clean fuel. Furthermore, there is high interest in producing hydrogen from biomass with a view to sustainability. The thermochemical process for hydrogen production, i.e. gasification, is the focus of this work. This paper discusses the mathematical modeling of hydrogen production process via biomass steam gasification with calcium oxide as sorbent in a gasifier. A modelling framework consisting of kinetics models for char gasification, methanation, Boudouard, methane reforming, water gas shift and carbonation reactions to represent the gasification and CO2 adsorption in the gasifier, is developed and implemented in MATLAB. The scope of the work includes an investigation of the influence of the temperature, steam/biomass ratio and sorbent/biomass ratio on the amount of hydrogen produced, product gas compositions and carbon conversion. The importance of different reactions involved in the process is also discussed. It is observed that hydrogen production and carbon conversion increase with increasing temperature and steam/biomass ratio. The model predicts a maximum hydrogen mole fraction in the product gas of 0.81 occurring at 950 K, steam/biomass ratio of 3.0 and sorbent/biomass ratio of 1.0. In addition, at sorbent/biomass ratio of 1.52, purity of H2 can be increased to 0.98 mole fraction with all CO2 present in the system adsorbed.

  5. Development of a surrogate model for analysis of ex-vessel steam explosion in Nordic type BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Basso, Simone, E-mail: simoneb@kth.se; Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se

    2016-12-15

    Highlights: • Severe accident. • Steam explosion. • Surrogate model. • Sensitivity study. • Artificial neural networks. - Abstract: Severe accident mitigation strategy adopted in Nordic type Boiling Water Reactors (BWRs) employs ex-vessel core melt cooling in a deep pool of water below reactor vessel. Energetic fuel–coolant interaction (steam explosion) can occur during molten core release into water. Dynamic loads can threaten containment integrity increasing the risk of fission products release to the environment. Comprehensive uncertainty analysis is necessary in order to assess the risks. Computational costs of the existing fuel–coolant interaction (FCI) codes is often prohibitive for addressing the uncertainties, including the effect of stochastic triggering time. This paper discusses development of a computationally efficient surrogate model (SM) for prediction of statistical characteristics of steam explosion impulses in Nordic BWRs. The TEXAS-V code was used as the Full Model (FM) for the calculation of explosion impulses. The surrogate model was developed using artificial neural networks (ANNs) and the database of FM solutions. Statistical analysis was employed in order to treat chaotic response of steam explosion impulse to variations in the triggering time. Details of the FM and SM implementation and their verification are discussed in the paper.

  6. Study of Interdigitated Electrode Arrays Using Experiments and Finite Element Models for the Evaluation of Sterilization Processes

    Directory of Open Access Journals (Sweden)

    Jan Oberländer

    2015-10-01

    Full Text Available In this work, a sensor to evaluate sterilization processes with hydrogen peroxide vapor has been characterized. Experimental, analytical and numerical methods were applied to evaluate and study the sensor behavior. The sensor set-up is based on planar interdigitated electrodes. The interdigitated electrode structure consists of 614 electrode fingers spanning over a total sensing area of 20 mm2. Sensor measurements were conducted with and without microbiological spores as well as after an industrial sterilization protocol. The measurements were verified using an analytical expression based on a first-order elliptical integral. A model based on the finite element method with periodic boundary conditions in two dimensions was developed and utilized to validate the experimental findings.

  7. Study of interdigitated electrode arrays using experiments and finite element models for the evaluation of sterilization processes.

    Science.gov (United States)

    Oberländer, Jan; Jildeh, Zaid B; Kirchner, Patrick; Wendeler, Luisa; Bromm, Alexander; Iken, Heiko; Wagner, Patrick; Keusgen, Michael; Schöning, Michael J

    2015-10-14

    In this work, a sensor to evaluate sterilization processes with hydrogen peroxide vapor has been characterized. Experimental, analytical and numerical methods were applied to evaluate and study the sensor behavior. The sensor set-up is based on planar interdigitated electrodes. The interdigitated electrode structure consists of 614 electrode fingers spanning over a total sensing area of 20 mm². Sensor measurements were conducted with and without microbiological spores as well as after an industrial sterilization protocol. The measurements were verified using an analytical expression based on a first-order elliptical integral. A model based on the finite element method with periodic boundary conditions in two dimensions was developed and utilized to validate the experimental findings.

  8. A comprehensive flow-induced vibration model to predict crack growth and leakage potential in steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    El Bouzidi, Salim [School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Hassan, Marwan, E-mail: mahassan@uoguelph.ca [School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Riznic, Jovica [Operational Engineering Assessment Division, Canadian Nuclear Safety Commission, Ottawa, Ontario K1P 5S9 (Canada)

    2015-10-15

    Highlights: • Comprehensive flow induced vibrations time domain model was developed. • Simulations of fluidelastic instability and turbulence were conducted. • Nonlinear effect due to the clearances at the supports was studied. • Prediction of stresses due to fluid excitation was obtained. • Deterministic and stochastic analyses for crack and leakage rate were conducted. - Abstract: Flow-induced vibrations (FIVs) are a major threat to the operation of nuclear steam generators. Turbulence and fluidelastic instability are the two main excitation mechanisms leading to tube vibrations. The consequences to the operation of steam generators are premature wear of the tubes, as well as development of cracks that may leak hazardous fluids. This paper investigates the effect of tube support clearance on the integrity of tube bundles within steam generators. Special emphasis will be placed on crack propagation and leakage rates. A crack growth model is used to simulate the growth of surface flaws and through-wall cracks of various initial sizes due to a wide range of support clearances. Leakage rates are predicted using a two-phase flow leakage model. Nonlinear finite element analysis is used to simulate a full U-bend subjected to fluidelastic and turbulence forces. Monte Carlo simulations are then used to conduct a probabilistic assessment of steam generator life due to crack development.

  9. Steam reforming of tar model compound using Pd catalyst on alumina tube.

    Science.gov (United States)

    Nisamaneenate, Jurarat; Atong, Duangduen; Sricharoenchaikul, Viboon

    2012-12-01

    Gasification processing of biomass as a renewable energy source generates tar in the product gas. Tar leads to foul-up of the process equipment by corrosion and deposit formation. Catalytic elimination of tars is a crucial step to improve fuel gas quality from the process. In this study, a palladium catalyst on alumina (Pd/Al2O3) was used in steam reforming of benzene as a biomass gasification tar model compound. The reaction was carried out in a laboratory-scale tube reactor made of stainless steel to study the effect of reaction temperature, catalyst loading, quantity of palladium catalyst tubes, steam to carbon ratio (S/C), and residence time on catalytic performance and stability. Pd/Al2O3 showed high efficiency ofbenzene decomposition and enhanced the formation of fuel gas. Hydrogen and carbon conversions increased with reaction temperature. Although the benzene concentration increased from 2000 to 5000 mg/l, the catalytic performance at 600 degrees C and 800 degrees C was similar. 1.0 wt% Pd/Al2O3 showed excellent catalytic activity with the highest hydrogen and carbon conversions of 83% and 81%, respectively at 800 degrees C. This result is attributed to the smooth surface of the palladium, as noted from scanning electron microscopy imaging. An S/C of 2 provided the highest conversion. The addition of catalyst from four and seven tubes did not result in any great difference in terms of benzene cracking efficiency. The fourth cyclic usage of 1.0 wt% Pd/Al2O3 exhibited a higher conversion than that of 0.5 wt%.

  10. On the 100th anniversary of sterile catgut kuhn: Franz Kuhn (1866-1929) and the epistemology of catgut sterilization.

    Science.gov (United States)

    Dietz, Ulrich A; Kehl, Franz; Hamelmann, Wulf; Weisser, Christoph

    2007-12-01

    The long road to effective catgut sterilization began with the work of Lord Joseph Lister (1867) and did not end until 40 years later. At the end of the nineteenth century dozens of different techniques were used to "sterilize" catgut, by immersing the cord in a cold chemical solution, by exposing it to steam, or by a combination of the two techniques, yet none of these approaches offered the ultimate solution. One of the many physicians working on the catgut problem at that time was the German surgeon Franz Kuhn (1866-1929), best known as a pioneer of intubation anesthesia. This review offers a brief biographical sketch of Kuhn's life and career on the occasion of the centenary of Sterile Catgut Kuhn. The goal of the present study is to describe several landmarks in the development of the catgut sterilization method. To explain this process, two approaches are taken: first, an analysis to see whether the character traits of the typical surgeon at that time provided the soil in which innovation could thrive, and second, an epistemological examination of the conceptual models for the attainment of knowledge current at that time. Perspectives for the future are explored in light of the "imperative of responsibility" of Hans Jonas.

  11. Estimation of the residual life of steam-turbine condensers based on statistical models

    Science.gov (United States)

    Murmansky, B. E.; Aronson, K. E.; Brodov, Yu. M.

    2015-11-01

    The article presents the results of a study aimed at estimation of the state and prediction of the residual life of steam-turbine condensers on the basis of statistical analysis. The possibility of such evaluation during the operation of steam-turbine plants with accuracy sufficient for practical purposes is demonstrated. It is shown that identification of the operating period, viz., the initial period, the normal operation period, or the period of the lifetime exhaustion, as well as determination of the condenser's operating time at the moment when the failure of an individual tube occurs, is very important for statistical evaluation of the condenser state. Two statistical models are proposed and comparative analysis of the results calculated by these models for the residual life of the condensers at the Reftinskaya SDPP has been performed. The first model can be used when comprehensive information about the condenser's operating time before the tubes have failed is available as well as a priori information—or information based on analysis of the condenser tube metal—that the condenser is in its normal operation period. In this case, the fact of exhaustion of the condenser's lifetime is established by reaching the limit of the failed condenser tubes, which is determined by technical and economic analysis of losses caused by operating the turbine with a reduced heat-exchange surface of the condenser. The distribution function for the operating time of the failed tubes is approximated by a normal distribution. In the cases when no precise information on the condenser tubes' operating time is available at the thermoelectric power plant (TEPP), the second statistical model based on censored samples is proposed for estimation of the condenser state. An expression to assess the confidence interval that determines the significant difference between the distribution functions for complete and censored operating time values has been derived. It is shown that this model

  12. Analysis of pulsed eddy current data using regression models for steam generator tube support structure inspection

    Science.gov (United States)

    Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2016-02-01

    Nuclear steam generators (SGs) are a critical component for ensuring safe and efficient operation of a reactor. Life management strategies are implemented in which SG tubes are regularly inspected by conventional eddy current testing (ECT) and ultrasonic testing (UT) technologies to size flaws, and safe operating life of SGs is predicted based on growth models. ECT, the more commonly used technique, due to the rapidity with which full SG tube wall inspection can be performed, is challenged when inspecting ferromagnetic support structure materials in the presence of magnetite sludge and multiple overlapping degradation modes. In this work, an emerging inspection method, pulsed eddy current (PEC), is being investigated to address some of these particular inspection conditions. Time-domain signals were collected by an 8 coil array PEC probe in which ferromagnetic drilled support hole diameter, depth of rectangular tube frets and 2D tube off-centering were varied. Data sets were analyzed with a modified principal components analysis (MPCA) to extract dominant signal features. Multiple linear regression models were applied to MPCA scores to size hole diameter as well as size rectangular outer diameter tube frets. Models were improved through exploratory factor analysis, which was applied to MPCA scores to refine selection for regression models inputs by removing nonessential information.

  13. CFD Modeling of Wall Steam Condensation: Two-Phase Flow Approach versus Homogeneous Flow Approach

    Directory of Open Access Journals (Sweden)

    S. Mimouni

    2011-01-01

    Full Text Available The present work is focused on the condensation heat transfer that plays a dominant role in many accident scenarios postulated to occur in the containment of nuclear reactors. The study compares a general multiphase approach implemented in NEPTUNE_CFD with a homogeneous model, of widespread use for engineering studies, implemented in Code_Saturne. The model implemented in NEPTUNE_CFD assumes that liquid droplets form along the wall within nucleation sites. Vapor condensation on droplets makes them grow. Once the droplet diameter reaches a critical value, gravitational forces compensate surface tension force and then droplets slide over the wall and form a liquid film. This approach allows taking into account simultaneously the mechanical drift between the droplet and the gas, the heat and mass transfer on droplets in the core of the flow and the condensation/evaporation phenomena on the walls. As concern the homogeneous approach, the motion of the liquid film due to the gravitational forces is neglected, as well as the volume occupied by the liquid. Both condensation models and compressible procedures are validated and compared to experimental data provided by the TOSQAN ISP47 experiment (IRSN Saclay. Computational results compare favorably with experimental data, particularly for the Helium and steam volume fractions.

  14. Development and experimental validation of a computational model for a helically coiled steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Colorado, D.; Hernandez, J.A. [Centro de Investigacion en Ingenieria y Ciencia Aplicadas (CIICAp), Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos (Mexico); Papini, D.; Santini, L.; Ricotti, M.E. [Department of Energy, CeSNEF-Nuclear Engineering Division, Politecnico di, Milano, Via La Masa, 34, 20156, Milan (Italy)

    2011-04-15

    A computational model is developed to describe the thermo-fluid-dynamic behaviour of a helically coiled steam generator device working with water and widely adopted in the nuclear industry. The discretized governing equations are coupled using an implicit step by step method. The mathematical model includes: a subcooled liquid region, a two-phase flow region, and a superheated vapour region (according to the once-through nature of the heat exchanger). All the flow variables (enthalpies, temperatures, pressures, vapour qualities, velocities, heat fluxes, etc.), together with the thermo-physical properties, are evaluated at each point of the grid in which the domain is discretized. A full-scale experimental investigation carried out at SIET thermal-hydraulics labs in Piacenza (Italy), and aimed at characterizing the fluid-dynamic behaviour of two-phase flows in helically coiled tubes, is referenced in the present paper. Two-phase pressure drops data reduction allowed optimizing a suitable form of the friction factor multiplier required by momentum balance equation. Comparisons of the numerical simulations with a wide range of two-phase pressure drops measurements (experiments conducted both in diabatic and adiabatic conditions) are shown in order to validate the proposed model. (authors)

  15. Modelling Aedes aegypti mosquito control via transgenic and sterile insect techniques: endemics and emerging outbreaks.

    Science.gov (United States)

    Seirin Lee, S; Baker, R E; Gaffney, E A; White, S M

    2013-08-21

    The invasion of pest insects often changes or destroys a native ecosystem, and can result in food shortages and disease endemics. Issues such as the environmental effects of chemical control methods, the economic burden of maintaining control strategies and the risk of pest resistance still remain, and mosquito-borne diseases such as malaria and dengue fever prevail in many countries, infecting over 100 million worldwide in 2010. One environmentally friendly method for mosquito control is the Sterile Insect Technique (SIT). This species-specific method of insect control relies on the mass rearing, sterilization and release of large numbers of sterile insects. An alternative transgenic method is the Release of Insects carrying a Dominant Lethal (RIDL). Our objective is to consider contrasting control strategies for two invasive scenarios via SIT and RIDL: an endemic case and an emerging outbreak. We investigate how the release rate and size of release region influence both the potential for control success and the resources needed to achieve it, under a range of conditions and control strategies, and we discuss advantageous strategies with respect to reducing the release resources and strategy costs (in terms of control mosquito numbers) required to achieve complete eradication of wild-type mosquitoes.

  16. Modelling Aedes aegypti mosquito control via transgenic and sterile insect techniques: Endemics and emerging outbreaks

    KAUST Repository

    Seirin Lee, S.

    2013-08-01

    The invasion of pest insects often changes or destroys a native ecosystem, and can result in food shortages and disease endemics. Issues such as the environmental effects of chemical control methods, the economic burden of maintaining control strategies and the risk of pest resistance still remain, and mosquito-borne diseases such as malaria and dengue fever prevail in many countries, infecting over 100 million worldwide in 2010. One environmentally friendly method for mosquito control is the Sterile Insect Technique (SIT). This species-specific method of insect control relies on the mass rearing, sterilization and release of large numbers of sterile insects. An alternative transgenic method is the Release of Insects carrying a Dominant Lethal (RIDL). Our objective is to consider contrasting control strategies for two invasive scenarios via SIT and RIDL: an endemic case and an emerging outbreak. We investigate how the release rate and size of release region influence both the potential for control success and the resources needed to achieve it, under a range of conditions and control strategies, and we discuss advantageous strategies with respect to reducing the release resources and strategy costs (in terms of control mosquito numbers) required to achieve complete eradication of wild-type mosquitoes. © 2013 Elsevier Ltd.

  17. Experimental and Modeling Studies of the Methane Steam Reforming Reaction at High Pressure in a Ceramic Membrane Reactor

    OpenAIRE

    Hacarlioglu, Pelin

    2007-01-01

    This dissertation describes the preparation of a novel inorganic membrane for hydrogen permeation and its application in a membrane reactor for the study of the methane steam reforming reaction. The investigations include both experimental studies of the membrane permeation mechanism and theoretical modeling of mass transfer through the membrane and simulation of the membrane reactor with 1-D and 2-D models. A hydrothermally stable and hydrogen selective membrane composed of silica and a...

  18. The role of CFD combustion modelling in hydrogen safety management – VI: Validation for slow deflagration in homogeneous hydrogen-air-steam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cutrono Rakhimov, A., E-mail: cutrono@nrg.eu [Nuclear Research and Consultancy Group (NRG), Westerduinweg 3, 1755 ZG Petten (Netherlands); Visser, D.C., E-mail: visser@nrg.eu [Nuclear Research and Consultancy Group (NRG), Westerduinweg 3, 1755 ZG Petten (Netherlands); Holler, T., E-mail: tadej.holler@ijs.si [Jožef Stefan Institute (JSI), Jamova cesta 39, 1000 Ljubljana (Slovenia); Komen, E.M.J., E-mail: komen@nrg.eu [Nuclear Research and Consultancy Group (NRG), Westerduinweg 3, 1755 ZG Petten (Netherlands)

    2017-01-15

    Highlights: • Deflagration of hydrogen-air-steam homogeneous mixtures is modeled in a medium-scale containment. • Adaptive mesh refinement is applied on flame front positions. • Steam effect influence on combustion modeling capabilities is investigated. • Mean pressure rise is predicted with 18% under-prediction when steam is involved. • Peak pressure is evaluated with 5% accuracy when steam is involved. - Abstract: Large quantities of hydrogen can be generated during a severe accident in a water-cooled nuclear reactor. When released in the containment, the hydrogen can create a potential deflagration risk. The dynamic pressure loads resulting from hydrogen combustion can be detrimental to the structural integrity of the reactor. Therefore, accurate prediction of these pressure loads is an important safety issue. In previous papers, we validated a Computational Fluid Dynamics (CFD) based method to determine the pressure loads from a fast deflagration. The combustion model applied in the CFD method is based on the Turbulent Flame Speed Closure (TFC). In our last paper, we presented the extension of this combustion model, Extended Turbulent Flame Speed Closure (ETFC), and its validation against hydrogen deflagration experiments in the slow deflagration regime. During a severe accident, cooling water will enter the containment as steam. Therefore, the effect of steam on hydrogen deflagration is important to capture in a CFD model. The primary objectives of the present paper are to further validate the TFC and ETFC combustion models, and investigate their capability to predict the effect of steam. The peak pressures, the trends of the flame velocity, and the pressure rise with an increase in the initial steam dilution are captured reasonably well by both combustion models. In addition, the ETFC model appeared to be more robust to mesh resolution changes. The mean pressure rise is evaluated with 18% under-prediction and the peak pressure is evaluated with 5

  19. Numerical discretization analysis of a HTR steam generator model for the thermal-hydraulics code trace

    Directory of Open Access Journals (Sweden)

    Esch Markus

    2014-01-01

    Full Text Available For future high temperature reactor projects, e. g., for electricity production or nuclear process heat applications, the steam generator is a crucial component. A typical design is a helical coil steam generator consisting of several tubes connected in parallel forming cylinders of different diameters. This type of steam generator was a significant component used at the thorium high temperature reactor. In the work presented the temperature profile is being analyzed by the nodal thermal hydraulics code TRACE for the thorium high temperature reactor steam generator. The influence of the nodalization is being investigated within the scope of this study and compared to experimental results from the past. The results of the standard TRACE code are compared to results using a modified Nusselt number for the primary side. The implemented heat transfer correlation was developed within the past German HTR program. This study shows that both TRACE versions are stable and provides a discussion of the nodalization requirements.

  20. Steam Turbines

    Science.gov (United States)

    1981-01-01

    Turbonetics Energy, Inc.'s steam turbines are used as power generating systems in the oil and gas, chemical, pharmaceuticals, metals and mining, and pulp and paper industries. The Turbonetics line benefited from use of NASA research data on radial inflow steam turbines and from company contact with personnel of Lewis Research Center, also use of Lewis-developed computer programs to determine performance characteristics of turbines.

  1. A Differential-Algebraic Model for the Once-Through Steam Generator of MHTGR-Based Multimodular Nuclear Plants

    Directory of Open Access Journals (Sweden)

    Zhe Dong

    2015-01-01

    Full Text Available Small modular reactors (SMRs are those fission reactors whose electrical output power is no more than 300 MWe. SMRs usually have the inherent safety feature that can be applicable to power plants of any desired power rating by applying the multimodular operation scheme. Due to its strong inherent safety feature, the modular high temperature gas-cooled reactor (MHTGR, which uses helium as coolant and graphite as moderator and structural material, is a typical SMR for building the next generation of nuclear plants (NGNPs. The once-through steam generator (OTSG is the basis of realizing the multimodular scheme, and modeling of the OTSG is meaningful to study the dynamic behavior of the multimodular plants and to design the operation and control strategy. In this paper, based upon the conservation laws of mass, energy, and momentum, a new differential-algebraic model for the OTSGs of the MHTGR-based multimodular nuclear plants is given. This newly-built model can describe the dynamic behavior of the OTSG in both the cases of providing superheated steam and generating saturated steam. Numerical simulation results show the feasibility and satisfactory performance of this model. Moreover, this model has been applied to develop the real-time simulation software for the operation and regulation features of the world first underconstructed MHTGR-based commercial nuclear plant—HTR-PM.

  2. Modeling of the steam hydrolysis in a two-step process for hydrogen production by solar concentrated energy

    Science.gov (United States)

    Valle-Hernández, Julio; Romero-Paredes, Hernando; Pacheco-Reyes, Alejandro

    2017-06-01

    In this paper the simulation of the steam hydrolysis for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 to lower-valence cerium oxide, at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. The modeling of endothermic reduction step was presented at the Solar Paces 2015. This work shows the modeling of the exothermic step; the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For this model, three sections of the pipe where the reaction occurs were considered; the steam water inlet, the porous medium and the hydrogen outlet produced. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

  3. A simple physical model for steam absorption into a falling film of aqueous lithium bromide solution on a horizontal tube

    Science.gov (United States)

    Auracher, Hein; Wohlfeil, Arnold; Ziegler, Felix

    2008-03-01

    For one horizontal tube in an absorber the Nusselt solution for film thickness and velocity distribution was applied, assuming steady state in heat transfer and a semi-infinite body’s concentration profile with unsteady state mass transfer. The model was applied to the absorption of steam into aqueous lithium bromide in absorption chillers. The results are compared to published experimental values and show fair agreement.

  4. 过热蒸汽处理对脱水蒜片杀菌效果及品质影响%Effects of superheated steam on sterilization and major quality of the dehydrated garlic slices

    Institute of Scientific and Technical Information of China (English)

    王书兰; 张静林; 陶阳; 赵颖; 韩永斌; 葛以兵

    2016-01-01

    利用过热蒸汽对脱水蒜片进行减菌处理,并测定品质变化。结果表明脱水蒜片中的菌落总数随着蒸汽处理时间或蒸汽温度的上升而下降。当处理温度为110℃,处理时间为9min时,菌落总数达到最小值3.53 log(cfu/g),较对照减少了1.36 log(cfu/g)。随着蒸汽处理时间的延长,脱水蒜片的色泽会逐渐加深,当处理温度为105℃,处理时间超过5 min时,脱水蒜片色泽发生改变,当处理时间达到9 min时,可观察到较显著差异。脱水蒜片的复水比随着蒸汽处理时间的延长,会有一定程度的下降,但变化并不显著。过热蒸汽对于脱水蒜片中的蛋白质含量有一定的影响,当110℃处理9 min时,可溶性蛋白含量由220.3 mg/g降至200.3mg/g。经过热蒸汽处理后大蒜素显著减少,以致在加热时间超过5 min时,采用高效液相色谱方法检测不出。为此,尽管过热蒸汽可有效减少大蒜片中的微生物,但对大蒜片的感官和大蒜素的破坏较严重。%Put dehydrated garlic slices on the gauze and then placed in high pressure steam boiler for processing. The results showed that:when the steam processing time or steam temperature rose, the total number of colonies declined. When the temperature was 110℃and the time was 9 min, the total number of colonies reached a minimum value (3.53 log cfu/g), which was reduced by 1.36 log (cfu/g). With the increase of steam treatment time , the color of dehydrated garlic changed markedly. When processing time reached 9 min, a significant difference in color was observed. The recovery of dehydrated garlic slice decreased with the increase of steam treatment time. Superheated steam had a certain effect on the protein content of dehydrated garlic tablets, and the soluble protein content decreased from 220.3mg/g to 200.3mg/g after treatment at 110℃for 9 min. After heat steam treatment, garlicin significantly declined, and HPLC

  5. Evaluation on the process challenge device and internal chemical indicators used for the detection of steam sterilization%PCD批量检测与化学指示卡检测灭菌效果的比较

    Institute of Scientific and Technical Information of China (English)

    林娟; 王海花

    2012-01-01

    目的 比较PCD批量检测及包内化学指示卡在高压灭菌质量监控中的可靠性,为医院供应室灭菌质量监控提供参考.方法 利用批量检测系统PCD包内化学指示卡、生物指示卡3种质控方式对高压灭菌质量进行监控,记录数据并进行分析.结果 自2010年1月~2010年12月期间,该院供应室共灭菌405次,PCD检测化学指示卡405张,其中合格399张;405批次灭菌中共放置生物检测卡2430张,其中有效2419张.PCD检测合格的399批次中,生物监测卡(2394张)全部显示合格;PCD检测不合格的6个批次灭菌中,有8张生物检测卡显示灭菌失败.PCD检测合格的399批次中包内化学指示卡63840张,合格63019张,显示不合格731张,其中335张出现于玻璃器皿包中,396张出现于金属类包中,布类包中均未发现有不合格包内化学指示卡.结论 PCD批量检测对灭菌效果较包内化学指示卡的指示效果可靠,值得推广.%OBJECTIVE To evaluate the sterilization monitoring of Process Challenge Device and Internal chemical indicators, and to provide laboratory data for quality monitoring and management. METHODS Three methods were used for the sterilization monitoring at the same lime which included Process Challenge Device, Internal chemical indicators and bioindicators. The records were analyzed. RESULTS 405 sterilization happened during 2010. We got 405 biochemical indicators bom PCD of which 399 indicated success and 6 indicated failure. 2 430 bioindicators were used in the 405 sterilizations of which 2 419 indicated success. All of the 2 394 bioindicators gave the same result among the 399 successful sterilizations indicated by PCD and 8 bioindicators gave the failure result among the 6 failed sterilizations indicated by PCD. Among the 399 sterilization, 63 840 Internal chemical indicators were got of which 63 019 gave successful indication and the other 731 gave failed indication.396 failed Internal chemical indicators were from

  6. Regenerative superheated steam turbine cycles

    Science.gov (United States)

    Fuller, L. C.; Stovall, T. K.

    1980-01-01

    PRESTO computer program was developed to analyze performance of wide range of steam turbine cycles with special attention given to regenerative superheated steam turbine cycles. It can be used to model standard turbine cycles, including such features as process steam extraction, induction and feedwater heating by external sources, peaking, and high back pressure. Expansion line efficiencies, exhaust loss, leakages, mechanical losses, and generator losses are used to calculate cycle heat rate and generator output. Program provides power engineer with flexible aid for design and analysis of steam turbine systems.

  7. Steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Beckmann, G.; Gilli, P.V.; Fritz, K.; Lippitsch, J.

    1975-12-02

    A steam generator is disclosed which is particularly adapted to be used in nuclear power plants. A casing is provided with an inlet and outlet to receive and discharge a primary heating fluid from which heat is to be extracted. A pair of tube plates extend across the interior of the casing at the region of the inlet and outlet thereof, and a plurality of tubes extend along the interior of the casing and are connected in parallel between the tube plates with all of the tubes having open ends communicating with the inlet and outlet of the casing so that the primary heating fluid will flow through the interior of the tubes while a fluid in the casing at the exterior of the tubes will extract heat from the primary fluid. The casing has between the tubes at the region of the inlet a superheating chamber and at the region of the outlet a preheating chamber and between the latter chambers an evaporating chamber, the casing receiving water through an inlet at the preheating chamber and discharging superheated steam through an outlet at the superheating chamber. A separator communicates with the evaporating chamber to receive a mixture of steam and water therefrom for separating the steam from the water and for delivering the separated steam to the superheating chamber.

  8. Scaled physical model studies of the steam drive process. First annual report, September 1977-September 1978

    Energy Technology Data Exchange (ETDEWEB)

    Doscher, T M

    1980-12-01

    Scaling laws of the heat transport mechanism in steam displacement processes are developed based upon an integral energy balance equation. Unlike the differential approach adopted by previous workers, the above scaling laws do not necessitate the use of any empirical correction factor as has been done in previous scaling calculations. The results provide a complete and consistent scale-down of the energy transport behavior, which is the critical mechanism for the success of a steam injection process. In the course of the study, the scaling problems associated with relative permeability and capillary pressure are also discussed. A method which has often been used in scaling nonthermal displacement processes is applied to reduce errors due to scaling in relative permeability. Both dimensional and inspectional analyses are applied to illustrate their use in steam processes. Scale-up laws appeared in the literature and those used in this study are compared and numerical examples are given.

  9. Modelling of WWER-1000 steam generators by REALP5/MOD3.2 code

    Energy Technology Data Exchange (ETDEWEB)

    D`Auria, F.; Galassi, G.M. [Univ. of Pisa (Italy); Frogheri, M. [Univ. of Genova (Italy)

    1997-12-31

    The presentation summarises the results of best estimate calculations carried out with reference to the WWER-1000 Nuclear Power Plant, utilizing a qualified nodalization set-up for the Relap5/Mod3.2 code. The nodalization development has been based on the data of the Kozloduy Bulgarian Plant. The geometry of the steam generator imposed drastic changes in noding philosophy with respect to what is suitable for the U-tubes steam generators. For the secondary side a symmetry axis was chosen to separate (in the nodalization) the hot and the cold sides of the tubes. In this way the secondary side of the steam generators was divided into three zones: (a) the hot zone including the hot collector and the hot l/2 parts of the tubes; (b) the cold zone including the cold collector and the cold 1/2 parts of the tubes; (c) the downcomer region, where down flow is assumed. As a consequence of above in the primary side more nodes are placed on the hot side of the tubes. Steady state and transient qualification has been achieved, considering the criteria proposed at the University of Pisa, utilizing plant transient data from the Kozloduy and the Ukrainian Zaporosche Plants. The results of the application of the qualified WWER-1000 Relap5/Mod3.2 nodalization to various transients including large break LOCA, small break LOCA and steam generator tube rupture, together with a sensitivity analysis on the steam generators, are reported in the presentation. Emphasis is given to the prediction of the steam generators performances. 23 refs.

  10. Trends in international trade in steam coal. Lessons from the COALMOD-World model; Entwicklungen des internationalen Handels mit Kesselkohle. Lehren aus dem COALMOD-World-Modell

    Energy Technology Data Exchange (ETDEWEB)

    Haftendorn, Clemens; Holz, Franziska; Winke, Tim; Hirschhausen, Christian von [Deutsches Institut fuer Wirtschaftsforschung, Berlin (Germany). Abt. Energie, Verkehr und Umwelt

    2011-12-15

    The global steam coal market has changed dramatically in the last ten years as a result of increasing demand, more flexible terms of trade and intensified exchange transactions. To analyse future market trends the equilibrium model COALMOD-World, which simulates the national and global steam coal market over several periods, is described in this article. Both international maritime trade and the relevant domestic markets are represented for this purpose. The market equilibria determined annually permit regional predictions of the coal quantities traded and the prices up to the year 2030. It is shown in different scenarios that the trend on the steam coal market is heavily dependent on the readiness of the suppliers to invest and the international climate policy. In all scenarios the Asian region will play the most important role in the global steam coal market. China and India in particular will increase their imports on the steam coal market in the next few years, because indigenous deposits are required for the domestic energy market and, in the case of India, diminishing deposits of high-quality coal give rise to an increase in production costs. (orig.)

  11. Modeling of the process of heat transfer formation during steam flooding

    Energy Technology Data Exchange (ETDEWEB)

    Malofeev, G.E.; Sheinman, A.B.; Kennavi, F.A.

    1971-01-01

    This work describes experimental data on distribution of temperature in a formation and loss of heat during radial flow of saturated steam. The problem is formulated mathematically and dimensionless parameters characterizing the process are described. The study also throws light on laboratory equipment, experimental techniques and the results obtained. Experimental data are compared with calculated values. The results can be used for evaluating thermal phenomena in high temperature formations in the presence of natural convection and for determining temperature distribution in the case of artificial steam injection. (14 refs.)

  12. Cost efficiency of Japanese steam power generation companies: A Bayesian comparison of random and fixed frontier models

    Energy Technology Data Exchange (ETDEWEB)

    Assaf, A. George [Isenberg School of Management, University of Massachusetts-Amherst, 90 Campus Center Way, Amherst 01002 (United States); Barros, Carlos Pestana [Instituto Superior de Economia e Gestao, Technical University of Lisbon, Rua Miguel Lupi, 20, 1249-078 Lisbon (Portugal); Managi, Shunsuke [Graduate School of Environmental Studies, Tohoku University, 6-6-20 Aramaki-Aza Aoba, Aoba-Ku, Sendai 980-8579 (Japan)

    2011-04-15

    This study analyses and compares the cost efficiency of Japanese steam power generation companies using the fixed and random Bayesian frontier models. We show that it is essential to account for heterogeneity in modelling the performance of energy companies. Results from the model estimation also indicate that restricting CO{sub 2} emissions can lead to a decrease in total cost. The study finally discusses the efficiency variations between the energy companies under analysis, and elaborates on the managerial and policy implications of the results. (author)

  13. Hydrogen production by steam reforming of DME in a large scale CFB reactor. Part I:computational model and predictions

    OpenAIRE

    Elewuwa, Francis A.; Makkawi, Yassir T.

    2015-01-01

    This study presents a computational fluid dynamic (CFD) study of Dimethyl Ether steam reforming (DME-SR) in a large scale Circulating Fluidized Bed (CFB) reactor. The CFD model is based on Eulerian-Eulerian dispersed flow and solved using commercial software (ANSYS FLUENT). The DME-SR reactions scheme and kinetics in the presence of a bifunctional catalyst of CuO/ZnO/Al2O3+ZSM-5 were incorporated in the model using in-house developed user-defined function. The model was validated by comparing...

  14. Graphical procedure for comparing thermal death of Bacillus stearothermophilus spores in saturated and superheated steam.

    Science.gov (United States)

    SHULL, J J; ERNST, R R

    1962-09-01

    The thermal death curve of dried spores of Bacillus stearothermophilus in saturated steam was characterized by three phases: (i) a sharp initial rise in viable count; (ii) a low rate of death which gradually increased; and (iii) logarithmic death at maximal rate. The first phase was a reflection of inadequate heat activation of the spore population. The second and third phases represented the characteristic thermal death curve of the spores in saturated steam. A jacketed steam sterilizer, equipped with a system for initial evacuation of the chamber, was examined for superheat during normal operation. Measurements of spore inactivation and temperature revealed superheat in surface layers of fabrics being processed in steam at 121 C. The high temperature of the fabric surfaces was attributed to absorption of excess heat energy from superheated steam. The superheated steam was produced at the beginning of the normal sterilizing cycle by transfer of heat from the steam-heated jacket to saturated steam entering the vessel.

  15. Naturally light sterile neutrinos

    CERN Document Server

    Sarkar, U

    1999-01-01

    A simple model to accomodate light sterile neutrinos naturally with large mixing with the usual neutrinos has been proposed. The standard model gauge group is extended to include an $SU(2)_S$ gauge symmetry. Heavy triplet higgs scalars give small masses to the left-handed neutrinos, while a heavy doublet higgs scalar give mixing with the sterile neutrinos of the same order of magnitude. The neutrino mass matrix thus obtained can explain the solar neutrino deficit, the atmospheric neutrino deficit, the LSND data and hot dark matter. Lepton number is violated here through decays of the heavy triplet higgs, which generates the lepton asymmetry of the universe, which in turn generates a baryon asymmetry of the universe.

  16. Model biogas steam reforming in a thin Pd-supported membrane reactor to generate clean hydrogen for fuel cells

    Science.gov (United States)

    Iulianelli, A.; Liguori, S.; Huang, Y.; Basile, A.

    2015-01-01

    Steam reforming of a model biogas mixture is studied for generating clean hydrogen by using an inorganic membrane reactor, in which a composite Pd/Al2O3 membrane separates part of the produced hydrogen through its selective permeation. The characteristics of H2 perm-selectivity of the fresh membrane is expressed in terms of H2/N2 ideal selectivity, in this case equal to 4300. Concerning biogas steam reforming reaction, at 380 °C, 2.0 bar H2O:CH4 = 3:1, GHSV = 9000 h-1 the permeate purity of the recovered hydrogen is around 96%, although the conversion (15%) and hydrogen recovery (>20%) are relatively low; on the contrary, at 450 °C, 3.5 bar H2O:CH4 = 4:1, GHSV = 11000 h-1 the conversion is increased up to more than 30% and the recovery of hydrogen to about 70%. This novel work constitutes a reference study for new developments on biogas steam reforming reaction in membrane reactors.

  17. Sustainable hydrogen from bio-oil - Steam reforming of acetic acid as a model oxygenate

    NARCIS (Netherlands)

    Takanabe, K.; Takanabe, Kazuhiro; Aika, Ken-ichi; Seshan, Kulathuiyer; Lefferts, Leonardus

    2004-01-01

    Steam reforming of acetic acid over Pt/ZrO2 catalysts has been investigated. Pt/ZrO2 catalysts are very active, completely converting acetic acid, and give a hydrogen yield close to thermodynamic equilibrium. The catalyst deactivated by formation of oligomers which block the active sites. The

  18. Phenomenology of the Sterile Neutrinos

    CERN Document Server

    Tabrizi, Zahra

    2016-01-01

    In this thesis we investigate several topics in neutrino physics, with an em- phasis on the phenomenology of the sterile neutrinos. We study the existence of a light sterile neutrino within the so called 3+1 scenario using the data of the medium baseline reactor experiments. We will also probe the parameters of the Large Extra Dimension model with the high energy atmospheric data of the IceCube experiment, and will find an equivalence between the Kaluza Klein modes and the sterile neutrinos. We will study the secret interaction of the ster- ile neutrinos which is proposed to solve the tension between cosmology and the sterile neutrino hypothesis. In addition to these, we will show that a minimal 2-Higgs-Doublet-Model extended with a U(1) or Z_2 symmetry cannot explain the smallness of the neutrino masses.

  19. General purpose steam table library :

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, John H.; Belcourt, Kenneth Noel; Nourgaliev, Robert

    2013-08-01

    Completion of the CASL L3 milestone THM.CFD.P7.04 provides a general purpose tabular interpolation library for material properties to support, in particular, standardized models for steam properties. The software consists of three parts, implementations of analytic steam models, a code to generate tables from those models, and an interpolation package to interface the tables to CFD codes such as Hydra-TH. Verification of the standard model is maintained through the entire train of routines. The performance of interpolation package exceeds that of freely available analytic implementation of the steam properties by over an order of magnitude.

  20. Sterilization monitoring by biological indicators and conventional swab test of different sterilization processes used in orthodontics: A comparative study

    Directory of Open Access Journals (Sweden)

    Shantanu Khattri

    2015-01-01

    Full Text Available Introduction: The need of effective sterilization method and their monitoring is necessary. Biological indicators are specific microorganisms with high resistance toward particular sterilization methods. Their processes include steam autoclave, dry heat sterilizer, ethylene oxide sterilizer. This article has considered various methods to monitor the effectiveness of different sterilization methods used in orthodontics. Materials and Methods: The parameters for comparison were the control and experimental instruments utilized in orthodontic treatment. The efficacy of sterilization was evaluated by comparison of bacterial growth obtained in monitoring by biological indicators and swab test method. Results: No spore growth was found when sterilization process was evaluated by biological indicators in comparison to swab test where spore growth was present. Instruments dipped in Bioclenz-G solution for 10 min showed spore growth, but no spore growth was seen in 10 h cycle. Discussion: The result of the study verifies the established effectiveness of biological indicators over conventional swab test method in monitoring various sterilization processes used in orthodontics. Bioclenz-G solution can be used as an effective cold sterilization method for sterilization. Conclusion: For evaluating the effectiveness of sterilization, biological indicators preclude the drawbacks of incomplete verification of destruction of all vegetation and inordinate delay in procurement of results as is the case with chemical indicators and lab culture, respectively.

  1. 压力蒸汽灭菌对口腔高速手机乙型肝炎表面抗原的消毒效果%The disinfection effect of pressure steam sterilization on hepatitis B surface antigen in dental high speed handpiece

    Institute of Scientific and Technical Information of China (English)

    王静娴

    2013-01-01

    目的 探讨压力蒸汽灭菌对口腔高速手机乙型肝炎表面抗原(HBsAg)的消毒效果.方法 将乙肝患者使用过的污染口腔科高速手机30把随机分为A、B、C3组,A组采用2%戊二醛浸泡消毒,B组采用消毒剂擦拭法消毒,C组采用压力蒸汽灭菌消毒,采用酶联免疫吸附法检测3种方式消毒后的口腔科高速手机HBsAg的阳性情况.结果 乙肝患者使用过的口腔科高速手机的HBsAg的阳性率为30.0%,A组和C组中HBsAg均为阴性,B组中HBsAg的阳性率为10.0%.A组和C组中无细菌生长,B组细菌超标率为10.0%.结论 压力蒸汽灭菌对口腔高速手机的消毒效果较好,不容易造成环境污染,是目前较为理想的消毒口腔高速手机的方法.%Objective To investigate the disinfection effect of pressure steam sterilization on hepatitis B surface antigen in dental high speed handpiece.Methods A total of 30 polluted high-speed handpiece of stomatology department by hepatitis B patients were randomly divided into A,B,C three groups,group A was used 2% glutaraldehyde immersion disinfection,group B was used disinfectant disinfection method,group C was used pressure steam sterilization,The positive rate of HBsAg in high-speed mobile phone by 3 ways of disinfecting was detected by ELISA method.Results The positive rate of HBsAg was 30% in dental high speed handpiece,HBsAg were negative between group A and group C,the positive rate of HBsAg was 10% in group B.No bacterial growth in group A and C group,bacteria exceed the standard rate was 10% in group B.Conclusions The disinfection effect of pressure steam sterilization in dental high speed handpiece is good; it does not cause environmental pollution and it is a ideal method in disinfection of dental high-speed handpiece.

  2. Neutrino-4 experiment on search for sterile neutrino with multi-section model of detector

    CERN Document Server

    Serebrov, A P; Samoilov, R M; Fomin, A K; Zinoviev, V G; Neustroev, P V; Golovtsov, V L; Gruzinskiy, N V; Solovey, V A; Chernyj, A V; Zherebtsov, O M; Martemyanov, V P; Tsynoev, V G; Tarasenkov, V G; Aleshin, V I; Petelin, A L; Ishutov, A L; Tuzov, A A; Sazontov, S A; Ryazanov, D K; Gromov, M O; Afanasiev, V V; Zaytsev, M E; Chaikovskii, M E

    2016-01-01

    In order to carry out research in the field of possible existence of sterile neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was created to search for oscillations of reactor antineutrino. The prototype of a multi-section neutrino detector with liquid scintillator volume of 350 l was installed in the middle of 2015. It is a moveable inside the passive shielding detector, which can be set at distance range from 6 to 11 meters from the reactor core. The measurements of antineutrino flux at such small distances from the reactor core carried out for the first time. The different methods of cosmic background suppression were researched in order to increase the precision of the experiment. After collecting data for half a year, measurement accuracy for the nearest point (6.5 m) comprised 10%. The full-scale detector with volume of liquid scintillator 3 m3 (5x10 sections) is at the stage of preparation. It will allow us to obtain up to 1.5-3.0% statistic accuracy of measurements at the distances...

  3. Loss of feed flow, steam generator tube rupture and steam line break thermohydraulic experiments

    Energy Technology Data Exchange (ETDEWEB)

    Mendler, O J; Takeuchi, K; Young, M Y

    1986-10-01

    The Westinghouse Model Boiler No. 2 (MB-2) steam generator test model at the Engineering Test Facility in Tampa, Florida, was reinstrumented and modified for performing a series of tests simulating steam generator accident transients. The transients simulated were: loss of feed flow, steam generator tube rupture, and steam line break events. This document presents a description of (1) the model boiler and the associated test facility, (2) the tests performed, and (3) the analyses of the test results.

  4. MECHANISTIC KINETIC MODELS FOR STEAM REFORMING OF CONCENTRATED CRUDE ETHANOL ON NI/AL2O3 CATALYST

    Directory of Open Access Journals (Sweden)

    O. A. OLAFADEHAN

    2015-05-01

    Full Text Available Mechanistic kinetic models were postulated for the catalytic steam reforming of concentrated crude ethanol on a Ni-based commercial catalyst at atmosphere pressure in the temperature range of 673-863 K, and at different catalyst weight to the crude ethanol molar flow rate ratio (in the range 0.9645-9.6451 kg catalyst h/kg mole crude ethanol in a stainless steel packed bed tubular microreactor. The models were based on Langmuir-Hinshelwood-Hougen-Watson (LHHW and Eley-Rideal (ER mechanisms. The optimization routine of Nelder-Mead simplex algorithm was used to estimate the inherent kinetic parameters in the proposed models. The selection of the best kinetic model amongst the rival kinetic models was based on physicochemical, statistical and thermodynamic scrutinies. The rate determining step for the steam reforming of concentrated crude ethanol on Ni/Al2O3 catalyst was found to be surface reaction between chemisorbed CH3O and O when hydrogen and oxygen were adsorbed as monomolecular species on the catalyst surface. Excellent agreement was obtained between the experimental rate of reaction and conversion of crude ethanol, and the simulated results, with ADD% being ±0.46.

  5. Model-based process management and process optimisation of industrial steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Kaestner, Wolfgang; Hampel, Rainer; Foerster, Tom; Freund, Matthias [Univ. of Applied Sciences Zittau/Goerlitz, Zittau (Germany). IPM; Haake, Dietmar; Kanisch, Heiko [Vattenfall Europe Generation AG, Cottbus (Germany); Altmann, Ulrich-Steffen; Mueller, Frank [CombTec GmbH, Zittau (Germany)

    2010-07-01

    Within the framework of a joint project sponsored by BMBF the development of algorithms for the optimal process management of industrial steam generators was carried out. The research work was focussed on the reduction of high-temperature corrosion at the membrane walls of lignite-fired steam generators. In the result a system for demonstration of technology was installed successfully in a Vattenfall power plant in 2009. During the operation of the power plant the capability of the system to guarantee a stable and symmetric fire position was demonstrated. Current work is focussed on the further development and retrofitting of the system to apply it under real condition in a Vattenfall power plant. (orig.)

  6. Steam reforming of tars at low temperature and elevated pressure for model tar component naphthalene

    OpenAIRE

    Speidel, Michael; Fischer, Holger

    2016-01-01

    A process of pressurized gasification and power generation in a hybrid system of Solid Oxide Fuel Cell (SOFC) and gas turbine enables an efficient use of biomass. This process requires tar reforming in order to protect the SOFC from plugging. Tars must be converted at 5 bar absolute pressure (bara) while avoiding secondary steam reforming of methane in order to reduce the required heat input for the tar reformer. This can be realized at low reforming temperatures (

  7. Steam generator tube integrity program

    Energy Technology Data Exchange (ETDEWEB)

    Dierks, D.R.; Shack, W.J. [Argonne National Laboratory, IL (United States); Muscara, J.

    1996-03-01

    A new research program on steam generator tubing degradation is being sponsored by the U.S. Nuclear Regulatory Commission (NRC) at Argonne National Laboratory. This program is intended to support a performance-based steam generator tube integrity rule. Critical areas addressed by the program include evaluation of the processes used for the in-service inspection of steam generator tubes and recommendations for improving the reliability and accuracy of inspections; validation and improvement of correlations for evaluating integrity and leakage of degraded steam generator tubes, and validation and improvement of correlations and models for predicting degradation in steam generator tubes as aging occurs. The studies will focus on mill-annealed Alloy 600 tubing, however, tests will also be performed on replacement materials such as thermally-treated Alloy 600 or 690. An overview of the technical work planned for the program is given.

  8. Comparative study of two theoretical models of methane and ethane steam reforming process

    Science.gov (United States)

    Brus, Grzegorz; Kaczmarczyk Marcin Tomiczek, Robert; Mozdzierz, Marcin

    2016-09-01

    From the chemical point of view the reforming process of heavy hydrocarbons such as Associated Petroleum Gas (APG) is very complex. One of the main issue is a set of undesired chemical reactions that causes deposition of solid carbon and consequently block catalytic property of a reactor. The experimental investigation is crucial to design APG reforming reactors. However, the experiment needs to be preceded by careful thermodynamical analysis to design safe operation conditions. In case of small number of reactants and reactions such as in case of steam reforming of pure methane, the problem can be solved by treating each equilibrium reaction constant as an element of the system of non-linear equations. The system of equations can be solved by Newton-Raphson method. However in case of large number of reactants and reaction, such as in case of APG reforming this method is inefficient. A large number of strongly non-linear equations leads often to converge problem. In this paper the authors suggest to use different approach called Parametric Equation Method. In this method a system of non-linear equations is replaced by a set of single non-linear equations solved separately. The methods were used to simulate steam reforming of methane-ethane rich fuel. The results of computations from both methods were juxtaposed and comparative study were conducted. Finally safe operation conditions for steam reforming of methane-ethane fuel were calculated and presented.

  9. Contribution to the development of the simulation model for the rotary cap burner in the marine steam boiler

    Directory of Open Access Journals (Sweden)

    Dvornik Joško

    2015-01-01

    Full Text Available This paper presents the simulation model for determining the intervals of preventive replacement of the system's components. The application of the Weibull distribution has been proved to be efficient in the approximation of many forms of delay, while numerical integration supported by Simpson formula and Fortran software has been applied to simulate optimum values of the preventive replacement of the components of the rotary cap burner SAACKE, type SKV 60 in the marine steam boiler, on the basis of the available data gathered through the system's exploitation and through empirical assumptions.

  10. A Novel Hybrid Approach for Numerical Modeling of the Nucleating Flow in Laval Nozzle and Transonic Steam Turbine Blades

    Directory of Open Access Journals (Sweden)

    Edris Yousefi Rad

    2017-08-01

    Full Text Available In the present research, considering the importance of desirable steam turbine design, improvement of numerical modeling of steam two-phase flows in convergent and divergent channels and the blades of transonic steam turbines has been targeted. The first novelty of this research is the innovative use of combined Convective Upstream Pressure Splitting (CUSP and scalar methods to update the flow properties at each calculation point. In other words, each property (density, temperature, pressure and velocity at each calculation point can be computed from either the CUSP or scalar method, depending on the least deviation criterion. For this reason this innovative method is named “hybrid method”. The next novelty of this research is the use of an inverse method alongside the proposed hybrid method to find the amount of the important parameter z in the CUSP method, which is herein referred to as “CUSP’s convergence parameter”. Using a relatively simple computational grid, firstly, five cases with similar conditions to those of the main cases under study in this research with available experimental data were used to obtain the value of z by the Levenberg-Marquardt inverse method. With this innovation, first, an optimum value of z = 2.667 was obtained using the inverse method and then directly used for the main cases considered in the research. Given that the aim is to investigate the two-dimensional, steady state, inviscid and adiabatic modeling of steam nucleating flows in three different nozzle and turbine blade geometries, flow simulation was performed using a relatively simple mesh and the innovative proposed hybrid method (scalar + CUSP, with the desired value of z = 2.667 . A comparison between the results of the hybrid modeling of the three main cases with experimental data showed a very good agreement, even within shock zones, including the condensation shock region, revealing the efficiency of this numerical modeling method innovation

  11. Neutrinos in a Sterile Throat

    CERN Document Server

    Gripaios, Ben Matthew

    2007-01-01

    We consider field-theoretic models of a warped extra dimension with multiple throats, in which fermions that are singlets of the Standard Model gauge group propagate in a separate throat from the Standard Model fields, which we call the sterile throat. The singlets mix with Standard Model fields via interactions localized on the UV brane that connects the two throats. This leads to three, light, mostly-active, Majorana neutrinos via a higher-dimensional see-saw mechanism, together with Kaluza-Klein towers of mostly-sterile neutrinos, whose scale is set by the warp factor in the sterile throat and can be very low if the throat is deep. We suggest that a model of this kind may explain all the neutrino data, reconciling the LSND result with astrophysical constraints.

  12. Use of borehole radar reflection logging to monitor steam-enhanced remediation in fractured limestone-results of numerical modelling and a field experiment

    Science.gov (United States)

    Gregoire, C.; Joesten, P.K.; Lane, J.W.

    2006-01-01

    Ground penetrating radar is an efficient geophysical method for the detection and location of fractures and fracture zones in electrically resistive rocks. In this study, the use of down-hole (borehole) radar reflection logs to monitor the injection of steam in fractured rocks was tested as part of a field-scale, steam-enhanced remediation pilot study conducted at a fractured limestone quarry contaminated with chlorinated hydrocarbons at the former Loring Air Force Base, Limestone, Maine, USA. In support of the pilot study, borehole radar reflection logs were collected three times (before, during, and near the end of steam injection) using broadband 100 MHz electric dipole antennas. Numerical modelling was performed to predict the effect of heating on radar-frequency electromagnetic (EM) wave velocity, attenuation, and fracture reflectivity. The modelling results indicate that EM wave velocity and attenuation change substantially if heating increases the electrical conductivity of the limestone matrix. Furthermore, the net effect of heat-induced variations in fracture-fluid dielectric properties on average medium velocity is insignificant because the expected total fracture porosity is low. In contrast, changes in fracture fluid electrical conductivity can have a significant effect on EM wave attenuation and fracture reflectivity. Total replacement of water by steam in a fracture decreases fracture reflectivity of a factor of 10 and induces a change in reflected wave polarity. Based on the numerical modelling results, a reflection amplitude analysis method was developed to delineate fractures where steam has displaced water. Radar reflection logs collected during the three acquisition periods were analysed in the frequency domain to determine if steam had replaced water in the fractures (after normalizing the logs to compensate for differences in antenna performance between logging runs). Analysis of the radar reflection logs from a borehole where the temperature

  13. Hydrogen-rich gas production via CaO sorption-enhanced steam gasification of rice husk: a modelling study.

    Science.gov (United States)

    Beheshti, Sayyed Mohsen; Ghassemi, Hojat; Shahsavan-Markadeh, Rasoul; Fremaux, Sylvain

    2015-01-01

    Gasification is a thermochemical process in which solid or liquid fuels are transformed into synthesis gas through partial oxidation. In this paper, a kinetic model of rice husk gasification has been developed, which is interesting for the applications of the syngas produced. It is a zero-dimensional, steady-state model based on global reaction kinetic, empirical correlation of pyrolysis and is capable of predicting hydrogen yield in the presence of sorbent CaO. The model can also be used as a useful tool to investigate the influence of process parameters including steam/biomass ratio, CaO/fuel ratio (CaO/Fuel), and gasification temperature on hydrogen efficiency, CO2 capture ratio (CCR), and average carbonation conversion (Save). Similar to hydrogen formation, CCR also increases with increasing CaO/Fuel, but an opposite trend is exhibited in Save. Model predictions were compared with available data from the literature, which showed fairly good agreement.

  14. Cytotoxicity of poly(96L/4D-lactide) : the influence of degradation and sterilization

    NARCIS (Netherlands)

    Cordewener, FW; Joziasse, CAP; Schmitz, JP; Bos, RRM; Rozema, FR; Pennings, AJ

    2000-01-01

    The cytotoxicity of poly(96L/4D-lactide) (PLA96), and of its accumulated degradation products, was investigated following different sterilization methods and pre-determined heat-accelerated degradation intervals. PLA96 samples sterilized by either steam, ethylene oxide, or gamma irradiation were

  15. [Complications of tubal sterilization].

    Science.gov (United States)

    Schreiner, W E

    1986-05-01

    In Europe and the US, tubal sterilization by laparoscopy has become the most widely used technique for female sterilization. The overall rate of intra- and postoperative complications differs between 0.145% and 0.85% in the numerous studies which have been done. This means 1 severe complication in 120-700 laparoscopic sterilizations. The lethality of tubal sterilization by laparoscopy lies between 3-10 deaths/100,000 interventions. The so-called "post-tubal ligation syndrome" is a rare complication. The overall pregnancy rate after tubal sterilization is 3-10/1000 women. The rate of ectopic pregnancy is very high and varies between 13.6% and 90%. Only 5% of the sterilized women show dissatisfaction. Several factors are relevant with regard to psychological sequelae and must be considered before tubal sterilization can be performed. 1 of the most important is the individual comprehensive counselling of the female or the couple prior to the sterilization.

  16. Safe use of chemicals for sterilization in healthcare.

    Science.gov (United States)

    Warburton, P Richard

    2012-01-01

    Chemical sterilization is necessary for temperature sensitive items that cannot be sterilized with steam. These chemical sterilants are by their nature hazardous; otherwise, they would not function well. Modern sterilizers and associated equipment are designed so that these chemicals can be used safely. Whether through mechanical failure, wear and tear, or user error, leaks do sometimes occur. The maximum chemical exposure is determined by OSHA permissible exposure limits, if available, and if not available, employers should use recognized standards. Employers have a duty to ensure safe work environment and take appropriate action to mitigate potential risks. Employers should therefore assess the hazards of the chemicals used, the potential modes for leakage, means for identifying leaks and the risk of exposure of employees. Ideally, work practices should be developed by healthcare facilities so that sterile processing employees know what to do in case of a chemical leak or spill, and how to safely use these chemicals to ensure their own, and patient safety.

  17. Advanced technologies on steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, Kaoru; Nakamura, Yuuki [Mitsubishi Heavy Industry Co., Takasago (Japan); Nakamori, Nobuo; Mizutani, Toshiyuki; Uwagawa, Seiichi; Saito, Itaru [Mitsubishi Heavy Industry Co., Kobe (Japan); Matsuoka, Tsuyoshi [Mitsubishi Heavy Industry Co., Yokohama (Japan)

    1997-12-31

    The thermal-hydraulic tests for a horizontal steam generator of a next-generation PWR (New PWR-21) were performed. The purpose of these tests is to understand the thermal-hydraulic behavior in the secondary side of horizontal steam generator during the plant normal operation. A test was carried out with cross section slice model simulated the straight tube region. In this paper, the results of the test is reported, and the effect of the horizontal steam generator internals on the thermalhydraulic behavior of the secondary side and the circulation characteristics of the secondary side are discussed. (orig.). 3 refs.

  18. Development of a Robust Model-Based Water Level Controller for U-Tube Steam Generator

    Energy Technology Data Exchange (ETDEWEB)

    Basher, A.M.H.

    2001-09-04

    Poor control of steam generator water level of a nuclear power plant may lead to frequent nuclear reactor shutdowns. These shutdowns are more common at low power where the plant exhibits strong non-minimum phase characteristics and flow measurements at low power are unreliable in many instances. There is need to investigate this problem and systematically design a controller for water level regulation. This work is concerned with the study and the design of a suitable controller for a U-Tube Steam Generator (UTSG) of a Pressurized Water Reactor (PWR) which has time varying dynamics. The controller should be suitable for the water level control of UTSG without manual operation from start-up to full load transient condition. Some preliminary simulation results are presented that demonstrate the effectiveness of the proposed controller. The development of the complete control algorithm includes components such as robust output tracking, and adaptively estimating both the system parameters and state variables simultaneously. At the present time all these components are not completed due to time constraints. A robust tracking component of the controller for water level control is developed and its effectiveness on the parameter variations is demonstrated in this study. The results appear encouraging and they are only preliminary. Additional work is warranted to resolve other issues such as robust adaptive estimation.

  19. Steam Ejector’s Size Computation Program Based on Real Steam Model%基于水蒸气真实气体模型的蒸汽喷射器尺寸计算程序

    Institute of Scientific and Technical Information of China (English)

    廖国进; 华枫

    2015-01-01

    Based on Sokolov ejector design theory and combined with real steam properties, the size computation progamme of real steam ejector based on its model were proposed. Compared with the design using perfect fluid, the result shows that using real steam to calculate the ejector’s size makes much difference, however it’s accurate. So it is necessary for us to concern about this problem when designing a ejector.%在索科洛夫喷射泵尺寸设计理论基础上,结合水蒸气真实气体物性,给出了一种应用水蒸气真实气体模型计算喷射器尺寸的计算程序。结果证明,应用水蒸气真实气体模型计算与采用理想流体计算的喷射器尺寸有一定的差别,因而有必要在设计过程中考虑采用水蒸气真实气体模型进行尺寸的计算,提高计算结果的精度。

  20. Biosorptive uptake of arsenic(V) by steam activated carbon from mung bean husk: equilibrium, kinetics, thermodynamics and modeling

    Science.gov (United States)

    Mondal, Sandip; Aikat, Kaustav; Halder, Gopinath

    2017-07-01

    The present investigation emphasizes on the biosorptive removal of toxic pentavalent arsenic from water using steam activated carbon prepared from mung bean husk (SAC-MBH). Characterization of the synthesized sorbent was done using different instrumental techniques, i.e., SEM, BET and point of zero charge. Sorptive uptake of As(V) over steam activated MBH as a function of pH (3-9), agitation speed (40-200 rpm), dosage (50-1000 mg) and temperature (298-313 K) was studied by batch process at arsenic concentration of 2 mg L-1. Lower pH increases the arsenic removal over the pH range of 3-9. Among three adsorption isotherm models examined, Langmuir model was observed to show superior results over Freundlich model. The mean sorption energy (E) estimated by Dubinin-Radushkevich model suggested that the process of adsorption was chemisorption. Thermodynamic parameters confer that the sorption process was spontaneous, exothermic and feasible in nature. The pseudo-second-order rate kinetics of arsenic gave better correlation coefficients as compared to pseudo-first-order kinetics equation. Three process parameters, viz. adsorbent dosage, agitation speed and pH were opted for optimizing As(V) elimination using central composite design matrix of response surface methodology (RSM). The identical design setup was used for artificial neural network (ANN) for comparing its prediction capability with RSM towards As(V) removal. Maximum arsenic removal was observed to be 98.75% at sorbent dosage 0.75 gm L-1, pH 3.0, agitation speed 160 rpm and temperature 308 K. The study concluded that SAC-MBH could be a competent adsorbent for As(V) removal and ANN model was better in arsenic removal predictability results than RSM model.

  1. Dynamic model for predicting growth of Salmonella spp. in ground sterile pork.

    Science.gov (United States)

    Velugoti, Padmanabha Reddy; Bohra, Lalit K; Juneja, Vijay K; Huang, Lihan; Wesseling, Audrey L; Subbiah, Jeyamkondan; Thippareddi, Harshavardhan

    2011-06-01

    A predictive model for Salmonella spp. growth in ground pork was developed and validated using kinetic growth data. Salmonella spp. kinetic growth data in ground pork were collected at several isothermal conditions (between 10 and 45°C) and Baranyi model was fitted to describe the growth at each temperature, separately. The maximum growth rates (μ(max)) estimated from the Baranyi model were modeled as a function of temperature using a modified Ratkowsky equation. To estimate bacterial growth under dynamic temperature conditions, the differential form of the Baranyi model, in combination with the modified Ratkowsky equation for rate constants, was solved numerically using fourth order Runge-Kutta method. The dynamic model was validated using five different dynamic temperature profiles (linear cooling, exponential cooling, linear heating, exponential heating, and sinusoidal). Performance measures, root mean squared error, accuracy factor, and bias factor were used to evaluate the model performance, and were observed to be satisfactory. The dynamic model can estimate the growth of Salmonella spp. in pork within a 0.5 log accuracy under both linear and exponential cooling profiles, although the model may overestimate or underestimate at some data points, which were generallySalmonella spp., since low temperature conditions could alter the cell physiology. To obtain an accurate estimate of Salmonella spp. growth using the models reported in this work, it is suggested that the models be used at temperatures above 7°C, the minimum growth temperature for Salmonella spp. in pork.

  2. Doppler method leak detection for LMFBR steam generators. Pt. 1. Experimental results of bubble detection using small models

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab

    1999-05-01

    To prevent the expansion of the tube damage and to maintain structural integrity in the steam generators (SGs) of fast breeder reactors (FBRs), it is necessary to detect precisely and immediately the leakage of water from heat transfer tubes. Therefore, an active acoustic method was developed. Previous studies have revealed that in practical steam generators the active acoustic method can detect bubbles of 10 l/s within 10 seconds. To prevent the expansion of damage to neighboring tubes, it is necessary to detect smaller leakages of water from the heat transfer tubes. The Doppler method is designed to detect small leakages and to find the source of the leak before damage spreads to neighboring tubes. To evaluate the relationship between the detection sensitivity of the Doppler method and the bubble volume and bubble size, the structural shapes and bubble flow conditions were investigated experimentally, using a small structural model. The results show that the Doppler method can detect the bubbles under bubble flow conditions, and it is sensitive enough to detect small leakages within a short time. The doppler method thus has strong potential for the detection of water leakage in SGs. (author)

  3. Modeling the kinetics of methane conversion in steam reforming process of coke-oven gas based on experimental data

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-yuan; ZHOU Jie-min

    2007-01-01

    Steam-reforming is an effective approach for upgrading methane and hydrocarbon of coke-oven gas into CO and H2, but the kinetic behavior needs more study. We investigated the conversion of methane in coke-oven gas by steam reforming process in an electric tubular flow at 14 kPa with temperature varying from 500℃ to 950℃, and developed a kenetic model for , ignoring the effects of adsorption and diffusion. The optimal dynamic conditions for methane conversion 14 kPa are as follows: the ratio of the amount of water to the amount of methane is from 1.1 to 1.3; the reaction temperature is from 1 223 K to 1 273 K. The methane conversion rate is larger than 95% when the ratio of the amount of water to the amount of methane is 1.2 at a temperature above 1 223 K with the residence time up to 0.75 s.

  4. C. botulinum inactivation kinetics implemented in a computational model of a high-pressure sterilization process.

    Science.gov (United States)

    Juliano, Pablo; Knoerzer, Kai; Fryer, Peter J; Versteeg, Cornelis

    2009-01-01

    High-pressure, high-temperature (HPHT) processing is effective for microbial spore inactivation using mild preheating, followed by rapid volumetric compression heating and cooling on pressure release, enabling much shorter processing times than conventional thermal processing for many food products. A computational thermal fluid dynamic (CTFD) model has been developed to model all processing steps, including the vertical pressure vessel, an internal polymeric carrier, and food packages in an axis-symmetric geometry. Heat transfer and fluid dynamic equations were coupled to four selected kinetic models for the inactivation of C. botulinum; the traditional first-order kinetic model, the Weibull model, an nth-order model, and a combined discrete log-linear nth-order model. The models were solved to compare the resulting microbial inactivation distributions. The initial temperature of the system was set to 90 degrees C and pressure was selected at 600 MPa, holding for 220 s, with a target temperature of 121 degrees C. A representation of the extent of microbial inactivation throughout all processing steps was obtained for each microbial model. Comparison of the models showed that the conventional thermal processing kinetics (not accounting for pressure) required shorter holding times to achieve a 12D reduction of C. botulinum spores than the other models. The temperature distribution inside the vessel resulted in a more uniform inactivation distribution when using a Weibull or an nth-order kinetics model than when using log-linear kinetics. The CTFD platform could illustrate the inactivation extent and uniformity provided by the microbial models. The platform is expected to be useful to evaluate models fitted into new C. botulinum inactivation data at varying conditions of pressure and temperature, as an aid for regulatory filing of the technology as well as in process and equipment design.

  5. Steam Drum Design for Direct Steam Generation

    OpenAIRE

    Willwerth, Lisa; Müller, Svenja; Krüger, Joachim; Succo, Manuel; Feldhoff, Jan Fabian; Tiedemann, Jörg; Pandian, Juvaraj; Krüger, Dirk; Hennecke, Klaus

    2016-01-01

    For the direct steam generation in solar fields, the recirculation concept has been demonstrated in several installations. Water masses in the solar field vary during transient phases, such as passing clouds. The volume of the steam drum can serve as a buffer during such transients by taking in excess water and providing water storage. The saturated steam mass flow to the superheating section or the consumer can be maintained almost constant during short transients; therefore the steam drum p...

  6. Genomic networks of hybrid sterility.

    Directory of Open Access Journals (Sweden)

    Leslie M Turner

    2014-02-01

    Full Text Available Hybrid dysfunction, a common feature of reproductive barriers between species, is often caused by negative epistasis between loci ("Dobzhansky-Muller incompatibilities". The nature and complexity of hybrid incompatibilities remain poorly understood because identifying interacting loci that affect complex phenotypes is difficult. With subspecies in the early stages of speciation, an array of genetic tools, and detailed knowledge of reproductive biology, house mice (Mus musculus provide a model system for dissecting hybrid incompatibilities. Male hybrids between M. musculus subspecies often show reduced fertility. Previous studies identified loci and several X chromosome-autosome interactions that contribute to sterility. To characterize the genetic basis of hybrid sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL. Many trans eQTL cluster into eleven 'hotspots,' seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL-but not cis eQTL-were substantially lower when mapping was restricted to a 'fertile' subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. The integrated mapping approach we employed is

  7. Genomic networks of hybrid sterility.

    Science.gov (United States)

    Turner, Leslie M; White, Michael A; Tautz, Diethard; Payseur, Bret A

    2014-02-01

    Hybrid dysfunction, a common feature of reproductive barriers between species, is often caused by negative epistasis between loci ("Dobzhansky-Muller incompatibilities"). The nature and complexity of hybrid incompatibilities remain poorly understood because identifying interacting loci that affect complex phenotypes is difficult. With subspecies in the early stages of speciation, an array of genetic tools, and detailed knowledge of reproductive biology, house mice (Mus musculus) provide a model system for dissecting hybrid incompatibilities. Male hybrids between M. musculus subspecies often show reduced fertility. Previous studies identified loci and several X chromosome-autosome interactions that contribute to sterility. To characterize the genetic basis of hybrid sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven 'hotspots,' seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL-but not cis eQTL-were substantially lower when mapping was restricted to a 'fertile' subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. The integrated mapping approach we employed is applicable in a broad

  8. Sterile neutrinos at the CNGS

    CERN Document Server

    Donini, A; Meloni, D; Migliozzi, P; Terranova, F

    2007-01-01

    We study the potential of the CNGS beam in constraining the parameter space of a model with three active plus one sterile neutrino such as to explain the LSND results. We perform our analysis using the OPERA detector as a reference (our analysis can be upgraded including a detailed simulation of the ICARUS detector). We point out that the best channel to look for sterile neutrinos at the CNGS beam is numu to nutau, that is precisely the main signal for which both OPERA and ICARUS have been designed. We also analyse numu to nue oscillations. We take advantage of the expected efficiencies and backgrounds for these signals and evaluate the OPERA potential to look for sterile neutrinos. Combination of data from both channels permit to cover almost all of the allowed CP-conserving 3+1 neutrino model parameter space.

  9. Finite element modeling of wall-loss sizing in a steam generator tube using a pulsed eddy current probe

    Science.gov (United States)

    Babbar, V. K.; Lepine, B.; Buck, J.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2015-03-01

    Inspection of steam generator (SG) tubes by conventional eddy current may, in general, involve analysis of indications from volumetric wall loss, cracks, fouling and support-plate degradation; however, it may be difficult to size or quantify effects from support-to-tube gap and tube tilt, especially in the presence of support plates. Pulsed eddy current (PEC) technology is being developed to investigate such complex tube and flaw geometries. The present work employs finite element modeling to investigate the effectiveness of PEC in identifying and sizing the outer diameter wall-loss in SG tubes. The signals analyzed using a modified principal components analysis (PCA) method reveal the potential success of a PEC-PCA combination to produce scores that can be used to size the wall-loss in the presence of support plates. The modeling results are in good agreement with experimental observations.

  10. Finite Element Modeling of Material Fatigue and Cracking Problems for Steam Power System HP Devices Exposed to Thermal Shocks

    Directory of Open Access Journals (Sweden)

    Pawlicki Jakub

    2016-09-01

    Full Text Available The paper presents a detailed analysis of the material damaging process due to low-cycle fatigue and subsequent crack growth under thermal shocks and high pressure. Finite Element Method (FEM model of a high pressure (HP by-pass valve body and a steam turbine rotor shaft (used in a coal power plant is presented. The main damaging factor in both cases is fatigue due to cycles of rapid temperature changes. The crack initiation, occurring at a relatively low number of load cycles, depends on alternating or alternating-incremental changes in plastic strains. The crack propagation is determined by the classic fracture mechanics, based on finite element models and the most dangerous case of brittle fracture. This example shows the adaptation of the structure to work in the ultimate conditions of high pressure, thermal shocks and cracking.

  11. A Shipping Container-Based Sterile Processing Unit for Low Resources Settings.

    Science.gov (United States)

    Boubour, Jean; Jenson, Katherine; Richter, Hannah; Yarbrough, Josiah; Oden, Z Maria; Schuler, Douglas A

    2016-01-01

    Deficiencies in the sterile processing of medical instruments contribute to poor outcomes for patients, such as surgical site infections, longer hospital stays, and deaths. In low resources settings, such as some rural and semi-rural areas and secondary and tertiary cities of developing countries, deficiencies in sterile processing are accentuated due to the lack of access to sterilization equipment, improperly maintained and malfunctioning equipment, lack of power to operate equipment, poor protocols, and inadequate quality control over inventory. Inspired by our sterile processing fieldwork at a district hospital in Sierra Leone in 2013, we built an autonomous, shipping-container-based sterile processing unit to address these deficiencies. The sterile processing unit, dubbed "the sterile box," is a full suite capable of handling instruments from the moment they leave the operating room to the point they are sterile and ready to be reused for the next surgery. The sterile processing unit is self-sufficient in power and water and features an intake for contaminated instruments, decontamination, sterilization via non-electric steam sterilizers, and secure inventory storage. To validate efficacy, we ran tests of decontamination and sterilization performance. Results of 61 trials validate convincingly that our sterile processing unit achieves satisfactory outcomes for decontamination and sterilization and as such holds promise to support healthcare facilities in low resources settings.

  12. A Shipping Container-Based Sterile Processing Unit for Low Resources Settings.

    Directory of Open Access Journals (Sweden)

    Jean Boubour

    Full Text Available Deficiencies in the sterile processing of medical instruments contribute to poor outcomes for patients, such as surgical site infections, longer hospital stays, and deaths. In low resources settings, such as some rural and semi-rural areas and secondary and tertiary cities of developing countries, deficiencies in sterile processing are accentuated due to the lack of access to sterilization equipment, improperly maintained and malfunctioning equipment, lack of power to operate equipment, poor protocols, and inadequate quality control over inventory. Inspired by our sterile processing fieldwork at a district hospital in Sierra Leone in 2013, we built an autonomous, shipping-container-based sterile processing unit to address these deficiencies. The sterile processing unit, dubbed "the sterile box," is a full suite capable of handling instruments from the moment they leave the operating room to the point they are sterile and ready to be reused for the next surgery. The sterile processing unit is self-sufficient in power and water and features an intake for contaminated instruments, decontamination, sterilization via non-electric steam sterilizers, and secure inventory storage. To validate efficacy, we ran tests of decontamination and sterilization performance. Results of 61 trials validate convincingly that our sterile processing unit achieves satisfactory outcomes for decontamination and sterilization and as such holds promise to support healthcare facilities in low resources settings.

  13. Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.L.; Zhou, W.R.; Wu, Y.H.; Cheng, Y. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); State Key Laboratory for Turbulence and Complex System, College of Engineering, Peking University, Beijing 100871 (China); Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2013-10-15

    The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process.

  14. Study of connected system of automatic control of load and operation efficiency of a steam boiler with extremal controller on a simulation model

    Science.gov (United States)

    Sabanin, V. R.; Starostin, A. A.; Repin, A. I.; Popov, A. I.

    2017-02-01

    The problems of operation effectiveness increase of steam boilers are considered. To maintain the optimum fuel combustion modes, it is proposed to use an extremal controller (EC) determining the value of airflow rate, at which the boiler generating the desired amount of heat will consume a minimum amount of fuel. EC sets the determined value of airflow rate to airflow rate controller (ARC). The test results of numerical simulation dynamic nonlinear model of steam boiler with the connected system of automatic control of load and combustion efficiency using EC are presented. The model is created in the Simulink modeling package of MATLAB software and can be used to optimize the combustion modes. Based on the modeling results, the conclusion was drawn about the possibility in principle of simultaneously boiler load control and optimizing by EC the combustion modes when changing the fuel combustion heat and the boiler characteristics and its operating mode. It is shown that it is possible to automatically control the operation efficiency of steam boilers when using EC without applying the standard flue gas analyzers. The article considers the numerical simulation dynamic model of steam boiler with the schemes of control of fuel consumption and airflow rate, the steam pressure and EC; the purpose of using EC in the scheme with linear controllers and the requirements to the quality of its operation; the results of operation of boiler control schemes without EC with estimation of influence of roughness of thermal mode maps on the nature of static and dynamic connection of the control units of fuel consumption and airflow rate; the phase trajectories and the diagrams of transient processes occurring in the control scheme with EC with stepped changing the fuel quality and boiler characteristics; analysis of modeling results and prospects for using EC in the control schemes of boilers.

  15. Sterile neutrino constraints from cosmology

    DEFF Research Database (Denmark)

    Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.

    2012-01-01

    The presence of light particles beyond the standard model's three neutrino species can profoundly impact the physics of decoupling and primordial nucleosynthesis. I review the observational signatures of extra light species, present constraints from recent data, and discuss the implications...... of possible sterile neutrinos with O(eV)-masses for cosmology....

  16. Clomiphene citrate reduces procarbazine-induced sterility in a rat model.

    Science.gov (United States)

    Weissenberg, R; Lahav, M; Raanani, P; Singer, R; Regev, A; Sagiv, M; Giler, S; Theodor, E

    1995-01-01

    Chemotherapy with the cytotoxic drug procarbazine (PCB) causes permanent infertility in most male patients. Since many patients treated with this cytotoxic drug are of reproductive age, it is important to develop a method to protect spermatogenesis and fertility. It has been hypothesised that 'spermatogenic arrest' by pharmacological intervention may render the testes less susceptible to the effects of chemotherapy. The present study investigated whether recovery of fertility in a male rat model could be achieved by suppression of spermatogenesis with high doses of clomiphene citrate (CC) prior to PCB administration. It was demonstrated that young male rats treated with a combination of CC and PCB partially recovered spermatogenesis and achieved almost normal fertility. In contrast, animals treated with PCB alone exhibited abnormal spermatogenesis and remained infertile.

  17. Simulation of biomass-steam gasification in fluidized bed reactors: Model setup, comparisons and preliminary predictions.

    Science.gov (United States)

    Yan, Linbo; Lim, C Jim; Yue, Guangxi; He, Boshu; Grace, John R

    2016-12-01

    A user-defined solver integrating the solid-gas surface reactions and the multi-phase particle-in-cell (MP-PIC) approach is built based on the OpenFOAM software. The solver is tested against experiments. Then, biomass-steam gasification in a dual fluidized bed (DFB) gasifier is preliminarily predicted. It is found that the predictions agree well with the experimental results. The bed material circulation loop in the DFB can form automatically and the bed height is about 1m. The voidage gradually increases along the height of the bed zone in the bubbling fluidized bed (BFB) of the DFB. The U-bend and cyclone can separate the syngas in the BFB and the flue gas in the circulating fluidized bed. The concentration of the gasification products is relatively higher in the conical transition section, and the dry and nitrogen-free syngas at the BFB outlet is predicted to be composed of 55% H2, 20% CO, 20% CO2 and 5% CH4.

  18. Long-term sterility of orthodontic-surgical appliances.

    Science.gov (United States)

    Brusca, María I; Nastri, Natalia; Mosca, Christian O; Nastri, María L; Rosa, Alcira C

    2004-01-01

    The aim of this study was to evaluate the long-term sterility of new dental appliances according to the non rigid wrapping employed and assess the effectiveness of sterilization in a steam autoclave at 134 degrees for 20 minutes using physical, chemical, and biological indicators. All the experimental (E) samples and the control samples (C) were assigned to one of three groups according to the type of packaging: paper bag (E1), paper/plastic pouch (E2), nylon tubing bag (E3). Each bag contained standardized orthodontic wires and brackets and sterility indicators. The samples were evaluated at the following experimental times: immediately, and 6, 12, 24 and 30 months post-sterilization. The samples were analyzed under aerobic and anaerobic conditions in keeping with the protocol currently in use at the Department of Microbiology, School of Dentistry, University of Buenos Aires. The group of control, non-sterilized samples (C1, C2, C3) were analyzed prior to the onset of the study, and were found to be contaminated. None of the sterilized samples in any of the three experimental groups evidenced contamination at any of the experimental times. The results showed that, under the present conditions, the packages and orthodontic appliances remained sterile for 30 months. These results show the importance of controlling sterility and the storage conditions over time for all the orthodontic/surgical appliances used in invasive treatments.

  19. The challenges of heat sterilization of peritoneal dialysis solutions: is there an alternative?

    Science.gov (United States)

    Hanrahan, Conor T; Himmele, Rainer; Diaz-Buxo, Jose A

    2012-01-01

    Peritoneal dialysis (PD) solutions are currently sterilized in an autoclave using high-temperature saturated steam. Although thermal methods are an effective means of sterilization, the heating of PD solutions results in the formation of toxic glucose degradation products (GDPs). Here, we review basic concepts in the sterilization of PD solutions and discuss possible alternatives to steam sterilization, including filtration, ohmic heat, ionizing radiation, and pulsed ultraviolet light. Although the latter methods have several advantages, many also have prohibitive limitations or have not been adequately studied for use on PD solutions. Thus, in the absence of suitable alternatives, conventional heat sterilization, in combination with low-GDP manufacturing practices, remains the best option at the present time.

  20. Relationship between lumen diameter and length sterilized in the 125L ozone sterilizer.

    Science.gov (United States)

    Dufresne, Sylvie; Leblond, Hélène; Chaunet, Marc

    2008-05-01

    A safe alternative to ethylene oxide for reprocessing heat-sensitive lumen medical devices, such as endoscopes, is needed. The effectiveness of a new, safe, low-cost, and environmentally friendly low-temperature sterilization process using ozone was assessed. Rigid lumen devices were used to assess the maximum length of lumens of different internal diameters that can be sterilized in the TSO(3) model 125L ozone sterilizer. Two inoculation techniques were used. An inoculated wire was placed inside lumens with internal diameters of 0.8 mm and larger, whereas lumens with an internal diameter of 0.5 mm were inoculated directly. Lumens with internal diameters of 0.5 mm, 1 mm, 2 mm, 3 mm, and 4 mm with lengths varying between 45 and 70 cm can be sterilized with ozone. Calculation of the log reduction value for each size demonstrated the achievement of a sterility assurance level of 10(-6). Experimental results demonstrated a linear relationship (with r(2) = 0.990) between the length of lumen that can be sterilized in the 125L ozone sterilizer and its internal diameter. Effective sterilization of an ACMI ureteroscope that is more challenging in terms of sterilant penetration in a small lumen (0.8 mm) compared with the stated lumen claims confirms that the relationship can conservatively be used to predict the length of a lumen device that can be sterilized in the 125L ozone sterilizer for a given diameter. Intermediate sizes of lumen devices that can be sterilized in the 125L ozone sterilizer can be interpolated from the linear relationship between diameter and length found in the present study.

  1. Suppression of Pest Lepidoptera by Releasing Partially Sterile Males

    Science.gov (United States)

    Knipling. E. F.

    1970-01-01

    Uses population growth models to calculate the theoretical suppression of reproduction achieved by releasing irradiated male moths carrying genetic sterility factors. Shows that releasing partially sterile males should be more effective than releasing fully sterile males. Discusses the costs and advantages of applying this approach to the control…

  2. Differential geometry based model for eddy current inspection of U-bend sections in steam generator tubes

    Science.gov (United States)

    Mukherjee, Saptarshi; Rosell, Anders; Udpa, Lalita; Udpa, Satish; Tamburrino, Antonello

    2017-02-01

    The modeling of U-Bend segment in steam generator tubes for predicting eddy current probe signals from cracks, wear and pitting in this region poses challenges and is non-trivial. Meshing the geometry in the cartesian coordinate system might require a large number of elements to model the U-bend region. Also, since the lift-off distance between the probe and tube wall is usually very small, a very fine mesh is required near the probe region to accurately describe the eddy current field. This paper presents a U-bend model using differential geometry principles that exploit the result that Maxwell's equations are covariant with respect to changes of coordinates and independent of metrics. The equations remain unaltered in their form, regardless of the choice of the coordinates system, provided the field quantities are represented in the proper covariant and contravariant form. The complex shapes are mapped into simple straight sections, while small lift-off is mapped to larger values, thus reducing the intrinsic dimension of the mesh and stiffness matrix. In this contribution, the numerical implementation of the above approach will be discussed with regard to field and current distributions within the U-bend tube wall. For the sake of simplicity, a two dimensional test case will be considered. The approach is evaluated in terms of efficiency and accuracy by comparing the results with that obtained using a conventional FE model in cartesian coordinates.

  3. Sterile Neutrino Search with MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Devan, Alena V. [College of William and Mary, Williamsburg, VA (United States)

    2015-08-01

    MINOS, Main Injector Neutrino Oscillation Search, is a long-baseline neutrino oscillation experiment in the NuMI muon neutrino beam at the Fermi National Accelerator Laboratory in Batavia, IL. It consists of two detectors, a near detector positioned 1 km from the source of the beam and a far detector 734 km away in Minnesota. MINOS is primarily designed to observe muon neutrino disappearance resulting from three flavor oscillations. The Standard Model of Particle Physics predicts that neutrinos oscillate between three active flavors as they propagate through space. This means that a muon-type neutrino has a certain probability to later interact as a different type of neutrino. In the standard picture, the neutrino oscillation probabilities depend only on three neutrino flavors and two mass splittings, Δm2. An anomaly was observed by the LSND and MiniBooNE experiments that suggests the existence of a fourth, sterile neutrino flavor that does not interact through any of the known Standard Model interactions. Oscillations into a theoretical sterile flavor may be observed by a deficit in neutral current interactions in the MINOS detectors. A distortion in the charged current energy spectrum might also be visible if oscillations into the sterile flavor are driven by a large mass-squared difference, ms2 ~ 1 eV2. The results of the 2013 sterile neutrino search are presented here.

  4. Research on Mechanisms of Steam Breakthrough and Profile Control Design for Steam Soaking Well

    Institute of Scientific and Technical Information of China (English)

    Liu Huiqing; Zhang Hongling; Wang Shulin; Wang Han; Bao Shucheng

    2006-01-01

    Scaled physical model tests for steam breakthrough were conducted based on the analysis of mechanisms and influence factors of steam breakthrough. Physical simulation results showed that at the initial steam breakthrough, preferential flow channels were formed in narrow sand packs and most residual oil left in these channels was immobile. This shortened the steam breakthrough time of follow-up steam flooding and decreased the increment of oil recovery efficiency. Steam breakthrough occurred easily for a smaller producer-injector spacing, and a bigger difference in physical properties between fluids and rock. Steam breakthrough is more likely to occur at a larger formation permeability (k), greater steam displacement velocity (u) and smaller producer-injector spacing (L). Steam breakthrough time is a function of the parameter group (uk/L), i.e. tb=3.2151 (uk/L) -0.5142. A non piston-like displacement model was built based on steam breakthrough observation for a steam stimulated well in the Jinglou Oilfield, Henan Oilfield Company. The steam volume swept in different directions could be obtained from inter-well permeability capacity and breakthrough angle, and the steam swept pore volume (SSPV) was also determined. Numerical simulation showed that steam sweep efficiency reached its peak value when a slug of profile control agent (slug size 10%-15% SSPV) was set at one half of the inter-well spacing. Field test with 12.5% SSPV of profile control agents in the Jinglou Oilfield achieved success in sealing breakthrough channels and good production performance of adjacent producers.

  5. Catalytic Steam Reforming of Toluene as a Model Compound of Biomass Gasification Tar Using Ni-CeO2/SBA-15 Catalysts

    Directory of Open Access Journals (Sweden)

    Erik Dahlquist

    2013-07-01

    Full Text Available Nickel supported on SBA-15 doped with CeO2 catalysts (Ni-CeO2/SBA-15 was prepared, and used for steam reforming of toluene which was selected as a model compound of biomass gasification tar. A fixed-bed lab-scale set was designed and employed to evaluate the catalytic performances of the Ni-CeO2/SBA-15 catalysts. Experiments were performed to reveal the effects of several factors on the toluene conversion and product gas composition, including the reaction temperature, steam/carbon (S/C ratio, and CeO2 loading content. Moreover, the catalysts were subjected to analysis of their carbon contents after the steam reforming experiments, as well as to test the catalytic stability over a long experimental period. The results indicated that the Ni-CeO2/SBA-15 catalysts exhibited promising capabilities on the toluene conversion, anti-coke deposition and catalytic stability. The toluene conversion reached as high as 98.9% at steam reforming temperature of 850 °C and S/C ratio of 3 using the Ni-CeO2(3wt%/SBA-15 catalyst. Negligible coke formation was detected on the used catalyst. The gaseous products mainly consisted of H2 and CO, together with a little CO2 and CH4.

  6. Sterile neutrinos at the CNGS

    Science.gov (United States)

    Donini, Andrea; Maltoni, Michele; Meloni, Davide; Migliozzi, Pasquale; Terranova, Francesco

    2007-12-01

    We study the potential of the CNGS beam in constraining the parameter space of a model with one sterile neutrino separated from three active ones by an Script O(eV2) mass-squared difference, Δ mSBL2. We perform our analysis using the OPERA detector as a reference (our analysis can be upgraded including a detailed simulation of the ICARUS detector). We point out that the channel with the largest potential to constrain the sterile neutrino parameter space at the CNGS beam is νμ→ντ. The reason for that is twofold: first, the active-sterile mixing angle that governs this oscillation is the less constrained by present experiments; second, this is the signal for which both OPERA and ICARUS have been designed, and thus benefits from an extremely low background. In our analysis we also took into account νμ→νe oscillations. We find that the CNGS potential to look for sterile neutrinos is limited with nominal intensity of the beam, but it is significantly enhanced with a factor 2 to 10 increase in the neutrino flux. Data from both channels allow us, in this case, to constrain further the four-neutrino model parameter space. Our results hold for any value of Δ mSBL2gtrsim0.1 eV2, i.e. when oscillations driven by this mass-squared difference are averaged. We have also checked that the bound on θ13 that can be put at the CNGS is not affected by the possible existence of sterile neutrinos.

  7. Steam Digest 2001

    Energy Technology Data Exchange (ETDEWEB)

    2002-01-01

    Steam Digest 2001 chronicles BestPractices Program's contributions to the industrial trade press for 2001, and presents articles that cover technical, financial and managerial aspects of steam optimization.

  8. Reionisation in sterile neutrino cosmologies

    CERN Document Server

    Bose, Sownak; Jun, Hou; Lacey, Cedric G; Lovell, Mark R

    2016-01-01

    We investigate the process of reionisation in a model in which the dark matter is a warm elementary particle such as a sterile neutrino. We focus on models that are consistent with the dark matter decay interpretation of the recently detected line at 3.5 keV in the X-ray spectra of galaxies and clusters. In warm dark matter models the primordial spectrum of density perturbations has a cut-off on the scale of dwarf galaxies. Structure formation therefore begins later than in the standard cold dark matter (CDM) model and very few objects form below the cut-off mass scale. To calculate the number of ionising photons, we use the Durham semi-analytic model of galaxy formation, GALFORM. We find that even the most extreme 7 keV sterile neutrino we consider is able to reionise the Universe early enough to be compatible with the bounds on the epoch of reionisation from Planck. This, perhaps surprising, result arises from the rapid build-up of high redshift galaxies in the sterile neutrino models which is also reflecte...

  9. Phenology, sterility and inheritance of two environment genic male sterile (EGMS) lines for hybrid rice

    NARCIS (Netherlands)

    El-Namaky, R.; Oort, van P.A.J.

    2017-01-01

    Background: There is still limited quantitative understanding of how environmental factors affect sterility of Environment-conditioned genic male sterility (EGMS) lines. A model was developed for this purpose and tested based on experimental data from Ndiaye (Senegal) in 2013-2015. For the two

  10. Phenology, sterility and inheritance of two environment genic male sterile (EGMS) lines for hybrid rice

    NARCIS (Netherlands)

    El-Namaky, R.; Oort, van P.A.J.

    2017-01-01

    Background: There is still limited quantitative understanding of how environmental factors affect sterility of Environment-conditioned genic male sterility (EGMS) lines. A model was developed for this purpose and tested based on experimental data from Ndiaye (Senegal) in 2013-2015. For the two EG

  11. Steam Digest Volume IV

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-07-01

    This edition of the Steam Digest is a compendium of 2003 articles on the technical and financial benefits of steam efficiency, presented by the stakeholders of the U.S. Department of Energy's BestPractices Steam effort.

  12. The Invisibility of Steam

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2014-01-01

    Almost everyone "knows" that steam is visible. After all, one can see the cloud of white issuing from the spout of a boiling tea kettle. In reality, steam is the gaseous phase of water and is invisible. What you see is light scattered from the tiny droplets of water that are the result of the condensation of the steam as its temperature…

  13. [Sterilization and eugenics].

    Science.gov (United States)

    Shasha, Shaul M

    2011-04-01

    The term "eugenics" was coined by Francis Galton in 1883 and was defined as the science of the improvement of the human race by better breeding. "Positive eugenics" referred to methods of encouraging the "most fit" to reproduce more often, while "negative eugenics" was related to ways of discouraging or preventing the "less fit" from reproducing by birth control and sterilization. Many western countries adopted eugenics programs including Britain, Canada, Norway, Australia, Switzerland and others. In Sweden more then 62,000 "unfits" were forcibly sterilized. Many states in the U.S.A. had adopted marriage laws with eugenics criteria including forced sterilization. Approximately 64,000 individuals were sterilized. Eugenics considerations also lay behind the adoption of the Immigration Restriction Act of 1924. The Largest plan on eugenics was adopted by the Nazi regime in Germany. Hundreds of thousands of people, who were viewed as being "unfit", were forcibly sterilized by different methods: Surgical sterilization or castration with severe complications and high mortality rates. X-ray irradiation. The method was suggested by Brack, and tested by Schuman using prisoners in Block No. 10 in Auschwitz and Birkenau. Experiments were also performed by Brack on prisoners using the "window method". "Klauberg method"--injection of irritating materials into the uterus. Experiments were conducted using the plant Caladium Seguinum which was believed to have sterilization and castration properties.

  14. Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure

    CERN Document Server

    Harada, Akira; Yoshida, Naoki

    2016-01-01

    We perform a set of cosmological simulations of structure formation in a mixed dark matter (MDM) model. Our model is motivated by the recently identified $3.5\\,{\\rm keV}$ X-ray line that can be explained by the decay of non-resonantly produced sterile neutrinos, if they account for $10$-$60\\%$ of the dark matter in the Universe. The non-resonantly produced sterile neutrino has sizable free-streaming length and hence behaves effectively as warm dark matter (WDM). Assuming the rest of dark matter is composed of some stable and cold particles, i.e. cold dark matter (CDM), we follow the coevolution of the CDM and WDM density perturbations. Specifically, we consider the models with the warm component fraction of $r_{\\rm warm}=0.25$ and $0.5$. Our MDM model predicts that the comoving Jeans length at the matter-radiation equality is close to that of the thermally produced warm dark matter model with particle mass $m_{\\rm WDM}=2.4\\,{\\rm keV}$ but that the suppression in the fluctuation power spectrum is weaker. We pe...

  15. A novel model to assess the efficacy of steam surface pasteurization of cooked surimi gels inoculated with realistic levels of Listeria innocua.

    Science.gov (United States)

    Skåra, Torstein; Valdramidis, Vasilis P; Rosnes, Jan Thomas; Noriega, Estefanía; Van Impe, Jan F M

    2014-12-01

    Steam surface pasteurization is a promising decontamination technology for reducing pathogenic bacteria in different stages of food production. The effect of the artificial inoculation type and initial microbial load, however, has not been thoroughly assessed in the context of inactivation studies. In order to optimize the efficacy of the technology, the aim of this study was to design and validate a model system for steam surface pasteurization, assessing different inoculation methods and realistic microbial levels. More specifically, the response of Listeria innocua, a surrogate organism of Listeria monocytogenes, on a model fish product, and the effect of different inoculation levels following treatments with a steam surface pasteurization system was investigated. The variation in the resulting inoculation level on the samples was too large (77%) for the contact inoculation procedure to be further considered. In contrast, the variation of a drop inoculation procedure was 17%. Inoculation with high levels showed a rapid 1-2 log decrease after 3-5 s, and then no further inactivation beyond 20 s. A low level inoculation study was performed by analysing the treated samples using a novel contact plating approach, which can be performed without sample homogenization and dilution. Using logistic regression, results from this method were used to model the binary responses of Listeria on surfaces with realistic inoculation levels. According to this model, a treatment time of 23 s will result in a 1 log reduction (for P = 0.1).

  16. Thiamine losses during storage of pasteurised and sterilized model systems of minced chicken meat with addition of fresh and oxidized fat, and antioxidants

    Directory of Open Access Journals (Sweden)

    Krystyna Szymandera-Buszka

    2014-12-01

    Full Text Available Background. The aim of the study was to determine the effect of pasteurisation and sterilization of model systems of minced chicken meat in the presence of low or high-oxidised pork lard, soy and sunfl ower oil, as well as casein hydrolysate and rosemary extract, on losses of thiamine in model systems. Material and methods. In the samples, the thiamine content was analysed periodically by thiochromium method, as well as rate of lipid oxidation based on measurement of peroxide value (PV by iodometric method and p-anisidine value (AV by spectrophotometric method. Results. It was observed that the thiamine losses in model systems of minced chicken after pasteurisation (61-71% were higher than after sterilization (57-67%. Introduction of high-oxidised fat increased the total thiamine losses both during thermal processing and storage of meat samples (to 23%. A strong relationship was established between thiamine losses and rate of fat oxidation. The lowest total thiamine losses were observed in the samples with low-oxidised pork lard. Antioxidant addition (rosemary extract or casein hydrolysate into meat samples limited the thiamine losses. However, the effect depended on oxidation of fat that was mixed with meat. In the samples with low-oxidised fat, higher protective effect was found for rosemary extract (7-11%. In the samples with high-oxidised fat, casein hydrolysate was superior to rosemary extract (14%. Conclusions. In order to increase the stability of thiamine in pasteurized or sterilized meat products with fats, the infl uence of fat type and its oxidative stability should be taken under consideration. Moreover, the addition of rosemary extract or casein hydrolysate has impact on the thiamine losses since it slows down lipid oxidation to a signifi cant extent.

  17. Steam reforming of biomass gasification tar using benzene as a model compound over various Ni supported metal oxide catalysts.

    Science.gov (United States)

    Park, Hyun Ju; Park, Sung Hoon; Sohn, Jung Min; Park, Junhong; Jeon, Jong-Ki; Kim, Seung-Soo; Park, Young-Kwon

    2010-01-01

    The steam reforming of benzene as a model compound of biomass gasification tar was carried out over various Ni/metal oxide catalysts. The effects of the support, temperature, Ni-precursor, Ni loading and reaction time were examined, and their catalytic performance was compared with that of a commercial Ni catalyst. Among the Ni/metal oxide catalysts used, 15 wt% Ni/CeO(2)(75%)-ZrO(2)(25%) showed the highest catalytic performance owing to its greater redox characteristics and increased surface area, irrespective of the reaction temperature. The catalytic activity of 15 wt% Ni/CeO(2)(75%)-ZrO(2)(25%) was higher than that of the commercial Ni catalyst. Moreover, the catalyst activity was retained due to its excellent resistance to coke deposition even after 5h. The Ni-precursor played a critical role in the catalytic activity. With the exception of nickel nitrate, all the Ni-precursors (chloride and sulfate) caused deactivation of the catalyst.

  18. Signatures of extra dimensional sterile neutrinos

    Directory of Open Access Journals (Sweden)

    Werner Rodejohann

    2014-10-01

    Full Text Available We study a large extra dimension model with active and sterile Dirac neutrinos. The sterile neutrino masses stem from compactification of an extra dimension with radius R and are chosen to have masses around eV or keV, in order to explain short-baseline anomalies or act as warm dark matter candidates. We study the effect of the sterile neutrino Kaluza–Klein tower in short-baseline oscillation experiments and in the beta spectrum as measurable by KATRIN-like experiments.

  19. Signatures of extra dimensional sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Rodejohann, Werner, E-mail: werner.rodejohann@mpi-hd.mpg.de; Zhang, He, E-mail: he.zhang@mpi-hd.mpg.de

    2014-10-07

    We study a large extra dimension model with active and sterile Dirac neutrinos. The sterile neutrino masses stem from compactification of an extra dimension with radius R and are chosen to have masses around eV or keV, in order to explain short-baseline anomalies or act as warm dark matter candidates. We study the effect of the sterile neutrino Kaluza–Klein tower in short-baseline oscillation experiments and in the beta spectrum as measurable by KATRIN-like experiments.

  20. Review of Physical Metallurgy of Creep Steel for the Design of Modern Steam Power Plants – Fundamental Theories and Parametric Models

    Directory of Open Access Journals (Sweden)

    V. C. Igwemezie

    2015-12-01

    Full Text Available The need for electricity supply has increased tremendously in recent time thereby necessitating an improvement in the efficiency of steam power plant. A greater efficiency leads to a saving in fuel for a given electricity output with a consequential reduction in the rate at which damage is done to the earth’s environment. This paper looks at the physical metallurgy theories and parametric models that have been the bases in the design of steel for power plant applications.

  1. Modelling and simulation of a circulating fluidized-bed steam generator as an aid for process analysis and automation. Modellierung und Simulation eines ZWS-Dampferzeugers als Hilfsmittel zur Prozessanalyse und -automatisierung

    Energy Technology Data Exchange (ETDEWEB)

    Karbach, A.; Peters, R.; Schaub, G. (Lurgi GmbH, Frankfurt am Main (Germany, F.R.))

    1990-04-01

    This book deals with the development and application of mathematical model for the simulation of a steam generator with fluidized-bed combustion (coal combustion in the circulating fluidized-bed combustion). (orig./EF).

  2. Gas-Cooled Reactor Programs annual progress report for period ending December 31, 1973. [HTGR fuel reprocessing, fuel fabrication, fuel irradiation, core materials, and fission product distribution; GCFR fuel irradiation and steam generator modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kasten, P.R.; Coobs, J.H.; Lotts, A.L.

    1976-04-01

    Progress is summarized in studies relating to HTGR fuel reprocessing, refabrication, and recycle; HTGR fuel materials development and performance testing; HTGR PCRV development; HTGR materials investigations; HTGR fuel chemistry; HTGR safety studies; and GCFR irradiation experiments and steam generator modeling.

  3. Steam pretreatment for coal liquefaction

    Science.gov (United States)

    Ivanenko, Olga

    The objectives of this work are to test the application of steam pretreatment to direct coal liquefaction, to investigate the reaction of model compounds with water, and to explore the use of zeolites in these processes. Previous work demonstrated the effectiveness of steam pretreatment in a subsequent flash pyrolysis. Apparently, subcritical steam ruptures nearly all of the ether cross links, leaving a partially depolymerized structure. It was postulated that very rapid heating of the pretreated coal to liquefaction conditions would be required to preserve the effects of such treatment. Accordingly, a method was adopted in which coal slurry is injected into a hot autoclave containing solvent. Since oxygen is capable of destroying the pretreatment effect, precautions were taken for its rigorous exclusion. Tests were conducted with Illinois No. 6 coal steam treated at 340sp°C, 750 psia for 15 minutes. Both raw and pretreated samples were liquified in deoxygenated tetralin at high severity (400sp°C, 30 min.) and low severity (a: 350sp°C, 30 min., and b: 385sp°C, 15 min.) conditions under 1500 psia hydrogen. Substantial improvement in liquid product quality was obtained and the need for rapid heating and oxygen exclusion demonstrated. Under low severity conditions, the oil yield was more than doubled, going from 12.5 to 29 wt%. Also chemistry of the pretreatment process was studied using aromatic ethers as model compounds. alpha-Benzylnaphthyl ether (alpha-BNE), alpha-naphthylmethyl phenyl (alpha-NMPE), and 9-phenoxyphenanthrene were exposed to steam and inert gas at pretreatment conditions and in some cases to liquid water at 315sp°C. alpha-BNE and alpha-NMPE showed little difference in conversion in inert gas and in steam. Hence, these compounds are poor models for coal in steam pretreatment. Thermally stable 9-phenoxyphenanthrene, however, was completely converted in one hour by liquid water at 315sp°C. At pretreatment conditions mostly rearranged starting

  4. Sterilization by Laparoscopy

    Science.gov (United States)

    ... If pregnancy does occur, the risk of an ectopic pregnancy is higher than in women who did not ... pregnant. Also, the risk of problems, such as ectopic pregnancy, is increased. What are some alternatives to sterilization? ...

  5. Modeling and simulation of biomass air-steam gasification in a fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    By considering the features of fluidized-bed reactors and the kinetic mechanism of biomass gasification,a steady-state,isothermal,one-dimensional and twophase mathematical model of biomass gasification kinetics in bubbling fluidized beds was developed.The model assumes the existence of two phases - a bubble and an emulsion phase - with chemical reactions occurring in both phases.The axial gas dispersion in the two phases is accounted for and the pyrolysis of biomass is taken to be instantaneous.The char and gas species CO,CO2,H2,H2O,CH4 and 8 chemical reactions are included in the model.The mathematical model belongs to a typical boundary value problem of ordinary differential equations and its solution is obtained by a Matlab program.Utilizing wood powder as the feedstock,the calculated data show satisfactory agreement with experimental results and proves the effectiveness and reliability of the model.

  6. Sterile neutrinos as dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, S. [Fermi National Accelerator Lab., Batavia, IL (United States); Widrow, L.M. [Queen`s Univ., Kingston, ON (Canada). Dept. of Physics]|[Toronto Univ., ON (Canada). Canadian Inst. for Theoretical Astrophysics

    1993-03-01

    The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed or sterile neutrinos. This model has been studied extensively in the context of the hot dark matter scenario. We reexamine this model and find that hot, warm, and cold dark matter are all possibilities. We focus on the case where sterile neutrinos are the dark matter. Since their only direct coupling is to left-handed or active neutrinos, the most efficient production mechanism is via neutrino oscillations. If the production rate is always less than the expansion rate, then these neutrinos will never be in thermal equilibrium. However, they may still play a significant role in the dynamics of the Universe and possibly provide the missing mass necessary for closure. We consider a single generation of neutrino fields ({nu}{sub L}, {nu}{sub R}) with a Dirac mass, {mu}, and a Majorana mass for the right-handed components only, M. For M {much_gt} {mu} we show that the number density of sterile neutrinos is proportional to {mu}{sup 2}/M so that the energy density today is independent of M. However M is crucial in determining the large scale structure of the Universe. In particular, M {approx_equal} 0.1--1.0 key leads to warm dark matter and a structure formation scenario that may have some advantages over both the standard hot and cold dark matter scenarios.

  7. Analysis of experimental characteristics of multistage steam-jet electors of steam turbines

    Science.gov (United States)

    Aronson, K. E.; Ryabchikov, A. Yu.; Brodov, Yu. M.; Brezgin, D. V.; Zhelonkin, N. V.; Murmanskii, I. B.

    2017-02-01

    A series of questions for specification of physical gas dynamics model in flow range of steam-jet unit and ejector computation methodology, as well as functioning peculiarities of intercoolers, was formulated based on analysis of experimental characteristics of multistage team-jet steam turbines. It was established that coefficient defining position of critical cross-section of injected flow depends on characteristics of the "sound tube" zone. Speed of injected flow within this tube may exceed that of sound, and pressure jumps in work-steam decrease at the same time. Characteristics of the "sound tube" define optimal axial sizes of the ejector. According to measurement results, the part of steam condensing in the first-stage coolant constitutes 70-80% of steam amount supplied into coolant and is almost independent of air content in steam. Coolant efficiency depends on steam pressure defined by operation of steam-jet unit of ejector of the next stage after coolant of steam-jet stage, temperature, and condensing water flow. As a rule, steam entering content of steam-air mixture supplied to coolant is overheated with respect to saturation temperature of steam in the mixture. This should be taken into account during coolant computation. Long-term operation causes changes in roughness of walls of the ejector's mixing chamber. The influence of change of wall roughness on ejector characteristic is similar to the influence of reverse pressure of the steam-jet stage. Until some roughness value, injection coefficient of the ejector stage operating in superlimiting regime hardly changed. After reaching critical roughness, the ejector switches to prelimiting operating regime.

  8. Characterization of chemical-induced sterile inflammation in vitro: application of the model compound ketoconazole in a human hepatic co-culture system.

    Science.gov (United States)

    Wewering, Franziska; Jouy, Florent; Wissenbach, Dirk K; Gebauer, Scarlett; Blüher, Matthias; Gebhardt, Rolf; Pirow, Ralph; von Bergen, Martin; Kalkhof, Stefan; Luch, Andreas; Zellmer, Sebastian

    2017-02-01

    Liver injury as a result of a sterile inflammation is closely linked to the activation of immune cells, including macrophages, by damaged hepatocytes. This interaction between immune cells and hepatocytes is as yet not considered in any of the in vitro test systems applied during the generation of new drugs. Here, we established and characterized a novel in vitro co-culture model with two human cell lines, HepG2 and differentiated THP-1. Ketoconazole, an antifungal drug known for its hepatotoxicity, was used as a model compound in the testing of the co-culture. Single cultures of HepG2 and THP-1 cells were studied as controls. Different metabolism patterns of ketoconazole were observed for the single and co-culture incubations as well as for the different cell types. The main metabolite N-deacetyl ketoconazole was found in cell pellets, but not in supernatants of cell cultures. Global proteome analysis showed that the NRF2-mediated stress response and the CXCL8 (IL-8) pathway were induced by ketoconazole treatment under co-culture conditions. The upregulation and ketoconazole-induced secretion of several pro-inflammatory cytokines, including CXCL8, TNF-α and CCL3, was observed in the co-culture system only, but not in single cell cultures. Taking together, we provide evidence that the co-culture model applied might be suitable to serve as tool for the prediction of chemical-induced sterile inflammation in liver tissue in vivo.

  9. Auditing radiation sterilization facilities

    Science.gov (United States)

    Beck, Jeffrey A.

    The diversity of radiation sterilization systems available today places renewed emphasis on the need for thorough Quality Assurance audits of these facilities. Evaluating compliance with Good Manufacturing Practices is an obvious requirement, but an effective audit must also evaluate installation and performance qualification programs (validation_, and process control and monitoring procedures in detail. The present paper describes general standards that radiation sterilization operations should meet in each of these key areas, and provides basic guidance for conducting QA audits of these facilities.

  10. Computer models of steam pipeline components in the evaluation of their local strength

    OpenAIRE

    J. Okrajni; W. Essler

    2010-01-01

    Purpose: The paper discusses the issue of modelling the heating and cooling processes of T-pipes in a power plant pipeline in the start-up conditions of a boiler. The main purpose of this work is the description of the mechanical behaviour of power plant components working under mechanical and thermal loading and validation of the computer modelling methods.Design/methodology/approach: The FEM modelling has been used to describe the local stress-strain behaviour of the chosen component.Findin...

  11. Sterile neutrinos facing kaon physics experiments

    Science.gov (United States)

    Abada, A.; Bečirević, D.; Sumensari, O.; Weiland, C.; Funchal, R. Zukanovich

    2017-04-01

    We discuss weak kaon decays in a scenario in which the Standard Model is extended by massive sterile fermions. After revisiting the analytical expressions for leptonic and semileptonic decays we derive the expressions for decay rates with two neutrinos in the final state. By using a simple effective model with only one sterile neutrino, compatible with all current experimental bounds and general theoretical constraints, we conduct a thorough numerical analysis which reveals that the impact of the presence of massive sterile neutrinos on kaon weak decays is very small, less than 1% on decay rates. The only exception is B (KL→ν ν ) , which can go up to O (10-10), thus possibly within the reach of the KOTO, NA62 and SHIP experiments. Plans have also been proposed to search for this decay at the NA64 experiment. In other words, if all the future measurements of weak kaon decays turn out to be compatible with the Standard Model predictions, this will not rule out the existence of massive light sterile neutrinos with non-negligible active-sterile mixing. Instead, for a sterile neutrino of mass below mK, one might obtain a huge enhancement of B (KL→ν ν ), otherwise negligibly small in the Standard Model.

  12. Scale Model Test and Transient Analysis of Steam Injector Driven Passive Core Injection System for Innovative-Simplified Nuclear Power Plant

    Science.gov (United States)

    Ohmori, Shuichi; Narabayashi, Tadashi; Mori, Michitsugu

    A steam injector (SI) is a simple, compact and passive pump and also acts as a high-performance direct-contact compact heater. This provides SI with capability to serve also as a direct-contact feed-water heater that heats up feed-water by using extracted steam from turbine. Our technology development aims to significantly simplify equipment and reduce physical quantities by applying "high-efficiency SI", which are applicable to a wide range of operation regimes beyond the performance and applicable range of existing SIs and enables unprecedented multistage and parallel operation, to the low-pressure feed-water heaters and emergency core cooling system of nuclear power plants, as well as achieve high inherent safety to prevent severe accidents by keeping the core covered with water (a severe accident-free concept). This paper describes the results of the scale model test, and the transient analysis of SI-driven passive core injection system (PCIS).

  13. Steam reforming of cyclic model compounds of bio-oil over Ni-based catalysts: Product distribution and carbon formation

    DEFF Research Database (Denmark)

    Trane-Restrup, Rasmus; Jensen, Anker Degn

    2015-01-01

    Steam reforming (SR) and oxidative steam reforming (OSR) of furfural, 2-methylfuran, and guaiacol have been investigated in the temperature range 400-800°C at a steam to carbon (S/C)-ratio of 5 and oxygen to carbon (O/C)-ratio of 0.2-1.4 over Ni/CeO2-K/MgAl2O4. Carbon oxides and H2 were the major...... products in the SR of 2-methylfuran and furfural, while the by-products were methane, ethanol, 2-propanol, and acetone. Temperatures of 500°C or above were needed to minimize the formation of by-products in the SR of 2-methylfuran and furfural. Phenolics, like benzenediols and phenol, were produced in high...

  14. The Improvement and Affecting Factors Analysis of Steam Flooding Production Model%蒸汽驱产量模型改进及影响因素分析

    Institute of Scientific and Technical Information of China (English)

    范英才; 赵杰

    2011-01-01

    Jones' steam flooding production calculation model is improved, and according to this, oil production performance is analyzed and predicted in Qi-40 in Liaohe Oilfield.The results shows: ( 1 ) Through the historical fitting, the results predicted by Jones model are agreed with the production history well, and it can be used to foretell the trend of production performance changes; (2) The rate of oil production will increase as steam injection rate and steam quality get larger; (3) If the oil saturation enlarges, the rate of oil production will increase greatly.%改进了Jones蒸汽驱产量计算模型.据此,对辽河油田齐-40块蒸汽驱生产状态进行了分析和预测.结果表明:(1)通过历史拟合,Jones模型预测结果与生产历史吻合,可用来估计生产动态变化趋势;(2)注蒸汽速度和蒸汽干度的增加,会增加原油采油速度;(3)原始含油饱和度增加会明显地增加采油速度.

  15. Gamma scintigraphy and biodistribution of (99m)Tc-cefotaxime sodium in preclinical models of bacterial infection and sterile inflammation.

    Science.gov (United States)

    Ilem-Ozdemir, Derya; Asikoglu, Makbule; Ozkilic, Hayal; Yilmaz, Ferda; Hosgor-Limoncu, Mine; Ayhan, Semin

    2016-03-01

    (99m)Tc-cefotaxime sodium ((99m)Tc-CEF) was developed and standardized under varying conditions of reducing and antioxidant agent concentration, pH, radioactivity dose, and reducing agent type. Labeling studies were performed by changing the selected parameters one by one, and optimum labeling conditions were determined. After observing the conditions for maximum labeling efficiency and stability, lyophilized freeze dry kits were prepared accordingly. Simple method for radiolabeling of CEF with (99m)Tc has been developed and standardized. Labeling efficiency of (99m)Tc-CEF was assessed by both radio thin-layer chromatography and radio high-performance liquid chromatography and found higher than 90%. The labeled compound was found to be stable in saline and human serum up to 24 h. Two different freeze dry kits were developed and evaluated. Based on the data obtained from this study, both products were stable for 6 months with high labeling efficiency. The prepared cold kit was found sterile and pyrogen free. The bacterial infection and sterile inflammation imaging capacity of (99m)Tc-CEF was evaluated. Based on the in vivo studies, (99m)Tc-CEF has higher uptake in infected and inflamed thigh muscle than healthy thigh muscle.

  16. Status on the Component Models Developed in the Modelica Framework: High-Temperature Steam Electrolysis Plant & Gas Turbine Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Suk Kim, Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); McKellar, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bragg-Sitton, Shannon M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boardman, Richard D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-10-01

    This report has been prepared as part of an effort to design and build a modeling and simulation (M&S) framework to assess the economic viability of a nuclear-renewable hybrid energy system (N-R HES). In order to facilitate dynamic M&S of such an integrated system, research groups in multiple national laboratories have been developing various subsystems as dynamic physics-based components using the Modelica programming language. In fiscal year (FY) 2015, Idaho National Laboratory (INL) performed a dynamic analysis of two region-specific N-R HES configurations, including the gas-to-liquid (natural gas to Fischer-Tropsch synthetic fuel) and brackish water reverse osmosis desalination plants as industrial processes. In FY 2016, INL has developed two additional subsystems in the Modelica framework: a high-temperature steam electrolysis (HTSE) plant and a gas turbine power plant (GTPP). HTSE has been proposed as a high priority industrial process to be integrated with a light water reactor (LWR) in an N-R HES. This integrated energy system would be capable of dynamically apportioning thermal and electrical energy (1) to provide responsive generation to the power grid and (2) to produce alternative industrial products (i.e., hydrogen and oxygen) without generating any greenhouse gases. A dynamic performance analysis of the LWR/HTSE integration case was carried out to evaluate the technical feasibility (load-following capability) and safety of such a system operating under highly variable conditions requiring flexible output. To support the dynamic analysis, the detailed dynamic model and control design of the HTSE process, which employs solid oxide electrolysis cells, have been developed to predict the process behavior over a large range of operating conditions. As first-generation N-R HES technology will be based on LWRs, which provide thermal energy at a relatively low temperature, complementary temperature-boosting technology was suggested for integration with the

  17. Hard sludge removal in steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Santibanez, M.; Stoss, J.

    2013-07-01

    One of the majors problems during the life of Nuclear power plants is the efficiency lost in steam generator due to, among issues, the plugging and therefore useless, of tubes which presented possibility of cracking in the future. The hard sludge produced in the steam generators secondary side and deposited on the tube sheet or around the tubes as collar shape are one of the main agent causing this problem, so their elimination is considered a major topic in order to keep the steam generators in an optimum condition along the whole plant life. AREVA is aware of this global problem, therefore a process and tools have been continuously developed since 1995 in order to eliminate the hard deposits in a effective way, with no damage to steam generator's components and adaptable for the different steam generators models existing in the market.

  18. Nanoscale topographic changes on sterilized glass surfaces affect cell adhesion and spreading.

    Science.gov (United States)

    Wittenburg, Gretel; Lauer, Günter; Oswald, Steffen; Labudde, Dirk; Franz, Clemens M

    2014-08-01

    Producing sterile glass surfaces is of great importance for a wide range of laboratory and medical applications, including in vitro cell culture and tissue engineering. However, sterilization may change the surface properties of glass and thereby affect its use for medical applications, for instance as a substrate for culturing cells. To investigate potential effects of sterilization on glass surface topography, borosilicate glass coverslips were left untreated or subjected to several common sterilization procedures, including low-temperature plasma gas, gamma irradiation and steam. Imaging by atomic force microscopy demonstrated that the surface of untreated borosilicate coverslips features a complex landscape of microislands ranging from 1000 to 3000 nm in diameter and 1 to 3 nm in height. Steam treatment completely removes these microislands, producing a nanosmooth glass surface. In contrast, plasma treatment partially degrades the microisland structure, while gamma irradiation has no effect on microisland topography. To test for possible effects of the nanotopographic structures on cell adhesion, human gingival fibroblasts were seeded on untreated or sterilized glass surfaces. Analyzing fibroblast adhesion 3, 6, and 24 h after cell seeding revealed significant differences in cell attachment and spreading depending on the sterilization method applied. Furthermore, single-cell force spectroscopy revealed a connection between the nanotopographic landscape of glass and the formation of cellular adhesion forces, indicating that fibroblasts generally adhere weakly to nanosmooth but strongly to nanorough glass surfaces. Nanotopographic changes induced by different sterilization methods may therefore need to be considered when preparing sterile glass surfaces for cell culture or biomedical applications.

  19. Phenomenological and mathematical modeling of a high pressure steam driven jet injector. Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Anand, G.

    1993-12-31

    An injector is a particular type of jet pump which uses condensable vapor to entrain a liquid and discharge against a pressure higher than either motive or suction pressures. The injector has no moving parts and requires no external power supply nor any complex control system. Thus, the injector is particularly suited for emergency core cooling operations. A detailed survey has indicated that various injector designs are available for operating pressures below 250 psig. However, the design of these injectors from the viewpoint of a basic understanding of heat and mass transfer processes has not been well developed. A critical review of the models showed serious discrepancies between the analytical models and the experimental observations. The discrepancies evolved from the neglect of non-equilibrium aspects of the flow. The origin of the non-equilibrium aspects can be traced to the extremely small time scales governing the flow in the injector. Thus, time scales of the order of 10{sup {minus}2} seconds are involved in the injector, accompanied by mass, momentum, and heat transfer rates of orders of magnitude higher than that observed in conventional two-phase flows. The present study focuses on the phenomenological and mathematical modeling of the processes in the injector from the viewpoint of its non-equilibrium nature.

  20. Hybrid sterility in plant: stories from rice.

    Science.gov (United States)

    Ouyang, Yidan; Liu, Yao-Guang; Zhang, Qifa

    2010-04-01

    Hybrid sterility is the most common form of postzygotic reproductive isolation in plants. The best-known example is perhaps the hybrid sterility between indica and japonica subspecies of Asian cultivated rice (Oryza sativa L.). Major progress has been reported recently in rice in identifying and cloning hybrid sterility genes at two loci regulating female and male fertility, respectively. Genetic analyses and molecular characterization of these genes, together with the results from other model organisms especially Drosophila, have advanced the understanding of the processes underlying reproductive isolation and speciation. These findings also have significant implications for crop genetic improvement, by providing the feasibility and strategies for overcoming intersubspecific hybrid sterility thus allowing the development of intersubspecific hybrids.

  1. Cosmological and astrophysical implications of sterile neutrinos

    Science.gov (United States)

    Petraki, Kalliopi

    The discovery of neutrino masses suggests that the Standard Model should be supplemented with new gauge-singlet fermions, often called sterile neutrinos. The interplay among the new couplings introduced in the Standard Model can accommodate the neutrino oscillation data for a variety of choices: the new particles can be extremely heavy and practically unobservable, or they can be light, in which case they can solve several long-standing puzzles. It has been shown, for example, that sterile neutrinos in some range of masses can account for dark matter, their emission from a supernova can explain pulsar kicks, arid their decays can play an important role in the formation of the first stars. Though indirect, these clues indicate that sterile neutrinos can be the minimal solution to a variety of unsolved problems. This emphasizes the importance of investigating further the consequences of these new degrees of freedom for cosmology and astrophysics. In this dissertation, I explore the possible role of sterile neutrinos of different mass scales in some cosmological and astrophysical phenomena. A minimal extension of the Higgs sector of the Standard Model, with a gauge- singlet boson coupled to sterile neutrinos, can provide a consistent framework for the theory of neutrino masses, and can produce a relic population of keV sterile neutrinos via decays of the singlet Higgs. The latter can account for the dark matter of the universe. The mechanism operates around the electroweak scale, and has interesting consequences for the electroweak phase transition. Relic sterile neutrinos produced via decays at the electroweak scale constitute colder dark matter than those produced via other previously suggested mechanisms. The primordial thermal content of dark matter has important implications for the formation of cosmic structures, such as clusters and galaxies. The assessment of the relevant properties suggests that sterile neutrinos produced at the electroweak scale are a

  2. VERA-CS Modeling and Simulation of PWR Main Steam Line Break Core Response to DNB

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K [ORNL; Sung, Yixing [Westinghouse Electric Company, Cranberry Township; Kucukboyaci, Vefa [Westinghouse Electric Company, Cranberry Township; Xu, Yiban [Westinghouse Electric Company, Cranberry Township; Cao, Liping [Westinghouse Electric Company, Cranberry Township

    2016-01-01

    The Virtual Environment for Reactor Applications core simulator (VERA-CS) being developed by the Consortium for the Advanced Simulation of Light Water Reactors (CASL) includes coupled neutronics, thermal-hydraulics, and fuel temperature components with an isotopic depletion capability. The neutronics capability employed is based on MPACT, a three-dimensional (3-D) whole core transport code. The thermal-hydraulics and fuel temperature models are provided by the COBRA-TF (CTF) subchannel code. As part of the CASL development program, the VERA-CS (MPACT/CTF) code system was applied to model and simulate reactor core response with respect to departure from nucleate boiling ratio (DNBR) at the limiting time step of a postulated pressurized water reactor (PWR) main steamline break (MSLB) event initiated at the hot zero power (HZP), either with offsite power available and the reactor coolant pumps in operation (high-flow case) or without offsite power where the reactor core is cooled through natural circulation (low-flow case). The VERA-CS simulation was based on core boundary conditions from the RETRAN-02 system transient calculations and STAR-CCM+ computational fluid dynamics (CFD) core inlet distribution calculations. The evaluation indicated that the VERA-CS code system is capable of modeling and simulating quasi-steady state reactor core response under the steamline break (SLB) accident condition, the results are insensitive to uncertainties in the inlet flow distributions from the CFD simulations, and the high-flow case is more DNB limiting than the low-flow case.

  3. Sterility Maintenance Assessment of Moist/Wet Material After Steam Sterilization and 30-day Storage Evaluación de la manutención de la esterilidad de materiales húmedos/mojados después de esterilizados con vapor y almacenados por 30 días Avaliação da manutenção da esterilidade de materiais úmidos/molhados após a esterilização por vapor e armazenamento por 30 dias

    Directory of Open Access Journals (Sweden)

    Giovana Abrahão de Araújo Moriya

    2010-08-01

    Full Text Available Moist/wet materials stored after autoclaving are considered contaminated and not recommended for use. This study evaluates the maintenance of sterility in moist/wet material after being submitted to steam sterilization and stored for a period of 30 days. Aiming to support decision-making in emergency situations, 40 surgical boxes packed in nonwoven cloth covering Spunbound, Metblouwn, Spunbound (SMS: half (the experimental group were placed in an autoclave but the drying phase was interrupted, yielding moist/wet materials and the other half (the negative control group underwent the complete cycle. The external parts of each surgical box were deliberately contaminated with Serratia marcescens and subsequently stored for 30 days. After this period, the boxes' contents were submitted to sterility tests and no growth was observed. The presence of moisture inside the surgical boxes did not interfere with maintaining their sterility.Se consideran como contaminados los objetos mojados/húmedos almacenados después de ser esterilizados en autoclave, no siendo recomendados para uso. El objetivo del estudio fue evaluar la manutención de la esterilidad de los materiales mojados/húmedos después de sometidos al proceso de esterilización por vapor y almacenados por un intervalo de 30 días. Con la finalidad de auxiliar en la toma de decisiones en situaciones de emergencia, fueron preparadas 40 cajas quirúrgicas embaladas en SMS, siendo la mitad (experimental sometidas a un proceso de esterilización en autoclave, con fase de secado interrumpida, liberando material mojado/húmedo y otras 20 (control con el ciclo completo. Las partes externas de cada caja fueron intencionalmente contaminadas con Serratia marcescens y posteriormente almacenadas por 30 días. Después ese período, los contenidos de las cajas fueron sometidos a pruebas de esterilidad, acusando ausencia total de crecimiento. La presencia de humedad dentro de las cajas no interfirió en la

  4. Steam distillation extraction kinetics regression models to predict essential oil yield, composition, and bioactivity of chamomile oil

    Science.gov (United States)

    Chamomile (Matricaria chamomilla L.) is one of the most widely spread and used medicinal and essential oil crop in the world. Chamomile essential oil is extracted via steam distillation of the inflorescences (flowers). In this study, distillation time (DT) was found to be a crucial determinant of yi...

  5. Modeling the cost-effectiveness of insect rearing on artificial diets: A test with a tephritid fly used in the sterile insect technique

    Science.gov (United States)

    Birke, Andrea; Williams, Trevor; Aluja, Martín

    2017-01-01

    We modeled the cost-effectiveness of rearing Anastrepha ludens, a major fruit fly pest currently mass reared for sterilization and release in pest control programs implementing the sterile insect technique (SIT). An optimization model was generated by combining response surface models of artificial diet cost savings with models of A. ludens pupation, pupal weight, larval development time and adult emergence as a function of mixtures of yeast, a costly ingredient, with corn flour and corncob fractions in the diet. Our model revealed several yeast-reduced mixtures that could be used to prepare diets that were considerably cheaper than a standard diet used for mass rearing. Models predicted a similar production of insects (pupation and adult emergence), with statistically similar pupal weights and larval development times between yeast-reduced diets and the standard mass rearing diet formulation. Annual savings from using the modified diets could be up to 5.9% of the annual cost of yeast, corn flour and corncob fractions used in the standard diet, representing a potential saving of US $27.45 per ton of diet (US $47,496 in the case of the mean annual production of 1,730.29 tons of artificial diet in the Moscafrut mass rearing facility at Metapa, Chiapas, Mexico). Implementation of the yeast-reduced diet on an experimental scale at mass rearing facilities is still required to confirm the suitability of new mixtures of artificial diet for rearing A. ludens for use in SIT. This should include the examination of critical quality control parameters of flies such as adult flight ability, starvation resistance and male sexual competitiveness across various generations. The method used here could be useful for improving the cost-effectiveness of invertebrate or vertebrate mass rearing diets worldwide. PMID:28257496

  6. Effectiveness of Bench Top Non-Vacuum Autoclaves on Dental Turbine Chamber Sterilization Effectiveness of Bench Top Non-Vacuum Autoclaves on Dental Turbine Chamber Sterilization

    Directory of Open Access Journals (Sweden)

    Taraneh Movahhed

    2013-06-01

    Full Text Available Introduction: Dental turbine chamber is a suitable reservoir for living microorganisms, so chamber sterilization is necessary for reducing cross contamination risk. On the other hand, in non-vacuum autoclaves, steam penetration into turbine chamber is doubtful, while they are still in use in dental clinics. In this study, performance of small non-vacuum autoclave in turbine chamber sterilization was evaluated. Methods: A total of 48 dental turbines were sterilized by large vacuum autoclaves. The turbin chamber cap was opened in aseptic enviroment and a strip contaminated with bacillus stearothermophilus endospores was placed into chamber and chamber cap was closed. Twelve dental turbines were loaded in each of four autoclaves (2 large pre-vacuum autoclaves, 2 bench top non-vacuum autoclaves and sterilization process preformed according to the manufacturer's instructions. After the sterilization cycle, the strips were transferred to culture medium and incubated at 56°C for 48 Hours. As control sample, a biologic indicator that had not been autoclaved was used for each group. Results: Being loaded in different autoclaves, All 48 turbines were sterilized properly and all the cultures were negative. The culture results of four control indicators which were not sterilized, were positive. Conclusion: There was no difference between performance of vacuum and non-vacuum autoclaves in dental turbine chamber sterilization. Both types performed sterilization properly.

  7. Preliminary analysis of modeling of Pars and steam injectors to support long-term operation of LWR passive ECCS using a best estimate thermal-hydraulics code

    Energy Technology Data Exchange (ETDEWEB)

    Morales S, J. B.; Sanchez J, J. [UNAM, Facultad de Ingenieria, Circuito Interior s/n, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Espinosa P, G., E-mail: jaimebmoraless@gmail.co [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)

    2010-10-15

    pools. This work presents Pars and steam injectors models, simulations and results of implementations in a best estimated thermal-hydraulics code, which are to be used for evaluations of these systems as long-term supports to ECCS. Lumped parameter models based on heat and mass balances have also been developed to test required additional best estimated code routines needed for the representation of Pars. (Author)

  8. An Isothermal Steam Expander for an Industrial Steam Supplying System

    OpenAIRE

    Chen-Kuang Lin; Guang-Jer Lai; Yoshiyuki Kobayashi; Masahiro Matsuo; Min-Chie Chiu

    2015-01-01

    Steam is an essential medium used in the industrial process. To ensure steam quality, small and middle scale boilers are often adopted. However, because a higher steam pressure (compared to the necessary steam pressure) is generated, the boiler’s steam pressure will be reduced via a pressure regulator before the steam is directed through the process. Unfortunately, pressure is somewhat wasted during the reducing process. Therefore, in order to promote energy efficiency, a pressure regulator i...

  9. Light sterile neutrinos

    Science.gov (United States)

    Gariazzo, S.; Giunti, C.; Laveder, M.; Li, Y. F.; Zavanin, E. M.

    2016-03-01

    The theory and phenomenology of light sterile neutrinos at the eV mass scale is reviewed. The reactor, gallium and Liquid Scintillator Neutrino Detector anomalies are briefly described and interpreted as indications of the existence of short-baseline oscillations which require the existence of light sterile neutrinos. The global fits of short-baseline oscillation data in 3 + 1 and 3 + 2 schemes are discussed, together with the implications for β-decay and neutrinoless double-β decay. The cosmological effects of light sterile neutrinos are briefly reviewed and the implications of existing cosmological data are discussed. The review concludes with a summary of future perspectives. This review is dedicated to the memory of Hai-Wei Long, our dear friend and collaborator, who passed away on 29 May 2015. He was an exceptionally kind person and an enthusiastic physicist. We deeply miss him.

  10. The effect of clinical use and sterilization on selected orthodontic arch wires.

    Science.gov (United States)

    Smith, G A; von Fraunhofer, J A; Casey, G R

    1992-08-01

    The effect of clinical use and various sterilization/disinfection protocols on three types of nickel-titanium, and one type each of beta-titanium and stainless steel arch wire was evaluated. The sterilization/disinfection procedures included disinfection alone or in concert with steam autoclave, dry heat, or cold solution sterilization. No clinically significant differences were found between new and used arch wires. The direction of load application to the arch wire and the particular segment of arch wire tested was found to cause substantial differences in generated loads for certain arch wire types.

  11. Thermodynamics of supersaturated steam: Molecular simulation results

    Science.gov (United States)

    Moučka, Filip; Nezbeda, Ivo

    2016-12-01

    Supersaturated steam modeled by the Gaussian charge polarizable model [P. Paricaud, M. Předota, and A. A. Chialvo, J. Chem. Phys. 122, 244511 (2005)] and BK3 model [P. Kiss and A. Baranyai, J. Chem. Phys. 138, 204507 (2013)] has been simulated at conditions occurring in steam turbines using the multiple-particle-move Monte Carlo for both the homogeneous phase and also implemented for the Gibbs ensemble Monte Carlo molecular simulation methods. Because of these thermodynamic conditions, a specific simulation algorithm has been developed to bypass common simulation problems resulting from very low densities of steam and cluster formation therein. In addition to pressure-temperature-density and orthobaric data, the distribution of clusters has also been evaluated. The obtained extensive data of high precision should serve as a basis for development of reliable molecular-based equations for properties of metastable steam.

  12. BEST sensitivity to O(1) eV sterile neutrino

    CERN Document Server

    Barinov, Vladislav; Gorbunov, Dmitry; Ibragimova, Tatiana

    2016-01-01

    Numerous anomalous results in neutrino oscillation experiments can be attributed to interference of ~1 eV sterile neutrino. The specially designed to fully explore the Gallium anomaly Baksan Experiment on Sterile Transitions (BEST) starts next year. We investigate the sensitivity of BEST in searches for sterile neutrino mixed with electron neutrino. Then, performing the combined analysis of all the Gallium experiments (SAGE, GALLEX, BEST) we find the regions in model parameter space (sterile neutrino mass and mixing angle), which will be excluded if BEST agrees with no sterile neutrino hypothesis. For the opposite case, if BEST observes the signal as it follows from the sterile neutrino explanation of the Gallium (SAGE and GALLEX) anomaly, we show how BEST will improve upon the present estimates of the model parameters.

  13. Sterile Neutrinos in Cold Climates

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Benjamin J.P. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-09-01

    Measurements of neutrino oscillations at short baselines contain an intriguing set of experimental anomalies that may be suggestive of new physics such as the existence of sterile neutrinos. This three-part thesis presents research directed towards understanding these anomalies and searching for sterile neutrino oscillations. Part I contains a theoretical discussion of neutrino coherence properties. The open-quantum-system picture of neutrino beams, which allows a rigorous prediction of coherence distances for accelerator neutrinos, is presented. Validity of the standard treatment of active and sterile neutrino oscillations at short baselines is verified, and non-standard coherence loss effects at longer baselines are predicted. Part II concerns liquid argon detector development for the MicroBooNE experiment, which will search for short-baseline oscillations in the Booster Neutrino Beam at Fermilab. Topics include characterization and installation of the MicroBooNE optical system; test-stand measurements of liquid argon optical properties with dissolved impurities; optimization of wavelength-shifting coatings for liquid argon scintillation light detection; testing and deployment of high-voltage surge arrestors to protect TPC field cages; and software development for optical and TPC simulation and reconstruction. Part III presents a search for sterile neutrinos using the IceCube neutrino telescope, which has collected a large sample of atmospheric-neutrino-induced events in the 1-10 TeV energy range. Sterile neutrinos would modify the detected neutrino flux shape via MSW-resonant oscillations. Following a careful treatment of systematic uncertainties in the sample, no evidence for MSW-resonant oscillations is observed, and exclusion limits on 3+1 model parameter space are derived. Under the mixing assumptions made, the 90% confidence level exclusion limit extends to sin224 ≤ 0.02 at m2 ~ 0.3 eV2, and the LSND and Mini

  14. Bactericidal activity does not predict sterilizing activity: the case of rifapentine in the murine model of Mycobacterium ulcerans disease.

    Directory of Open Access Journals (Sweden)

    Deepak V Almeida

    Full Text Available BACKGROUND: Since 2004, treatment of Mycobacterium ulcerans disease, or Buruli ulcer, has shifted from surgery to daily treatment with streptomycin (STR + rifampin (RIF for 8 weeks. For shortening treatment duration, we tested the potential of daily rifapentine (RPT, a long-acting rifamycin derivative, as a substitute for RIF. METHODOLOGY/PRINCIPAL FINDINGS: BALB/c mice were infected with M. ulcerans in the right hind footpad and treated either daily (7/7 with STR+RIF or five days/week (5/7 with STR+RIF or STR+RPT for 4 weeks, beginning 28 days after infection when CFU counts were 4.88±0.51. The relative efficacy of the drug treatments was compared by footpad CFU counts during treatment and median time to footpad swelling after treatment cessation as measure of sterilizing activity. All drug treatments were bactericidal. After 1 week of treatment, the decline in CFU counts was significantly greater in treated mice but not different between the three treated groups. After 2 weeks of treatment, the decline in CFU was greater in mice treated with STR+RPT 5/7 than in mice treated with STR+RIF 7/7 and STR+RIF 5/7. After 3 and 4 weeks of treatment, CFU counts were nil in mice treated with STR+RPT and reduced by more than 3 and 4 logs in mice treated with STR+RIF 5/7 and STR+RIF 7/7, respectively. In sharp contrast to the bactericidal activity, the sterilizing activity was not different between all drug regimens although it was in proportion to the treatment duration. CONCLUSIONS/SIGNIFICANCE: The better bactericidal activity of daily STR+RIF and especially of STR+RPT did not translate into better prevention of relapse, possibly because relapse-freecure after treatment of Buruli ulcer is more related to the reversal of mycolactone-induced local immunodeficiency by drug treatment rather than to the bactericidal potency of drugs.

  15. Steam gasification of wood biomass in a fluidized biocatalytic system bed gasifier: A model development and validation using experiment and Boubaker Polynomials Expansion Scheme BPES

    Directory of Open Access Journals (Sweden)

    Luigi Vecchione

    2015-07-01

    Full Text Available One of the most important issues in biomass biocatalytic gasification is the correct prediction of gasification products, with particular attention to the Topping Atmosphere Residues (TARs. In this work, performedwithin the European 7FP UNIfHY project, we develops and validate experimentally a model which is able of predicting the outputs,including TARs, of a steam-fluidized bed biomass gasifier. Pine wood was chosen as biomass feedstock: the products obtained in pyrolysis tests are the relevant model input. Hydrodynamics and chemical properties of the reacting system are considered: the hydrodynamic approach is based on the two phase theory of fluidization, meanwhile the chemical model is based on the kinetic equations for the heterogeneous and homogenous reactions. The derived differentials equations for the gasifier at steady state were implemented MATLAB. Solution was consecutively carried out using the Boubaker Polynomials Expansion Scheme by varying steam/biomass ratio (0.5-1 and operating temperature (750-850°C.The comparison between models and experimental results showed that the model is able of predicting gas mole fractions and production rate including most of the representative TARs compounds

  16. Safety Picks up "STEAM"

    Science.gov (United States)

    Roy, Ken

    2016-01-01

    This column shares safety information for the classroom. STEAM subjects--science, technology, engineering, art, and mathematics--are essential for fostering students' 21st-century skills. STEAM promotes critical-thinking skills, including analysis, assessment, categorization, classification, interpretation, justification, and prediction, and are…

  17. MINOS Sterile Neutrino Search

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, David Jason [Univ. College London, Bloomsbury (United Kingdom)

    2009-02-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline accelerator neutrino experiment designed to measure properties of neutrino oscillation. Using a high intensity muon neutrino beam, produced by the Neutrinos at Main Injector (NuMI) complex at Fermilab, MINOS makes two measurements of neutrino interactions. The first measurement is made using the Near Detector situated at Fermilab and the second is made using the Far Detector located in the Soudan Underground laboratory in northern Minnesota. The primary goal of MINOS is to verify, and measure the properties of, neutrino oscillation between the two detectors using the v μ→ Vτ transition. A complementary measurement can be made to search for the existence of sterile neutrinos; an oft theorized, but experimentally unvalidated particle. The following thesis will show the results of a sterile neutrino search using MINOS RunI and RunII data totaling ~2.5 x 1020 protons on target. Due to the theoretical nature of sterile neutrinos, complete formalism that covers transition probabilities for the three known active states with the addition of a sterile state is also presented.

  18. Radiation sterilization of ketoprofen

    Energy Technology Data Exchange (ETDEWEB)

    Katusin-Razem, Branka [Ruder Boskovic Institute, P.O.B 180, Zagreb 10000 (Croatia)]. E-mail: brazem@irb.hr; Hamitouche, Katia [Centre de Recherche et Developpement Saidal, El Harrach (Algeria); Maltar-Strmecki, Nadica [Faculty of Veterinary Medicine, University of Zagreb, Zagreb 10000 (Croatia); Kos, Karmen [Belupo Pharmaceutical Works, Koprivnica 48000 (Croatia); Pucic, Irina [Ruder Boskovic Institute, P.O.B 180, Zagreb 10000 (Croatia); Britvic-Budicin, Smiljana [Ruder Boskovic Institute, P.O.B 180, Zagreb 10000 (Croatia); Razem, Dusan [Ruder Boskovic Institute, P.O.B 180, Zagreb 10000 (Croatia)

    2005-06-01

    Radiation sterilization of ketoprofen (KP) dry powder was investigated by selected physico-chemical methods. High-performance liquid chromatography, ultraviolet spectrophotometry, infrared spectrophotometry, differential scanning calorimetry, X-ray diffraction and electron spin resonance spectroscopy did not show any significant degradation at sterilization dose 25 kGy. To determine the nature, extent and direction of radiation-induced changes, KP was irradiated to extremely high doses, much higher than necessary to achieve sterility. The irradiated KP did not show any difference of XRD patterns up to 200 kGy; with DSC and IR some changes were detected only above 1000 and 2000 kGy, respectively; HPLC has shown about 5% destruction at 2000 kGy. Acetyl benzophenon (AcBph) was generated by irradiation with G(AcBph)=(1.6{+-}0.1)x10{sup -8} mol J{sup -1}. Ames test has shown no mutagenicity of KP irradiated with 3000 kGy or of the oily mixture of radiolytic products isolated from it. Solid KP has proven to be very stable on irradiation, and irradiation has been found to be a suitable method for its sterilization.

  19. Radiation sterilization of ketoprofen

    Science.gov (United States)

    Katušin-Ražem, Branka; Hamitouche, Katia; Maltar-Strmečki, Nadica; Kos, Karmen; Pucić, Irina; Britvić-Budicin, Smiljana; Ražem, Dušan

    2005-06-01

    Radiation sterilization of ketoprofen (KP) dry powder was investigated by selected physico-chemical methods. High-performance liquid chromatography, ultraviolet spectrophotometry, infrared spectrophotometry, differential scanning calorimetry, X-ray diffraction and electron spin resonance spectroscopy did not show any significant degradation at sterilization dose 25 kGy. To determine the nature, extent and direction of radiation-induced changes, KP was irradiated to extremely high doses, much higher than necessary to achieve sterility. The irradiated KP did not show any difference of XRD patterns up to 200 kGy; with DSC and IR some changes were detected only above 1000 and 2000 kGy, respectively; HPLC has shown about 5% destruction at 2000 kGy. Acetyl benzophenon (AcBph) was generated by irradiation with G(AcBph)=(1.6±0.1)×10 -8 mol J -1. Ames test has shown no mutagenicity of KP irradiated with 3000 kGy or of the oily mixure of radiolytic products isolated from it. Solid KP has proven to be very stable on irradiation, and irradiation has been found to be a suitable method for its sterilization.

  20. Heat sterilization of wood

    Science.gov (United States)

    Xiping Wang

    2010-01-01

    Two important questions should be considered in heat sterilizing solid wood materials: First, what temperature–time regime is required to kill a particular pest? Second, how much time is required to heat the center of any wood configuration to the kill temperature? The entomology research on the first question has facilitated the development of international standards...

  1. Research of tare hydrodynamic behaviour at sterilization of canned fish

    OpenAIRE

    2016-01-01

    The paper is devoted to research on improving the equipment that ensures the absolute safety of mineral nutrients in the production of sterilized canned fish. The results of experimental study of hydrodynamic characteristics moving sterilized jars of canned fish of different sizes under the influence of circulating gas-liquid heat-carrying medium in the capacity have been presented. Some experimental setup with organized top-down and bottom-up flows in it modeling a sterilizer (autoclave) has...

  2. A comparison of physicochemical properties of sterilized chitosan hydrogel and its applicability in a canine model of periodontal regeneration.

    Science.gov (United States)

    Zang, Shengqi; Dong, Guangying; Peng, Bo; Xu, Jie; Ma, Zhiwei; Wang, Xinwen; Liu, Lingxia; Wang, Qintao

    2014-11-26

    Chitosan has previously been exploited as a scaffold in tissue engineering processes. To avoid infection, chitosan must be sterilized prior to contact with bodily fluids or blood. Previous research has shown that autoclaved chitosan solution lead to decreased molecular weight, dynamic viscosity, and rate of gelling. We prepared a thermosensitive chitosan hydrogel using autoclaved chitosan powder (121 °C, 10 min) and β-glycerophosphate (chitosan-PA/GP) and compared the physicochemical properties and biocompatibility in vitro with autoclaved chitosan solution/GP hydrogel. The chitosan-PA/GP hydrogel had a shortened gelation time, higher viscosity, increased water absorption, appropriate degradation time, porous structure, and no obvious cytotoxicity on human periodontal ligament cells. Scanning electron microscopy demonstrated that the cells exhibited a normal morphology. The chitosan-PA/GP hydrogel promoted periodontal tissue regeneration in dog class III furcation defects. The chitosan-PA/GP thermosensitive hydrogel displayed suitable physicochemical properties and biocompatibilities and represents a promising candidate as an injectable tissue engineering scaffold.

  3. Validation of CTF Droplet Entrainment and Annular/Mist Closure Models using Riso Steam/Water Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wysocki, Aaron J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-02-01

    This report summarizes the work done to validate the droplet entrainment and de-entrainment models as well as two-phase closure models in the CTF code by comparison with experimental data obtained at Riso National Laboratory. The Riso data included a series of over 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions were set so that the majority of cases were in the annular/mist ow regime. Measurements included liquid lm ow rate, droplet ow rate, lm thickness, and two-phase pressure drop. CTF was used to model 180 of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet ow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor and entrained liquid ow fractions, pressure drop per unit length, and liquid lm thickness. The entire process of generating CTF input decks, running cases, extracting data, and generating comparison plots was scripted using Python and Matplotlib for a completely automated validation process. All test cases and scripting tools have been committed to the COBRA-TF master repository and selected cases have been added to the continuous testing system to serve as regression tests. The dierences between the CTF- and experimentally-calculated ow fraction values were con- sistent with previous calculations by Wurtz, who applied the same entrainment correlation to the same data. It has been found that CTF's entrainment/de-entrainment predictive capability in the annular/mist ow regime for this particular facility is comparable to the licensed industry code, COBRAG. While lm and droplet predictions are generally good, it has been found that accuracy is diminished at lower ow qualities. This nding is consistent with the noted deciencies in the Wurtz entrainment model employed by CTF. The CTF predicted two-phase pressure drop in

  4. Pressure-assisted thermal sterilization of soup

    Science.gov (United States)

    Shibeshi, Kidane; Farid, Mohammed M.

    2010-12-01

    The overall efficiency of an existing scale-up pressure-assisted thermal sterilization (PATS) unit was investigated with regards to inactivation of Geobacillus stearothermophilus spores suspended in pumpkin soup. The PATS unit is a double pipe heat exchanger in which the soup is pumped into its inner high pressure tube and constrained by two high pressure valves, while steam is continuously passed through the annular region to heat the content. The technology is based on pressure generation by thermal expansion of the liquid in an enclosure. In this work, the addition of an air line to push the treated liquid food out of the existing PATS unit has improved the overall quality of the treated samples, as evidenced by achieving higher log reduction of the spores. Compared with thermal processing, the application of PATS shows the potential for lowering the thermal treatment temperature, offering improved food quality.

  5. Biocompatibility of supercritical CO2-treated titanium implants in a rat model.

    Science.gov (United States)

    Hill, C M; Kang, Q K; Wahl, C; Jimenez, A; Laberge, M; Drews, M; Matthews, M A; An, Y H

    2006-04-01

    Supercritical phase CO2 is a promising method for sterilizing implantable devices and tissue grafts. The goal of this study is to evaluate the biocompatibility of titanium implants sterilized by supercritical phase CO2 in a rat subcutaneous implantation model. At 5 weeks post implantation titanium implants sterilized by supercritical phase CO2 produce a soft tissue reaction that is comparable to other methods of sterilization (steam autoclave, ultraviolet light radiation, ethylene oxide gas, and radio-frequency glow-discharge), as indicated by the thickness and density of the foreign body capsule, although there were some differences on the capillary density. Overall the soft tissue response to the implants was similar among all methods of sterilization, indicating supercritical phase CO2 treatment did not compromise the biocompatibility of the titanium implant.

  6. Solar steam generation: Steam by thermal concentration

    Science.gov (United States)

    Shang, Wen; Deng, Tao

    2016-09-01

    The solar-driven generation of water steam at 100 °C under one sun normally requires the use of optical concentrators to provide the necessary energy flux. Now, thermal concentration is used to raise the vapour temperature to 100 °C without the need for costly optical concentrators.

  7. Experimental investigation of the steam wetness in a 1000 MW steam turbine

    Science.gov (United States)

    Kolovratník, Michal; Bartoš, Ondřej

    2016-03-01

    The aim of this paper is to introduce the experimental data of the wetness distribution obtained in the year 2015 in front of and behind the last stage of the 1000MW steam turbine in the power plant Temelín. Two different optical probes developed at Czech Technical University were used. For the first time in the Czech Republic pneumatic and optical measurement of the wet steam flow field in front of the last stage of a nuclear power-station steam turbine was provided. This unique measurement opportunity provided lots of new information for the manufacturer and operator of the steam turbine and valuable experimental data for the phase transition modelling in the wet steam flow. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  8. Experimental investigation of the steam wetness in a 1000 MW steam turbine

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2016-01-01

    Full Text Available The aim of this paper is to introduce the experimental data of the wetness distribution obtained in the year 2015 in front of and behind the last stage of the 1000MW steam turbine in the power plant Temelín. Two different optical probes developed at Czech Technical University were used. For the first time in the Czech Republic pneumatic and optical measurement of the wet steam flow field in front of the last stage of a nuclear power-station steam turbine was provided. This unique measurement opportunity provided lots of new information for the manufacturer and operator of the steam turbine and valuable experimental data for the phase transition modelling in the wet steam flow. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  9. Use of Lagrangian transport models and Sterilized High Volume Sampling to pinpoint the source region of Kawasaki disease and determine the etiologic agent

    Science.gov (United States)

    Curcoll Masanes, Roger; Rodó, Xavier; Anton, Jordi; Ballester, Joan; Jornet, Albert; Nofuentes, Manel; Sanchez-Manubens, Judith; Morguí, Josep-Anton

    2015-04-01

    Kawasaki disease (KD) is an acute, coronary artery vasculitis of young children, and still a medical mystery after more than 40 years. A former study [Rodó et al. 2011] demonstrated that certain patterns of winds in the troposphere above the earth's surface flowing from Asia were associated with the times of the annual peak in KD cases and with days having anomalously high numbers of KD patients. In a later study [Rodó et al. 2014], we used residence times from an Air Transport Model to pinpoint the source region for KD. Simulations were generated from locations spanning Japan from days with either high or low KD incidence. In order to cope with stationarity of synoptic situations, only trajectories for the winter months, when there is the maximum in KD cases, were considered. Trajectories traced back in time 10 days for each dataset and location were generated using the flexible particle Lagrangian dispersion model (FLEXPART Version 8.23 [Stohl et al. 2005]) run in backward mode. The particles modeled were air tracers, with 10,000 particles used on each model run. The model output used was residence time, with an output grid of 0.5° latitude × longitude and a time resolution of 3 h. The data input used for the FLEXPART model was gridded atmospheric wind velocity from the European Center for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim at 1°). Aggregates of winter period back-trajectories were calculated for three different regions of Japan. A common source of wind air masses was located for periods with High Kawasaki disease. Knowing the trajectories of winds from the air transport models, a sampling methodology was developed in order to capture the possible etiological agent or other tracers that could have been released together. This methodology is based on the sterilized filtering of high volumes of the transported air at medium tropospheric levels by aircraft sampling and a later analyze these filters with adequate techniques. High purity

  10. Dark Matter Relic Abundance and Light Sterile Neutrinos

    CERN Document Server

    Tang, Yi-Lei

    2016-01-01

    In this paper, we calculate the relic abundance of the dark matter particles when they can annihilate into sterile neutrinos with the mass $\\lesssim 100 \\text{ GeV}$ in a simple model. Unlike the usual standard calculations, the sterile neutrino may fall out of the thermal equilibrium with the thermal bath before the dark matter freezes out. In such case, if the Yukawa coupling between Higgs and sterile neutrino $y_N$ is small, this process gives rise to a larger $\\Omega_{\\text{DM}} h^2$ so we need a larger coupling between dark matter and the sterile neutrino for a correct relic abundance.

  11. Ukraine Steam Partnership

    Energy Technology Data Exchange (ETDEWEB)

    Gurvinder Singh

    2000-02-15

    The Ukraine Steam Partnership program is designed to implement energy efficiency improvements in industrial steam systems. These improvements are to be made by the private plants and local government departments responsible for generation and delivery of energy to end-users. One of the activities planned under this program was to provide a two-day training workshop on industrial steam systems focusing on energy efficiency issues related to the generation, distribution, and consumption of steam. The workshop was geared towards plant managers, who are not only technically oriented, but are also key decision makers in their respective companies. The Agency for Rational Energy Use and Ecology (ARENA-ECO), a non-governmental, not-for-profit organization founded to promote energy efficiency and environmental protection in Ukraine, in conjunction with the Alliance staff in Kiev sent out invitations to potential participants in all the regions of Ukraine. The purpose of this report is the describe the proceedings from the workshop and provide recommendations from the workshop's roundtable discussion. The workshop was broken down into two main areas: (1) Energy efficient boiler house steam generation; and Energy efficient steam distribution and consumption. The workshop also covered the following topics: (1) Ukrainian boilers; (2) Water treatment systems; (3) A profile of UKRESCO (Ukrainian Energy Services Company); (4) Turbine expanders and electricity generation; (5) Enterprise energy audit basics; and (6) Experience of steam use in Donetsk oblast.

  12. Steam generator tube failures

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  13. Disinfection and sterilization: an overview.

    Science.gov (United States)

    Rutala, William A; Weber, David J

    2013-05-01

    All invasive procedures involve contact by a medical device or surgical instrument with a patient's sterile tissue or mucous membranes. The level of disinfection or sterilization is dependent on the intended use of the object: critical (items that contact sterile tissue such as surgical instruments), semicritical (items that contact mucous membrane such as endoscopes), and noncritical (devices that contact only intact skin such as stethoscopes) items require sterilization, high-level disinfection, and low-level disinfection, respectively. Cleaning must always precede high-level disinfection and sterilization.

  14. A contribution to the modelling of steam reformers for natural gas fuelled fuel cell heating systems; Ein Beitrag zur Modellierung von Dampfreformern fuer erdgasbetriebene Brennstoffzellenheizgeraete

    Energy Technology Data Exchange (ETDEWEB)

    Nietzsche, Joerg

    2010-10-29

    The author attempted to verify the assumptions and simplifications of common mathematical models of small-scale steam reformers. The emphasis was on the derivation of important model parameters on the basis of easily identifiable catalyst, fluid and reactor characteristics. An easily validated 2D model of a reformer tube is then used for a wide sensitivity analysis and a comparative investigation of various reactor types. [German] Die Motivation dieser Arbeit liegt in der Ueberpruefung der bislang in mathematischen Modellen von kleintechnischen Dampfreformern getroffenen Annahmen und Vereinfachungen, mit speziellem Augenmerk auf die Aufklaerung der Herkunft wichtiger Modellparameter anhand von leicht bestimmbaren Katalysator-, Fluid- und Reaktoreigenschaften. Ein leicht zu validierendes, zweidimensionales Modell eines Reformerrohres soll im Anschluss fuer eine breit angelegte Sensitivitaetsanalyse und eine vergleichende Untersuchung verschiedener Reaktortypen dienen.

  15. Thermoelastic steam turbine rotor control based on neural network

    Science.gov (United States)

    Rzadkowski, Romuald; Dominiczak, Krzysztof; Radulski, Wojciech; Szczepanik, R.

    2015-12-01

    Considered here are Nonlinear Auto-Regressive neural networks with eXogenous inputs (NARX) as a mathematical model of a steam turbine rotor for controlling steam turbine stress on-line. In order to obtain neural networks that locate critical stress and temperature points in the steam turbine during transient states, an FE rotor model was built. This model was used to train the neural networks on the basis of steam turbine transient operating data. The training included nonlinearity related to steam turbine expansion, heat exchange and rotor material properties during transients. Simultaneous neural networks are algorithms which can be implemented on PLC controllers. This allows for the application neural networks to control steam turbine stress in industrial power plants.

  16. [Cost management: the implementation of the activity-based costing method in sterile processing department].

    Science.gov (United States)

    Jericó, Marli de Carvalho; Castilho, Valéria

    2010-09-01

    This exploratory case study was performed aiming at implementing the Activity-based Costing (ABC) method in a sterile processing department (SPD) of a major teaching hospital. Data collection was performed throughout 2006. Documentary research techniques and non participant closed observation were used. The ABC implementation allowed for learning the activity-based costing of both the chemical and physical disinfection cycle/load: (dollar 9.95) and (dollar 12.63), respectively; as well as the cost for sterilization by steam under pressure (autoclave) (dollar 31.37) and low temperature steam and gaseous formaldehyde sterilization (LTSF) (dollar 255.28). The information provided by the ABC method has optimized the overall understanding of the cost driver process and provided the foundation for assessing performance and improvement in the SPD processes.

  17. The general equilibrium model: static or sterile? El modelo de equilibrio general: ¿estático o estéril?

    Directory of Open Access Journals (Sweden)

    Cataño José Félix

    1997-12-01

    Full Text Available The Arrow-Debreu model is, of course, a static model; however, that is not its main weakness. This article tries to show that the
    interpretation of Lozano, Villa, and Monsalve about the extent and the content of this model contains some errors which hide the sterility of the Arrow-Debreu Model-- that is, its incapacity to resolve the problem which gave rise to it: the coordination of independent individuals in a static and perfect market.El modelo de Arrow y Debreu es, por supuesto, un modelo estático: sin embargo, ésta no es su principal debilidad. Este artículo intenta demostrar que la interpretación de Lozano, Villa y Monsalve acerca del alcance y contenido de este modelo contiene algunos errores que ocultan la esterilidad del Modelos Arrow-Debreu, es decir, su incapacidad para resolver el problema que lo originó: la coordinación de los individuos independientes en un mercado estático y perfecto.

  18. Sterilization by oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Adir Jose; Mansano, Ronaldo Domingues; Andreoli Pinto, Terezinha de Jesus; Ruas, Ronaldo; Silva Zambon, Luis da; Silva, Monica Valero da; Verdonck, Patrick Bernard

    2004-07-31

    The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site and it also affects the bulk properties of the polymers. The use of a gas plasma is an elegant alternative sterilization technique. The plasma promotes an efficient inactivation of the micro-organisms, minimises the damage to the materials and presents very little danger for personnel and the environment. Pure oxygen reactive ion etching type of plasmas were applied to inactivate a biologic indicator, the Bacillus stearothermophilus, to confirm the efficiency of this process. The sterilization processes took a short time, in a few minutes the mortality was complete. In situ analysis of the micro-organisms' inactivating time was possible using emission spectrophotometry. The increase in the intensity of the 777.5 nm oxygen line shows the end of the oxidation of the biologic materials. The results were also observed and corroborated by scanning electron microscopy.

  19. Surface characterization of titanium alloys sterilized for biomedical applications

    Science.gov (United States)

    Hernández de Gatica, Norma L.; Jones, Gary L.; Gardella, Joseph A.

    1993-05-01

    The high biocompatibility of Ti and Ti-based implants is closely related to the properties of the surface oxide formed during the implant preparation stages. During the machining process, the metal is exposed to the ambient atmosphere and oxidized. This surface oxide layer may be modified during the subsequent implant preparation steps: cleaning and sterilization. In this study, surface elemental and chemical information as well as the thickness of the oxide layer are evaluated for the Ti-6Al-4V alloy before and after different sterilization procedures: UV radiation, steam autoclaving, and radio-frequency glow-discharge (RFGD) treatment in argon atmosphere. The analytical techniques used are: X-ray photoelectron spectroscopy (XPS or ESCA) and the scanning Auger microprobe (SAM). The results of this study indicate that among steam autoclaving, UV radiation and RFGD treatment, the latter yields cleaner surfaces. Also, depth profiles of the specimens treated with RFGD in argon showed an increase in the oxide layer thickness with respect to the values observed for non-sterilized samples.

  20. Gene, protein and network of male sterility in rice

    Directory of Open Access Journals (Sweden)

    Wang eKun

    2013-04-01

    Full Text Available Rice is one of the most important model crop plants whose heterosis has been well exploited in commercial hybrid seed production via a variety of types of male sterile lines. Hybrid rice cultivation area is steadily expanding around the world, especially in Southern Asia. Characterization of genes and proteins related to male sterility aims to understand how and why the male sterility occurs, and which proteins are the key players for microspores abortion. Recently, a series of genes and proteins related to cytoplasmic male sterility, photoperiod sensitive male sterility, self-incompatibility and other types of microspores deterioration have been characterized through genetics or proteomics. Especially the latter, offers us a powerful and high throughput approach to discern the novel proteins involving in male-sterile pathways which may help us to breed artificial male-sterile system. This represents an alternative tool to meet the critical challenge of further development of hybrid rice. In this paper, we reviewed the recent developments in our understanding of male sterility in rice hybrid production across gene, protein and integrated network levels, and also, present a perspective on the engineering of male sterile lines for hybrid rice production.

  1. Gene, protein, and network of male sterility in rice.

    Science.gov (United States)

    Wang, Kun; Peng, Xiaojue; Ji, Yanxiao; Yang, Pingfang; Zhu, Yingguo; Li, Shaoqing

    2013-01-01

    Rice is one of the most important model crop plants whose heterosis has been well-exploited in commercial hybrid seed production via a variety of types of male-sterile lines. Hybrid rice cultivation area is steadily expanding around the world, especially in Southern Asia. Characterization of genes and proteins related to male sterility aims to understand how and why the male sterility occurs, and which proteins are the key players for microspores abortion. Recently, a series of genes and proteins related to cytoplasmic male sterility (CMS), photoperiod-sensitive male sterility, self-incompatibility, and other types of microspores deterioration have been characterized through genetics or proteomics. Especially the latter, offers us a powerful and high throughput approach to discern the novel proteins involving in male-sterile pathways which may help us to breed artificial male-sterile system. This represents an alternative tool to meet the critical challenge of further development of hybrid rice. In this paper, we reviewed the recent developments in our understanding of male sterility in rice hybrid production across gene, protein, and integrated network levels, and also, present a perspective on the engineering of male-sterile lines for hybrid rice production.

  2. Polymer electrolyte membrane fuel cell grade hydrogen production by methanol steam reforming: A comparative multiple reactor modeling study

    Science.gov (United States)

    Katiyar, Nisha; Kumar, Shashi; Kumar, Surendra

    2013-12-01

    Analysis of a fuel processor based on methanol steam reforming has been carried out to produce fuel cell grade H2. Six reactor configurations namely FBR1 (fixed bed reactor), MR1 (H2 selective membrane reactor with one reaction tube), MR2 (H2 selective membrane reactor with two reaction tubes), FBR2 (FBR1 + preferential CO oxidation (PROX) reactor), MR3 (MR1 + PROX), and MR4 (MR2 + PROX) are evaluated by simulation to identify the suitable processing scheme. The yield of H2 is significantly affected by H2 selective membrane, residence time, temperature, and pressure conditions at complete methanol conversion. The enhancement in residence time in MR2 by using two identical reaction tubes provides H2 yield of 2.96 with 91.25 mol% recovery at steam/methanol ratio of 1.5, pressure of 2 bar and 560 K temperature. The exit retentate gases from MR2 are further treated in PROX reactor of MR4 to reduce CO concentration to 4.1 ppm to ensure the safe discharge to the environment. The risk of carbon deposition on reforming catalyst is highly reduced in MR4, and MR4 reactor configuration generates 7.4 NL min-1 of CO free H2 from 0.12 mol min-1 of methanol which can provide 470 W PEMFC feedstock requirement. Hence, process scheme in MR4 provides a compact and innovative fuel cell grade H2 generating unit.

  3. Pulsar Kicks With Sterile Neutrinos and Landau Levels

    CERN Document Server

    Kisslinger, Leonard S; Johnson, Mikkel B

    2007-01-01

    We use a model with two sterile neutrinos obtained by fits to the MiniBoone and LSND experiments. Using formulations with neutrinos created by URCA Processes in a strong magnetic field, so the lowest Landau level has a sizable probability, we find that with known paramenters the assymetric sterile neutrino emissivity might account for large pulsar kicks.

  4. Numerical simulation in steam injection process by a mechanistic approach

    Energy Technology Data Exchange (ETDEWEB)

    De Souza, J.C.Jr.; Campos, W.; Lopes, D.; Moura, L.S.S. [Petrobras, Rio de Janeiro (Brazil)

    2008-10-15

    Steam injection is a common thermal recovery method used in very viscous oil reservoirs. The method involves the injection of heat to reduce viscosity and mobilize oil. A steam generation and injection system consists primarily of a steam source, distribution lines, injection wells and a discarding tank. In order to optimize injection and improve the oil recovery factor, one must determine the parameters of steam flow such as pressure, temperature and steam quality. This study focused on developing a unified mathematical model by means of a mechanistic approach for two-phase steam flow in pipelines and wells. The hydrodynamic and heat transfer mechanistic model was implemented in a computer simulator to model the parameters of steam injection while trying to avoid the use of empirical correlations. A marching algorithm was used to determine the distribution of pressure and temperature along the pipelines and wellbores. The mathematical model for steam flow in injection systems, developed by a mechanistic approach (VapMec) performed well when the simulated values of pressures and temperatures were compared with the values measured during field tests. The newly developed VapMec model was incorporated in the LinVap-3 simulator that constitutes an engineering supporting tool for steam injection wells operated by Petrobras. 23 refs., 7 tabs., 6 figs.

  5. Evaluation of different sterilization and disinfection methods on commercially made preformed crowns

    Directory of Open Access Journals (Sweden)

    Yilmaz Y

    2008-01-01

    Full Text Available The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM. Preformed crowns (NuSmile Primary Anterior Crown (NSC, Kinder Krowns (KK, Pedo Pearls (PP and polycarbonate crowns (PC were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group; steam autoclaving at 134 °C (30 psi for 4 min (G2; steam autoclaving at 134 °C (30 psi for 12 min (G3; steam autoclaving at 121 °C (15 psi for 30 min (G4; and ultrasonication in a bath containing 4% Lysetol ® AF for 5 min at room temperature (chemical disinfection (G5. Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05 crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients.

  6. Evaluation of different sterilization and disinfection methods on commercially made preformed crowns.

    Science.gov (United States)

    Yilmaz, Y; Guler, C

    2008-12-01

    The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM). Preformed crowns (NuSmile Primary Anterior Crown (NSC), Kinder Krowns (KK), Pedo Pearls (PP) and polycarbonate crowns (PC)) were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group); steam autoclaving at 134 degrees C (30 psi) for 4 min (G2); steam autoclaving at 134 degrees C (30 psi) for 12 min (G3); steam autoclaving at 121 degrees C (15 psi) for 30 min (G4); and ultrasonication in a bath containing 4% Lysetol AF for 5 min at room temperature (chemical disinfection) (G5). Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05) crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients.

  7. Doppler method leak detection for LMFBR steam generators. Pt. 2. Detection characteristics of bubble in-water using large scale SG model

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab

    2000-06-01

    To prevent the expansion of tube damage and to maintain structural integrity in the steam generators (SGs) of a fast breeder reactor (FBR), it is necessary to detect precisely and immediately the leakage of water from heat transfer tubes. Therefore, an active acoustic method was developed. Previous studies have revealed that, in practical steam generators, the active acoustic method can detect bubbles of 10 l/s within 10 seconds. However to prevent the expansion of damage to neighboring tubes, it is necessary to detect smaller leakages of water from the heat transfer tubes. The Doppler method is designed to detect small leakages and to find the source of a leak before damage spreads to neighboring tubes. The detection sensitivity of the Doppler method and the influence of background noise were investigated experimentally. In-water experiments were performed using an SG full-sector model that simulates actual SGs. The results show that the Doppler method can detect bubbles of 0.1 l/s (equivalent to a water leak rate of about 0.1 g/s) within a few seconds and that the background noise has little effect on water leak detection performance. The Doppler method thus has great potential for the detection of water leakage in SGs. (author)

  8. Sterile Neutrinos: An Introduction to Experiments

    CERN Document Server

    Conrad, J M

    2016-01-01

    This paper is written as one chapter in a collection of essays on neutrino physics for beginning graduate students. The text presents important experimental methods and issues for those interested in searches for sterile neutrinos. Other essays in the collection, written by other authors, will cover introduction to neutrinos in the Standard Model, a description of the theory, and discussion of details of detectors, thus these aspects are not covered here. However, beyond these points, this represents a self-contained tutorial on experimental studies of sterile neutrino oscillations, covering such issues as signals vs. limits, designing experiments, and performing and interpreting global fits to the oscillation data.

  9. Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles.

    Science.gov (United States)

    Neumann, Oara; Feronti, Curtis; Neumann, Albert D; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J

    2013-07-16

    The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator.

  10. Cytoplasmic Male Sterility in Maize

    Institute of Scientific and Technical Information of China (English)

    RONG Ting-zhao; LI Wan-chen; CAO Mo-ju; HU Chang-yuan

    2002-01-01

    14 isoplasmic and allonuclear cytoplasmic male sterile lines were used as female parents, 8 tester lines as male parents, 101 F1 progenies were obtained. Fertility restoration response of 101 F1 progenies were investigated through field observation and pollen stainability examination under microscope. 14 isoplasmic and allonuclear cytoplasmic male sterile lines were developed by repeated backcross with recurrent male parent lines for more than 8 generations. The result shows: tester line Zifeng1 not only restored the isoplasmic and allonuclear sterile lines of group C backcrossed with Mo17, Yu30 and Heer, but also completely restored the isoplasmic and allonuclear cytoplasm male sterile lines of group T backcrossed with Mo17, HZS , 1792 ,292 and Yu30. Therefore, nuclear background limits the use of Zifeng1 as a tester for identification of cytoplasmic male sterility. Furthermore RFLPs of mitochondrial DNA of 6 isonuclear and alloplasmic cytoplasmic male sterile lines were analyzed with Bam H Ⅰ and Hind Ⅲ restriction endonuclease and mitochondrial DNA probes pBcmH3 and Cox Ⅱ. The same RFLPs were found within sterile cytoplasm of group C, including C,Chuan G, Lei 2 and Lei 3, but a different RFLP pattern was observed among sterile cytoplasm of group S, C,T and the normal cytoplasm. This result suggested that the RFLP markers tightly linked to sterile mitochondrial genes of different groups could be applied in the identifcation of cytoplasmic male sterility.

  11. Effect of the sterilization method on the properties of Bombyx mori silk fibroin films

    Energy Technology Data Exchange (ETDEWEB)

    George, Karina A. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059 (Australia); Shadforth, Audra M.A. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Chirila, Traian V., E-mail: traian.chirila@qei.org.au [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, 4072 (Australia); Faculty of Health Sciences, University of Queensland, Herston, Queensland 4006 (Australia); Faculty of Science and Engineering, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Laurent, Matthieu J. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Ecole Superieure d' Ingenieurs de Luminy (ESIL), Universite de la Mediterranee Aix-Marseille II, Luminy case 925 13288, Marseille, Cedex 09 (France); Stephenson, Sally-Anne [Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059 (Australia); Faculty of Health, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Edwards, Grant A. [Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, 4072 (Australia); Madden, Peter W. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Faculty of Health Sciences, University of Queensland, Herston, Queensland 4006 (Australia); and others

    2013-03-01

    We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method. - Highlights: Black-Right-Pointing-Pointer The effects of four methods of sterilization on the properties of silk fibroin films were investigated. Black-Right-Pointing-Pointer Steam treatment leads to stiffer films but to lower transparency and variable surface topography. Black-Right-Pointing-Pointer Degradation of fibroin is enhanced in the films that were gamma-irradiated. Black-Right-Pointing-Pointer The effects on mechanical properties are explained through changes in both primary and secondary structure of fibroin. Black-Right-Pointing-Pointer Gamma-irradiation and immersion in aqueous ethanol are suggested as preferred methods of sterilization.

  12. Electric dipole moments of charged leptons with sterile fermions

    CERN Document Server

    Abada, Asmaa

    2016-01-01

    We address the impact of sterile fermions on charged lepton electric dipole moments. We show that in order to have a non-vanishing contribution to electric dipole moments, the minimal extension necessitates the addition of at least two sterile fermion states. Sterile neutrinos can give significant contributions to the charged lepton electric dipole moments if the masses of the non-degenerate sterile states are both above the electroweak scale. In addition, the Majorana nature of neutrinos is also important. Furthermore, we apply the computations of the electric dipole moments for the most minimal realisation of the Inverse Seesaw mechanism, in which the Standard Model is extended by two right-handed neutrinos and two sterile fermion states. We show that the two pairs of (heavy) pseudo-Dirac mass eigenstates can give significant contributions to the electron electric dipole moment, lying close to future experimental sensitivity. We further discuss the possibility of beyond the minimal Inverse Seesaw models and...

  13. Sterile neutrinos with pseudoscalar self-interactions and cosmology

    CERN Document Server

    Archidiacono, Maria; Hansen, Rasmus Sloth; Tram, Thomas

    2015-01-01

    Sterile neutrinos in the electronvolt mass range are hinted at by a number of terrestrial neutrino experiments. However, such neutrinos are highly incompatible with data from the Cosmic Microwave Background and large scale structure. This paper discusses how charging sterile neutrinos under a new pseudoscalar interaction can reconcile eV sterile neutrinos with terrestrial neutrino data. We show that this model can reconcile eV sterile neutrinos in cosmology, providing a fit to all available data which is way better than the standard $\\Lambda$CDM model with one additional fully thermalized sterile neutrino. In particular it also prefers a value of the Hubble parameter much closer to the locally measured value.

  14. Modeling Cyclic Fatigue Hysteresis Loops of 2D Woven Ceramic Matrix Composites at Elevated Temperatures in Steam

    Directory of Open Access Journals (Sweden)

    Longbiao Li

    2016-05-01

    Full Text Available In this paper, the cyclic fatigue hysteresis loops of 2D woven SiC/SiC ceramic matrix composites (CMCs at elevated temperatures in steam have been investigated. The interface slip between fibers and the matrix existing in matrix cracking modes 3 and 5, in which matrix cracking and interface debonding occurred in longitudinal yarns, is considered as the major reason for hysteresis loops of 2D woven CMCs. The hysteresis loops of 2D SiC/SiC composites corresponding to different peak stresses, test conditions, and loading frequencies have been predicted using the present analysis. The damage parameter, i.e., the proportion of matrix cracking mode 3 in the entire matrix cracking modes of the composite, and the hysteresis dissipated energy increase with increasing fatigue peak stress. With increasing cycle number, the interface shear stress in the longitudinal yarns decreases, leading to transition of interface slip types of matrix cracking modes 3 and 5.

  15. Simulation Model for Stochastic Analysis and Performance Evaluation of Steam Generator System of a Thermal Power Plant

    Directory of Open Access Journals (Sweden)

    Yogesh Vora,

    2011-06-01

    Full Text Available This paper presents the stochastic analysis and performance evaluation of turbo generator system of a thermal plant by making the use of performance evaluation using probabilistic approach. The steam generator system of thermal power plant under the research study consists mainly sub-systems boiler, super heater and reheaterarranged in series with two feasible states: working and failed. Failure and repair rates for all the sub-systems are assumed to be constant. Initially transition diagram representing the operational behavior is drawn and then problem formulation is done using Markov approach. Based on the data collection and its analysis for thermal Power Plant, Performance matrix for each subsystem is also developed. Then from these results, availability matrices and graphs of failure and repair rates for maximum availability of each system is analysed and then condition based maintenance decisions are decided.

  16. Sterile neutrinos: fact or fiction?

    Science.gov (United States)

    Huber, Patrick

    2017-01-01

    In this talk I will critically review some of the anomalies which in combination could point to the existence of a eV-scale sterile neutrino. Each of these anomalies is well below the 5 sigma level individually and may have explanations besides sterile neutrinos. At the same time each anomaly requires a separate explanation if it is not caused by a sterile neutrino. To further complicate the gpicture, some data sets are in mutual disagreement.

  17. Diluted equilibrium sterile neutrino dark matter

    Science.gov (United States)

    Patwardhan, Amol V.; Fuller, George M.; Kishimoto, Chad T.; Kusenko, Alexander

    2015-11-01

    We present a model where sterile neutrinos with rest masses in the range ˜keV to ˜MeV can be the dark matter and be consistent with all laboratory, cosmological, and large-scale structure, as well as x-ray constraints. These sterile neutrinos are assumed to freeze out of thermal and chemical equilibrium with matter and radiation in the very early Universe, prior to an epoch of prodigious entropy generation ("dilution") from out-of-equilibrium decay of heavy particles. In this work, we consider heavy, entropy-producing particles in the ˜TeV to ˜EeV rest-mass range, possibly associated with new physics at high-energy scales. The process of dilution can give the sterile neutrinos the appropriate relic densities, but it also alters their energy spectra so that they could act like cold dark matter, despite relatively low rest masses as compared to conventional dark matter candidates. Moreover, since the model does not rely on active-sterile mixing for producing the relic density, the mixing angles can be small enough to evade current x-ray or lifetime constraints. Nevertheless, we discuss how future x-ray observations, future lepton number constraints, and future observations and sophisticated simulations of large-scale structure could, in conjunction, provide evidence for this model and/or constrain and probe its parameters.

  18. The influence of sterilization processes on the micromechanical properties of carbon fiber-reinforced PEEK composites for bone implant applications.

    Science.gov (United States)

    Godara, A; Raabe, D; Green, S

    2007-03-01

    The effect of sterilization on the structural integrity of the thermoplastic matrix composite polyetheretherketone (PEEK) reinforced with carbon fibers (CF) is investigated by nanoindentation and nanoscratch tests. The use of the material as a medical implant grade requires a detailed understanding of the micromechanical properties which primarily define its in vivo behavior. Sterilization is a mandatory process for such materials used in medical applications like bone implants. The steam and gamma radiation sterilization processes employed in this study are at sufficient levels to affect the micromechanical properties of some polymer materials, particularly in the interphase region between the polymer matrix and the reinforcing fibers. Nanoindentation and nanoscratch tests are used in this work to reveal local gradients in the hardness and the elastic properties of the interphase regions. Both methods help to explore microscopic changes in the hardness, reduced stiffness and scratch resistance in the interphase region and in the bulk polymer matrix due to the different sterilization processes employed. The results reveal that neither steam nor gamma radiation sterilization entails significant changes of the reduced elastic modulus, hardness or coefficient of friction in the bulk polymer matrix. However, minor material changes of the PEEK matrix were observed in the interphase region. Of the two sterilization methods used, the steam treatment has a more significant influence on these small changes in this region and appears to increase slightly the thickness of the interphase zone.

  19. New disinfection and sterilization methods.

    Science.gov (United States)

    Rutala, W. A.; Weber, D. J.

    2001-01-01

    New disinfection methods include a persistent antimicrobial coating that can be applied to inanimate and animate objects (Surfacine), a high-level disinfectant with reduced exposure time (ortho-phthalaldehyde), and an antimicrobial agent that can be applied to animate and inanimate objects (superoxidized water). New sterilization methods include a chemical sterilization process for endoscopes that integrates cleaning (Endoclens), a rapid (4-hour) readout biological indicator for ethylene oxide sterilization (Attest), and a hydrogen peroxide plasma sterilizer that has a shorter cycle time and improved efficacy (Sterrad 50). PMID:11294738

  20. Steam treatment of volcanic cinder media for the eradication of Rotylenchulus reniformis

    Science.gov (United States)

    Volcanic cinder has historically been free of plant parasitic nematodes. The recent contamination of cinder media by Rotylenchulus reniformis in Hawaii necessitates growers to steam sterilize cinder used in potted plant exports. Certification requirements call for the center of the media to reach ...

  1. In-flight cLFV conversion. e - μ, e - τ and μ - τ in minimal extensions of the standard model with sterile fermions

    Energy Technology Data Exchange (ETDEWEB)

    Abada, A. [CNRS, Univ. Paris-Sud, Universite Paris-Saclay, Laboratoire de Physique Theorique, Orsay (France); Romeri, V. de [IFT-UAM/CSIC, Universidad Autonoma de Madrid, Departamento de Fisica Teorica and Instituto de Fisica Teorica, Madrid (Spain); Orloff, J.; Teixeira, A.M. [Laboratoire de Physique Corpusculaire, CNRS/IN2P3-UMR 6533, Aubiere (France)

    2017-05-15

    We revisit charged lepton flavour in-flight conversions, in which a beam of electrons or muons is directed onto a fixed target, e + N → μ + N, e + N → τ + N and μ + N → τ + N, focusing on elastic interactions with a nucleus N. After a general discussion of this observable, we carry a full phenomenological analysis in the framework of minimal Standard Model extensions via sterile neutrinos, with a strong emphasis on the role of the increasingly more stringent constraints arising from other (low-energy) charged lepton flavour-violation observables. Despite the potential interest of this observable, in particular in the light of certain upcoming facilities with the capability of very intense lepton beams, our study suggests that due to current bounds on three-body decays (l{sub i} → 3l{sub j}) and μ - e conversion in nuclei, the expected number of conversions in such a minimal framework is dramatically reduced. An experimental observation of such a conversion would thus signal the presence of another source of flavour violation, possibly at tree level. (orig.)

  2. The effects of inbreeding and heat stress on male sterility in Drosophila melanogaster

    DEFF Research Database (Denmark)

    Pedersen, Louise Dybdahl; Pedersen, Asger Roer; Bijlsma, Kuke

    2011-01-01

    in benign and stressful environments using Drosophila melanogaster as a model organism. Male sterility was compared in 21 inbred lines and five non-inbred control lines at 25.0 and 29.0 °C. The effect of inbreeding on sterility was significant only at 29.0 °C. This stress-induced increase in sterility...

  3. Development of a water leak detection system for LMFBR steam generator. Pt. 3. Experimental results for detection of bubbles using the SG sector model

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi; Yoshida, Kazuo [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab.

    1995-05-01

    In order to prevent the expansion of tube damages and to maintain structural safety in steam generators (SG) of liquid metal fast breeder reactor (LMFBR), it is necessary to detect precisely and immediately the leakage of water from tubes of heat exchangers. The active acoustic detection method, which detects the sound attenuation due to bubbles generated at the sodium-water reactions, has drawn general interests owing to its short response time and reduction of the influence of background noise. Sound attenuation is also subjected to structures such as heat transfer tubes and shrouds. Accordingly, it is necessary to evaluate the sound attenuation due to structures. However, studies in these respects are very few. In this paper, using the water bath and SG sector model, the attenuation characteristics of sounds due to flat plates and heat transfer tubes are investigated under various conditions and discussed. (author).

  4. Diluted Equilibrium Sterile Neutrino Dark Matter

    CERN Document Server

    Patwardhan, Amol V; Kishimoto, Chad T; Kusenko, Alexander

    2015-01-01

    We present a model where sterile neutrinos with rest masses in the range ~ keV to ~ MeV can be the dark matter and be consistent with all laboratory, cosmological, large scale structure, and X-ray constraints. These sterile neutrinos are assumed to freeze out of thermal and chemical equilibrium with matter and radiation in the very early universe, prior to an epoch of prodigious entropy generation ("dilution") from out-of-equilibrium decay of heavy particles. In this work, we consider heavy, entropy-producing particles in the ~ TeV to ~ EeV rest mass range, possibly associated with new physics at high energy scales. The process of dilution can give the sterile neutrinos the appropriate relic densities, but it also alters their energy spectra so that they could act like cold dark matter, despite relatively low rest masses as compared to conventional dark matter candidates. Moreover, since the model does not rely on active-sterile mixing for producing the relic density, the mixing angles can be small enough to ...

  5. Thermal hydraulic studies in steam generator test facility

    Energy Technology Data Exchange (ETDEWEB)

    Vinod, V.; Suresh Kumar, V.A.; Noushad, I.B.; Ellappan, T.R.; Rajan, K.K.; Rajan, M.; Vaidyanathan, G. [Engineering Development Group Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2005-07-01

    Full text of publication follows: A 500 MWe fast breeder reactor is being constructed at Kalpakkam, India. This is a sodium cooled reactor with two primary and two secondary sodium loops with total 8 steam generators. The typical advantage of fast breeder plants is the high operating temperature of steam cycles and the high plant efficiency. To produce this high pressure and high temperature steam, once through straight tube vertical sodium heated steam generators are used. The steam is generated from the heat produced in the reactor core and being transported through primary and secondary sodium circuits. The steam generator is a 25 m high middle supported steam generator with expansion bend and 23 m heat transfer length. Steam Generator Test Facility (SGTF) constructed at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam aims at performing various tests on a 5.5 MWt steam generator. This vertically simulated test article is similar in all respects to the proposed 157 MWt steam generator module for the Prototype Fast Breeder Reactor (PFBR), with reduced number of tubes. Heat transfer performance tests are done with this 19 tube steam generator at various load conditions. Sodium circuit for the SGTF is equipped with oil fired heater as heat source and centrifugal sodium pump, to pump sodium at 105 m{sup 3}/hr flow rate. Other typical components like sodium to air heat exchanger, sodium purification system and hydrogen leak detection system is also present in the sodium circuit. High pressure steam produced in the steam generator is dumped in a condenser and recycled. Important tests planned in SGTF are the heat transfer performance test, stability test, endurance test and performance test of steam generator under various transients. The controlled operation of steam generator will be studied with possible control schemes. A steady state simulation of the steam generator is done with a mathematical model. This paper gives the details of heat transfer

  6. The nuclear power steam turbine modeling based on modular method%基于模块化方法的核动力汽轮机建模

    Institute of Scientific and Technical Information of China (English)

    余海燕; 杨永强; 汪伟

    2011-01-01

    汽轮机为核动力装置二回路系统重要部件,对整个系统的特性具有重要影响.根据模块化建模思想,将汽轮机划分为通用子模块,主要包括流动阻力型模块、流动存储型模块和转子模块.建立这些通用子模块的详细数学模型,利用不同模块的组合可以开发多种类型的汽轮机,提高汽轮机建模的效率.计算结果表明,建立的汽轮机模型可以满足大工况变动要求,为模拟整个核动力装置二回路系统提供可靠基础.%The steam turbine is an important component of the nuclear power plant second loop system,which has great influence on the characteristic of the power system.According to the modular method, the turbine is divided into some general sub modules, which mainly consist of the fluid resislive module,the fluid storage module and the rotational module.The advantage is that various turbines can he developed througb the assembly of the differenl modules,which improves the efficiency of steam turbine modeling.The results show that the models developed can successfully simulate the large disturbance transient process,and can provide reliable basis to simulate whole nuclear power plant second loop system.

  7. Influence of different sterilization processes on the properties of commercial poly(lactic acid).

    Science.gov (United States)

    Savaris, M; Santos, V Dos; Brandalise, R N

    2016-12-01

    This study aims at analyzing the modifications in the morphological, physical, chemical and thermal properties of commercial poly(lactic acid) (PLA) films after exposure to five different sterilization processes. Films were obtained by compression molding, hygienized and sterilized by ethylene oxide (SEtO), hydrogen peroxide plasma (SH2O2), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLASEtO, PLASH2O2, PLASEB and PLASGR exhibited thermal and physical changes after being submitted to sterilization processes. PLASSS showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH2O2, SEB and EGR can be applied for the sterilization of PLA films and the SSS process is not recommended in view of the data obtained and test conditions reported in this study for PLA films.

  8. [Monitoring the physical processes of sterilization in hospitals in the state of Goiás].

    Science.gov (United States)

    Tipple, Anaclara Ferreira Veiga; Pires, Francine Vieira; Guadagnin, Simone Vieira Toledo; Melo, Dulcelene de Sousa

    2011-06-01

    The objective of this descriptive study was to identify the physical, chemical and biological controls of the sterilization process by saturated steam in Pasteur autoclaves at Material and Sterilization Centers (MSC). The data was obtained by interviewing the worker responsible for the MSC of the largest hospital in every city in the interior of Goiás that had population of at least 20,000, in the period from August 2005 to June 2006. A total 44 municipalities participated. The analysis was performed using SPSS software. In 31 (94.0%) hospitals there were no nurses exclusive to the MSC, the workers responsible for the center were nursing aides and technicians. Most did not perform any physical, chemical and biological control of the sterilization process, and, in one case only these controls were performed simultaneously. Failing to monitor the sterilization cycles, and thus not ensuring the quality of the processes, is a risk to the population being assisted.

  9. High performance steam development

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, T.; Schneider, P. [Solar Turbines Inc., San Diego, CA (United States)

    1995-10-01

    Over 30 years ago U.S. industry introduced the world`s highest temperature (1200{degrees}F at 5000 psig) and most efficient power plant, the Eddystone coal-burning steam plant. The highest alloy material used in the plant was 316 stainless steel. Problems during the first few years of operation caused a reduction in operating temperature to 1100{degrees}F which has generally become the highest temperature used in plants around the world. Leadership in high temperature steam has moved to Japan and Europe over the last 30 years.

  10. STEAM GENERATOR GROUP PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Clark, R. A.; Lewis, M

    1985-09-01

    This report is a summary of progress in the Surry Steam Generator Group Project for 1984. Information is presented on the analysis of two baseline eddy current inspections of the generator. Round robin series of tests using standard in-service inspection techniques are described along with some preliminary results. Observations are reported of degradation found on tubing specimens removed from the generator, and on support plates characterized in-situ. Residual stresses measured on a tubing specimen are reported. Two steam generator repair demonstrations are described; one for antivibration bar replacement, and one on tube repair methods. Chemical analyses are shown for sludge samples removed from above the tube sheet.

  11. Conditional sterility in plants

    Science.gov (United States)

    Meagher, Richard B.; McKinney, Elizabeth; Kim, Tehryung

    2010-02-23

    The present disclosure provides methods, recombinant DNA molecules, recombinant host cells containing the DNA molecules, and transgenic plant cells, plant tissue and plants which contain and express at least one antisense or interference RNA specific for a thiamine biosynthetic coding sequence or a thiamine binding protein or a thiamine-degrading protein, wherein the RNA or thiamine binding protein is expressed under the regulatory control of a transcription regulatory sequence which directs expression in male and/or female reproductive tissue. These transgenic plants are conditionally sterile; i.e., they are fertile only in the presence of exogenous thiamine. Such plants are especially appropriate for use in the seed industry or in the environment, for example, for use in revegetation of contaminated soils or phytoremediation, especially when those transgenic plants also contain and express one or more chimeric genes which confer resistance to contaminants.

  12. Optimizing sterilization logistics in hospitals.

    Science.gov (United States)

    van de Klundert, Joris; Muls, Philippe; Schadd, Maarten

    2008-03-01

    This paper deals with the optimization of the flow of sterile instruments in hospitals which takes place between the sterilization department and the operating theatre. This topic is especially of interest in view of the current attempts of hospitals to cut cost by outsourcing sterilization tasks. Oftentimes, outsourcing implies placing the sterilization unit at a larger distance, hence introducing a longer logistic loop, which may result in lower instrument availability, and higher cost. This paper discusses the optimization problems that have to be solved when redesigning processes so as to improve material availability and reduce cost. We consider changing the logistic management principles, use of visibility information, and optimizing the composition of the nets of sterile materials.

  13. Pseudoscalar - sterile neutrino interactions: reconciling the cosmos with neutrino oscillations

    CERN Document Server

    Archidiacono, Maria; Giunti, Carlo; Hannestad, Steen; Hansen, Rasmus; Laveder, Marco; Tram, Thomas

    2016-01-01

    The Short BaseLine (SBL) neutrino oscillation anomalies hint at the presence of a sterile neutrino with a mass of around 1 eV. However, such a neutrino is incompatible with cosmological data, in particular observations of the Cosmic Microwave Background (CMB) anisotropies. However, this conclusion can change by invoking new physics. One possibility is to introduce a secret interaction in the sterile neutrino sector mediated by a light pseudoscalar. In this pseudoscalar model, CMB data prefer a sterile neutrino mass that is fully compatible with the mass ranges suggested by SBL anomalies. In addition, this model predicts a value of the Hubble parameter which is completely consistent with local measurements.

  14. Steam microturbines in distributed cogeneration

    CERN Document Server

    Kicinski, Jan

    2014-01-01

    This book presents the most recent trends and concepts in power engineering, especially with regard to prosumer and civic energy generation. In so doing, it draws widely on his experience gained during the development of steam microturbines for use in small combined heat and power stations based on the organic Rankine cycle (CHP-ORC). Major issues concerning the dynamic properties of mechanical systems, in particular rotating systems, are discussed, and the results obtained when using unconventional bearing systems, presented. Modeling and analysis of radial-flow and axial-flow microturbines a

  15. Development of Japonica Male Sterile Lines Integrating Cytoplasmic Male Sterility and Photosensitive Genic Male Sterility

    Institute of Scientific and Technical Information of China (English)

    WANG Shou-hai; DU Shi-yun; WANG De-zheng; LI Cheng-quan

    2005-01-01

    It has been previously established that the BT type of cytoplasmic male sterility (CMS) is induced by high temperatures,while photosensitive genic male sterility (PGMS) seed sets by low temperatures induce. In the current study, we have bred photosensitive cytoplasmic male sterility (PCMS) lines (2308SA and 2310SA) by crossing the CMS line with the PGMS japonica line with maintainer genes. The sterility of PCMS japonica was consequently controlled by two groups of male sterile genes resulting from the integration of PGMS and CMS genes. The results on plant fertility, at different sowing times, were as follows: (a) Under conditions of natural long-day photoperiod and at temperatures above 35℃, the PGMS gene regulated PCMS japonica sterility - the higher the temperature, the lower the pollen fertility. However, bagged seed sets of PCMS japonica, not exposed to high temperatures, induced the CMS seed set. (b) Exposure to long-day photoperiod and temperature conditions between 35℃ and the critical sterility inducing temperature of PGMS resulted in both PGMS and CMS gene controlled sterility of PCMS japonica, which exhibited stable characteristics. (c) When exposed to critical sterility inducing temperatures or short-day photoperiod and daily high temperatures below 32℃, the BT type of the CMS gene regulated PCMS sterility. Under these conditions, the PGMS gene rendered male sterility insusceptible to occasional cool summer days when this PCMS line, adopted for hybrid seed production, develops into panicle differentiation stage.The present study also investigated the fertility restoration, seed production and combining ability of PCMS japonica so as to optimize its use.

  16. Maximal oil recovery by simultaneous condensation of alkane and steam

    NARCIS (Netherlands)

    Bruining, J.; Marchesin, D.

    2007-01-01

    This paper deals with the application of steam to enhance the recovery from petroleum reservoirs. We formulate a mathematical and numerical model that simulates coinjection of volatile oil with steam into a porous rock in a one-dimensional setting. We utilize the mathematical theory of conservation

  17. Teachers' Perceptions and Practices of STEAM Education in South Korea

    Science.gov (United States)

    Park, HyunJu; Byun, Soo-yong; Sim, Jaeho; Han, Hyesook; Baek, Yoon Su

    2016-01-01

    This study examined teachers' perceptions and practices of science, technology, engineering, arts, and mathematics (STEAM) education in South Korea, drawing on a survey of teachers in STEAM model schools. Results showed that the majority of Korean teachers, especially experienced teachers and male teachers, had a positive view on the role of STEAM…

  18. Electrolytic silver ion cell sterilizes water supply

    Science.gov (United States)

    Albright, C. F.; Gillerman, J. B.

    1968-01-01

    Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

  19. Constraining Sterile Neutrinos Using Reactor Neutrino Experiments

    CERN Document Server

    Girardi, Ivan; Ohlsson, Tommy; Zhang, He; Zhou, Shun

    2014-01-01

    Models of neutrino mixing involving one or more sterile neutrinos have resurrected their importance in the light of recent cosmological data. In this case, reactor antineutrino experiments offer an ideal place to look for signatures of sterile neutrinos due to their impact on neutrino flavor transitions. In this work, we show that the high-precision data of the Daya Bay experi\\-ment constrain the 3+1 neutrino scenario imposing upper bounds on the relevant active-sterile mixing angle $\\sin^2 2 \\theta_{14} \\lesssim 0.06$ at 3$\\sigma$ confidence level for the mass-squared difference $\\Delta m^2_{41}$ in the range $(10^{-3},10^{-1}) \\, {\\rm eV^2}$. The latter bound can be improved by six years of running of the JUNO experiment, $\\sin^22\\theta_{14} \\lesssim 0.016$, although in the smaller mass range $ \\Delta m^2_{41} \\in (10^{-4} ,10^{-3}) \\, {\\rm eV}^2$. We have also investigated the impact of sterile neutrinos on precision measurements of the standard neutrino oscillation parameters $\\theta_{13}$ and $\\Delta m^2...

  20. Validation of Effective Models for Simulation of Thermal Stratification and Mixing Induced by Steam Injection into a Large Pool of Water

    Directory of Open Access Journals (Sweden)

    Hua Li

    2014-01-01

    Full Text Available The Effective Heat Source (EHS and Effective Momentum Source (EMS models have been proposed to predict the development of thermal stratification and mixing during a steam injection into a large pool of water. These effective models are implemented in GOTHIC software and validated against the POOLEX STB-20 and STB-21 tests and the PPOOLEX MIX-01 test. First, the EHS model is validated against STB-20 test which shows the development of thermal stratification. Different numerical schemes and grid resolutions have been tested. A 48×114 grid with second order scheme is sufficient to capture the vertical temperature distribution in the pool. Next, the EHS and EMS models are validated against STB-21 test. Effective momentum is estimated based on the water level oscillations in the blowdown pipe. An effective momentum selected within the experimental measurement uncertainty can reproduce the mixing details. Finally, the EHS-EMS models are validated against MIX-01 test which has improved space and time resolution of temperature measurements inside the blowdown pipe. Excellent agreement in averaged pool temperature and water level in the pool between the experiment and simulation has been achieved. The development of thermal stratification in the pool is also well captured in the simulation as well as the thermal behavior of the pool during the mixing phase.

  1. A light sterile neutrino from Friedberg–Lee symmetry

    National Research Council Canada - National Science Library

    He, Xiao-Gang; Liao, Wei

    2014-01-01

    .... In this article we show that such an eV scale light sterile neutrino candidate can be obtained in a seesaw model in which the right-handed neutrinos satisfy a softly-broken Friedberg-Lee (FL) symmetry...

  2. Effect of the sterilization method on the properties of Bombyx mori silk fibroin films.

    Science.gov (United States)

    George, Karina A; Shadforth, Audra M A; Chirila, Traian V; Laurent, Matthieu J; Stephenson, Sally-Anne; Edwards, Grant A; Madden, Peter W; Hutmacher, Dietmar W; Harkin, Damien G

    2013-03-01

    We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method.

  3. Dehumidification System with Steam Permeability Films

    Science.gov (United States)

    Ishikwa, Masaaki; Sekimori, Souji; Ogiwara, Shigeaki; Ochiai, Tetsunari; Hirata, Tetsuo

    In a factory with a clean room facility in cold regions, dew-condensation on walls of the facility is one of the most serious problems in winter. In this study, a new dehumidification system in which a steam permeability film is located between humid air in a clean room and dry air from outside to exchange steam is proposed. This system can treat a lot of humid air with small energy only for driving fans to flow air. Some films are examined in two kinds of steam exchangers; double tube type and flat p1ate type. Steam permeability resistance and therma1 resistance of each film are first obtained in a double tube type exchanger. An analytica1 model for a flat plate type exchanger is then proposed, which shows good agreement with experimental data. Steam and heat transfer characteristics of a flat plate type exchanger are also evaluated experimentally. One film on a flat plate type exchanger shows dehumidification capacity of 0.033g/s(=120g/h )with its area of 2.232m2.

  4. Development of a sterilizing in-place application for a production machine using Vaporized Hydrogen Peroxide.

    Science.gov (United States)

    Mau, T; Hartmann, V; Burmeister, J; Langguth, P; Häusler, H

    2004-01-01

    The use of steam in sterilization processes is limited by the implementation of heat-sensitive components inside the machines to be sterilized. Alternative low-temperature sterilization methods need to be found and their suitability evaluated. Vaporized Hydrogen Peroxide (VHP) technology was adapted for a production machine consisting of highly sensitive pressure sensors and thermo-labile air tube systems. This new kind of "cold" surface sterilization, known from the Barrier Isolator Technology, is based on the controlled release of hydrogen peroxide vapour into sealed enclosures. A mobile VHP generator was used to generate the hydrogen peroxide vapour. The unit was combined with the air conduction system of the production machine. Terminal vacuum pumps were installed to distribute the gas within the production machine and for its elimination. In order to control the sterilization process, different physical process monitors were incorporated. The validation of the process was based on biological indicators (Geobacillus stearothermophilus). The Limited Spearman Karber Method (LSKM) was used to statistically evaluate the sterilization process. The results show that it is possible to sterilize surfaces in a complex tube system with the use of gaseous hydrogen peroxide. A total microbial reduction of 6 log units was reached.

  5. Peracetic acid: a practical agent for sterilizing heat-labile polymeric tissue-engineering scaffolds.

    Science.gov (United States)

    Yoganarasimha, Suyog; Trahan, William R; Best, Al M; Bowlin, Gary L; Kitten, Todd O; Moon, Peter C; Madurantakam, Parthasarathy A

    2014-09-01

    Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000 ppm or above sterilized electrospun scaffolds in 15 min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000 ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering.

  6. [Effect of methods of sterilization on thermoplastics with special reference to modified surfaces].

    Science.gov (United States)

    Müller, T; Käufer, H

    1999-01-01

    For materials intended for use in the medical setting their sterilizability is an indispensable prerequisite. In the case of most polymers the usual sterilization methods result in changes that even extend to cleavage of the polymer chains. A particular problem in this respect are the surfaces modified for improved biocompatibility investigated in the present study, which are characterised by enlarged contact areas. For this reason, possible changes to three different thermoplastics commonly used for medical applications (polyethylene, thermoplastic polyurethane, polycarbonate) were investigated. Steam, gas and radiation were used for sterilization. Tensile tests were employed to identify changes in mucosal characteristics caused by different sterilization techniques irrespective of the surface modification. Sterilization-related changes to the structure of the modified surfaces were investigated with the scanning electron microscope (SEM). Differential thermo analysis (DTA) was used to determine changes in the thermal characteristics of the plastics. Clear tendencies with regard to the behaviour of the plastics after sterilization with various techniques were found. A general statement about the compatibility of plastic materials with a specific sterilization method is not possible on the basis of this study. For every new polymeric product used for medical purposes, the characteristics required must first be defined and compliance with the permissible variations of these characteristics investigated for each of the various sterilization techniques available.

  7. Disinfection, sterilization and operation theater guidelines for dermatosurgical practitioners in India.

    Science.gov (United States)

    Patwardhan, Narendra; Kelkar, Uday

    2011-01-01

    Modern day dermatologists conduct different esthetic and surgical procedures, with risk of infective complications. Hence, infection control practices need to be established in dermatological practice to minimize the risk of exogenous infections. These practices include hand washing, cleaning, sterilization, disinfection, operation theater sterilization and specifications. Proper hand washing after examination of each patient and prior to any surgery with a formulation containing alcohol alone or as a combination with other agents reduces the chances of transferring infections to and from patients. Sterilization and disinfection constitute the most important aspect of infection control. Disinfectants and disinfecting procedures vary according to the environment and equipment. Proper knowledge of different processes/agents for sterilization and disinfection is essential. Disinfectants for use in hospitals should always be freshly prepared and should be of adequate strength. Sterilization is carried out most commonly using steam sterilizers or ethylene dioxide sterilizers. The waste generated during practice is a potential source of nosocomial infections and should be treated as per the proper protocol and guidelines. Trained staff to carry out these practices is essential.

  8. Disinfection, sterilization and operation theater guidelines for dermatosurgical practitioners in India

    Directory of Open Access Journals (Sweden)

    Narendra Patwardhan

    2011-01-01

    Full Text Available Modern day dermatologists conduct different esthetic and surgical procedures, with risk of infective complications. Hence, infection control practices need to be established in dermatological practice to minimize the risk of exogenous infections. These practices include hand washing, cleaning, sterilization, disinfection, operation theater sterilization and specifications. Proper hand washing after examination of each patient and prior to any surgery with a formulation containing alcohol alone or as a combination with other agents reduces the chances of transferring infections to and from patients. Sterilization and disinfection constitute the most important aspect of infection control. Disinfectants and disinfecting procedures vary according to the environment and equipment. Proper knowledge of different processes/agents for sterilization and disinfection is essential. Disinfectants for use in hospitals should always be freshly prepared and should be of adequate strength. Sterilization is carried out most commonly using steam sterilizers or ethylene dioxide sterilizers. The waste generated during practice is a potential source of nosocomial infections and should be treated as per the proper protocol and guidelines. Trained staff to carry out these practices is essential.

  9. Dual Pressure versus Hybrid Recuperation in an Integrated Solid Oxide Fuel Cell Cycle – Steam Cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    steam in a HRSG (heat recovery steam generator). The bottoming steam cycle was modeled with two configurations: (1) a simple single pressure level and (2) a dual pressure level with both a reheat and a pre-heater. The SOFC stacks in the present SOFC-ST hybrid cycles were not pressurized. The dual...

  10. Digest of "Invariant Method of Load Independent Pressure Control in Steam Boiler"

    OpenAIRE

    Sniders, Andris; Komass, Toms

    2012-01-01

    The paper considers the possibility of steam production and supply process improvement by perfection of the steam boiler control system, applying invariance principle that makes possible preemptive compensation of the influence of steam expenditure as a disturbance on the control process quality and efficiency. For the development of invariant control system, the mathematical modeling and simulation in MATLAB - SIMULINK environment is made. The control unit is low pressure steam boiler with o...

  11. Market structure scenarios in international steam coal

    Energy Technology Data Exchange (ETDEWEB)

    Trueby, Johannes; Paulus, Moritz

    2011-04-15

    The seaborne steam coal market changed in recent years. Trade volumes grew dynamically, important players emerged and since 2007 prices increased significantly and remained relatively high since then. In this paper we analyse market equilibria in the years 2006 and 2008 by testing for two possible market structure scenarios in this market: perfect competition and an oligopoly setup with major exporters competing in quantities. We conclude from our results that international steam coal trade is not perfectly competitive as there is a large spread between marginal costs and prices and a low capacity utilisation in 2008. Further, trade flows are generally more diversified in reality than in the competitive scenario. However, also the Cournot scenarios fail to accurately explain real market outcomes. We conclude that only more sophisticated models of strategic behaviour can predict market equilibria in international steam coal trade. (orig.)

  12. Fourth international seminar on horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Tuomisto, H. [ed.] [IVO Group, Vantaa (Finland); Purhonen, H. [ed.] [VTT, Espoo (Finland); Kouhia, V. [ed.] [Lappeenranta Univ. of Technology (Finland)

    1997-12-31

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.

  13. Sintering of nickel steam reforming catalysts

    DEFF Research Database (Denmark)

    Sehested, Jens; Larsen, Niels Wessel; Falsig, Hanne;

    2014-01-01

    . In this paper, particle migration and coalescence in nickel steam reforming catalysts is studied. Density functional theory calculations indicate that Ni-OH dominate nickel transport at nickel surfaces in the presence of steam and hydrogen as Ni-OH has the lowest combined energies of formation and diffusion...... compared to other potential nickel transport species. The relation between experimental catalyst sintering data and the effective mass diffusion constant for Ni-OH is established by numerical modelling of the particle migration and coalescence process. Using this relation, the effective mass diffusion...

  14. A Numerical Study on the Supersonic Steam Ejector Use in Steam Turbine System

    Directory of Open Access Journals (Sweden)

    Lin Cai

    2013-01-01

    Full Text Available Supersonic steam ejector is widely used in steam energy systems such as refrigeration, wood drying equipment, papermaking machine, and steam turbine. In this paper the Computational Fluids Dynamics (CFD method was employed to simulate a supersonic steam ejector, SST k-w turbulence model was adopted, and both real gas model and ideal gas model for fluid property were considered and compared. The mixing chamber angle, throat length, and nozzle exit position (NXP primary pressure and temperature effects on entrainment ratio were investigated. The results show that performance of the ejector is underestimated using ideal gas model, and the entrainment ratio is 20%–40% lower than that when using real gas model. There is an optimum mixing chamber angel and NXP makes the entrainment ratio achieve its maximum; as throat length is decreased within a range, the entrainment ratio remains unchanged. Primary fluid pressure has a critical value, and the entrainment ratio reaches its peak at working critical pressure; when working steam superheat degree increases, the entrainment ratio is increased.

  15. Sterile Keratitis following Collagen Crosslinking

    Science.gov (United States)

    Javadi, Mohammad-Ali; Feizi, Sepehr

    2014-01-01

    Purpose: To report a keratoconic eye that developed severe sterile keratitis and corneal scar after collagen crosslinking necessitating corneal transplantation. Case Report: A 26-year-old man with progressive keratoconus underwent collagen crosslinking and presented with severe keratitis 72 hours after the procedure. The initial impression was infectious corneal ulcer and a fortified antibiotic regimen was administered. However, the clinical course and confocal microscopy results prompted a diagnosis of sterile keratitis. The eye developed severe corneal scars leading to reduced visual acuity and necessitating corneal transplantation. Conclusion: Sterile keratitis may develop after collagen crosslinking resulting in profound visual loss leading to corneal transplantation. PMID:25709779

  16. Low reheating temperature and the visible sterile neutrino.

    Science.gov (United States)

    Gelmini, Graciela; Palomares-Ruiz, Sergio; Pascoli, Silvia

    2004-08-20

    We present here a scenario, based on a low reheating temperature T(R)inflation, in which the coupling of sterile neutrinos to active neutrinos can be as large as experimental bounds permit (thus making this neutrino "visible" in future experiments). In previous models this coupling was forced to be very small to prevent a cosmological overabundance of sterile neutrinos. Here the abundance depends on how low the reheating temperature is. For example, the sterile neutrino required by the Liquid Scintillator Neutrino Detector result may not have any cosmological problem within our scenario.

  17. Steam reforming of light oxygenates

    DEFF Research Database (Denmark)

    Trane-Restrup, Rasmus; Resasco, Daniel E; Jensen, Anker Degn

    2013-01-01

    Steam reforming (SR) of ethanol, acetic acid, acetone, acetol, 1-propanol, and propanal has been investigated over Ni/MgAl2O4 at temperatures between 400 and 700 degrees C and at a steam-to-carbon-ratio (S/C) of 6. The yield of H-2 and conversion increased with temperature, while the yield of by-products...... decreased with temperature in the SR of the investigated compounds. The yield of H2 approached the thermodynamic limit at the highest temperatures investigated. No significant differences in conversion as a function of temperature among the different model compounds were observed. However, the product...... distribution depended on the model compound, and C-3-oxygenates produced a larger fraction of by-products compared to C-2-oxygenates. Temperatures of 600 degrees C or above were generally needed to minimize the fraction of by-products and obtain a syngas containing mainly CO, CO2, H-2, and H2O with only traces...

  18. Male gametophytic sterility. 1 - Gametic sterilities and deletions in petunia

    Energy Technology Data Exchange (ETDEWEB)

    Cornu, A.; Maizonnier, D. (Station d' Amelioration des Plantes de l' I.N.R.A., Dijon (France))

    1982-01-01

    Terminal deletions induced by ionizing radiations in Petunia are not sexually transmitted. Cytogenetic study of plants with a heterozygous deletion and their progenies shows that this lack of transmission is accompanied by a gametic semi-sterility due to the fact that gametes carrying the deleted chromosome are not viable. The interest of such a male sterility with a gametophytic determinism for the study of sporophyte-gametophyte relationships is underlined.

  19. Modeling Open-Flow Steam Reforming of Methanol over Cu/ZnO/Al2O3 Catalyst in an Axisymmetric Reactor

    Directory of Open Access Journals (Sweden)

    Leonardo Pacheco

    2015-01-01

    Full Text Available This paper describes a CFD study of the steam-reforming process (SRP of methanol in a short pseudo-contact time reactor of fixed bed type, in axi-symmetric conditions. The SRP is important sake for hydrogen production, and the design /scale-up/control of the industrial processes in the future are supported by a reliable knowledge and prediction of the catalytic reaction. The difficulty of determining the reaction scheme and the associated constants is wellknown, due to the necessity of identifying the reaction kinetics in purely chemical regime, meaning with a perfect homogeneity and flow independence. Practically these ideal conditions, albeit assumed, are not fulfilled so that the intrinsic chemical kinetics is not reached. For the case of SRP, we have attempted here to validate the Peppley’s model by a numerical modelling reproducing exactly the local conditions in the experimental duct, accounting for gradients in the cross section. The numerical results show the same trends than the experimental one, but with a slight shift of 20% as a consequence of the reactor heterogeneity. This result seems acceptable to validate the use of the Peepley’s model for further studies in other types of complex flow reactors.

  20. Condensation heat transfer of pure steam and steam from gas-steam mixture in tubes of AES-2006 PHRS SG heat exchanger

    Science.gov (United States)

    Balunov, B. F.; Il'in, V. A.; Shcheglov, A. A.; Lychakov, V. D.; Alekseev, S. B.; Kuhtevich, V. O.; Svetlov, S. V.; Sidorov, V. G.

    2017-01-01

    Results of experimental determination of the average heat transfer coefficient upon condensation of pure steam αc and steam from air-steam mixture αas.m in tubes of a large-scale model of the emergency cooling heat exchanger in the system of passive heat removal through steam generators of AES-2006 project at Leningrad II NPP are presented. The model contained 16 parallel tubes with a diameter of 16 × 2 mm and a length of 2.9 m connected to the upper steam distributing and lower condensate gathering horizontal collectors; the distance between their axes was 2.28 m. The tube segments were vertical, horizontal, or inclined. The internal diameter of the collectors was 40 or 60 mm. The model was placed in the lower part of a tank with a height of 6.5 m and a volume of 5.85 m3 filled with boiling water at atmospheric pressure. The experimental parameters were as follows: pressure range 0.43-7.77 MPa, condensate Reynolds number Ref = (0.87-9.3) × 103, and average air volume fraction at the segment with air-steam mixture 0.18-0.85. The studies showed that nonuniformity of static pressure distribution along the steam-distributing collector strongly influences the reduction of αc value (ejecting effect). The agreement between experimental and calculated according to statutory guidelines values of αc for vertical tubes is achieved if the dynamic head of the steam flow at the input of the steam-distributing collector does not exceed 1 kPa. Equations for calculation of the diffusion heat transfer coefficient at steam condensation from the air-steam mixture αas.m on the internal tube surface are proposed. In the considered conditions, air is completely displaced by steam flow from the upper to the lower part of the tubes. The boundary between these regions is characterized by an average reduced steam velocity through this cross section of 1.6 ± 0.4 m/s. Above the boundary cross section, it is recommended to calculate αc. according to [1].

  1. Food irradiation and sterilization

    Science.gov (United States)

    Josephson, Edward S.

    Radiation sterilization of food (radappertization) requires exposing food in sealed containers to ionizing radiation at absorbed doses high enough (25-70 kGy) to kill all organisms of food spoilage and public health significance. Radappertization is analogous to thermal canning is achieving shelf stability (long term storage without refrigeration). Except for dry products in which autolysis is negligible, the radappertization process also requires that the food be heated to an internal temperature of 70-80°C (bacon to 53°C) to inactivate autolytic enzymes which catalyze spoilage during storage without refrigeration. To minimize the occurence of irradiation induced off-flavors and odors, undesirable color changes, and textural and nutritional losses from exposure to the high doses required for radappertization, the foods are vacuum sealed and irradiated frozen (-40°C to -20°C). Radappertozed foods have the characteristic of fresh foods prepared for eating. Radappertization can substitute in whole or in part for some chemical food additives such as ethylene oxide and nitrites which are either toxic, carcinogenic, mutagenic, or teratogenic. After 27 years of testing for "wholesomeness" (safety for consumption) of radappertized foods, no confirmed evidence has been obtained of any adverse effecys of radappertization on the "wholesomeness" characteristics of these foods.

  2. 水蒸气对煅烧石灰石碳酸化反应影响的实验与模型分析%Experimental and model study of carbonation of calcined limestone in presence of steam

    Institute of Scientific and Technical Information of China (English)

    刘洋; 杨勇平

    2015-01-01

    Steam is present in combustion flue gas, oxy-fuel combustor/calciner and fuel gas. Some previous works in this field have examined the reactivity of calcium oxide in the presence of steam. There is general agreement that the presence of steam increases the rate of carbonation even at low concentrations. However, there is no description about the effect of steam on the carbonation reaction of calcined limestone. The effects of temperature, concentration of steam on carbonation were investigated in a thermogravimetric analyzer. The understanding of the mechanisms participating in the carbonation reaction could be arrived at through the use of model interpretations of the rate controlling process. The experimental data were analyzed by means of the random pore model. During carbonation reaction, a very initial rapid reaction was followed by the second stage of the reaction occurring in the next slower regime. The experiment results showed that the effect of steam on carbonation could be neglected during the first stage of reaction. However, the conversion of carbonation in the presence of 1.5%(vol), 10%(vol) and 20%(vol) steam were 19.8%, 27.2%and 30.5%higher than the conversion without steam after 10 min during the second stage of reaction at 500℃. Steam was beneficial to enhancing the conversion of carbonation, but the extent of increase became not significant with increasing concentration of steam. The linearity of the second stage reaction data strongly suggested that this stage was controlled by a diffusion process occurring in a layer of calcium carbonate surrounding the calcium oxide in the pores of the solid. The parameters related to effective product layer diffusivities were plotted in Arrhenius form and the changes in activation energy at various steam concentrations were also shown. Comparison with the experimental effective diffusivities calculated for the carbonation reaction showed that the activation energies in the lower temperature range were in

  3. Neutrophil Responses to Sterile Implant Materials

    OpenAIRE

    Siddharth Jhunjhunwala; Stephanie Aresta-DaSilva; Katherine Tang; David Alvarez; Webber, Matthew J.; Tang, Benjamin C.; Lavin, Danya M.; Omid Veiseh; Doloff, Joshua C; Suman Bose; Arturo Vegas; Minglin Ma; Gaurav Sahay; Alan Chiu; Andrew Bader

    2015-01-01

    In vivo implantation of sterile materials and devices results in a foreign body immune response leading to fibrosis of implanted material. Neutrophils, one of the first immune cells to be recruited to implantation sites, have been suggested to contribute to the establishment of the inflammatory microenvironment that initiates the fibrotic response. However, the precise numbers and roles of neutrophils in response to implanted devices remains unclear. Using a mouse model of peritoneal microcap...

  4. Documentation requirements for radiation sterilization

    DEFF Research Database (Denmark)

    Miller, A.

    1995-01-01

    Several standards are recently approved or are under development by the standard organizations ISO and CEN in the field of radiation sterilization. Particularly in Europe these standards define new requirements on some issues and on other issues they emphasize the necessary documentation for appr......Several standards are recently approved or are under development by the standard organizations ISO and CEN in the field of radiation sterilization. Particularly in Europe these standards define new requirements on some issues and on other issues they emphasize the necessary documentation...... for approval of radiation sterilized products. The impact of these standards on the radiation sterilization is discussed, with special attention given to a few special issues, mainly traceability and uncertainty of measurement results....

  5. Sterile pyuria: a forgotten entity

    OpenAIRE

    Goonewardene, Sanchia; Persad, Raj

    2015-01-01

    Sterile pyuria is a common entity. Yet there are no guidelines to address this issue. We have conducted a systematic review over 20 years and reviewed the results. Guidelines for assessment, diagnosis and management are developed based on these results.

  6. Sterile pyuria: a forgotten entity.

    Science.gov (United States)

    Goonewardene, Sanchia; Persad, Raj

    2015-10-01

    Sterile pyuria is a common entity. Yet there are no guidelines to address this issue. We have conducted a systematic review over 20 years and reviewed the results. Guidelines for assessment, diagnosis and management are developed based on these results.

  7. Sterilization of silicone-based hydrogels for biomedical application using ozone gas: Comparison with conventional techniques.

    Science.gov (United States)

    Galante, Raquel; Ghisleni, Daniela; Paradiso, Patrizia; Alves, Vitor D; Pinto, Terezinha J A; Colaço, Rogério; Serro, Ana Paula

    2017-09-01

    Sterilization of hydrogels is challenging due to their often reported sensitivity to conventional methods involving heat or radiation. Although aseptic manufacturing is a possibility, terminal sterilization is safer in biological terms, leading to a higher overall efficiency, and thus should be used whenever it is possible. The main goal of this work was to study the applicability of an innovative ozone gas terminal sterilization method for silicone-based hydrogels and compare its efficacy and effects with those of traditional sterilization methods: steam heat and gamma irradiation. Ozone gas sterilization is a method with potential interest since it is reported as a low cost green method, does not leave toxic residues and can be applied to thermosensitive materials. A hydrogel intended for ophthalmological applications, based on tris(trimethylsiloxy)silyl] propyl methacrylate, was prepared and extensively characterized before and after the sterilization procedures. Alterations regarding transparency, swelling, wettability, ionic permeability, friction coefficient, mechanical properties, topography and morphology and chemical composition were monitored. Efficacy of the ozonation was accessed by performing controlled contaminations and sterility tests. In vitro cytotoxicity testes were also performed. The results show that ozonation may be applied to sterilize the studied material. A treatment with 8 pulses allowed sterilizing the material with bioburdens≤10(3)CFU/mL, preserving all the studied properties within the required known values for contact lenses materials. However, a higher exposure (10 pulses) led to some degradation of the material and induced mild cytotoxicity. Steam heat sterilization led to an increase of swelling capacity and a decrease of the water contact angle. Regarding gamma irradiation, the increase of irradiation dose led to an increase of the friction coefficient. The higher dose (25kGy) originated surface degradation and affected the

  8. Light sterile neutrinos from a late phase transition

    CERN Document Server

    Vecchi, Luca

    2016-01-01

    Light sterile neutrinos represent a well-motivated extension of the 3-neutrino paradigm. However, the impressive agreement between standard cosmology and data casts doubts on their existence. Here we present a class of scenarios that robustly avoids this tension. In these models the sterile neutrinos are light, chiral states of a new sector interacting with the Standard Model via the right-handed neutrino portal and, crucially, active-sterile neutrino oscillations require a phase transition in the hidden sector. We explore the hidden-couplings/critical-temperature plane and identify regions where several sterile neutrinos can be accommodated. A late phase transition is usually preferred and may also ward off a potential threat posed by the formation of topologically stable defects.

  9. Light sterile neutrinos from a late phase transition

    Science.gov (United States)

    Vecchi, Luca

    2016-12-01

    Light sterile neutrinos represent a well-motivated extension of the 3-neutrino paradigm. However, the impressive agreement between standard cosmology and data casts doubts on their existence. Here, we present a class of scenarios that robustly avoids this tension. In these models the sterile neutrinos are light, chiral states of a new sector interacting with the Standard Model via the right-handed neutrino portal, and crucially active-sterile neutrino oscillations require a phase transition in the hidden sector. We explore the hidden-couplings/critical-temperature plane and identify regions where several sterile neutrinos can be accommodated. A late phase transition is usually preferred and may also ward off a potential threat posed by the formation of topologically stable defects.

  10. Food packaging and radiation sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Yoko [Division of Food Additives, National Institute of Health Sciences, Tokyo (Japan)

    1998-12-31

    Radiation sterilization has several merits that it is a positively effective sterilization method, it can be used to sterilize low heat-resistant containers and high gas barrier films, and there is no possibility of residual chemicals being left in the packages. It has been commercially used in `Bag in a Box` and some food containers. The {gamma} ray and an electron beam are commonly used in radiation sterilization. The {gamma} ray can sterilize large size containers and containers with complex shapes or sealed containers due to its strong transmission capability. However, since the equipment tends to be large and expensive, it is generally used in off production lines. On the other hand, it is possible to install and electron beam system on food production lines since the food can be processed in a short time due to its high beam coefficient and its ease of maintenance, even though an electron beam has limited usage such as sterilizing relatively thin materials and surface sterilization due to the weak transmission. A typical sterilization dose is approximately 10-30 kGy. Direct effects impacting packaging materials, particularly plastics, include scission of polymer links, cross-linkage between polymers, and generating radiolysis products such as hydrogen, methane, aliphatic hydrocarbons, etc. Furthermore, under the existence of oxygen, the oxygen radicals generated by the radiation will oxidize and peroxidize polymer chains and will generate alcohol and carbonyl groups, which shear polymer links, and generate oxygen containing low molecular compounds. As a result, degradation of physical strength such as elongation and seal strength, generating foreign odor, and an increase in global migration values shown in an elution test are sometimes evident. The food packages have different shapes, materials, additives, number of microorganisms and purpose. Therefor the effects of radiation, the optimum dose and so on must be investigated on the individual package. (J.P.N.)

  11. New disinfection and sterilization methods.

    OpenAIRE

    2001-01-01

    New disinfection methods include a persistent antimicrobial coating that can be applied to inanimate and animate objects (Surfacine), a high-level disinfectant with reduced exposure time (ortho-phthalaldehyde), and an antimicrobial agent that can be applied to animate and inanimate objects (superoxidized water). New sterilization methods include a chemical sterilization process for endoscopes that integrates cleaning (Endoclens), a rapid (4-hour) readout biological indicator for ethylene oxid...

  12. A PORTABLE DENTAL STERILIZING CYLINDER

    Science.gov (United States)

    The report describes an aluminum cylinder in which dental instruments could be sterilized under emergency field conditions and at the same time be...protected against corrosion. The procedure involves loading the cylinder with dental instruments, flushing it with ethylene oxide-Freon gas, closing it...and then immersing it in boiling water for l hour. In preliminary experiments with a prototype of the sterilizing cylinder, dental instruments were

  13. LMFBR steam generator systems development program progress report

    Energy Technology Data Exchange (ETDEWEB)

    None

    The intent of this program is to investigate methods of producing 2-1/4 Cr-1Mo duplex tubing to meet the structural, thermal/hydraulic and leak detection design requirements of the duplex tube leak detection concept for application on the Demonstration Plant and/or prototype steam generator. The leak detection concept as envisioned for LMFBR steam generator application will be analyzed regarding response to credible leak situations. The results of testing will be used for this analysis. The third fluid system will be conceptually designed including the two plena design adaptations being considered and the advantages and disadvantages of each will be assessed. The test program for the single-tube steam generator model will be developed in accordance with the technical and schedular objectives of the LMFBR duplex tube steam generator development program. A conceptual steam generator configuration will be established for use as a reference in the on-going feasibility studies and Demo Plant system development.

  14. Radiation sterilization of skin allograft

    Science.gov (United States)

    Kairiyama, E.; Horak, C.; Spinosa, M.; Pachado, J.; Schwint, O.

    2009-07-01

    In the treatment of burns or accidental loss of skin, cadaveric skin allografts provide an alternative to temporarily cover a wounded area. The skin bank facility is indispensable for burn care. The first human skin bank was established in Argentina in 1989; later, 3 more banks were established. A careful donor selection is carried out according to the national regulation in order to prevent transmissible diseases. As cadaveric human skin is naturally highly contaminated, a final sterilization is necessary to reach a sterility assurance level (SAL) of 10 -6. The sterilization dose for 106 batches of processed human skin was determined on the basis of the Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control (2004) and ISO 11137-2 (2006). They ranged from 17.6 to 33.4 kGy for bioburdens of >10-162.700 CFU/100 cm 2. The presence of Gram negative bacteria was checked for each produced batch. From the analysis of the experimental results, it was observed that the bioburden range was very wide and consequently the estimated sterilization doses too. If this is the case, the determination of a tissue-specific dose per production batch is necessary to achieve a specified requirement of SAL. Otherwise if the dose of 25 kGy is preselected, a standardized method for substantiation of this dose should be done to confirm the radiation sterilization process.

  15. Wet steam wetness measurement in a 10 MW steam turbine

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2014-03-01

    Full Text Available The aim of this paper is to introduce a new design of the extinction probes developed for wet steam wetness measurement in steam turbines. This new generation of small sized extinction probes was developed at CTU in Prague. A data processing technique is presented together with yielded examples of the wetness distribution along the last blade of a 10MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  16. Wet steam wetness measurement in a 10 MW steam turbine

    OpenAIRE

    Kolovratník Michal; Bartoš Ondřej

    2014-01-01

    The aim of this paper is to introduce a new design of the extinction probes developed for wet steam wetness measurement in steam turbines. This new generation of small sized extinction probes was developed at CTU in Prague. A data processing technique is presented together with yielded examples of the wetness distribution along the last blade of a 10MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  17. Quasi Goldstone fermion as a sterile neutrino

    CERN Document Server

    Chun, E J; Smirnov, Yu A

    1996-01-01

    The existence of sterile neutrino is hinted by simultaneous explanation of diverse neutrino anomalies. We suggest that the quasi Goldstone fermions (QGF) arising in supersymmetric theory as a result of spontaneous breaking of global symmetry like the Peccei-Quinn symmetry or the lepton number symmetry can play a role of the sterile neutrino. The smallness of mass of QGF (m_S \\sim 10^{-3}-10 eV) can be related to the specific choice of superpotential or K\\"ahler potential (e.g., no-scale kinetic terms for certain superfields). Mixing of QGF with neutrinos implies the R-parity violation. It can proceed via the coupling of QGF with the Higgs supermultiplets or directly with the lepton doublet. A model which accounts for the solar and atmospheric anomalies and the dark matter is presented.

  18. 汽轮机叶片汽道的结构模型研究%Study on structural model of steam turbine blade

    Institute of Scientific and Technical Information of China (English)

    曾岳飞; 谌永祥; 钟成明; 江敏; 吴越

    2012-01-01

    As an important part of the steam turbine,blade determines the energy conversion efficiency.The features of the structure of steam turbine blades will be researched in it.And according to the characteristics of blade profile as well as the requirements of STEP issued by ISO, Cubic Uniform Rational B-spline and 2×3 drgee Non-Uniform Rational B-spline will be chosen to build the mathematical model of the blade,which matrix expression is later deduced respectively that prove the continuity of the curve,realize the digital expression for the blades. From the matrix expression, obvious Cubic Uniform Rational B-spline has more advantages than 2×3 drgee Non-Uniform Rational B-spline method,such as less computations ,simple and easy control, etc, which can provide theoretical support for subsequent interpolation algorithms.%叶片作为汽轮机的重要组成部分,决定着能量的转换效率.对汽轮机动叶片的结构特征进行了研究,从叶型的特点,结合国际标准化组织颁布的工业产品数据交换标准的要求,选取了三次均匀有理B样条和2×3次非均匀有理B样条为叶型的数学模型,推导了各自的矩阵表达式,证明了曲线的连续性,实现了叶片的数字化表示.由矩阵表达式可以看出,明显的三次均匀有理B样条比2×3次非均匀有理B样条方法的计算量小、简单和便于控制等,为后续的插补算法研究提供了理论支持.

  19. Neutrino Oscillations With Two Sterile Neutrinos

    Science.gov (United States)

    Kisslinger, Leonard S.

    2016-10-01

    This work estimates the probability of μ to e neutrino oscillation with two sterile neutrinos using a 5×5 U-matrix, an extension of the previous estimate with one sterile neutrino and a 4×4 U-matrix. The sterile neutrino-active neutrino mass differences and the mixing angles of the two sterile neutrinos with the three active neutrinos are taken from recent publications, and the oscillation probability for one sterile neutrino is compared to the previous estimate.

  20. Neutrino Oscillations With Two Sterile Neutrinos

    CERN Document Server

    Kisslinger, Leonard S

    2016-01-01

    This work estimates the probability of $\\mu$ to $e$ neutrino oscillation with two sterile neutrinos using a 5x5 U-matrix, an extension of the previous estimate with one sterile neutrino and a 4x4 U-matrix. The sterile neutrino-active neutrino mass differences and the mixing angles of the two sterile neutrinos with the three active neutrinos are taken from recent publications, and the oscillation probability for one sterile neutrino is compared to the previous estimate.

  1. νΛMDM: A model for sterile neutrino and dark matter reconciles cosmological and neutrino oscillation data after BICEP2

    Directory of Open Access Journals (Sweden)

    P. Ko

    2014-12-01

    Full Text Available We propose an ultraviolet complete theory for cold dark matter (CDM and sterile neutrinos that can accommodate both cosmological data and neutrino oscillation experiments within 1σ level. We assume a new U(1X dark gauge symmetry which is broken at ∼O(MeV scale resulting light dark photon. Such a light mediator for DM's self-scattering and scattering-off sterile neutrinos can resolve three controversies for cold DM on small cosmological scales: cusp vs. core, too-big-to-fail and missing satellites. We can also accommodate ∼O(1 eV scale sterile neutrinos as the hot dark matter (HDM and can fit some neutrino anomalies from neutrino oscillation experiments within 1σ. Finally, the right amount of HDM can make a sizable contribution to dark radiation, and also helps to reconcile the tension between the data on the tensor-to-scalar ratio reported by Planck and BICEP2 Collaborations.

  2. 高温气冷堆螺旋管直流蒸汽发生器时域模型%Time domain model for once-through helical coil steam generator for high-temperature gas-cooled reactors

    Institute of Scientific and Technical Information of China (English)

    朱宏晔; 居怀明; 段日强; 薄涵亮

    2012-01-01

    The once-through helical coil steam generator(SG) is one of the key parts of high-temperature gas-cooled reactor systems.A time domain model was developed for the steam generator to investigate the dynamic heat transfer and flow processes in both the helium and water/steam sides.A drift-flux model was used for the water/steam two-phase flow,while the helium flow was described by a one-dimensional compressible flow model.The heat transfer and flow resistance were computed by correlations.To improve convergence,a pressure-correction method capable of solving low-speed compressible flows was used for both the helium and water/steam flows.The predicted steady state temperature fields in the steam generator agree well with THTR-300 SG experiments.Typical two-phase flow oscillations can also be captured.%螺旋管直流蒸汽发生器(SG)是高温气冷堆核电站的关键部件。为研究SG内氦气、水/蒸汽流动和换热的动态过程,该文建立了SG时域模型并编制了计算程序。其中,水/蒸汽两相流采用一维漂移流模型描述;氦气采用一维、可压缩流动模型描述;两侧流体与管壁的换热系数和流动阻力系数采用经验关系式计算。求解方法采用适用于动态、低速、可压缩流动的压力修正算法,以克服低Mach数造成的数值不稳定。采用此模型计算了THTR-300SG温度分布,计算结果与实验结果相比平均温度误差小于10℃。动态计算结果表明,此模型可以捕捉到规律的两相流脉动。利用此模型可以进行SG热工设计、不稳定性分析以及电站系统的工艺设计。

  3. Active acoustic leak detection for LMFBR steam generator. Pt. 5. Experiment for detection of bubbles using the SG full sector model

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab.

    1997-05-01

    In order to prevent the expansion of tube damages and to maintain structural safety in steam generators (SG) of fast breeder reactors (FBR), it is necessary to detect precisely and immediately the leakage of water from tubes of heat exchangers. Therefore, an active acoustic method, which detects the sound attenuation due to bubbles generated in the sodium-water reactions, it being developed. In this paper, the attenuation characteristics of sound attenuated by bubbles and influence of background noise are investigated experimentally by using an SG full sector model (diameter ratio about 1/1, height ratio about 1/7) simulating the actual SG. As an experimental result, the received sound attenuation for ten seconds was more than 10 dB from air bubble injection when injected bubble of 10 l/s (equivalence water leak rate about 10 g/s). The attenuation of sound are least affected by bubble injection position of heat exchanger tube bunch department. And the time was about 25 seconds till the sound attenuation became 10 dB in case of quantity of air bubble 1 l/s (equivalent water leak rate about 1 g/s). It is clarified that the background noise hardly influenced water leak detection performance as a result of having examined influence of background noise. (author)

  4. Active acoustic leak detection for LMFBR steam generators. Pt. 4. Experimental results for detection of bubble using the SG full sector model

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab.

    1996-06-01

    In order to prevent the expansion of tube damages and to maintain structural safety in steam generators (SG) of fast breeder reactor (FBR), it is necessary to detect precisely and immediately the leakage of water from tubes of heat exchangers. The active acoustic method, which detects the sound attenuation due to bubbles generated at the sodium-water reactions, is being developed. In this paper, the attenuation characteristics of sound attenuated by bubbles are investigated experimentally by using the SG full sector model simulating the actual SG. An emitter and a receiver sensor are attached to the SG shell, and the attenuation of sounds due to passing of bubbles through the sound field is detected and measured. As a experimental result, it is clarified that the received sound attenuates immediately upon injection of bubbles, and the attenuation of sound are 2-5 dB at after 10 seconds from bubble injection of 10 l/s. The attenuation of sound are least affected by bubble injection location. (author)

  5. Process for purifying geothermal steam

    Science.gov (United States)

    Li, C.T.

    Steam containing hydrogen sulfide is purified and sulfur recovered by passing the steam through a reactor packed with activated carbon in the presence of a stoichiometric amount of oxygen which oxidizes the hydrogen sulfide to elemental sulfur which is adsorbed on the bed. The carbon can be recycled after the sulfur has been recovered by vacuum distillation, inert gas entrainment or solvent extraction. The process is suitable for the purification of steam from geothermal sources which may also contain other noncondensable gases.

  6. Wet steam treatment with oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Ruehle, W.; Enkler, G. [EnBW Kraftwerke AG, Kernkraftwerk Philippsburg (Germany)

    1999-07-01

    After many years of excellent results using high all volatile treatment (HAVT) for operation of the secondary system of a PWR, flow assisted corrosion in the heating pipes of the intermediate steam reheaters has been experienced. Oxygen addition into the heating steam before the reheater is expected to improve the protective oxide layers formation. The reaction of oxygen with the alkalizing steam ingredients is described. (orig.)

  7. A Sterile Neutrino at DUNE

    CERN Document Server

    Berryman, Jeffrey M; Kelly, Kevin J; Kobach, Andrew

    2015-01-01

    We investigate the potential for the Deep Underground Neutrino Experiment (DUNE) to probe the existence and effects of a fourth neutrino mass-eigenstate. We study the mixing of the fourth mass-eigenstate with the three active neutrinos of the Standard Model, including the effects of new sources of CP-invariance violation, for a wide range of new mass-squared differences, from lower than 10^-5 eV^2 to higher than 1 eV^2. DUNE is sensitive to previously unexplored regions of the mixing angle - mass-squared difference parameter space. If there is a fourth neutrino, in some regions of the parameter space, DUNE is able to measure the new oscillation parameters (some very precisely) and clearly identify two independent sources of CP-invariance violation. Finally, we use the hypothesis that there are four neutrino mass-eigenstates in order to ascertain how well DUNE can test the limits of the three-massive-neutrinos paradigm. In this way, we briefly explore whether light sterile neutrinos can serve as proxies for ot...

  8. Effects of active-sterile neutrino mixing during primordial nucleosynthesis

    CERN Document Server

    Civitarese, Osvaldo; Saez, Maria Manuela

    2016-01-01

    In the present work, we discuss the effects of the inclusion of sterile-active neutrino oscillations during the production of primordial light-nuclei. We assume that the sterile neutrino mass-eigenstate might oscillate with the two lightest active neutrino mass- eigenstates, with mixing angles ${\\phi}_1$ and ${\\phi}_2$. We also allow a constant renormalization (represented by a parameter (${\\zeta}$)) of the sterile neutrino occupation factor. Taking ${\\zeta}$ and the mixing angles as free parameters, we have computed distribution functions of active and sterile neutrinos and primordial abundances. Using observable data we set constrains in the free parameters of the model. It is found that the data on primordial abundances are consistent with small mixing angles and with a value of ${\\zeta}$ smaller than 0.65 at 3${\\sigma}$ level.

  9. The limits of sterility assurance.

    Science.gov (United States)

    von Woedtke, Thomas; Kramer, Axel

    2008-09-03

    Sterility means the absence of all viable microorganisms including viruses. At present, a sterility assurance level (SAL) of 10(-6) is generally accepted for pharmacopoeial sterilization procedures, i.e., a probability of not more than one viable microorganism in an amount of one million sterilised items of the final product. By extrapolating the reduction rates following extreme artificial initial contamination, a theoretical overall performance of the procedure of at least 12 lg increments (overkill conditions) is demanded to verify an SAL of 10(-6). By comparison, other recommendations for thermal sterilization procedures demand only evidence that the difference between the initial contamination and the number of test organisms at the end of the process amount to more than six orders of magnitude. However, a practical proof of the required level of sterility assurance of 10(-6) is not possible. Moreover, the attainability of this condition is fundamentally dubious, at least in non-thermal procedures. Thus, the question is discussed whether the undifferentiated adherence to the concept of sterility assurance on the basis of a single SAL of 10(-6) corresponds with the safety requirements in terms of patient or user safety, costs and energy efficiency. Therefore, in terms of practical considerations, a concept of tiered SALs is recommended, analogous to the comparable and well-established categorization into "High-level disinfection", "Intermediate-level disinfection" and "Low-level disinfection". The determination of such tiered SALs is geared both to the intended application of the sterilized goods, as well as to the characteristics of the products and the corresponding treatment options.In the case of aseptic preparation, filling and production procedures, a mean contamination probability of 10(-3) is assumed. In automated processes, lower contamination rates can be realized. In the case of the production of re-usable medical devices, a reduction of at least 2

  10. Influence of feedwater and blowdown systems on the mineral distribution in WWER steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Papp, L. [Inst. of Material Engineering, Ostrava (Switzerland)

    1995-12-31

    After modification of Dukovany NPP steam generator (SG) feedwater system, the increased concentration of minerals was measured in the cold leg of modified SG. Some modifications were performed on operating WWER 1000 steam generators with aim to optimize the water chemistry in the collectors area. Since the distribution of minerals can substantially affect on corrosion processes in steam generators, VITKOVICE, as a producer of WWER steam generators has focused the attention to the optimizing of these systems. To predict the mineral distribution on the secondary side of steam generators for considered feedwater/blowdown systems, the simple model of the flow distribution in the secondary side of SG was developed.

  11. On calculation of a steam-water flow in a geothermal well

    Science.gov (United States)

    Shulyupin, A. N.; Chermoshentseva, A. A.

    2013-08-01

    Approaches to calculation of a steam-water flow in a geothermal well are considered. For hydraulic applications, a WELL-4 model of a steam-water well is developed. Data obtained using this model are compared with experimental data and also with calculations by similar models including the well-known HOLA model. The capacity of the A-2 well in the Mutnovskoe flash-steam field (Kamchatka half-island, Russia) after planned reconstruction is predicted.

  12. Sterilization can change properties of bioceramics; Ein Sterilisationsprozess kann die Eigenschaften von Biokeramik veraendern

    Energy Technology Data Exchange (ETDEWEB)

    Willmann, G. [CeramTec AG, Postfach 1149, D-73201 Plochingen (Germany)

    2003-02-01

    Bioceramics made of bioinert alumina or zirconia and bioactive hydroxyapatite are well established implant materials. Implants have to be cleaned and sterilized. When sterilized some bioceramics change their color. This may effect their properties. No decrease of mechanical strength is observed when sterilizing alumina and the novel ceramic biocomposite AMC (Alumina Matrix Composite) with steam or Co{sup 60} Gamma irradiation. When sterilizing Y-TZP zirconia with steam a decrease of strength is observed. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Biokeramik auf Basis von bioinertem Aluminium- und Zirkonoxid, so wie bioaktivem Hydroxylapatit sind etablierte Werkstoffe fuer Implantate. Implantate muessen gereinigt und sterilisiert werden. Bei einigen Biokeramiken koennen beim Sterilisieren Veraenderungen ihrer Farbe auftreten, die aber keinen unguenstigen Einfluss auf die Gebrauchseigenschaften haben. Das Sterilisieren mit Dampf im Autoklaven und mit Co{sup 60} Gamma Strahlung verursacht keinen Festigkeitsabfall bei Aluminiumoxidkeramik und bei dem neuen, keramischen Biokomposit AMC (Alumina Matrix Composite). Bei Y-TZP Zirkonoxidkeramik dagegen wurde beim Sterilisieren mit Dampf ein Festigkeitsabfall gefunden. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  13. Viability of $\\Delta m^2\\sim$ 1 eV$^2$ sterile neutrino mixing models in light of MiniBooNE electron neutrino and antineutrino data from the Booster and NuMI beamlines

    CERN Document Server

    Karagiorgi, G; Conrad, J; Shaevitz, M H; Sorel, M

    2009-01-01

    This paper examines sterile neutrino oscillation models in light of recently published results from the MiniBooNE Experiment. The new MiniBooNE data include the updated neutrino results, including the low energy region, and the first antineutrino results, as well as first results from the off-axis NuMI beam observed in the MiniBooNE detector. These new global fits also include data from LSND, KARMEN, NOMAD, Bugey, CHOOZ, CCFR84, and CDHS. Constraints from atmospheric oscillation data have been imposed.

  14. Cosmological bounds of sterile neutrinos in a $SU(3)_C\\otimes SU(3)_L\\otimes SU(3)_R\\otimes U(1)_N$ model as dark matter candidates

    CERN Document Server

    Ferreira, Cesar P; de Holanda, Pedro C

    2015-01-01

    We study sterile neutrinos in an extension of the standard model, based on the gauge group $SU(3)_C\\otimes SU(3)_L\\otimes SU(3)_R\\otimes U(1)_N$, and use this model to illustrate how to apply cosmological limits to thermalized particles that decouple while relativistic. These neutrinos, $N_{aL}$, can be dark matter candidates, with a keV mass range arising rather naturally in this model. We analyse the cosmological limits imposed by $N_{eff}$ and dark matter abundance on these neutrinos. Assuming that these neutrinos have roughly equal masses and are not CDM, we conclude that the $N_{eff}$ experimental value can be satisfied in some cases and the abundance constraint implies that these neutrinos are hot dark matter. With this information, we give upper bounds on the Yukawa coupling between the sterile neutrinos and a scalar field, the possible values of the VEV of this scalar field and lower bounds to the mass of one gauge boson of the model.

  15. Steam refining as an alternative to steam explosion.

    Science.gov (United States)

    Schütt, Fokko; Westereng, Bjørge; Horn, Svein J; Puls, Jürgen; Saake, Bodo

    2012-05-01

    In steam pretreatment the defibration is usually achieved by an explosion at the end of the treatment, but can also be carried out in a subsequent refiner step. A steam explosion and a steam refining unit were compared by using the same raw material and pretreatment conditions, i.e. temperature and time. Smaller particle size was needed for the steam explosion unit to obtain homogenous slurries without considerable amounts of solid chips. A higher amount of volatiles could be condensed from the vapour phase after steam refining. The results from enzymatic hydrolysis showed no significant differences. It could be shown that, beside the chemical changes in the cell wall, the decrease of the particle size is the decisive factor to enhance the enzymatic accessibility while the explosion effect is not required.

  16. Gamma-Ray Sterilization of Mars Analog Rocks and Minerals

    Science.gov (United States)

    Allen, C. C.

    1998-01-01

    Samples of rock and soil, collected by robotic spacecraft on Mars, will be returned to terrestrial laboratories early in the next century. Plans call for the samples to be placed immediately in biological containment and tested for signs of present or past life and biological hazard. It is recommended that "controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized." While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth. Various techniques are routinely used to sterilize biological samples. These include dry heating to temperatures of 150C or higher, heating in the presence of steam, exposure to poisonous gases such as formaldehyde and propiolactone, exposure to H2O2 vapor or plasma, exposure to ultraviolet light, and exposure to gamma radiation. The appropriate technique depends on the physical characteristics of the sample and the desired results. Gamma radiation is routinely used to inactivate viruses and destroy bacteria in medical research. The most commercial sterilizers use Cobalt 60, which emits gamma photons with energies of 1. 173 and 1. 332 MeV. Absorbed doses of approximately 106 rad (104 gamma ray is equal to 104 ergs/gm) are sufficient to destroy most bacteria. The current study is designed to investigate the effects of lethal doses of Cobalt 60 gamma radiation on geologic materials analogous to the first samples to be returned from Mars. The goals are (1) to determine the gamma ray dose required to kill microorganisms within geologic samples, and (2) to determine the effects of lethal doses of gamma radiation on the physical and chemical properties of the samples.

  17. Methane Steam Reforming Kinetics for a Rhodium-Based Catalyst

    DEFF Research Database (Denmark)

    Jakobsen, Jon Geest; Jakobsen, M.; Chorkendorff, Ib

    2010-01-01

    Methane steam reforming is the key reaction to produce synthesis gas and hydrogen at the industrial scale. Here the kinetics of methane steam reforming over a rhodium-based catalyst is investigated in the temperature range 500-800 A degrees C and as a function of CH4, H2O and H-2 partial pressures....... The methane steam reforming reaction cannot be modeled without taking CO and H coverages into account. This is especially important at low temperatures and higher partial pressures of CO and H-2. For methane CO2 reforming experiments, it is also necessary to consider the repulsive interaction of CO...

  18. Thermodynamic wetness loss calculation in a steam turbine rotor tip section: nucleating steam flow

    Science.gov (United States)

    Joseph, Joby; Sathyanarayanan, S.; K, Vigney; Prasad, B. V. S. SS; Biswas, D.; Jimbo, T.

    2016-09-01

    Rapid expansion of steam in the last stages of a steam turbine causes condensation. The formation of liquid droplets due to condensation results in wetness losses, which include aerodynamic losses (due to friction between liquid droplets and the vapour), thermodynamic losses (due to irreversible heat addition), and braking losses (due to the impact of liquid droplets on the blade). The thermodynamic loss contributes up to 80% to the wetness losses when the diameter of the droplets formed is less than 1 μm. In this study, the thermodynamic loss in a two-dimensional steam turbine rotor tip section is numerically investigated for various operating and off-design conditions. A pressure based, Eulerian-Eulerian approach is used to model the non-equilibrium condensation process. The entropy change due to condensation is used to compute the thermodynamic losses.

  19. Development of a 3D Electromagnetic Model for Eddy Current Tubing Inspection: Application to Steam Generator Tubing

    Science.gov (United States)

    Pichenot, G.; Prémel, D.; Sollier, T.; Maillot, V.

    2004-02-01

    In nuclear plants, the inspection of heat exchanger tubes is usually carried out by using eddy current nondestructive testing. A numerical model, based on a volume integral approach using the Green's dyadic formalism, has been developed, with support from the French Institute for Radiological Protection and Nuclear Safety, to predict the response of an eddy current bobbin coil to 3D flaws located in the tube's wall. With an aim of integrating this model into the NDE multi techniques platform CIVA, it has been validated with experimental data for 2D and 3D flaws.

  20. Numerical solution of the problem of optimizing the process of oil displacement by steam

    Science.gov (United States)

    Temirbekov, N. M.; Baigereyev, D. R.

    2016-06-01

    The paper is devoted to the problem of optimizing the process of steam stimulation on the oil reservoir by controlling the steam pressure on the injection well to achieve preassigned temperature distribution along the reservoir at a given time of development. The relevance of the study of this problem is related to the need to improve methods of heavy oil development, the proportion of which exceeds the reserves of light oils, and it tends to grow. As a mathematical model of oil displacement by steam, three-phase non-isothermal flow equations is considered. The problem of optimal control is formulated, an algorithm for the numerical solution is proposed. As a reference regime, temperature distribution corresponding to the constant pressure of injected steam is accepted. The solution of the optimization problem shows that choosing the steam pressure on the injection well, one can improve the efficiency of steam-stimulation and reduce the pressure of the injected steam.

  1. Sterile Neutrino Production Through a Matter Effect Enhancement at Long Baselines

    Science.gov (United States)

    Bramante, Joseph

    2013-06-01

    If sterile neutrinos have a neutral coupling to standard model fermions, matter effect resonant transitions to sterile neutrinos and excess neutral-current events could manifest at long baseline experiments. Assuming a single sterile neutrino with a neutral coupling to fermionic matter, we re-examine bounds on sterile neutrino production at long baselines from the MINOS result Pνμ →νs space of sterile neutrino matter effect fits of the LSND and MiniBooNe data, we show that in the case of a vector singlet coupling of sterile neutrinos to matter, some favored parametrizations of these fits would create neutral-current event excesses above standard model predictions at long baseline experiments (e.g. MINOS and OPERA).

  2. The condensation of steam from steam-water mixture on water jets at high pressure

    Science.gov (United States)

    Somova, E. V.; Kisina, V. I.; Shvarts, A. L.; Kolbasnikov, A. V.; Kanishchev, V. P.

    2009-01-01

    A physical model for condensation of steam in water flow at high pressure is developed, and analytical dependences for calculating heat transfer are obtained, in particular as applied to the operation of a direct-contact feedwater heater for a new-generation reactor plant with lead coolant.

  3. Sterile Neutrino Searches in MINOS and MINOS+ Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Junting [Univ. of Texas, Austin, TX (United States)

    2015-05-01

    This dissertation presents the searches on sterile neutrinos using the data collected in MINOS+ Experiment from September 2013 to September 2014, and the full data set of MINOS Experiment collected from 2005 to 2012. Anomalies in short baseline experiments, such as LSND and MiniBooNE, showed hints of sterile neutrinos, a type of neutrino that does not interact with the Standard Model particles. In this work, two models are considered: 3+1 and large extra dimension (LED). In the 3+1 model, one sterile neutrino state is added into the standard oscillation scheme consisting of three known active neutrino states ve, vμ and vτ. In the LED model, sterile neutrinos arise as Kaluza-Klein (KK) states due to assumed large extra dimensions. Mixing between sterile and active neutrino states may modify the oscillation patterns observed in the MINOS detectors. Both searches yield null results. For 3+1, a combined fit of MINOS and MINOS+ data gives a stronger limit on θ24 in the range of 10-2 eV2 < Δm412 < 1 eV2 than previous experiments. For LED, with the complete MINOS data set, the size of extra dimensions is constrained to be smaller than ~ 0.35 μm at 90% C.L. in the limit of a vanishing lightest neutrino mass.

  4. 基于模糊自适应 PID 的饱和蒸汽发电控制研究%Saturated Steam Power Generation Control Model Based on Fuzzy-PID

    Institute of Scientific and Technical Information of China (English)

    陈琳; 吴青柏; 张立杰

    2013-01-01

    The steam turbine in saturated steam power generation project is a typical industrial process control object ,with the features such as time‐varying ,nonlinear and hysteresis .Based on the control requirement of steam turbine generator operation ,this paper put forward a kind of adaptive fuzzy PID control method .Combining the features of the steam turbine generator operation and fuzzy PID controller ,the paper analyzed the data collected from power station ,established a control model ,and carried out the simulation study by MATLAB/Simulink .The simulation results verify the feasibility of this scheme and lay a good foundation for the control scheme’s application in generator operation process .%  饱和蒸汽发电项目中汽轮机是一个典型的工业过程控制对象,具有时变、非线性和滞后等显著特点。基于汽轮机发电机运行过程的控制要求,提出了一种自适应模糊PID控制方法。结合汽轮机发电机运行和模糊PID控制解决非线性、滞后性及时变等问题的特点,基于从发电站现场采集到的数据,建立了控制模型,并利用MATLAB/Simulink对系统进行了仿真,从而验证了该方案的可行性,为发电机控制提出了一种新的方案。

  5. Start with a Story: Five Schools and a Zoo Use the One Book, One Community Model to Bridge STEM into STEAM

    Science.gov (United States)

    Brock, Patricia; Dunifon, Sarah; Nagel, Lisa

    2016-01-01

    This article outlines an integrated STEAM project based on "The One and Only Ivan" by Katherine Applegate (2012). Elementary students focused on real-world, authentic problems presented in this 2013 Newbery Award-winning novel. The novel deals with difficult issues such as the humane treatment of animals, and has a powerful message of…

  6. Exploration, Drilling and Development Operations in the Bottle Rock Area of the Geysers Steam Field, With New Geologic Insights and Models Defining Reservoir Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Hebein, Jeffrey J.

    1983-12-15

    MCR Geothermal Corporation pioneered successful exploratiory drilling the Bottle Rock area of the Geysers Steam Field in 1976. The wellfield is characterized by a deep reservoir with varied flowrates, temperatures, pressures, and stem chemistries being quite acceptable. More detailed reservoir engineering tests will follow as production commences.

  7. On the gasification of biomass in a steam-oxygen blown CFB gasifier with the focus on gas quality upgrading: technology background, experiments and mathematical modeling

    NARCIS (Netherlands)

    Siedlecki, M.

    2011-01-01

    This work presents and discusses the results of the research on the gasification of biomass in an atmospheric circulating fluidized bed, with a mixture of steam and oxygen as fluidization / gasification medium. The main objectives of this research were to investigate and improve the gasification pro

  8. On the gasification of biomass in a steam-oxygen blown CFB gasifier with the focus on gas quality upgrading: technology background, experiments and mathematical modeling

    NARCIS (Netherlands)

    Siedlecki, M.

    2011-01-01

    This work presents and discusses the results of the research on the gasification of biomass in an atmospheric circulating fluidized bed, with a mixture of steam and oxygen as fluidization / gasification medium. The main objectives of this research were to investigate and improve the gasification pro

  9. Start with a Story: Five Schools and a Zoo Use the One Book, One Community Model to Bridge STEM into STEAM

    Science.gov (United States)

    Brock, Patricia; Dunifon, Sarah; Nagel, Lisa

    2016-01-01

    This article outlines an integrated STEAM project based on "The One and Only Ivan" by Katherine Applegate (2012). Elementary students focused on real-world, authentic problems presented in this 2013 Newbery Award-winning novel. The novel deals with difficult issues such as the humane treatment of animals, and has a powerful message of…

  10. Electron spin resonance studies of the effects of sterilization on poly(ethylene glycol) hydrogels.

    Science.gov (United States)

    Kanjickal, Deenu; Lopina, Stephanie; Evancho-Chapman, Mary Michelle; Schmidt, Steven; Inbaraj, Johnson J; Cardon, Thomas B; Lorigan, Gary A

    2009-02-01

    The effects of several sterilization procedures on a poly(ethylene glycol) (PEG) hydrogel have been examined by electron spin resonance (ESR) spectroscopy. The crosslinked polyurethanes were synthesized by reacting PEG with a tri-functional isocyanate. The free radical concentration of unsterilized, ethylene oxide (EtO), hydrogen peroxide (H(2)O(2)), and gamma sterilized hydrogels were monitored over time. Free radical presence was observed for all the treatments, unsterilized and sterilized PEG hydrogels. The unsterilized and the EtO sterilized samples elicited similar levels of free radical intensity whereas, the H(2)O(2) and gamma sterilized samples had a significantly higher free radical concentration. The spectra reveal overlapping resonances of a peroxy and a triphenylmethyl radical. The concentration of the free radicals increase for all the treatments over time except for the gamma sterilized sample. The increase is significantly higher in the H(2)O(2) sterilized sample. A tentative model is proposed to explain the reaction pathway leading to the production of the free radicals. The observed increases in the free radical concentrations of the EtO and hydrogen peroxide sterilized hydrogels over a five-month-period make it difficult to predict properties that are affected by free radical concentrations. In that light, gamma sterilization, that does not induce a change in free radical concentrations over a five month period, could be the sterilization method of choice for PEG hydrogels that could potentially be stored for undetermined periods of time prior to application.

  11. Transgenic technologies to induce sterility

    Directory of Open Access Journals (Sweden)

    Wimmer Ernst A

    2009-11-01

    Full Text Available Abstract The last few years have witnessed a considerable expansion in the number of tools available to perform molecular and genetic studies on the genome of Anopheles mosquitoes, the vectors of human malaria. As a consequence, knowledge of aspects of the biology of mosquitoes, such as immunity, reproduction and behaviour, that are relevant to their ability to transmit disease is rapidly increasing, and could be translated into concrete benefits for malaria control strategies. Amongst the most important scientific advances, the development of transgenic technologies for Anopheles mosquitoes provides a crucial opportunity to improve current vector control measures or design novel ones. In particular, the use of genetic modification of the mosquito genome could provide for a more effective deployment of the sterile insect technique (SIT against vector populations in the field. Currently, SIT relies on the release of radiation sterilized males, which compete with wild males for mating with wild females. The induction of sterility in males through the genetic manipulation of the mosquito genome, already achieved in a number of other insect species, could eliminate the need for radiation and increase the efficiency of SIT-based strategies. This paper provides an overview of the mechanisms already in use for inducing sterility by transgenesis in Drosophila and other insects, and speculates on possible ways to apply similar approaches to Anopheles mosquitoes.

  12. Integration of torrefaction with steam power plant

    Energy Technology Data Exchange (ETDEWEB)

    Zakri, B.; Saari, J.; Sermyagina, E.; Vakkilainen, E.

    2013-09-01

    Torrefaction is one of the pretreatment technologies to enhance the fuel characteristics of biomass. The efficient and continuous operation of a torrefaction reactor, in the commercial scale, demands a secure biomass supply, in addition to adequate source of heat. Biorefinery plants or biomass-fuelled steam power plants have the potential to integrate with the torrefaction reactor to exchange heat and mass, using available infrastructure and energy sources. The technical feasibility of this integration is examined in this study. A new model for the torrefaction process is introduced and verified by the available experimental data. The torrefaction model is then integrated in different steam power plants to simulate possible mass and energy exchange between the reactor and the plants. The performance of the integrated plant is investigated for different configurations and the results are compared. (orig.)

  13. MINET validation study using steam generator test data

    Energy Technology Data Exchange (ETDEWEB)

    Van Tuyle, G.J.; Guppy, J.G.

    1984-01-01

    Three steam generator transient test cases that were simulated using the MINET computer code are described, with computed results compared against experimental data. The MINET calculations closely agreed with the experiment for both the once-through and the U-tube steam generator test cases. The effort is part of an ongoing effort to validate the MINET computer code for thermal-hydraulic plant systems transient analysis, and strongly supports the validity of the MINET models.

  14. Hydraulic drag at the condensing steam flow in tubes

    Science.gov (United States)

    Leontiev, A. I.; Milman, O. O.

    2014-12-01

    The dependency of condensing steam flow parameters in tubes and channels was studied as a function of different flow modes for the coolant: counter-flow, co-flow, cross-flow. The drop for the total pressure of steam is higher for the counter-flow than for the co-flow or cross-flow modes. The pressure drop was estimated with different computation models as a function flow mode. Calculation results were compared with experimental data.

  15. Prediction and modeling of the two-dimensional separation characteristic of a steam generator at a nuclear power station with VVER-1000 reactors

    Science.gov (United States)

    Parchevsky, V. M.; Guryanova, V. V.

    2017-01-01

    A computational and experimental procedure for construction of the two-dimensional separation curve (TDSC) for a horizontal steam generator (SG) at a nuclear power station (NPS) with VVER-reactors. In contrast to the conventional one-dimensional curve describing the wetness of saturated steam generated in SG as a function of the boiler water level at one, usually rated, load, TDSC is a function of two variables, which are the level and the load of SGB that enables TDSC to be used for wetness control in a wide load range. The procedure is based on two types of experimental data obtained during rated load operation: the nonuniformity factor of the steam load at the outlet from the submerged perforated sheet (SPS) and the dependence of the mass water level in the vicinity of the "hot" header on the water level the "cold" end of SG. The TDSC prediction procedure is presented in the form of an algorithm using SG characteristics, such as steam load and water level as the input and giving the calculated steam wetness at the output. The zoneby-zone calculation method is used. The result is presented in an analytical form (as an empirical correlation) suitable for uploading into controllers or other controls. The predicted TDSC can be used during real-time operation for implementation of different wetness control scenarios (for example, if the effectiveness is a priority, then the minimum water level, minimum wetness, and maximum turbine efficiency should be maintained; if safety is a priority, then the maximum level at the allowable wetness and the maximum water inventory should be kept), for operation of NPS in controlling the frequency and power in a power system, at the design phase (as a part of the simulation complex for verification of design solutions), during construction and erection (in developing software for personnel training simulators), during commissioning tests (to reduce the duration and labor-intensity of experimental activities), and for training.

  16. Voluntary sterilization in Serbia: Unmet need?

    OpenAIRE

    Rašević Mirjana M.

    2002-01-01

    Is voluntary sterilization as a birth control method accepted in Serbia? This is certainly a question that is being imposed for research, regardless of the fact that voluntary sterilization is neither accessible nor promoted. Most importantly because there is no understanding in the social nor political sphere for legalization of voluntary sterilization as a form of birth control, apart from the clear necessity for this, first, step. They are: the recognition that voluntary sterilization is a...

  17. Modelagem de um reator integral aplicado na reação de reforma a vapor de metano = Modeling of integral reactor applied methane steam reforming

    Directory of Open Access Journals (Sweden)

    Giane Gonçalves

    2007-07-01

    Full Text Available Freqüentemente, a validação de modelos matemáticos aplicados a reatores industriais esbarra na dificuldade de obtenção de medidas experimentais confiáveis. Uma maneira de contornar esta limitação corresponde à implantação de uma unidade em escala de bancada devidamente instrumentada, na qual são obtidos dados experimentais emcondições controladas. Neste contexto, foram efetuados ensaios em um reator integral de reforma a vapor de metano em escala de bancada, em diversas condições experimentais. As medidas de temperatura no leito foram efetuadas por meio de um termopar multiponto em seis posições axiais distintas, enquanto a composição do efluente do reator foi determinada por cromatografia gasosa. Estes dados experimentais foram comparados com as previsões de um modelo pseudo-homogêneo, unidimensional e dinâmico. Os resultados indicam que o modelo é adequado, sendo que tanto a atividade catalítica como a conversão são sensíveis à temperatura operacional, enquanto a temperatura do leito é praticamente insensível à vazão nas condições experimentais exploradas.Frequently, the validation of applied mathematical models of industrial reactors dash into the difficulty of obtaining reliable experimental data. A way to overcome this limitation is the proper use and operation or a in bench scale, experimental setup from whichexperimental data can be obtained in controlled conditions. In this context, experiments were carried out in an integral reactor of steam reform, in different experimental conditions. Thermocouples were placed along the catalyst bed to allow for temperature monitoring in six equally spaced and distinct positions of the reactor, the composition of the effluent of the reactor was determined by gas chromatography. These experimental data were compared with the theoretical results of a pseudo-homogeneous one-dimensional,dynamic mathematical model. The results indicate that the model can successfully

  18. 具有不育控制的埃及伊蚊种群模型的全局动态%Global Dynamics of a Mathematical Model for the Control of Aedes aegypti Mosquitoes by the Sterile Insect Release Technique

    Institute of Scientific and Technical Information of China (English)

    聂玉稳; 刘贤宁; 宋杨

    2012-01-01

    给出了一个描述具有不育雄蚊作为生物控制的埃及伊蚊种群动力系统的模型.研究了边界平衡点及正平衡点存在和稳定的条件,得到了当正平衡点不存在时,边界平衡点全局渐近稳定的条件,即投放不育雄蚊使得野生蚊子种群灭亡的充分条件.%In this paper, a mathematical model is presented describing the dynamics of mosquito population with biological control by sterile male mosquito releasing. The existence and stability of the boundary and positive equilibria are investigated. We obtain the conditions for the global asymptotical stability of the boundary equilibrium when the positive equilibria do not exist, that is, the threshold for making wild mosquito population extinct by releasing sterile male mosquitoes.

  19. Biosorptive uptake of ibuprofen by steam activated biochar derived from mung bean husk: Equilibrium, kinetics, thermodynamics, modeling and eco-toxicological studies.

    Science.gov (United States)

    Mondal, Sandip; Bobde, Kiran; Aikat, Kaustav; Halder, Gopinath

    2016-11-01

    The present study explores the use of steam activated mung bean husk biochar (SA-MBHB) as a potential sorbent for the removal of non-steroidal and anti-inflammatory drug ibuprofen from aqueous solution. SA-MBHB was characterized by SEM, FTIR, BET, TGA, point of zero charge (pHPZC) and UV-Vis spectrophotometer. The relation between removal percentages of ibuprofen and parameters such as adsorbent dose (0.05 g-250 g), contact time (5 min-210 min), pH (2-10), speed of agitation (40-280 rpm), temperature (293-308 K) and initial ibuprofen concentration (5-100 ppm) was investigated and optimized by a series of batch sorption experiments. The optimized conditions achieved were: adsorbent dose 0.1 g/L, agitation speed 200 rpm, pH 2, initial ibuprofen concentration 20 mg L(-1), equilibrium time 120 min and temperature 20 °C for more than 99% adsorptive removal of ibuprofen. The equilibrium adsorption data were well fitted into the Langmuir isotherm model while kinetic data suggested the removal process to follow pseudo second order reaction. The adsorption phenomena were optimized and simulated by using response surface methodology (RSM) and artificial neural network (ANN). Effect of process variables viz. dose, agitation speed and pH on the sorbed amount of IBP was studied through a 2(3) full factorial central composite design (CCD). The comparative analysis was done for ibuprofen removal by constructing ANN model training using same experimental matrix of CCD. The growth of Scenedesmus abundans was also observed to be affected by the IBP solution whereas the biochar treated with IBP solution did not significantly affect the growth of the Scenedesmus abundans. The results revealed that SA-MBHB could be a cost-effective, efficient and non-hazardous adsorbent for the removal of ibuprofen from aqueous solution.

  20. Development and testing of a novel lab-scale direct steam-injection apparatus to hydrolyse model and saline crop slurries.

    Science.gov (United States)

    Santi, Guglielmo; Guglielmo, Santi; D'Annibale, Alessandro; Alessandro, D'Annibale; Petruccioli, Maurizio; Maurizio, Petruccioli; Crognale, Silvia; Silvia, Crognale; Ruzzi, Maurizio; Maurizio, Ruzzi; Valentini, Riccardo; Riccardo, Valentini; Moresi, Mauro; Moresi, Mauro

    2012-02-20

    In this work, a novel laboratory-scale direct steam-injection apparatus (DSIA) was developed to overcome the main drawback of the conventional batch-driven lab rigs, namely the long time needed to heat fiber slurry from room to reaction temperatures greater than 150 °C. The novel apparatus mainly consisted of three units: (i) a mechanically-stirred bioreactor where saturated steam at 5-30 bar can be injected; (ii) an automatic on-off valve to flash suddenly the reaction medium after a prefixed reaction time; (iii) a cyclone separator to recover the reacted slurry. This system was tested using 0.75 dm³ of an aqueous solution of H₂SO₄ (0.5%, v/v) enriched with 50 kg m⁻³ of either commercial particles of Avicel® and Larch xylan or 0.5 mm sieved particles of Tamarix jordanis. Each slurry was heated to about 200 °C by injecting steam at 28 bar for 90 s. The process efficiency was assessed by comparing the dissolution degree of suspended solid (Y(S)), as well as xylose (Y(X)), glucose (Y(G)), and furfural (Y(F)) yields, with those obtained in a conventional steam autoclave at 130 °C for 30 or 60 min. Treatment of T. jordanis particles in DSIA resulted in Y(S) and Y(G) values quite similar to those obtained in the steam autoclave at 130 °C for 60 min, but in a less efficient hemicellulose solubilization. A limited occurrence of pentose degradation products was observed in both equipments, suggesting that hydrolysis predominated over degradation reactions. The susceptibility of the residual solid fractions from DSIA treatment to a conventional 120 h long cellulolytic treatment using an enzyme loading of 5.4 FPU g⁻¹ was markedly higher than that of samples hydrolysed in the steam autoclave, their corresponding glucose yields being equal to 0.94 and 0.22 g per gram of initial cellulose, respectively. Thus, T. jordanis resulted to be a valuable source of sugars for bioethanol production as proved by preliminary tests in the novel lab rig developed here.

  1. STEAM DALAM PEMBUATAN PAKAN UNTUK KOMODITAS AKUAKULTUR

    OpenAIRE

    Sukarman Sukarman

    2010-01-01

    Kualitas fisik pakan (pelet) untuk hewan akuakultur sangat penting, karena akan dimasukkan ke dalam air dan diharapkan tidak banyak mencemari lingkungan. Salah satu faktor yang berpengaruh dalam menjaga kualitas fisik pakan adalah penambahan dan pengaturan steam pada saat proses pembuatan pelet. Steam adalah aliran gas yang dihasilkan oleh air pada saat mendidih. Steam dibagi menjadi 3 jenis yaitu steam basah, saturated steam, dan superheated steam. Steam yang digunakan dalam proses pembuatan...

  2. Microwave Sterilization and Depyrogenation System

    Science.gov (United States)

    Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

    2009-01-01

    A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time

  3. Axion-Assisted Production of Sterile Neutrino Dark Matter

    CERN Document Server

    Berlin, Asher

    2016-01-01

    Sterile neutrinos can be generated in the early universe through oscillations with active neutrinos and represent a popular and well-studied candidate for our universe's dark matter. Stringent constraints from X-ray and gamma-ray line searches, however, have excluded the simplest of such models. In this letter, we propose a novel alternative to the standard scenario in which the mixing angle between the sterile and active neutrinos is a dynamical quantity, induced through interactions with a light axion-like field. As the energy density of the axion-like particles is diluted by Hubble expansion, the degree of mixing is reduced at late times, suppressing the decay rate and easily alleviating any tension with X-ray or gamma-ray constraints. We present a simple model which illustrates the phenomenology of this scenario, and also describe a framework in which the QCD axion is responsible for the production of sterile neutrinos in the early universe.

  4. Performance of annular flow sterilizer irradiated by a germicidal lamp

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, T.; Yoneya, M.; Ohashi, H. (Akita Univ. (Japan))

    1981-10-01

    Theoretical and experimental studies were conducted on the UV-inactivation characteristics of Bacillus subtilis spores in an annular-flow sterilizer irradiated by a germicidal lamp located at the center of the inner tube. Experimental results for sterilizer performance in laminar spore-suspension flow were well simulated dynamically and statically by theoretical considerations which incorporated multi-targets with single-hit model for the UV-inactivation kinetic and the diffuse light model for the angle characteristic of lamp, along with due attention to the parabolic velocity distribution and the negligible diffusion of spores. Scale on the outside wall of the inner tube was checked by the use of a cylindrical chemical actinometer. Calculated examples elucidate the reason why careful inspection is needed of UV-inactivation kinetics, angle characteristics of lamp, and fluid mixing to evaluate performance of actual flow UV sterilizers at high extent of inactivation up to the order of 99.999%.

  5. Nonlinear H-infinity control of nuclear steam generators

    Science.gov (United States)

    Ramalho, Fernando Pinto

    Motivated by the fact that problems related to the control of steam generators are responsible for a significant amount of downtime in nuclear power plants, this thesis investigates the applicability of linear and nonlinear Hinfinity theory to the control of nuclear steam generators. A nonlinear model based on mass, energy, and momentum balances was developed for a U-tube steam generator, with the water level and steam quality at the exit of the riser considered as state variables. In this model the steam flow to the turbines and the heat flow from the primary to the secondary side are represented as disturbances affecting the system, while the feedwater flow is used to compensate for changes in the water level. The performance specifications for the feedback loop are encoded using weight functions incorporated into an augmented plant, and the control problem is formulated to minimize the effects of disturbances on the controlled variables. The solution of the optimization problem is reduced to the solution of a set of differential equations, which, in the linear case, is equivalent to the solution of Riccati equations. The linear Hinfinity controller and filter were obtained for the U-tube steam generator with and without weight functions, and simulations for a 50 s ramp transient resulting in 50% decrease in the heat and steam flows were performed over 300 s. The use of weights provided less variation in the water level, and an excellent noise rejection capability was observed. For the nonlinear Hinfinity formulation a finite-difference method was used to solve the state and costate equations numerically for optimal feedwater flow minimizing water level variations. The combined solution of the state equation in the forward direction and the costate equations in the backward direction converged in 10 iteractions. The nonlinear controller results in less variation in the water level than the corresponding linear Hinfinity controller, demonstrating the feasibility

  6. Steam turbine stress control using NARX neural network

    Science.gov (United States)

    Dominiczak, Krzysztof; Rzadkowski, Romuald; Radulski, Wojciech

    2015-11-01

    Considered here is concept of steam turbine stress control, which is based on Nonlinear AutoRegressive neural networks with eXogenous inputs. Using NARX neural networks,whichwere trained based on experimentally validated FE model allows to control stresses in protected thickwalled steam turbine element with FE model quality. Additionally NARX neural network, which were trained base on FE model, includes: nonlinearity of steam expansion in turbine steam path during transients, nonlinearity of heat exchange inside the turbine during transients and nonlinearity of material properties during transients. In this article NARX neural networks stress controls is shown as an example of HP rotor of 18K390 turbine. HP part thermodynamic model as well as heat exchange model in vicinity of HP rotor,whichwere used in FE model of the HP rotor and the HP rotor FE model itself were validated based on experimental data for real turbine transient events. In such a way it is ensured that NARX neural network behave as real HP rotor during steam turbine transient events.

  7. Subcooled choked flow through steam generator tube cracks

    Science.gov (United States)

    Wolf, Brian J.

    The work presented here describes an experimental investigation into the choked flow of initially subcooled water through simulated steam generator tube cracks at pressures up to 6.9 MPa. The study of such flow is relevant to the prediction of leak flow rates from a nuclear reactor primary side to secondary side through cracks in steam generator tubes. An experimental approach to measuring such flow is de- scribed. Experimental results from data found in literature as well as the data collected in this work are compared with predictions from presented models as well as predictions from the thermal-hydraulic system code RELAP5. It is found that the homogeneous equilibrium model underpredicts choked flow rates of subcooled water through slits and artificial steam generator tube cracks. Additional modeling of thermal non-equilibrium improves the predictibility of choking mass flux for homogeneous models, however they fail to account for the characteristics of the two-phase pressure drop. An integral modeling approach is enhanced using a correlation developed from the data herein. Also, an assessment of the thermal-hydraulics code RELAP5 is performed and it’s applicability to predict choking flow rates through steam generator tube cracks is addressed. This assessment determined that the Henry & Fauske model, as coded in RELAP5, is best suited for modeling choked flow through steam generator tube cracks. Finally, an approach to applying choked flow data that is not at the same thermo-dynamic conditions as a prototype is developed.

  8. Experimental study of formation heating during radial flow of steam

    Energy Technology Data Exchange (ETDEWEB)

    Malofeev, G.E.; Kennavi, F.A.; Sheinman, A.B.

    1969-06-01

    Hot water or steam was injected into a laboratory model of an oil formation, and the distribution of temperature within the model was determined at different times. The zone of interest in the model was 50 mm thick, thickness of overlying and underlying rock was 140 mm. Model diameter was 600 mm, porosity was 37%, and permeability 4 darcies. Well diameter was 6.5 mm. Dimensionless parameters were determined, so that thermal behavior of the model represented thermal behavior of a reservoir. Both vertical and radial temperature distributions in the model are shown graphically, as well as the relationship between the heat injected into the system and the heat accumulated by the system. It was found that there is formed in the sand a steam zone (zone of constant temperature) whose radius increases with time; and the coefficient of heat utilization does not depend on the quantity of injected steam.

  9. Outbreak of toxic anterior segment syndrome following cataract surgery associated with impurities in autoclave steam moisture.

    Science.gov (United States)

    Hellinger, Walter C; Hasan, Saiyid A; Bacalis, Laura P; Thornblom, Deborah M; Beckmann, Susan C; Blackmore, Carina; Forster, Terri S; Tirey, Jason F; Ross, Mary J; Nilson, Christian D; Mamalis, Nick; Crook, Julia E; Bendel, Rick E; Shetty, Rajesh; Stewart, Michael W; Bolling, James P; Edelhauser, Henry F

    2006-03-01

    Toxic anterior segment syndrome (TASS), a complication of cataract surgery, is a sterile inflammation of the anterior chamber of the eye. An outbreak of TASS was recognized at an outpatient surgical center and its affiliated hospital in December 2002. Medical records of patients who underwent cataract surgery during the outbreak were reviewed, and surgical team members who participated in the operations were interviewed. Potential causes of TASS were identified and eliminated. Feedwater from autoclave steam generators and steam condensates were analyzed by use of spectroscopy and ion chromatography. During the outbreak, 8 (38%) of 21 cataract operations were complicated by TASS, compared with 2 (0.07%) of 2,713 operations performed from January 1996 through November 2002. Results of an initial investigation suggested that cataract surgical equipment may have been contaminated by suboptimal equipment reprocessing or as a result of personnel changes. The frequency of TASS decreased (1 of 44 cataract operations) after reassignment of personnel and revision of equipment reprocessing procedures. Further investigation identified the presence of impurities (eg, sulfates, copper, zinc, nickel, and silica) in autoclave steam moisture, which was attributed to improper maintenance of the autoclave steam generator in the outpatient surgical center. When impurities in autoclave steam moisture were eliminated, no cases of TASS were observed after more than 1,000 cataract operations. Suboptimal reprocessing of cataract surgical equipment may evolve over time in busy, multidisciplinary surgical centers. Clinically significant contamination of surgical equipment may result from inappropriate maintenance of steam sterilization systems. Standardization of protocols for reprocessing of cataract surgical equipment may prevent outbreaks of TASS and may be of assistance during outbreak investigations.

  10. Modelling and simulation of a membrane reactor for the oxidation of methane with simultaneous steam reforming using O2-selective perowskite hollow fibres

    OpenAIRE

    Hamel, C.; Tota, A.; Wang, H.; Tablet, C.; Caro, J; Tsotsas, E.

    2006-01-01

    The generation of synthesis gas from methane is currently performed by conventional steam reforming or by partial oxidation (POX) in fixed-bed reactors using nickel or noble metal based catalysts. These catalysts offer the possibility to reach high yields at temperatures around 900°C [1]. In the last years several new reactor concepts were suggested to intensify the heat exchange, e.g. auto thermal reformers, catalytic coated wall reactors, fluidised bed or membrane reactors [2]. Improved POX...

  11. Laboratory investigations of the physics of steam flow in a porous medium

    Science.gov (United States)

    Herkelrath, W.N.; Moench, A.F.

    1982-01-01

    Experiments were carried out in the laboratory to test a theory of transient flow of pure steam in a uniform porous medium. This theory is used extensively in modeling pressure-transient behavior in vapor-dominated geothermal systems. Transient, superheated steam-flow experiments were run by bringing a cylinder of porous material to a uniform initial pressure, and then making a step increase in pressure at one end of the sample, while monitoring the pressure-transient breakthrough at the other end. It was found in experiments run at 100?, 125?, and 146?C that the time required for steam-pressure transients to propagate through an unconsolidated material containing sand, silt, and clay was 10 to 25 times longer than predicted by theory. It is hypothesized that the delay in the steam-pressure transient was caused by adsorption of steam in the porous sample. In order to account for steam adsorption, a sink term was included in the conservation of mass equation. In addition, energy transfer in the system has to be considered because latent heat is released when steam adsorption occurs, increasing the sample temperature by as much as 10?C. Finally, it was recognized that the steam pressure was a function of both the temperature and the amount of adsorption in the sample. For simplicity, this function was assumed to be in equilibrium adsorption isotherm, which was determined by experiment. By solving the modified mass and energy equations numerically, subject to the empirical adsorption isotherm relationship, excellent theoretical simulation of the experiments was achieved. The experiments support the hypothesis that adsorption of steam can strongly influence steam pressure-transient behavior in porous media; the results suggest that the modified steam-flow theory, which includes steam adsorption terms, should be used in modeling steam flow in vapor-dominated geothermal systems.

  12. Hydraulic model of the steam-lines network of the Cerro Prieto, B.C., geothermal field; Modelo hidraulico de la red de vaporductos del campo geotermico de Cerro Prieto, B.C.

    Energy Technology Data Exchange (ETDEWEB)

    Salaices, E; Garcia, A; Martinez J I; Ovando, R; Cecenas, M; Hernandez A F [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: salaices@iie.org.mx; Canchola, I; Mora, O; Miranda, C; Herandez, M; Lopez, S; Murillo, I [Comision Federal de Electricidad, B.C (Mexico)

    2007-01-15

    The steam-line network of the Cerro Prieto geothermal field is composed of 184 wells, and 162 of the wells are integrated and connected by pipes. Thirteen power units, with an installed electrical capacity of 720 MW, are fed by that network. The network length is 120 km, including pipes of several diameters with branches and interconnections. The extension and complexity of the steam-line system make it difficult to analyze the transport and supply of steam to the power plants. For that it was necessary to have a tool capable of analyzing the system and the performance of the network as a whole, as well as the direction and flow volumes in each part of the system. In this paper, a hydraulic model of the Cerro Prieto steam-line network is presented. The model can determine the performance of the whole network by quantifying the pressure drops, flows and heat losses of the components. The model analyses the consequences of changes in operating conditions, steam production, maintenance activities and design (such as the integration of new wells). The model was developed using PIPEPHASE 9.0, a numeric simulator of multi-phase flow in steady state with heat transfer. It is used to model systems and pipe networks for steam- and condensate-transport. [Spanish] La red de vaporductos del campo geotermico de Cerro Prieto esta compuesta por un conjunto de 184 pozos, de los cuales 162 son pozos integrados, interconectados entre si a traves de una red de tuberias. Por medio de esta red se alimentan 13 unidades generadoras de electricidad con una capacidad total instalada de 720 MWe. La red tiene una longitud aproximada de 120 kilometros y esta compuesta por tuberias de diferentes diametros, ramales, interconexiones, etc. La complejidad y extension del sistema de vaporductos hace muy dificil el analisis del transporte y suministro de vapor a las plantas generadoras. Lo anterior creo la necesidad de contar con una herramienta que ayudara en el analisis del sistema con el fin de

  13. Microwave sterilization method and apparatus

    OpenAIRE

    V. N. Vasilenko; Minuhin, V. V.; Podorozhnyak, A. A.; Trubaev, S. I.

    1995-01-01

    Experience of industrially developed countries in utilization of microwave radiation has been analyzed. Apparatus for realization of microwave method of sterilization has been designed. A number of experiments for the estimation of bactericidal, sporacidal, and virusidal properties of microwave radiation action has been carried out in 3 to 13 cm wavelength band. B. Lycheniform shtumm G., B. Subtilis ATTC 6633, E. Coli ATTC 25922 and bacterial virus FX 174 were used as test microbes. Effect of...

  14. Instrument sterilization in orthodontic offices.

    Science.gov (United States)

    Matlack, R E

    1979-07-01

    1. Three different quaternary ammonium compound solutions remained bactericidal against specific vegetative bacteria in three orthodontic offices over a ten day working period. However, no spore formers or viruses were tested. 2. Bacterial contaminants were cultured on pliers and scalers at the chair at least once in each of three orthodontic offices sampled twice a day for ten working days. 3. Sampled chairside instruments wiped with an alcohol sponge only, between patients, were contaminated an excessive 32.5% of the time, too frequently to be seriously considered for routine disinfection of pliers. 4. Chairside instruments, sampled regardless of other means of disinfection or sterilization used, were contaminated from 3.5 to 15% of the time. Therefore, storage and handling of orthodontic instruments must be evaluated and upgraded to prevent recontamination of previously sterilized instruments. 5. Staff personnel need courses in sterilization and disinfection procedures to prevent cross contamination from patient to patient and to protect themselves. These courses should be related specifically to orthodontic practice procedures.

  15. Thermomechanical Model and Bursting Tests to Evaluate the Risk of Swelling and Bursting of Modified 9Cr-1Mo Steel Steam Generator Tubes during a Sodium-Water Reaction Accident

    Directory of Open Access Journals (Sweden)

    C. Bertrand

    2014-01-01

    Full Text Available The MECTUB code was developed to evaluate the risk of swelling and bursting of Steam Generator (SG tubes. This code deals with the physic of intermediate steam-water leaks into sodium which induce a Sodium-Water Reaction (SWR. It is based on a one-dimensional calculation to describe the thermomechanical behavior of tubes under a high internal pressure and a fast external overheating. The mechanical model of MECTUB is strongly correlated with the kind of the material of the SG tubes. It has been developed and validated by using experiments performed on the alloy 800. A change to tubes made of Modified 9Cr-1Mo steel requires more knowledge of Modified 9Cr-1Mo steel behavior which influences the bursting time at high temperatures (up to 1200°C. Studies have been initiated to adapt the mechanical model and to qualify it for this material. The first part of this paper focuses on the mechanical law modelling (elasticity, plasticity, and creep for Modified 9Cr-1Mo steel and on overheating thermal data. In a second part, the results of bursting tests performed on Modified 9Cr-1Mo tubes in the SQUAT facility of CEA are used to validate the mechanical model of MECTUB for the Modified 9Cr-1Mo material.

  16. A light sterile neutrino from Friedberg–Lee symmetry

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiao-Gang [Shanghai Key Laboratory of Particle Physics and Cosmology, Shanghai (China); INPAC and Department of Physics, Shanghai Jiao Tong University, Shanghai (China); Physics Division, National Center for Theoretical Sciences, Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); CTS, CASTS and Department of Physics, National Taiwan University, Taipei, Taiwan (China); Liao, Wei, E-mail: liaow@ecust.edu.cn [Institute of Modern Physics, School of Science, East China University of Science and Technology, Shanghai (China)

    2014-01-20

    Light sterile neutrinos of mass about an eV with mixing U{sup -tilde}{sub ls} of a few percent to active neutrinos may solve some anomalies shown in experimental data related to neutrino oscillation. How to have light sterile neutrinos is one of the theoretical problems which have attracted a lot of attentions. In this article we show that such an eV scale light sterile neutrino candidate can be obtained in a seesaw model in which the right-handed neutrinos satisfy a softly-broken Friedberg–Lee (FL) symmetry. In this model a right-handed neutrino is guaranteed by the FL symmetry to be light comparing with other two heavy right-handed neutrinos. It can be of eV scale when the FL symmetry is softly broken and can play the role of eV scale sterile neutrino needed for explaining the anomalies of experimental data. This model predicts that one of the active neutrino is massless. We find that this model prefers inverted hierarchy mass pattern of active neutrinos than normal hierarchy. An interesting consequence of this model is that realizing relatively large |U{sup -tilde}{sub es}| and relatively small |U{sup -tilde}{sub μs}| in this model naturally leads to a relatively small |U{sup -tilde}{sub τs}|. This interesting prediction can be tested in future atmospheric or solar neutrino experiments.

  17. A light sterile neutrino from Friedberg-Lee symmetry

    Science.gov (United States)

    He, Xiao-Gang; Liao, Wei

    2014-01-01

    Light sterile neutrinos of mass about an eV with mixing U of a few percent to active neutrinos may solve some anomalies shown in experimental data related to neutrino oscillation. How to have light sterile neutrinos is one of the theoretical problems which have attracted a lot of attentions. In this article we show that such an eV scale light sterile neutrino candidate can be obtained in a seesaw model in which the right-handed neutrinos satisfy a softly-broken Friedberg-Lee (FL) symmetry. In this model a right-handed neutrino is guaranteed by the FL symmetry to be light comparing with other two heavy right-handed neutrinos. It can be of eV scale when the FL symmetry is softly broken and can play the role of eV scale sterile neutrino needed for explaining the anomalies of experimental data. This model predicts that one of the active neutrino is massless. We find that this model prefers inverted hierarchy mass pattern of active neutrinos than normal hierarchy. An interesting consequence of this model is that realizing relatively large |U| and relatively small |U| in this model naturally leads to a relatively small |U|. This interesting prediction can be tested in future atmospheric or solar neutrino experiments.

  18. Steam reforming of ethanol

    DEFF Research Database (Denmark)

    Trane-Restrup, Rasmus; Dahl, Søren; Jensen, Anker Degn

    2013-01-01

    Steam reforming (SR) of oxygenated species like bio-oil or ethanol can be used to produce hydrogen or synthesis gas from renewable resources. However, deactivation due to carbon deposition is a major challenge for these processes. In this study, different strategies to minimize carbon deposition...... on Ni-based catalysts during SR of ethanol were investigated in a flow reactor. Four different supports for Ni were tested and Ce0.6Zr0.4O2 showed the highest activity, but also suffered from severe carbon deposition at 600 °C or below. Operation at 600 °C or above were needed for full conversion...... 400 ppm of the carbon in the feed at approx. 600 °C. The different promoters did not influence the product distribution to any significant extent. Selective poisoning with small amounts of K2SO4 on Ni–CeO2/MgAl2O4 at 600 °C decreased carbon deposition from 900 to 200 ppm of the carbon in the feed...

  19. Steam foam studies in the presence of residual oil

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, D.A.; Demiral, B.; Castanier, L.M.

    1992-05-01

    The lack of understanding regarding foam flow in porous media necessitates further research. This paper reports on going work at Stanford University aimed at increasing our understanding in the particular area of steam foams. The behavior of steam foam is investigated with a one dimensional (6 ft. {times} 2.15 in.) sandpack under residual oil conditions of approximately 12 percent. The strength of the in-situ generated foam, indicated by pressure drops, is significantly affected by injection procedure, slug size, and steam quality. The surfactant concentration effect is minor in the range studied. In the presence of residual oil the simultaneous injection of steam and surfactant fails to generate foam in the model even though the same procedure generates a strong foam in the absence of oil. Nevertheless when surfactant is injected as a slug ahead of the steam using a surfactant alternating (SAG) procedure, foam is generated. The suggested reason for the success of SAG is the increased phase mixing that results from steam continually having to reestablish a path through a slug of surfactant solution.

  20. 电厂过热汽温串级系统的约束预测控制%Cascade Constrained Model Predictive Control for Power Plant Superheated Steam Temperature System

    Institute of Scientific and Technical Information of China (English)

    冯建苗; 李少远

    2011-01-01

    Power plant superheated steam temperature system is characterized by large inertia and large lag.Usually spray system is applied to form a cascade control system and cascade PID scheme is usually employed to control superheated steam temperature.The spray valve is subject to physical constraints so that actuator saturation happens because of the set point computed by the outer loop controller.The method of cascade model predictive control was applied.Constrained model predictive control(CMPC) was used to handle constraints and obtain optimal solution with system satisfying the corresponding constraints.In addition,simulation of superheated steam system was realized.%针对实际电厂过热汽温系统中减温水阀门受到物理约束限制,外环控制器计算的设定值造成执行机构饱和从而影响系统性能的问题,提出了串级预测控制算法,并采用约束预测控制算法进行求解,在系统约束范围内求得系统性能的优化解,对电厂过热汽温控制系统进行了仿真论证.仿真结果表明,过热汽温系统控制量能被有效控制在约束范围内,并且系统保持了良好的运行结果.

  1. The Portable Chemical Sterilizer (PCS), D-FENS, and D-FEND ALL: novel chlorine dioxide decontamination technologies for the military.

    Science.gov (United States)

    Doona, Christopher J; Feeherry, Florence E; Setlow, Peter; Malkin, Alexander J; Leighton, Terrence J

    2014-06-29

    There is a stated Army need for a field-portable, non-steam sterilizer technology that can be used by Forward Surgical Teams, Dental Companies, Veterinary Service Support Detachments, Combat Support Hospitals, and Area Medical Laboratories to sterilize surgical instruments and to sterilize pathological specimens prior to disposal in operating rooms, emergency treatment areas, and intensive care units. The following ensemble of novel, 'clean and green' chlorine dioxide technologies are versatile and flexible to adapt to meet a number of critical military needs for decontamination(6,15). Specifically, the Portable Chemical Sterilizer (PCS) was invented to meet urgent battlefield needs and close critical capability gaps for energy-independence, lightweight portability, rapid mobility, and rugged durability in high intensity forward deployments(3). As a revolutionary technological breakthrough in surgical sterilization technology, the PCS is a Modern Field Autoclave that relies on on-site, point-of-use, at-will generation of chlorine dioxide instead of steam. Two (2) PCS units sterilize 4 surgical trays in 1 hr, which is the equivalent throughput of one large steam autoclave (nicknamed "Bertha" in deployments because of its cumbersome size, bulky dimensions, and weight). However, the PCS operates using 100% less electricity (0 vs. 9 kW) and 98% less water (10 vs. 640 oz.), significantly reduces weight by 95% (20 vs. 450 lbs, a 4-man lift) and cube by 96% (2.1 vs. 60.2 ft(3)), and virtually eliminates the difficult challenges in forward deployments of repairs and maintaining reliable operation, lifting and transporting, and electrical power required for steam autoclaves.

  2. Reliability design method for steam turbine blades

    Institute of Scientific and Technical Information of China (English)

    Jinyuan SHI

    2008-01-01

    Based on theories of probability and statistics, and taking static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and exciting force frequencies of blades as random variables, a reliabil-ity design method for steam turbine blades is presented. The purport and calculation method for blade reliability are expounded. The distribution parameters of random variables are determined after analysis and numerical cal-culation of test data. The fatigue strength and the vibra-tion design reliability of turbine blades are determined with the aid of a probabilistic design method and by inter-ference models for stress distribution and strength distri-bution. Some blade reliability design calculation formulas for a dynamic stress design method, a safety ratio design method for fatigue strength, and a vibration reliability design method for the first and second types of tuned blades and a packet of blades on a disk connected closely, are given together with some practical examples. With these methods, the design reliability of steam turbine blades can be guaranteed in the design stage. This research may provide some scientific basis for reliability design of steam turbine blades.

  3. Neural Network Internal Model Control for Superheated Steam Temperature of Supercritical Boiler Unit%超临界锅炉过热汽温神经网络内模控制

    Institute of Scientific and Technical Information of China (English)

    马良玉; 冯谦; 易祖耀

    2013-01-01

    锅炉过热汽温是燃煤机组运行中的重要参数,过高、过低都会对机组的安全经济运行构成威胁.由于锅炉结构复杂,系统庞大,汽温对象具有变时滞、变参数等特性,喷水减温系统采用的串级PID控制,在大范围变工况下效果往往很不理想,且PID参数整定耗时耗力.为此,该文针对600 MW超临界锅炉过热器的喷水减温系统,研究了过热汽温神经网络(ANN)内模控制方案.基于Matlab建立了汽温系统的ANN正模型和逆模型,并设计出ANN内模实时控制器.仿真表明,与原串级PID控制相比,该方案显著改善了过热汽温的控制品质.%Boiler SST was an important parameter closely related to the safe and economic operation of a coal-fired power plant. Superheated steam temperature either too high or too low will pose a threat on the operation safety and economy. Because the boiler superheater system was relatively complex with large delay,large inertia and higher non-linearity, satisfactory control effects can often not be obtained with conventional cascade PID control scheme at wide operating range. Retuning of the PID parameters was often a time-consuming and labor-intensive work. For this reason, a neural network IMC scheme was studied for the two-stage desuperheating system of a 600 MW supercritical boiler unit, studying the system with the method based on superheated steam temperature control scheme. The neural network direct models and inverse models of the superheater system are built and trained with MATLAB software. Then neural network model based IMC controllers for the superheated steam temperature were designed,programmed and tested with a full-scope power plant simulator. It was shown that the neural network IMC scheme can significantly improve the superheated steam temperature control quality compared to the original cascade PID control.

  4. Materials Performance in USC Steam Portland

    Energy Technology Data Exchange (ETDEWEB)

    G.R. Holcomb; J. Tylczak; R. Hu

    2011-04-26

    Goals of the U.S. Department of Energy's Advanced Power Systems Initiatives include power generation from coal at 60% efficiency, which requires steam conditions of up to 760 C and 340 atm, co-called advanced ultrasupercritical (A-USC) steam conditions. A limitation to achieving the goal is a lack of cost-effective metallic materials that can perform at these temperatures and pressures. Some of the more important performance limitations are high-temperature creep strength, fire-side corrosion resistance, and steam-side oxidation resistance. Nickel-base superalloys are expected to be the materials best suited for steam boiler and turbine applications above about 675 C. Specific alloys of interest include Haynes 230 and 282, Inconel 617, 625 and 740, and Nimonic 263. Further validation of a previously developed chromia evaporation model is shown by examining the reactive evaporation effects resulting from exposure of Haynes 230 and Haynes 282 to moist air environments as a function of flow rate and water content. These two alloys differ in Ti and Mn contents, which may form outer layers of TiO{sub 2} or Cr-Mn spinels. This would in theory decrease the evaporation of Cr{sub 2}O{sub 3} from the scale by decreasing the activity of chromia at the scale surface, and be somewhat self-correcting as chromia evaporation concentrates the Ti and Mn phases. The apparent approximate chromia activity was found for each condition and alloy that showed chromia evaporation kinetics. As expected, it was found that increasing the gas flow rate led to increased chromia evaporation and decreased chromia activity. However, increasing the water content in moist air increased the evaporation, but results were mixed with its effect on chromia activity.

  5. Sterile neutrino portal to Dark Matter II: exact dark symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Escudero, Miguel; Rius, Nuria [Universidad de Valencia-CSIC, Departamento de Fisica Teorica and IFIC, C/Catedratico Jose Beltran, 2, 46980, Paterna (Spain); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)

    2017-06-15

    We analyze a simple extension of the standard model (SM) with a dark sector composed of a scalar and a fermion, both singlets under the SM gauge group but charged under a dark sector symmetry group. Sterile neutrinos, which are singlets under both groups, mediate the interactions between the dark sector and the SM particles, and generate masses for the active neutrinos via the seesaw mechanism. We explore the parameter space region where the observed Dark Matter relic abundance is determined by the annihilation into sterile neutrinos, both for fermion and scalar Dark Matter particles. The scalar Dark Matter case provides an interesting alternative to the usual Higgs portal scenario. We also study the constraints from direct Dark Matter searches and the prospects for indirect detection via sterile neutrino decays to leptons, which may be able to rule out Dark Matter masses below and around 100 GeV. (orig.)

  6. Sterile Neutrino portal to Dark Matter II: Exact Dark symmetry

    CERN Document Server

    Escudero, Miguel; Sanz, Verónica

    2016-01-01

    We analyze a simple extension of the Standard Model (SM) with a dark sector composed of a scalar and a fermion, both singlets under the SM gauge group but charged under a dark sector symmetry group. Sterile neutrinos, which are singlets under both groups, mediate the interactions between the dark sector and the SM particles, and generate masses for the active neutrinos via the seesaw mechanism. We explore the parameter space region where the observed Dark Matter relic abundance is determined by the annihilation into sterile neutrinos, both for fermion and scalar Dark Matter particles. The scalar Dark Matter case provides an interesting alternative to the usual Higgs portal scenario. We also study the constraints from direct Dark Matter searches and the prospects for indirect detection via sterile neutrino decays to leptons, which may be able to rule out Dark Matter masses below and around 100 GeV.

  7. Sterile neutrinos in the 3+s scenario and solar data

    CERN Document Server

    Pulido, Joao

    2013-01-01

    The flatness of the SuperKamiokande neutrino electron scattering spectrum and the apparent downturn of the charged current spectrum in the SNO data which the Large Mixing Angle solution (LMA) to the solar neutrino problem fails to predict are analysed in the context of an extension to the standard electroweak model with light sterile neutrinos. It is found that a sterile neutrino which is quasi degenerate with the active ones with $\\Delta m^2_{41}=10^{-5}eV^2$ and mixing $sin\\theta_{14}=0.04$ provides a suitable improvement to the LMA data fits.

  8. A computationally efficient and accurate numerical representation of thermodynamic properties of steam and water for computations of non-equilibrium condensing steam flow in steam turbines

    Directory of Open Access Journals (Sweden)

    Hrubý Jan

    2012-04-01

    Full Text Available Mathematical modeling of the non-equilibrium condensing transonic steam flow in the complex 3D geometry of a steam turbine is a demanding problem both concerning the physical concepts and the required computational power. Available accurate formulations of steam properties IAPWS-95 and IAPWS-IF97 require much computation time. For this reason, the modelers often accept the unrealistic ideal-gas behavior. Here we present a computation scheme based on a piecewise, thermodynamically consistent representation of the IAPWS-95 formulation. Density and internal energy are chosen as independent variables to avoid variable transformations and iterations. On the contrary to the previous Tabular Taylor Series Expansion Method, the pressure and temperature are continuous functions of the independent variables, which is a desirable property for the solution of the differential equations of the mass, energy, and momentum conservation for both phases.

  9. A computational model for reliability calculation of steam generators from defects in its tubes; Um modelo computacional para o calculo da confiabilidade de geradores de vapor a partir de defeitos em seus tubos

    Energy Technology Data Exchange (ETDEWEB)

    Rivero, Paulo C.M.; Melo, P.F. Frutuoso e [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

    2000-07-01

    Nowadays, probability approaches are employed for calculating the reliability of steam generators as a function of defects in their tubes without any deterministic association with warranty assurance. Unfortunately, probability models produce large failure values, as opposed to the recommendation of the U.S. Code of Federal Regulations, that is, failure probabilities must be as small as possible In this paper, we propose the association of the deterministic methodology with the probabilistic one. At first, the failure probability evaluation of steam generators follows a probabilistic methodology: to find the failure probability, critical cracks - obtained from Monte Carlo simulations - are limited to have length's in the interval defined by their lower value and the plugging limit one, so as to obtain a failure probability of at most 1%. The distribution employed for modeling the observed (measured) cracks considers the same interval. Any length outside the mentioned interval is not considered for the probability evaluation: it is approached by the deterministic model. The deterministic approach is to plug the tube when any anomalous crack is detected in it. Such a crack is an observed one placed in the third region on the plot of the logarithmic time derivative of crack lengths versus the mode I stress intensity factor, while for normal cracks the plugging of tubes occurs in the second region of that plot - if they are dangerous, of course, considering their random evolution. A methodology for identifying anomalous cracks is also presented. (author)

  10. [Assessment of disinfection and sterilization processes in dental practice as an important factors in prevention of infections].

    Science.gov (United States)

    Podgórska, Marta; Jakimiak, Bozenna; Röhm-Rodowald, Ewa; Chojecka, Agnieszka

    2009-01-01

    The dental health-care settings is an environment where disease transmission occurs easily. Prevention of cross infection is therefore a crucial aspect of dental practice and dental clinic stuffmust adopt certain basic routines while practicing. Infections may be transmitted in the dental operatory through direct contact with blood, oral fluids or other secretions; via indirect contact with contaminated instruments, equipment or environmental surfaces; or by contact with airborne contaminants present in either droplet splatter or aerosols of oral and respiratory fluids. Strategies to prevent dental patient infections have focused on disinfection and sterilization. This study evaluates basic routines in prevention of cross-infection in the dentistry. The sample comprised 100 dentists, who completed questionnaires. Based on inquires the conditions for disinfection and sterilization of medical devices were assessed. The following issues were taken into consideration: the way of disinfection and preparation of the disinfectants, the localization of disinfection, preparing to disinfection, washing and packing of dental devices, the frequency of disinfection, methods of sterilization and the monitoring system, type of sterilizers and the available cycles. The dental practices are well equiped to proceed the steam sterilization, but 33% of dentists don't know the available cycles in their autoclaves. Only 35% of them made sterilization process protocols. Very common are three failures of instruments disinfections: multiple use of disinfectant, adding of disinfectant, adding new instruments. There is still need for improvement in disinfection and sterilization in dental practice, especially including: monitoring and documentation of sterilization process, proper use of disinfectants according to manufactures instructions, frequent disinfection of surfaces which contact with patients. Dental stuff should take part in advanced training courses about disinfection and

  11. Plasma Sterilization: New Epoch in Medical Textiles

    Science.gov (United States)

    Senthilkumar, P.; Arun, N.; Vigneswaran, C.

    2015-04-01

    Clothing is perceived to be second skin to the human body since it is in close contact with the human skin most of the times. In hospitals, use of textile materials in different forms and sterilization of these materials is an essential requirement for preventing spread of germs. The need for appropriate disinfection and sterilization techniques is of paramount importance. There has been a continuous demand for novel sterilization techniques appropriate for use on various textile materials as the existing sterilization techniques suffer from various technical and economical drawbacks. Plasma sterilization is the alternative method, which is friendlier and more effective on the wide spectrum of prokaryotic and eukaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species. Plasma exposure can kill micro-organisms on a surface in addition to removing adsorbed monolayer of surface contaminants. Advantages of plasma surface treatment are removal of contaminants from the surface, change in the surface energy and sterilization of the surface. Plasma sterilization aims to kill and/or remove all micro-organisms which may cause infection of humans or animals, or which can cause spoilage of foods or other goods. This review paper emphasizes necessity for sterilization, essentials of sterilization, mechanism of plasma sterilization and the parameters influencing it.

  12. Sterile neutrinos in leptonic and semileptonic decays

    Energy Technology Data Exchange (ETDEWEB)

    Abada, A. [Laboratoire de Physique Théorique, CNRS - UMR 8627,Université de Paris-Sud 11, F-91405 Orsay Cedex (France); Teixeira, A.M. [Laboratoire de Physique Corpusculaire, CNRS/IN2P3 - UMR 6533,Campus des Cézeaux, 24 Av. des Landais, F-63171 Aubière Cedex (France); Vicente, A. [Laboratoire de Physique Théorique, CNRS - UMR 8627,Université de Paris-Sud 11, F-91405 Orsay Cedex (France); IFPA, Dep. AGO, Université de Liège,Bat B5, Sart-Tilman B-4000 Liège 1 (Belgium); Weiland, C. [Departamento de Física Teórica, Universidad Autónoma de Madrid,Cantoblanco, Madrid 28049 (Spain); Instituto de Física Teórica UAM/CSIC,Calle Nicolás Cabrera 13-15, Cantoblanco, Madrid 28049 (Spain)

    2014-02-21

    We address the impact of a modified Wℓν coupling on a wide range of observables, such as τ leptonic and mesonic decays, leptonic decays of pseudoscalar mesons, as well as semileptonic meson decays. In particular, we concentrate on deviations from lepton flavour universality, focusing on the ratios R{sub P}=Γ(P→ℓν)/Γ(P→ℓ′ν), with P=K,π,D,D{sub s}, R(D)=Γ(B{sup +}→Dτ{sup +}ν)/Γ(B{sup +}→Dℓ{sup +}ν), R{sub τ}=Γ(τ→μνν)/Γ(τ→eνν), R{sub P}{sup ℓτ}=Γ(τ→Pν)/Γ(P→ℓν), and BR(B→τν). We further consider leptonic gauge boson decays, such as W→ℓν and Z→νν. For all the above observables, we provide the corresponding complete analytical expressions, derived for the case of massive neutrinos. Working in the framework of the Standard Model extended by additional sterile fermions, which mix with the active (left-handed) neutrinos, we numerically study the impact of active-sterile mixings on the above mentioned observables.

  13. Sterile hypopyon secondary to ultrasonic cleaning solution.

    Science.gov (United States)

    Richburg, F A; Reidy, J J; Apple, D J; Olson, R J

    1986-05-01

    During a 20-week period, 21 cases of sterile hypopyon occurred 24 hours after uncomplicated extracapsular cataract extraction and in-the-bag posterior chamber intraocular lens implantation at the Valley Eye Institute. While all cases responded to steroid treatment and exhibited no residual ocular effects, the cause of the hypopyon remained a mystery despite an on-going reevaluation of the surgical procedure and sterilization techniques. Several suspected causes were investigated and eliminated. It was clinically determined that surgical instruments placed in older ultrasonic cleaning solution caused the hypopyons. Further analysis at the Center for Intraocular Research at the University of Utah revealed that the instruments were contaminated by a heat-stable endotoxin that remained on the instruments through the autoclaving process. Surgeons currently using ultrasonic instrument cleaners should be aware that, with some models, following the manufacturer's recommended fluid changing procedures could result in endotoxic contamination of surgical instruments which could, in turn, cause severe inflammatory reactions in the immediate postoperative period.

  14. Quasi Goldstone fermion as a sterile neutrino

    Energy Technology Data Exchange (ETDEWEB)

    Jin Chun, E. [International Center for Theoretical Physics, P.O. Box 586, 34100 Trieste (Italy); Joshipura, A.S. [Theoretical Physics Group, Physical Research Laboratory, Navarangpura, Ahmedabad, 380 009 (India); Smirnov, A.Y. [International Center for Theoretical Physics P.O. Box 586, 34100 Trieste (Italy)]|[Institute for Nuclear Research, Russian Academy of Sciences, 117312 Moscow (Russia)

    1996-10-01

    The existence of sterile neutrinos is hinted by the simultaneous presence of diverse neutrino anomalies. We suggest that the quasi Goldstone fermions (QGF{close_quote}s) arising in supersymmetric theory as a result of spontaneous breaking of global symmetry such as the Peccei-Quinn symmetry or the lepton number symmetry can play the role of the sterile neutrino. The smallness of the mass of QGF{close_quote}s ({ital m}{sub {ital S}}{approximately}10{sup {minus}3}{endash}10 eV) can be related to the specific choice of superpotential or K{umlt a}hler potential (e.g., no-scale kinetic terms for certain superfields). Mixing of QGF{close_quote}s with neutrinos implies {ital R}-parity violation. It can proceed via the coupling of QGF{close_quote}s with Higgs supermultiplets or directly with a lepton doublet. A model which accounts for the solar and atmospheric anomalies and dark matter is presented. {copyright} {ital 1996 The American Physical Society.}

  15. Can sterile neutrinos be the dark matter?

    CERN Document Server

    Seljak, U; McDonald, P; Trac, H; Seljak, Uros; Makarov, Alexey; Donald, Patrick Mc; Trac, Hy

    2006-01-01

    We use the Ly-alpha forest power spectrum measured by the SDSS and high-resolution spectroscopy observations in combination with cosmic microwave background and galaxy clustering constraints to place limits on a sterile neutrino as a dark matter candidate in the warm dark matter (WDM) scenario. Such a neutrino would be created in the early universe through mixing with an active neutrino and would suppress structure on scales smaller than its free streaming scale. We ran a series of high-resolution hydrodynamic simulations with varying neutrino mass to describe the effect of a sterile neutrino on the Ly-alpha forest power spectrum. We find that the mass limit is m_s >14 keV at 95% c.l. (10keV at 99.9%), which is nearly an order of magnitude tighter constraint than previously published limits and is above the upper limit allowed by X-ray constraints, excluding this candidate as dark matter in this model. The corresponding limit for a neutrino that decoupled early while in thermal equilibrium is 2.5keV (95% c.l....

  16. The gap junction modifier, GAP-134 [(2S,4R)-1-(2-aminoacetyl)-4-benzamido-pyrrolidine-2-carboxylic acid], improves conduction and reduces atrial fibrillation/flutter in the canine sterile pericarditis model.

    Science.gov (United States)

    Rossman, Eric I; Liu, Kun; Morgan, Gwen A; Swillo, Robert E; Krueger, Julie A; Gardell, Stephen J; Butera, John; Gruver, Matthew; Kantrowitz, Joel; Feldman, Hal S; Petersen, Jørgen S; Haugan, Ketil; Hennan, James K

    2009-06-01

    Gap junction uncoupling can alter conduction pathways and promote cardiac re-entry mechanisms that potentiate many supraventricular arrhythmias, such as atrial fibrillation (AF) and atrial flutter (AFL). Our objective was to determine whether GAP-134 [(2S,4R)-1-(2-aminoacetyl)-4-benzamido-pyrrolidine-2-carboxylic acid], a small dipeptide gap junction modifier, can improve conduction and ultimately prevent AF/AFL. In rat atrial strips subjected to metabolic stress, GAP-134 prevented significantly conduction velocity slowing at 10 nM compared with vehicle (p < 0.01). In the canine sterile pericarditis model, conduction time (CT; n = 5), atrial effective refractory period (AERP; n = 3), and AF/AFL duration/inducibility (n = 16) were measured 2 to 3 days postoperatively in conscious dogs. CT was significantly faster after GAP-134 infusion (average plasma concentration, 250 nM) at cycle lengths of 300 ms (66.2 +/- 1.0 versus 62.0 +/- 1.0 ms; p < 0.001) and 200 ms (64.4 +/- 0.9 versus 61.0 +/- 1.3 ms; p < 0.001). No significant changes in AERP were noted after GAP-134 infusion. The mean number of AF/AFL inductions per animal was significantly decreased after GAP-134 infusion (2.7 +/- 0.6 versus 1.6 +/- 0.8; p < 0.01), with total AF/AFL burden being decreased from 12,280 to 6063 s. Western blot experiments showed no change in connexin 43 expression. At concentrations exceeding those described in the AF/AFL experiments, GAP-134 had no effect on heart rate, blood pressure, or any electrocardiogram parameters. In conclusion, GAP-134 shows consistent efficacy on measures of conduction and AF/AFL inducibility in the canine sterile pericarditis model. These findings, along with its oral bioavailability, underscore its potential antiarrhythmic efficacy.

  17. Drying models and characteristics of thin layer sludge in superheated steam drying%污泥过热蒸汽薄层干燥特性及干燥模型构建

    Institute of Scientific and Technical Information of China (English)

    张绪坤; 孙瑞晨; 王学成; 苏志伟; 曹伟

    2014-01-01

    . The purpose of this study was to investigate the drying characteristics of superheated-steam on a thin layer of sludge. Thin layer drying experiments of sludge samples with different thicknesses under a series of superheated steam temperatures were carried out. Sludge samples were collected in a local wastewater treatment plant after mechanical dewatering. The size of the sludge samples were taken over an area of 100 mm×100 mm, having thicknesses of 2, 4, 6, and 10 mm, respectively. The temperatures of superheated steam were controlled by the amount of the access heaters. The experiments of superheated steam drying were conducted at 160, 200, 240, and 280℃, respectively. Relations between the model parameters and temperature and thickness for the moisture ratio of sludge in relation to drying time were determined. The results showed that sludge samples were not oxidized or burnt after superheated steam drying even at high temperatures. The dense crack and rough surface of sludge during superheated steam drying were beneficial to the drying process. At the beginning of the drying process, the mass of the samples increased due to superheated steam coming in contact with the cold surface of the sludge as the initial temperature of the sludge is close to room temperature (around 20℃). As a result, the drying time of sludge samples to reach a certain moisture content increased. The increase in the mass of condensation water and drying time was greatly influenced by the temperature of superheated steam. As a result, the higher the temperature, the smaller the increase. However, the increase was hardly influenced by the thickness of sludge. The Effective moisture diffusivity was calculated by using Fick’s second law. Thin layers of sludge formed by superheated steam drying having thicknesses of 2, 4, 6, and 10 mm had effective diffusion coefficient variations of 2.0641×10-9-8.8527×10-9, 4.3738×10-9-1.6626×10-8, 6.6082×10-9-2.46×10-8, and 1.1916×10-8-4.0806×10

  18. A Light Sterile Neutrino from Friedberg-Lee Symmetry

    CERN Document Server

    He, Xiao-Gang

    2013-01-01

    Light sterile neutrinos of mass about an eV with mixing $\\tilde U_{ls}$ of a few percent to active neutrinos may solve some anomalies shown in experimental data related to neutrino oscillation. How to have light sterile neutrinos is one of the theoretical problems which have attracted a lot of attentions. In this article we show that such an eV scale light sterile neutrino candidate can be obtained in a seesaw model in which the right-handed neutrinos satisfy a softly-broken Friedberg-Lee (FL) symmetry. In this model a right-handed neutrino is guaranteed by the FL symmetry to be light comparing with other two heavy right-handed neutrinos. It can be of eV scale when the FL symmetry is softly broken and can play the role of eV scale sterile neutrino needed for explaining the anomalies of experimental data. This model predicts that one of the active neutrino is massless. We find that this model prefers inverted hierarchy mass pattern of active neutrinos than normal hierarchy. An interesting consequence of this m...

  19. Thermodynamic Analysis on Steam Parameters of the Steam Boiler%油田注汽锅炉蒸汽参数的热力学分析

    Institute of Scientific and Technical Information of China (English)

    董珊珊; 王为民; 刘广鑫; 陈顺江; 张鑫; 贾冯睿; 赵桐

    2014-01-01

    Aiming at the problem of high energy consumption in the steam boiler, exergy analysis model of the steam boiler was established by "black box" model analysis method. Exergy efficiency and thermal efficiency of the steam boiler in a domestic oilfield were calculated. The influence of the steam pressure, the steam quality and the steam evaporation on the exergy efficiency and the thermal efficiency of the steam boiler was investigated. The research results show that, with increasing of the steam pressure and steam quality, the exergy efficiency and the thermal efficiency of the steam boiler decrease; but with increasing of the steam evaporation, the exergy efficiency and the thermal efficiency of the steam boiler increase. Among them, influence of the steam evaporation on the exergy efficiency and thermal efficiency of the boiler is the greatest; when the steam evaporation increases 0.2 t/h,the exergy efficiency of the steam boiler increases by about 0.30%, the thermal efficiency increases by about 0.70%.%针对油田注汽锅炉能耗过高问题,运用“黑箱”模型分析方法,建立了注汽锅炉火用分析模型,对国内某油田注汽锅炉进行了火用效率和热效率计算。分析了蒸汽压力、蒸汽干度和蒸汽蒸发量3个影响油田注汽锅炉火用效率和热效率的影响因素及其变化规律。研究表明,火用效率和热效率随蒸汽压力、蒸汽干度的增大而降低,随蒸汽蒸发量的增大而升高。其中,蒸汽蒸发量对锅炉火用效率和热效率影响最大,蒸汽蒸发量每增大0.2 t/h,锅炉火用效率增大约为0.30%,热效率增大约为0.70%。

  20. Steam jacket dynamics in underground coal gasification

    Science.gov (United States)

    Otto, Christopher; Kempka, Thomas

    2017-04-01

    Underground coal gasification (UCG) has the potential to increase the world-wide hydrocarbon reserves by utilization of deposits not economically mineable by conventional methods. In this context, UCG involves combusting coal in-situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from high economic potentials, in-situ combustion may cause environmental impacts such as groundwater pollution by by-product leakage. In order to prevent or significantly mitigate these potential environmental concerns, UCG reactors are generally operated below hydrostatic pressure to limit the outflow of UCG process fluids into overburden aquifers. This pressure difference effects groundwater inflow into the reactor and prevents the escape of product gas. In the close reactor vicinity, fluid flow determined by the evolving high reactor temperatures, resulting in the build-up of a steam jacket. Numerical modeling is one of the key components to study coupled processes in in-situ combustion. We employed the thermo-hydraulic numerical simulator MUFITS (BINMIXT module) to address the influence of reactor pressure dynamics as well as hydro-geological coal and caprock parameters on water inflow and steam jacket dynamics. The US field trials Hanna and Hoe Creek (Wyoming) were applied for 3D model validation in terms of water inflow matching, whereby the good agreement between our modeling results and the field data indicates that our model reflects the hydrothermal physics of the process. In summary, our validated model allows a fast prediction of the steam jacket dynamics as well as water in- and outflows, required to avoid aquifer contamination during the entire life cycle of in-situ combustion operations.

  1. Mechanism of Sterility and Breeding Strategies for Photoperiod/Thermo- Sensitive Genic Male Sterile Rice

    Institute of Scientific and Technical Information of China (English)

    CHEN Li-yun; XIAO Ying-hui; LEI Dong-yang

    2010-01-01

    To understand the male sterility mechanism of photoperiod/thermo-sensitive genic male sterile [P(T)GMS] lines in rice, the research progress on genetics of photoperiod and/or temperature sensitive genic male sterility in rice was reviewed. A new idea was proposed to explain the sterility mechanism of P(T)GMS rice. The fertility transition from sterile to fertile is the result of cooperative regulation of major-effect sterile genes with photoperiod and/or temperature sensitive genes, but not the so-called pgms gene in P(T)GMS rice. The minor-effect genes, which exhibit accumulative effect on sterility, are the important factors for the critical temperature of sterility transition. The more minor-effect genes the sterile line holds, the lower the critical temperature of sterility transition is. The critical temperature of sterility transition will be invariable if all the minor-effect genes are homozygous. The strategies for breeding P(T)GMS rice were also proposed. The selective indices of critical photoperiod and temperature for sterility transition should be set according to varietal type and ecological region. Imposing selection pressure is a key technology for breeding P(T)GMS rice with lower critical temperature for sterility, and improving the comprehensive performance of the whole traits and combining ability is vital for breeding P(T)GMS rice lines.

  2. Radiation sterilization of new drug delivery systems.

    Science.gov (United States)

    Abuhanoğlu, Gürhan; Ozer, A Yekta

    2014-06-01

    Radiation sterilization has now become a commonly used method for sterilization of several active ingredients in drugs or drug delivery systems containing these substances. In this context, many applications have been performed on the human products that are required to be sterile, as well as on pharmaceutical products prepared to be developed. The new drug delivery systems designed to deliver the medication to the target tissue or organ, such as microspheres, nanospheres, microemulsion, and liposomal systems, have been sterilized by gamma (γ) and beta (β) rays, and more recently, by e-beam sterilization. In this review, the sterilization of new drug delivery systems was discussed other than conventional drug delivery systems by γ irradiation.

  3. PMK-2. Experimental study on steam generator behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Ezsoel, G.; Szabados, L.; Trosztel, I. [KFKI Atomic Energy Research Inst., Budabest (Hungary)

    1995-12-31

    The PMK-2 is a full pressure scaled-down model of the Paks Nuclear Power Plant, with a 1:2070 scaling ratio for the volume and power. It has a steam generator model which is a vertical section of the horizontal steam generator. The model has hot and cold collectors similarly to the steam generators of the plant. The heat transfer tubes are horizontal tubes. There are 82 rows of tubes and the elevations, as well as the heat transfer surface distribution is the same as in the plant. The elevation of the feed water supply is similar to that of the plant. To study the temperature distribution in both the primary and the secondary side several thermocouples are built in, in addition to the overall instrumentation of the loop which has again a high number of measurement channels. Paper gives a description and results of SPE-4, with special respect to the steam generator behaviour in both steady state and transient conditions. Axial distribution of coolant and feedwater temperatures are given for the primary and the secondary side of hot and cold collectors and the temperature distribution in the centre of steam generator. (orig.).

  4. Steam Oxidation Testing in the Severe Accident Test Station

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McMurray, Jake W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-08-01

    Since 2011, Oak Ridge National Laboratory (ORNL) has been conducting high temperature steam oxidation testing of candidate alloys for accident tolerant fuel (ATF) cladding. These concepts are designed to enhance safety margins in light water reactors (LWR) during severe accident scenarios. In the US ATF community, the Severe Accident Test Station (SATS) has been evaluating candidate materials (including coatings) since 2012. Compared to the current UO2/Zr-based alloy fuel system, alternative cladding materials need to offer slower oxidation kinetics and a smaller enthalpy of oxidation in order to significantly reduce the rate of heat and hydrogen generation in the core during a coolant-limited severe accident. The steam oxidation behavior of candidate materials is a key metric in the evaluation of ATF concepts and also an important input into models. However, prior modeling work of FeCrAl cladding has used incomplete information on the physical properties of FeCrAl. Also, the steam oxidation data being collected at 1200°-1700°C is unique as no prior work has considered steam oxidation of alloys at such high temperatures. In some cases, the results have been difficult to interpret and more fundamental information is needed such as the stability of alumina in flowing steam at 1400°-1500°C. This report summarizes recent work to measure the steam oxidation kinetics of candidate alloys, the evaporation rate of alumina in steam and the development of integral data on FeCrAl compared to conventional Zr-based cladding.

  5. Sterile Neutrinos in the Early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Tamborra, Irene [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, 80805 München (Germany); Hannestad, Steen [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark); Tram, Thomas [Institut de Théorie des Phénomenènes Physiques, École Polytechnique Fédérale de Lausanne, 1015, Lausanne (Switzerland)

    2013-04-15

    Recent cosmological data favor additional relativistic degrees of freedom beyond the three active neutrinos and photons. Light sterile neutrinos are prime candidates for such additional radiation. However, constraints on sterile neutrinos based on the current cosmological data have been derived assuming that they are thermalized at the Big Bang Nucleosynthesis (BBN) epoch and such assumption is not justified a priori. We will discuss the evolution of light sterile neutrinos in the early universe and their thermalization just before BBN begins.

  6. Genome-wide dissection of hybrid sterility in Drosophila confirms a polygenic threshold architecture.

    Science.gov (United States)

    Morán, Tomás; Fontdevila, Antonio

    2014-01-01

    To date, different studies about the genetic basis of hybrid male sterility (HMS), a postzygotic reproductive barrier thoroughly investigated using Drosophila species, have demonstrated that no single major gene can produce hybrid sterility without the cooperation of several genetic factors. Early work using hybrids between Drosophila koepferae (Dk) and Drosophila buzzatii (Db) was consistent with the idea that HMS requires the cooperation of several genetic factors, supporting a polygenic threshold (PT) model. Here we present a genome-wide mapping strategy to test the PT model, analyzing serially backcrossed fertile and sterile males in which the Dk genome was introgressed into the Db background. We identified 32 Dk-specific markers significantly associated with hybrid sterility. Our results demonstrate 1) a strong correlation between the number of segregated sterility markers and males' degree of sterility, 2) the exchangeability among markers, 3) their tendency to cluster into low-recombining chromosomal regions, and 4) the requirement for a minimum number (threshold) of markers to elicit sterility. Although our findings do not contradict a role for occasional major hybrid-sterility genes, they conform more to the view that HMS primarily evolves by the cumulative action of many interacting genes of minor effect in a complex PT architecture.

  7. Feasibility Study on Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Inha

    2013-12-15

    This report on the 'Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation' is belonged to the final report on the preliminary study of the first subject in 2013 for civilian project. This was complimented on the responsible of the Korea Atomic Energy Research Institute for 1{sup st} of June 2013 to 30{sup th} of November 2013. We are going to make sterilization the badge using the gamma ray and supplying the oxygen by nano-bubble oxygen rich water for cultivating the Matsutake Mushroom, instead of the conventional process of sterilization of the badge by hot steam over 120 .deg. C consuming over 8 hours and expensive ventilation system for supplying the fresh air for delivering the oxygen.

  8. Validation of the efficacy of a solar-thermal powered autoclave system for off-grid medical instrument wet sterilization.

    Science.gov (United States)

    Kaseman, Tremayne; Boubour, Jean; Schuler, Douglas A

    2012-10-01

    This work describes the efficacy of a solar-thermal powered autoclave used for the wet sterilization of medical instruments in off-grid settings where electrical power is not readily available. Twenty-seven trials of the solar-thermal powered system were run using an unmodified non-electric autoclave loaded with a simulated bundle of medical instruments and biological test agents. Results showed that in 100% of the trials the autoclave achieved temperatures in excess of 121°C for 30 minutes, indicator tape displayed visible reactions to steam sterilization, and biological tests showed that microbial agents had been eliminated, in compliance with the Centers for Disease Control and Prevention requirements for efficacious wet sterilization.

  9. Sterile Neutrino Dark Matter with Supersymmetry

    CERN Document Server

    Shakya, Bibhushan

    2016-01-01

    Sterile neutrino dark matter, a popular alternative to the WIMP paradigm, has generally been studied in non-supersymmetric setups. If the underlying theory is supersymmetric, we find that several interesting and novel dark matter features can arise. In particular, in scenarios of freeze-in production of sterile neutrino dark matter, its superpartner, the sterile sneutrino, can play a crucial role in early Universe cosmology as the dominant source of cold, warm, or hot dark matter, or of a subdominant relativistic population of sterile neutrinos that can contribute to the effective number of relativistic degrees of freedom Neff during Big Bang nucleosynthesis.

  10. Steam Digest 2001: Office of Industrial Technologies

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2002-01-01

    Steam Digest 2001 chronicles Best Practices Program's contributions to the industrial trade press for 2001, and presents articles that cover technical, financial and managerial aspects of steam optimization.

  11. Continuous steam hydrolysis of tulip poplar

    Energy Technology Data Exchange (ETDEWEB)

    Fieber, C.A.; Roberts, R.S.; Faass, G.S.; Muzzy, J.D.; Colcord, A.R.; Bery, M.K.

    1982-01-01

    The continuous hydrolysis of poplar chips by steam at 300-350 psi resulted in the separation of hemicellulose (I) cellulose and lignin components. The I fraction was readily depolymerised by steam to acetic acid, furfural, methanol, and xylose.

  12. Study on premixing phase of steam explosion at JAERI

    Energy Technology Data Exchange (ETDEWEB)

    Yamano, Norihiro; Moriyama, Kiyofumi; Maruyama, Yu; Park, H.; Yang, Y.; Sugimoto, Jun [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-01-01

    Melt jet breakup (MJB) and fragmentation has been studied in the frame of ALPHA program. In the first two experiments of MJB series, jet of molten lead-bismuth eutectic alloy was released into a deep pool of saturated water. Steam generation rate was measured and correlated with the jet behavior observed by a high-speed camera. The jet breakup length and debris size distribution were also evaluated. In parallel with the experimental study, JASMINE code has been developed for the simulation of steam explosion. The melt jet breakup model and the particle breakup model in the code were tested by analyzing FARO-L14 and ALPHA MJB experiments. (author)

  13. An optimization model for the operations of steam production in industrial boilers Um modelo de otimização para as operações de produção de vapor em caldeiras industriais

    Directory of Open Access Journals (Sweden)

    Cleber Damião Rocco

    2012-01-01

    Full Text Available In this study, a mixed integer linear programming model is presented to support some of the key decisions in the steam production system with industrial boilers. The model approaches the fuel management decisions (fuel replenishment and its inventory control, boiler operational decisions (start-up, warm-up, and shutdown operations, and which boiler should produce steam. The model adjustments and its validation were carried out through a case study in a large food industry. In face of the good outcomes achieved in applying the model and the lack of optimization tools to support the decisions in this system, the proposed model is a suitable alternative to support some of the key decisions in the system of steam production with multiple industrial boilers.Apresenta-se neste trabalho um modelo de programação linear inteira mista para apoiar algumas das principais decisões na operação de produção de vapor em caldeiras industriais. O modelo contempla as decisões de gerenciamento dos combustíveis: compra nos fornecedores, transporte para a fábrica e níveis dos estoques, assim como determina o modo de funcionamento das caldeiras: momentos de acionamento (start-up, regime de aquecimento (warm-up e desligamento dos equipamentos (shutdown, e em quais deles haverá produção de vapor. Os ajustes e a validação do modelo ocorreram por meio de um estudo de caso realizado em uma indústria de alimentos de grande porte. Diante dos bons resultados obtidos com a aplicação do modelo e da ausência de protocolos ou ferramentas de otimização para apoiar as decisões no sistema estudado, o modelo proposto apresenta-se como uma alternativa viável para apoiar algumas das principais decisões no sistema de produção de vapor em caldeiras industriais.

  14. Measuring growth index in a Universe with sterile neutrinos

    Directory of Open Access Journals (Sweden)

    Jing-Fei Zhang

    2014-12-01

    Full Text Available Consistency tests for the general relativity (GR can be performed by constraining the growth index γ using the measurements of redshift-space distortions (RSD in conjunction with other observations. In previous studies, deviations from the GR expected value of γ≈0.55 at the 2–3σ level were found. In this work, we reconsider the measurement of γ in a Universe with sterile neutrinos. We constrain the sterile neutrino cosmological model using the RSD measurements combined with the cosmic microwave background data (Planck temperature data plus WMAP 9-yr polarization data, the baryon acoustic oscillation data, the Hubble constant direct measurement, the Planck Sunyaev–Zeldovich cluster counts data, and the galaxy shear data. We obtain the constraint result of the growth index, γ=0.584−0.048+0.047, well consistent with the GR expected value (the consistency is at the 0.6σ level. For the parameters of sterile neutrino, we obtain Neff=3.62−0.42+0.26 and mν,sterileeff=0.48−0.14+0.11 eV. We also consider the BICEP2 data and perform an analysis on the model with tensor modes. Similar fit results are obtained, showing that once light sterile neutrino is considered in the Universe, GR will become well consistent with the current observations.

  15. Neutrophil Responses to Sterile Implant Materials.

    Directory of Open Access Journals (Sweden)

    Siddharth Jhunjhunwala

    Full Text Available In vivo implantation of sterile materials and devices results in a foreign body immune response leading to fibrosis of implanted material. Neutrophils, one of the first immune cells to be recruited to implantation sites, have been suggested to contribute to the establishment of the inflammatory microenvironment that initiates the fibrotic response. However, the precise numbers and roles of neutrophils in response to implanted devices remains unclear. Using a mouse model of peritoneal microcapsule implantation, we show 30-500 fold increased neutrophil presence in the peritoneal exudates in response to implants. We demonstrate that these neutrophils secrete increased amounts of a variety of inflammatory cytokines and chemokines. Further, we observe that they participate in the foreign body response through the formation of neutrophil extracellular traps (NETs on implant surfaces. Our results provide new insight into neutrophil function during a foreign body response to peritoneal implants which has implications for the development of biologically compatible medical devices.

  16. Sterile neutrino dark matter: A tale of weak interactions in the strong coupling epoch

    CERN Document Server

    Venumadhav, Tejaswi; Abazajian, Kevork N; Hirata, Christopher M

    2015-01-01

    We perform a detailed study of the weak interactions of standard model neutrinos with the primordial plasma and their effect on the resonant production of sterile neutrino dark matter. Motivated by issues in cosmological structure formation on small scales, and reported X-ray signals that could be due to sterile neutrino decay, we consider $7$ keV-scale sterile neutrinos. Oscillation-driven production of such sterile neutrinos occurs at temperatures $T \\gtrsim 100$ MeV, where we study two significant effects of weakly charged species in the primordial plasma: (1) the redistribution of an input lepton asymmetry; (2) the opacity for active neutrinos. We calculate the redistribution analytically above and below the quark-hadron transition, and match with lattice QCD calculations through the transition. We estimate opacities due to tree level processes involving leptons and quarks above the quark-hadron transition, and the most important mesons below the transition. We report final sterile neutrino dark matter ph...

  17. Effect of Steam Addition on the Flow Field and NOx Emissions for Jet-A in an Aircraft Combustor

    Science.gov (United States)

    Xue, Rui; Hu, Chunbo; Nikolaidis, Theoklis; Pilidis, Pericle

    2016-12-01

    The steam injection technology for aircraft engines is gaining rising importance because of the strong limitations imposed by the legislation for NOx reduction in airports. In order to investigate the impact of steam addition on combustion and NOx emissions, an integrated performance-CFD-chemical reactor network (CRN) methodology was developed. The CFD results showed steam addition reduced the high temperature size and the radical pool moved downstream. Then different post-processing techniques are employed and CRN is generated to predict NOx emissions. This network consists of 14 chemical reactor elements and the results were in close agreement with the ICAO databank. The established CRN model was then used for steam addition study and the results showed under air/steam mixture atmosphere, high steam content could push the NOx formation region to the post-flame zone and a large amount of the NOx emission could be reduced when the steam mass fraction is quite high.

  18. Hybrid male sterility in rice controlled by interaction between divergent alleles of two adjacent genes.

    Science.gov (United States)

    Long, Yunming; Zhao, Lifeng; Niu, Baixiao; Su, Jing; Wu, Hao; Chen, Yuanling; Zhang, Qunyu; Guo, Jingxin; Zhuang, Chuxiong; Mei, Mantong; Xia, Jixing; Wang, Lan; Wu, Haibin; Liu, Yao-Guang

    2008-12-01

    Sterility is common in hybrids between divergent populations, such as the indica and japonica subspecies of Asian cultivated rice (Oryza sativa). Although multiple loci for plant hybrid sterility have been identified, it remains unknown how alleles of the loci interact at the molecular level. Here we show that a locus for indica-japonica hybrid male sterility, Sa, comprises two adjacent genes, SaM and SaF, encoding a small ubiquitin-like modifier E3 ligase-like protein and an F-box protein, respectively. Most indica cultivars contain a haplotype SaM(+)SaF(+), whereas all japonica cultivars have SaM(-)SaF(-) that diverged by nucleotide variations in wild rice. Male semi-sterility in this heterozygous complex locus is caused by abortion of pollen carrying SaM(-). This allele-specific gamete elimination results from a selective interaction of SaF(+) with SaM(-), a truncated protein, but not with SaM(+) because of the presence of an inhibitory domain, although SaM(+) is required for this male sterility. Lack of any one of the three alleles in recombinant plants does not produce male sterility. We propose a two-gene/three-component interaction model for this hybrid male sterility system. The findings have implications for overcoming male sterility in inter-subspecific hybrid rice breeding.

  19. Optimization of steam explosion pretreatment. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Foody, P.

    1980-04-01

    Different operating conditions are required to optimize the yield from each of the various fractions in the substrate. Xylose recovery is maximized at short cooking times whereas maximum lignin recovery requires much longer cooking times. Peak glucose yield and rumen digestibility occur at intermediate times. If process conditions are set for maximum glucose yield we have achieved a yield of 68% of the theoretical, based on an average of a dozen substrates tested. Individual results ranged from 46 to 87%. If the process is optimized for maximum total sugars (i.e. glucose plus xylose) we have obtained an average yield of 60%, with a range of 31 to 75%. With rumen microflora, the average value of the in-vitro cellulose digestibility was 82%, with a range of 41 to 90%. The optimum operating conditions for total sugars are a pressure of 500 to 550 psig with a cooking time of 40 to 50 seconds and 35% starting moisture content. Particle size is not a significant factor, nor is pre-steaming or use of a constricting die in the gun nozzle. High quality lignin can be extracted with 80% yield. The Iotech lignin is very soluble, has a low molecular weight and is reactive. The unique properties of the lignin derive from the explosion at the end of the pretreatment. A lignin formaldehyde resin has been successfully formulated and tested. It represents a high value utilization of the lignin byproduct with immediate market potential. A detailed engineering design of the process gives an estimated operating cost of $7.50/OD ton of biomass. At this low cost, the Iotech process achieves many important pretreatment goals in a single step. The substrate has been sterilized; it has been pulverized into a powder; the cellulose has been accessible; and a highly reactive lignin fraction can be recovered and utilized.

  20. Numerical Research of Steam and Gas Plant Efficiency of Triple Cycle for Extreme North Regions

    Directory of Open Access Journals (Sweden)

    Galashov Nikolay

    2016-01-01

    Full Text Available The present work shows that temperature decrease of heat rejection in a cycle is necessary for energy efficiency of steam turbine plants. Minimum temperature of heat rejection at steam turbine plant work on water steam is 15°C. Steam turbine plant of triple cycle where lower cycle of steam turbine plant is organic Rankine cycle on low-boiling substance with heat rejection in air condenser, which safely allows rejecting heat at condensation temperatures below 0°C, has been offered. Mathematical model of steam and gas plant of triple cycle, which allows conducting complex researches with change of working body appearance and parameters defining thermodynamic efficiency of cycles, has been developed. On the basis of the model a program of parameters and index cycles design of steam and gas plants has been developed in a package of electron tables Excel. Numerical studies of models showed that energy efficiency of steam turbine plants of triple cycle strongly depend on low-boiling substance type in a lower cycle. Energy efficiency of steam and gas plants net 60% higher can be received for steam and gas plants on the basis of gas turbine plant NK-36ST on pentane and its condensation temperature below 0°C. It was stated that energy efficiency of steam and gas plants net linearly depends on condensation temperature of low-boiling substance type and temperature of gases leaving reco very boiler. Energy efficiency increases by 1% at 10% decrease of condensation temperature of pentane, and it increases by 0.88% at 15°C temperature decrease of gases leaving recovery boiler.