Development and duration of accelerated degradation of nematicides in different soils

NARCIS (Netherlands)

Smelt, J.H.; Peppel-Groen, van de A.E.; Pas, van der L.J.T.; Dijksterhuis, A.

1996-01-01

The development and duration of accelerated degradation of nematicides were studied in incubation experiments with soils from three experimental fields that had been treated annually for three to ten years with aldicarb, oxamyl, ethoprophos, fenamiphos or 1,3-dichloropropene. Highly accelerated

A reproducible accelerated in vitro release testing method for PLGA microspheres.

Science.gov (United States)

Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J

2016-02-10

The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures). Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation of carrageenan by low energy electron accelerator

International Nuclear Information System (INIS)

Relleve, L.; Aranilla, C.; Abad, L.; Dela Rosa, A.; Nagasawa, Naotsugu; Yagi, Toshiaki; Kume, Tamikazu; Yoshii, Fumio

2004-01-01

Degradation of κ-carrageenan using vessel-type low energy electron accelerator was investigated. Carrageenan with different molecular weights were obtained from irradiation of high molecular weight (HMW) and low molecular weight (LMW) κ-carrageenan. Other results presented were obtained from degradation studies of carrageenan by gamma rays. The decrease in molecular weight was accompanied by partial desulfation. From comparison of radiation degradation yield (Gd), it was found that the susceptibility to radiation of the three types of carrageenans in aqueous/gel forms follows the order of λ->ι->>κ- and could have been influenced by their conformational state. κ-carrageenan with molecular weight of ca. 10,000 showed strong growth promotion effect for potato in tissue culture. (author)

Accelerated degradation of the D2 protein of photosystem II under ultraviolet radiation

International Nuclear Information System (INIS)

Jansen, M.A.K.; Edelman, M.; Greenberg, B.M.; Gaba, V.

1996-01-01

The D2 protein of photosystem II is relatively stable in vivo under photosynthetic active radiation, but its degradation accelerates under UVB radiation. Little is known about accelerated D2 protein degradation. We characterized wavelength dependence and sensitivity toward photosystem II inhibitors. The in vivo D2 degradation spectrum resembles the pattern for the rapidly turning over D1 protein of photosystem II, with rates being maximal in the UVB region. We propose that D2 degradation, like D1 degradation, is activated by distinct photosensitizers in the UVB and visible regions of the spectrum. In both wavelength regions, photosystem II inhibitors that are known to be targeted to the D1 protein affect D2 degradation. This suggests that degradation of the two proteins is coupled, D2 degradation being influenced by events occurring at the Q B niche on the D1 protein. (Author)

Reliability demonstration methodology for products with Gamma Process by optimal accelerated degradation testing

International Nuclear Information System (INIS)

Zhang, Chunhua; Lu, Xiang; Tan, Yuanyuan; Wang, Yashun

2015-01-01

For products with high reliability and long lifetime, accelerated degradation testing (ADT) may be adopted during product development phase to verify whether its reliability satisfies the predetermined level within feasible test duration. The actual degradation from engineering is usually a strictly monotonic process, such as fatigue crack growth, wear, and erosion. However, the method for reliability demonstration by ADT with monotonic degradation process has not been investigated so far. This paper proposes a reliability demonstration methodology by ADT for this kind of product. We first apply Gamma process to describe the monotonic degradation. Next, we present a reliability demonstration method by converting the required reliability level into allowable cumulative degradation in ADT and comparing the actual accumulative degradation with the allowable level. Further, we suggest an analytical optimal ADT design method for more efficient reliability demonstration by minimizing the asymptotic variance of decision variable in reliability demonstration under the constraints of sample size, test duration, test cost, and predetermined decision risks. The method is validated and illustrated with example on reliability demonstration of alloy product, and is applied to demonstrate the wear reliability within long service duration of spherical plain bearing in the end. - Highlights: • We present a reliability demonstration method by ADT for products with monotonic degradation process, which may be applied to verify reliability with long service life for products with monotonic degradation process within feasible test duration. • We suggest an analytical optimal ADT design method for more efficient reliability demonstration, which differs from the existed optimal ADT design for more accurate reliability estimation by different objective function and different constraints. • The methods are applied to demonstrate the wear reliability within long service duration of

Study of Operating Parameters for Accelerated Anode Degradation in SOFCs

DEFF Research Database (Denmark)

Ploner, Alexandra; Hagen, Anke; Hauch, Anne

2017-01-01

Solid oxide fuel cell (SOFC) applications require lifetimes of several years on the system level. A big challenge is to demonstrate such exceptionally long lifetimes in ongoing R&D projects. Accelerated or compressed testing are alternative methods to obtain this. Activities in this area have been...... carried out without arriving at a generally accepted methodology. This is mainly due to the complexity of degradation mechanisms on the single SOFC components as function of operating parameters. In this study, we present a detailed analysis of approx. 180 durability tests regarding degradation of single...... SOFC components as function of operating conditions. Electrochemical impedance data were collected on the fresh and long-term tested SOFCs and used to de-convolute the individual losses of single SOFC cell components – electrolyte, cathode and anode. The main findings include a time-dependent effect...

VUV/UV light inducing accelerated phenol degradation with a low electric input.

Science.gov (United States)

Li, Mengkai; Wen, Dong; Qiang, Zhimin; Kiwi, John

2017-01-23

This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4-6 min. The HO˙ and HO 2 ˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H 2 O 2 and Fe 3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H 2 O 2 or Fe 3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants.

Optimal design of constant-stress accelerated degradation tests using the M-optimality criterion

International Nuclear Information System (INIS)

Wang, Han; Zhao, Yu; Ma, Xiaobing; Wang, Hongyu

2017-01-01

In this paper, we propose the M-optimality criterion for designing constant-stress accelerated degradation tests (ADTs). The newly proposed criterion concentrates on the degradation mechanism equivalence rather than evaluation precision or prediction accuracy which is usually considered in traditional optimization criteria. Subject to the constraints of total sample number, test termination time as well as the stress region, an optimum constant-stress ADT plan is derived by determining the combination of stress levels and the number of samples allocated to each stress level, when the degradation path comes from inverse Gaussian (IG) process model with covariates and random effects. A numerical example is presented to verify the robustness of our proposed optimum plan and compare its efficiency with other test plans. Results show that, with a slightly relaxed requirement of evaluation precision and prediction accuracy, our proposed optimum plan reduces the dispersion of the estimated acceleration factor between the usage stress level and a higher accelerated stress level, which makes an important contribution to reliability demonstration and assessment tests. - Highlights: • We establish the necessary conditions for degradation mechanism equivalence of ADTs. • We propose the M-optimality criterion for designing constant-stress ADT plans. • The M-optimality plan reduces the dispersion of the estimated accelerated factors. • An electrical connector with its stress relaxation data is used for illustration.

Nuclear-waste-package materials degradation modes and accelerated testing

International Nuclear Information System (INIS)

1981-09-01

This report reviews the materials degradation modes that may affect the long-term behavior of waste packages for the containment of nuclear waste. It recommends an approach to accelerated testing that can lead to the qualification of waste package materials in specific repository environments in times that are short relative to the time period over which the waste package is expected to provide containment. This report is not a testing plan but rather discusses the direction for research that might be considered in developing plans for accelerated testing of waste package materials and waste forms

Degradation of naphthalene and fluorene by radiolysis using accelerated electrons

International Nuclear Information System (INIS)

Flores de Jesus, I.

2003-01-01

The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

NARCIS (Netherlands)

Yazdan Mehr, M.; van Driel, W.D.; Zhang, G.Q.

2015-01-01

A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

Light-current-induced acceleration of degradation of methylammonium lead iodide perovskite solar cells

Science.gov (United States)

Xiang, Yuren; Zhang, Fan; He, Junjie; Lian, Jiarong; Zeng, Pengju; Song, Jun; Qu, Junle

2018-04-01

The photo-conversion efficiency of perovskite solar cells (PSCs) has been improved considerably in recent years, but the poor stability of PSCs still prevents their commercialization. In this report, we use the rate of the integrated short-circuit current change (Drate) to investigate the performance degradation kinetics and identify the degradation of PSCs that is accelerated by the light current. The value of Drate increases by an order of magnitude from about 0.02 to 0.35 mA cm-2·min-1 after light-IV testing. The accelerated degradation progress is proven to be dominated by the hydration process and the migration of the iodine ions of the light current. The migration of the iodine ions enhances the hydration process through a chain reaction, enabling the formation of fast diffusion channels for both H2O and O2, which induce the rapid decomposition of the perovskite film and increase the density of the trap state. The X-ray photoelectron spectroscopy measurement data also indicate that the super oxygen may be formed due to the PCBM damage caused by the migration iodine ions. An understanding of the degradation acceleration mechanism would provide an insight into the effect of ion migration on the stability of PSCs.

Accelerated thermal and radiation-oxidation combined degradation of electric cable insulation materials

International Nuclear Information System (INIS)

Yagi, Toshiaki; Seguchi, Tadao; Yoshida, Kenzo

1986-03-01

For the development of accelerated testing methodology to estimate the life time of electric cable, which is installed in radiation field such as a nuclear reactor containment vessel, radiation and thermal combined degradation of cable insulation and jacketing materials was studied. The materials were two types of formulated polyethylene, ethylene-propylene rubber, Hypalon, and Neoprene. With Co-60 γ-rays the materials were irradiated up to 0.5 MGy under vacuum and in oxygen under pressure, then exposed to thermal aging at elevated temperature in oxygen. The degradation was investigated by the tensile test, gelfraction, and swelling measurements. The thermal degradation rate for each sample increases with increase of oxygen concentration, i.e. oxygen pressure, during the aging, and tends to saturate above 0.2 MPa of oxygen pressure. Then, the effects of irradiation and the temperature on the thermal degradation rate were investigated at the oxygen pressure of 0.2 MPa in the temperature range from 110 deg C to 150 deg C. For all of samples irradiated in oxygen, the following thermal degradation rate was accelerated by several times comparing with unirradiated samples, while the rate of thermal degradation for the sample except Neoprene irradiated under vacuum was nearly equal to that of unirradiated one. By the analysis of thermal degradation rate against temperature using Arrhenius equation, it was found that the activation energy tends to decrease for the samples irradiated in oxidation condition. (author)

Reliability residual-life prediction method for thermal aging based on performance degradation

International Nuclear Information System (INIS)

Ren Shuhong; Xue Fei; Yu Weiwei; Ti Wenxin; Liu Xiaotian

2013-01-01

The paper makes the study of the nuclear power plant main pipeline. The residual-life of the main pipeline that failed due to thermal aging has been studied by the use of performance degradation theory and Bayesian updating methods. Firstly, the thermal aging impact property degradation process of the main pipeline austenitic stainless steel has been analyzed by the accelerated thermal aging test data. Then, the thermal aging residual-life prediction model based on the impact property degradation data is built by Bayesian updating methods. Finally, these models are applied in practical situations. It is shown that the proposed methods are feasible and the prediction accuracy meets the needs of the project. Also, it provides a foundation for the scientific management of aging management of the main pipeline. (authors)

Accelerated degradation of methyl iodide by agrochemicals.

Science.gov (United States)

Zheng, Wei; Papiernik, Sharon K; Guo, Mingxin; Yates, Scott R

2003-01-29

The fumigant methyl iodide (MeI, iodomethane) is considered a promising alternative to methyl bromide (MeBr) for soil-borne pest control in high-cash-value crops. However, the high vapor pressure of MeI results in emissions of a significant proportion of the applied mass into the ambient air, and this may lead to pollution of the environment. Integrating the application of certain agrochemicals with soil fumigation provides a novel approach to reduce excessive fumigant emissions. This study investigated the potential for several agrochemicals that are commonly used in farming operations, including fertilizers and nitrification inhibitors, to transform MeI in aqueous solution. The pseudo-first-order hydrolysis half-life (t(1/2)) of MeI was approximately 108 d, while the transformation of MeI in aqueous solutions containing selected agrochemicals was more rapid, with t(1/2) agrochemicals on the rate of MeI degradation in soil was also determined. Adsorption to soil apparently reduced the availability of some nitrification inhibitors in the soil aqueous phase and lowered the degradation rate in soil. In contrast, addition of the nitrification inhibitors thiourea and allylthiourea to soil significantly accelerated the degradation of MeI, possibly due to soil surface catalysis. The t(1/2) of MeI was 300 h).

Accelerated in vitro release testing method for naltrexone loaded PLGA microspheres.

Science.gov (United States)

Andhariya, Janki V; Choi, Stephanie; Wang, Yan; Zou, Yuan; Burgess, Diane J; Shen, Jie

2017-03-30

The objective of the present study was to develop a discriminatory and reproducible accelerated release testing method for naltrexone loaded parenteral polymeric microspheres. The commercially available naltrexone microsphere product (Vivitrol ® ) was used as the testing formulation in the in vitro release method development, and both sample-and-separate and USP apparatus 4 methods were investigated. Following an in vitro drug stability study, frequent media replacement and addition of anti-oxidant in the release medium were used to prevent degradation of naltrexone during release testing at "real-time" (37°C) and "accelerated" (45°C), respectively. The USP apparatus 4 method was more reproducible than the sample-and-separate method. In addition, the accelerated release profile obtained using USP apparatus 4 had a shortened release duration (within seven days), and good correlation with the "real-time" release profile. Lastly, the discriminatory ability of the developed accelerated release method was assessed using compositionally equivalent naltrexone microspheres with different release characteristics. The developed accelerated USP apparatus 4 release method was able to detect differences in the release characteristics of the prepared naltrexone microspheres. Moreover, a linear correlation was observed between the "real-time" and accelerated release profiles of all the formulations investigated, suggesting that the release mechanism(s) may be similar under both conditions. These results indicate that the developed accelerated USP apparatus 4 method has the potential to be an appropriate fast quality control tool for long-acting naltrexone PLGA microspheres. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of impurities and degradation products from veterinary medicinal products by HPLC method

Directory of Open Access Journals (Sweden)

Elena Gabriela Oltean

2014-06-01

Full Text Available The organic or inorganic impurities in the veterinary medicinal product can derive from starting materials, manufacturing process, incomplete purification, inappropriate storage. The acceptable levels of impurities in pharmaceuticals are estimated by comparison with standard solutions, according to the appropriate monographs. Forced degradation studies determine the stability of the method of dosage for the active compounds and for the entire finished product under excessive accelerated degradation conditions. They also provide information on degradation pathways and selectivity of analytical methods applied. The information provided by the degradation studies on the active compound and finished pharmaceutical product should demonstrate the specificity of the analytical method regarding impurities. Forced degradation studies should demonstrate that the impurities and degradation products generated do not interfere with the active compound. The current forced degradation methods consist of acid hydrolysis, basic hydrolysis, oxidation, exposure of the medicinal product to temperature and light. HPLC methods are an integral analytical instrument for the analysis of the medicinal product. The HPLC method should be able to separate, detect and quantify various specific degradation products that can appear after manufacture or storage of the medicinal product, as well as new elements appearing after synthesis. FDA and ICH guidelines recommend the enclosure of the results, including the chromatograms specific to the forced degradation-subjected medicinal product, in the documentation for marketing authorization. Using HPLC methods in forced degradation studies on medicinal products provides relevant information on the method of determination for the formulation of the medicinal product, synthesis product, packaging methods and storage.

Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint

Energy Technology Data Exchange (ETDEWEB)

Pern, F. J.; Noufi, R.

2012-10-01

A step-stress accelerated degradation testing (SSADT) method was employed for the first time to evaluate the stability of CuInGaSe2 (CIGS) solar cells and device component materials in four Al-framed test structures encapsulated with an edge sealant and three kinds of backsheet or moisture barrier film for moisture ingress control. The SSADT exposure used a 15oC and then a 15% relative humidity (RH) increment step, beginning from 40oC/40%RH (T/RH = 40/40) to 85oC/70%RH (85/70) as of the moment. The voluminous data acquired and processed as of total DH = 3956 h with 85/70 = 704 h produced the following results. The best CIGS solar cells in sample Set-1 with a moisture-permeable TPT backsheet showed essentially identical I-V degradation trend regardless of the Al-doped ZnO (AZO) layer thickness ranging from standard 0.12 μm to 0.50 μm on the cells. No clear 'stepwise' feature in the I-V parameter degradation curves corresponding to the SSADT T/RH/time profile was observed. Irregularity in I-V performance degradation pattern was observed with some cells showing early degradation at low T/RH < 55/55 and some showing large Voc, FF, and efficiency degradation due to increased series Rs (ohm-cm2) at T/RH ≥ 70/70. Results of (electrochemical) impedance spectroscopy (ECIS) analysis indicate degradation of the CIGS solar cells corresponded to increased series resistance Rs (ohm) and degraded parallel (minority carrier diffusion/recombination) resistance Rp, capacitance C, overall time constant Rp*C, and 'capacitor quality' factor (CPE-P), which were related to the cells? p-n junction properties. Heating at 85/70 appeared to benefit the CIGS solar cells as indicated by the largely recovered CPE-P factor. Device component materials, Mo on soda lime glass (Mo/SLG), bilayer ZnO (BZO), AlNi grid contact, and CdS/CIGS/Mo/SLG in test structures with TPT showed notable to significant degradation at T/RH ≥ 70/70. At T/RH = 85/70, substantial blistering of

Insulin receptor degradation is accelerated in cultured lymphocytes from patients with genetic syndromes of extreme insulin resistance

International Nuclear Information System (INIS)

McElduff, A.; Hedo, J.A.; Taylor, S.I.; Roth, J.; Gorden, P.

1984-01-01

The insulin receptor degradation rate was examined in B lymphocytes that were obtained from peripheral blood of normal subjects and patients with several syndromes of extreme insulin resistance. The insulin receptors were surface labeled using Na 125 I/lactoperoxidase and the cells were returned to incubate in growth media. After varying periods of incubation, aliquots of cells were solubilized and the cell content of labeled receptor subunits were measured by immunoprecipitation with anti-receptor antibodies and NaDodSO4/polyacrylamide gel electrophoresis. In cell lines from four patients in whom the number of insulin receptors was reduced by greater than 90%, the rate of receptor loss was greater than normal (t1/2 equals 3.8 +/- 0.9 h vs. 6.5 +/- 1.2 h; mean +/- SD, P less than 0.01). However, a similar acceleration in receptor degradation was seen in cells from five patients with extreme insulin resistance but low-normal insulin receptor concentration (t1/2 equals 4.4 +/- 0.9 h). Thus, all the patients with genetic syndromes of insulin resistance had accelerated receptor degradation, regardless of their receptor concentration. By contrast, insulin receptors on cultured lymphocytes that were obtained from patients with extreme insulin resistance secondary to autoantibodies to the insulin receptor had normal receptor degradation (t1/2 equals 6.1 +/- 1.9 h). We conclude that (a) accelerated insulin receptor degradation is an additional feature of cells from patients with genetic forms of insulin resistance; (b) that accelerated insulin receptor degradation may explain the low-normal receptor concentrations that were seen in some patients with extreme insulin resistance; and (c) that accelerated degradation does not explain the decreased receptor concentration in patients with very low insulin receptor binding and, therefore, by inference, a defect in receptor synthesis must be present in this subgroup

An analysis of pipe degradation shape using potential drop method

International Nuclear Information System (INIS)

Jegal, S.; Lee, S. H.

1999-01-01

The Potential Drop (PD) method, one of NDE (Non-Destructive Evaluation) method is used to analyze the thickness distribution of pipes degraded by FAC (Flow Accelerated Corrosion). A DCPD (Direct Current Potential Drop) system which can measure PD for direct current was made, and the specimens with line defects and cylinder type defects have been used for experiments to prove the theory of Potential Drop method and to find out the effects of each factors. The experiment to find out defect distributions has been performed and it is found that PD method can analyze almost correct position of defects

Modelling of degradation processes in creep resistant steels through accelerated creep tests after long-term isothermal ageing

Energy Technology Data Exchange (ETDEWEB)

Sklenicka, V.; Kucharova, K.; Svoboda, M.; Kroupa, A.; Kloc, L. [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials; Cmakal, J. [UJP PRAHA a.s., Praha-Zbraslav (Czech Republic)

2010-07-01

Creep behaviour and degradation of creep properties of creep resistant materials are phenomena of major practical relevance, often limiting the lives of components and structures designed to operate for long periods under stress at elevated and/or high temperatures. Since life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for the projected designed life, methods of creep properties assessment based on microstructural evolution in the material during creep rather than simple parametric extrapolation of short-term creep tests are necessary. In this paper we will try to further clarify the creep-strength degradation of selected advanced creep resistant steels. In order to accelerate some microstructural changes and thus to simulate degradation processes in long-term service, isothermal ageing at 650 C for 10 000 h was applied to P91 and P23 steels in their as-received states. The accelerated tensile creep tests were performed at temperature 600 C in argon atmosphere on all steels both in the as-received state and after long-term isothermal ageing, in an effort to obtain a more complete description of the role of microstructural stability in high temperature creep of these steels. Creep tests were followed by microstructural investigations by means of both transmission and scanning electron microscopy and by the thermodynamic calculations. The applicability of the accelerated creep tests was verified by the theoretical modelling of the phase equilibria at different temperatures. It is suggested that under restructed oxidation due to argon atmosphere microstructural instability is the main detrimental process in the long-term degradation of the creep rupture strength of these steels. (orig.)

Accelerated degradation by UV radiation of adhesive materials used in solar equipment

International Nuclear Information System (INIS)

Tilca, F.; Acosta, D; Barcena, H.; Suarez, H.; Cadena, C.; Bolzi, Claudio

2003-01-01

Several materials which are used as common adhesives in photovoltaic cells, were tested in order to study their stability. Accelerated degradation effects were produced using high radiation doses of UV-C and UV-b in a previously described camera at different times. The exposed and unexposed films were studied by transmittance, X-ray diffraction and infrared. The results are in agreement with complex degradation process at long exposition times, while transmittance doesn't change significantly. (author)

A study on the evaluation of material degradation using ball indentation method

International Nuclear Information System (INIS)

Kim, Jeong Pyo; Seok, Chang Sung; Ahn, Ha Neul

2000-01-01

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the aging evaluation technique by the BI method. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree

Degradation mechanisms and accelerated testing in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

2010-01-01

The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Although there has been recent progress in improving durability, further improvements are needed to meet the commercialization targets. Past improvements have largely been made possible because of the fundamental understanding of the underlying degradation mechanisms. By investigating component and cell degradation modes; defining the fundamental degradation mechanisms of components and component interactions new materials can be designed to improve durability. Various factors have been shown to affect the useful life of PEM fuel cells. Other issues arise from component optimization. Operational conditions (such as impurities in either the fuel and oxidant stream), cell environment, temperature (including subfreezing exposure), pressure, current, voltage, etc.; or transient versus continuous operation, including start-up and shutdown procedures, represent other factors that can affect cell performance and durability. The need for Accelerated Stress Tests (ASTs) can be quickly understood given the target lives for fuel cell systems: 5000 hours ({approx} 7 months) for automotive, and 40,000 hrs ({approx} 4.6 years) for stationary systems. Thus testing methods that enable more rapid screening of individual components to determine their durability characteristics, such as off-line environmental testing, are needed for evaluating new component durability in a reasonable turn-around time. This allows proposed improvements in a component to be evaluated rapidly and independently, subsequently allowing rapid advancement in PEM fuel cell durability. These tests are also crucial to developers in order to make sure that they do not sacrifice durability while making improvements in costs (e.g. lower platinum group metal [PGM] loading) and performance (e.g. thinner membrane or a GDL with better water management properties). To

Lifetime prediction and reliability estimation methodology for Stirling-type pulse tube refrigerators by gaseous contamination accelerated degradation testing

Science.gov (United States)

Wan, Fubin; Tan, Yuanyuan; Jiang, Zhenhua; Chen, Xun; Wu, Yinong; Zhao, Peng

2017-12-01

Lifetime and reliability are the two performance parameters of premium importance for modern space Stirling-type pulse tube refrigerators (SPTRs), which are required to operate in excess of 10 years. Demonstration of these parameters provides a significant challenge. This paper proposes a lifetime prediction and reliability estimation method that utilizes accelerated degradation testing (ADT) for SPTRs related to gaseous contamination failure. The method was experimentally validated via three groups of gaseous contamination ADT. First, the performance degradation model based on mechanism of contamination failure and material outgassing characteristics of SPTRs was established. Next, a preliminary test was performed to determine whether the mechanism of contamination failure of the SPTRs during ADT is consistent with normal life testing. Subsequently, the experimental program of ADT was designed for SPTRs. Then, three groups of gaseous contamination ADT were performed at elevated ambient temperatures of 40 °C, 50 °C, and 60 °C, respectively and the estimated lifetimes of the SPTRs under normal condition were obtained through acceleration model (Arrhenius model). The results show good fitting of the degradation model with the experimental data. Finally, we obtained the reliability estimation of SPTRs through using the Weibull distribution. The proposed novel methodology enables us to take less than one year time to estimate the reliability of the SPTRs designed for more than 10 years.

Effect of actinobacteria agent inoculation methods on cellulose degradation during composting based on redundancy analysis.

Science.gov (United States)

Zhao, Yue; Lu, Qian; Wei, Yuquan; Cui, Hongyang; Zhang, Xu; Wang, Xueqin; Shan, Si; Wei, Zimin

2016-11-01

In this study, actinobacteria agent including Streptomyces sp. and Micromonospora sp. were inoculated during chicken manure composting by different inoculation methods. The effect of different treatments on cellulose degradation and the relationship between inoculants and indigenous actinobacteria were investigated during composting. The results showed that inoculation in different stages of composting all improved the actinobacteria community diversity particularly in the cooling stage of composting (M3). Moreover, inoculation could distinctly accelerate the degradation of organic matters (OM) especially celluloses. Redundancy analysis indicated that the correlation between indigenous actinobacteria and degradation of OM and cellulose were regulated by inoculants and there were significant differences between different inoculation methods. Furthermore, synergy between indigenous actinobacteria and inoculants for degradation of OM and cellulose in M3 was better than other treatments. Conclusively, we suggested an inoculation method to regulate the indigenous actinobacteria based on the relationship between inoculants and indigenous actinobacteria and degradation content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrodeless plasma acceleration system using rotating magnetic field method

Directory of Open Access Journals (Sweden)

T. Furukawa

2017-11-01

Full Text Available We have proposed Rotating Magnetic Field (RMF acceleration method as one of electrodeless plasma accelerations. In our experimental scheme, plasma generated by an rf (radio frequency antenna, is accelerated by RMF antennas, which consist of two-pair, opposed, facing coils, and these antennas are outside of a discharge tube. Therefore, there is no wear of electrodes, degrading the propulsion performance. Here, we will introduce our RMF acceleration system developed, including the experimental device, e.g., external antennas, a tapered quartz tube, a vacuum chamber, external magnets, and a pumping system. In addition, we can change RMF operation parameters (RMF applied current IRMF and RMF current phase difference ϕ, focusing on RMF current frequency fRMF by adjusting matching conditions of RMF, and investigate the dependencies on plasma parameters (electron density ne and ion velocity vi; e.g., higher increases of ne and vi (∼360 % and 55 %, respectively than previous experimental results were obtained by decreasing fRMF from 5 MHz to 0.7 MHz, whose RMF penetration condition was better according to Milroy’s expression. Moreover, time-varying component of RMF has been measured directly to survey the penetration condition experimentally.

Acceleration of the herbicide isoproturon degradation in wheat by glycosyltransferases and salicylic acid.

Science.gov (United States)

Lu, Yi Chen; Zhang, Shuang; Yang, Hong

2015-01-01

Isoproturon (IPU) is a herbicide widely used to prevent weeds in cereal production. Due to its extensive use in agriculture, residues of IPU are often detected in soils and crops. Overload of IPU to crops is associated with human health risks. Hence, there is an urgent need to develop an approach to mitigate its accumulation in crops. In this study, the IPU residues and its degradation products in wheat were characterized using ultra performance liquid chromatography-time of fight tandem-mass spectrometer/mass spectrometer (UPLC-TOF-MS/MS). Most detected IPU-derivatives were sugar-conjugated. Degradation and glycosylation of IPU-derivatives could be enhanced by applying salicylic acid (SA). While more sugar-conjugated IPU-derivatives were identified in wheat with SA application, lower levels of IPU were detected, indicating that SA is able to accelerate intracellular IPU catabolism. All structures of IPU-derivatives and sugar-conjugated products were characterized. Comparative data were provided with specific activities and gene expression of certain glucosyltransferases. A pathway with IPU degradation and glucosylation was discussed. Our work indicates that SA-accelerated degradation is practically useful for wheat crops growing in IPU-contaminated soils because such crops with SA application can potentially lower or minimize IPU accumulation in levels below the threshold for adverse effects. Copyright © 2014 Elsevier B.V. All rights reserved.

A novel method to control hydrolytic degradation of nanocomposite biocompatible materials via imparting superhydrophobicity

Energy Technology Data Exchange (ETDEWEB)

Khakbaz, Mobina [Department of Chemical Engineering, Islamic Azad University, Shahrood Branch, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Hejazi, Iman [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Seyfi, Javad, E-mail: Jseyfi@gmail.com [Department of Chemical Engineering, Islamic Azad University, Shahrood Branch, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Jafari, Seyed-Hassan [School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Khonakdar, Hossein Ali [Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of); Davachi, Seyed Mohammad [School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)

2015-12-01

Highlights: • Superhydrophobic surface was obtained from a terpolymer for biomedical applications. • Hydrolytic degradation was delayed notably through inducing superhydrophobicity. • A novel method including combined use of non-solvent and nanoparticles was used. • Extreme wettabilities are attained by varying non-solvent and nanoparticles content. • Use of nanoparticle increased pore size via accelerating the evaporation process. - Abstract: Acceleration of hydrolytic degradation of biomedical materials is not always desirable. For instance, terpolymers based on L-lactide, glycolide and trimethylene carbonate exhibit very fast hydrolytic degradation due to their amorphous structure, hydrophilicity, and high water absorption capability. Therefore, an attempt was made in the current study to impede the hydrolytic degradation for these materials through imparting superhydrophobicity to their surfaces. The used terpolymer has been shown to have promising potential applications as bio-absorbable surgical sutures and other biomedical materials, and thus, its applicability could be further extended upon impeding its hydrolytic degradation. Moreover, a novel method including combined use of non-solvent and nanoparticles was utilized to achieve superhydrophobicity. Very diverse wettability results were obtained which were attributed to the obtained various morphologies according to scanning electron microscopy results. More importantly, a unique hierarchical morphology was found to be responsible for the observed water repellent behavior. X-ray photoelectron spectroscopy results revealed co-existence of nanosilica particles and terpolymer chains on the surface's top layer. Finally, it was found that the superhydrophobic sample exhibited a significantly impeded hydrolytic degradation as compared with the hydrophilic pure terpolymer which was attributed to the formation of air pockets on the surface's top layer.

Die degradation effect on aging rate in accelerated cycling tests of SiC power MOSFET modules

DEFF Research Database (Denmark)

Luo, Haoze; Baker, Nick; Iannuzzo, Francesco

2017-01-01

In order to distinguish the die and bond wire degradations, in this paper both the die and bond wire resistances of SiC MOSFET modules are measured and tested during the accelerated cycling tests. It is proved that, since the die degradation under specific conditions increases the temperature swing...

A validated stability-indicating RP-HPLC method for levofloxacin in the presence of degradation products, its process related impurities and identification of oxidative degradant.

Science.gov (United States)

Lalitha Devi, M; Chandrasekhar, K B

2009-12-05

The objective of current study was to develop a validated specific stability indicating reversed-phase liquid chromatographic method for the quantitative determination of levofloxacin as well as its related substances determination in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its process related impurities. Forced degradation studies were performed on bulk sample of levofloxacin as per ICH prescribed stress conditions using acid, base, oxidative, water hydrolysis, thermal stress and photolytic degradation to show the stability indicating power of the method. Significant degradation was observed during oxidative stress and the degradation product formed was identified by LCMS/MS, slight degradation in acidic stress and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the impurity spiked solution. Good resolution between the peaks corresponds to process related impurities and degradation products from the analyte were achieved on ACE C18 column using the mobile phase consists a mixture of 0.5% (v/v) triethyl amine in sodium dihydrogen orthophosphate dihydrate (25 mM; pH 6.0) and methanol using a simple linear gradient. The detection was carried out at 294 nm. The limit of detection and the limit of quantitation for the levofloxacin and its process related impurities were established. The stressed test solutions were assayed against the qualified working standard of levofloxacin and the mass balance in each case was in between 99.4 and 99.8% indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of levofloxacin at the time of batch release and also during its stability studies (long term and accelerated stability).

New Method to Characterize Degradation of First Surface Aluminum Reflectors: Preprint

Energy Technology Data Exchange (ETDEWEB)

Sutter, F.; Heller, P.; Meyen, S.; Pitz-Paal, R.; Kennedy, C.; Fernandez-Garcia, A.; Schmucker, M.

2010-10-01

This paper reports the development of a new optical instrument capable of characterizing the aging process of enhanced first surface aluminum reflectors for concentrating solar power (CSP) application. Samples were exposed outdoors at different sites and in accelerated exposure tests. All samples exposed outdoors showed localized corrosion spots. Degradation originated from points of damage in the protective coating, but propagated underneath the protective coating. The degraded samples were analyzed with a microscope and with a newly designed space-resolved specular reflectometer (SR)2 that is capable of optically detecting and characterizing the corrosion spots. The device measures the specular reflectance at three acceptance angles and the wavelengths with spatial resolution using a digital camera's CMOS sensor. It can be used to measure the corrosion growth rate during outdoor and accelerated exposure tests. These results will allow a correlation between the degraded mirror surface and its specular reflectance.

Effectiveness of various transport synthetic acceleration methods with and without GMRES

International Nuclear Information System (INIS)

Chang, J.H.; Adams, M.L.

2005-01-01

We explore the effectiveness of three types of transport synthetic acceleration (TSA) methods as stand-alone methods and as pre-conditioners within the GMRES Krylov solver. The three types are β TSA, 'stretched' TSA, and 'stretched and filtered' (SF) TSA. We analyzed the effectiveness of these algorithms using Fourier mode analysis of model two-dimensional problems with periodic boundary conditions, including problems with alternating layers of different materials. The analyses revealed that both β-TSA and stretched TSA can diverge for fairly weak heterogeneities. Performance of SF TSA, even with the optimum filtering parameter, degrades with heterogeneity. However, with GMRES, all TSA methods are convergent. SF TSA with the optimum filtering parameter was the most effective method. Numerical results support our Fourier mode analysis. (authors)

A degradation approach to accelerate simulations to steady-state in a 3-D tracer transport model of the global ocean

Energy Technology Data Exchange (ETDEWEB)

Aumont, O.; Orr, J.C.; Marti, O. [CEA Saclay, Gif-sur-Yvette (France). Lab. de Modelisation du Climat et de l`Environnement; Jamous, D.; Monfray, P. [Centre des Faibles Radioactivites, Laboratoire mixte CNRS-CEA, L`Orme des Merisiers, Bt. 709/LMCE, CE Saclay, F-91191 Gif sur Yvette Cedex (France); Madec, G. [Laboratoire d`Oceanographie Dynamique et de Climatologie, (CNRS/ORSTOM/UPMC) Universite Paris VI, 4 place Jussieu, Paris (France)

1998-02-01

We have developed a new method to accelerate tracer simulations to steady-state in a 3D global ocean model, run off-line. Using this technique, our simulations for natural {sup 14}C ran 17 times faster when compared to those made with the standard nonaccelerated approach. For maximum acceleration we wish to initialize the model with tracer fields that are as close as possible to the final equilibrium solution. Our initial tracer fields were derived by judiciously constructing a much faster, lower-resolution (degraded), off-line model from advective and turbulent fields predicted from the parent on-line model, an ocean general circulation model (OGCM). No on-line version of the degraded model exists; it is based entirely on results from the parent OGCM. Degradation was made horizontally over sets of four adjacent grid-cell squares for each vertical layer of the parent model. However, final resolution did not suffer because as a second step, after allowing the degraded model to reach equilibrium, we used its tracer output to reinitialize the parent model (at the original resolution). After reinitialization, the parent model must then be integrated only to a few hundred years before reaching equilibrium. To validate our degradation-integration technique (DEGINT), we compared {sup 14}C results from runs with and without this approach. Differences are less than 10 permille throughout 98.5% of the ocean volume. Predicted natural {sup 14}C appears reasonable over most of the ocean. In the Atlantic, modeled {Delta}{sup 14}C indicates that as observed, the North Atlantic Deep Water (NADW) fills the deep North Atlantic, and Antartic Intermediate Water (AAIW) infiltrates northward. (orig.) With 12 figs., 1 tab., 42 refs.

Mechanical properties of electrospun PCL scaffold under in vitro and accelerated degradation conditions

DEFF Research Database (Denmark)

Løvdal, Alexandra Liv Vest; Vange, Jakob; Nielsen, Lene Feldskov

2014-01-01

Within recent years, researchers have looked into using polycaprolactone (PCL) as a synthetic biodegradable scaffold for tissue engineering purposes. This study investigated the mechanical properties of an electrospun PCL, while being exposed to physiological fluids at 37C (in vitro conditions) w...... in buffer (pH 12). The accelerated study showed a linear decrease in both elastic modulus and yield stress as a function of degradation time....

Results of metallographical diagnostic examination of Navy half-watt thermoelectric converters degraded by accelerated tests

International Nuclear Information System (INIS)

Rosell, F.E. Jr.; Rouklove, P.G.

1977-01-01

To verify the 15-year reliability of the Navy half-watt radioisotope thermoelectric generator (RTG), bismuth--telluride thermoelectric converters were submitted to testing at high temperatures which accelerated the degradation and caused failure of the converters. Metallographic diagnostic examination of failed units verified failure mechanisms. Results of diagnostic examinations are presented

Coupling and decoupling of the accelerating units for pulsed synchronous linear accelerator

Science.gov (United States)

Shen, Yi; Liu, Yi; Ye, Mao; Zhang, Huang; Wang, Wei; Xia, Liansheng; Wang, Zhiwen; Yang, Chao; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun

2017-12-01

A pulsed synchronous linear accelerator (PSLA), based on the solid-state pulse forming line, photoconductive semiconductor switch, and high gradient insulator technologies, is a novel linear accelerator. During the prototype PSLA commissioning, the energy gain of proton beams was found to be much lower than expected. In this paper, the degradation of the energy gain is explained by the circuit and cavity coupling effect of the accelerating units. The coupling effects of accelerating units are studied, and the circuit topologies of these two kinds of coupling effects are presented. Two methods utilizing inductance and membrane isolations, respectively, are proposed to reduce the circuit coupling effects. The effectiveness of the membrane isolation method is also supported by simulations. The decoupling efficiency of the metal drift tube is also researched. We carried out the experiments on circuit decoupling of the multiple accelerating cavity. The result shows that both circuit decoupling methods could increase the normalized voltage.

Coating and Interface Degradation of Coated steel, Part 2: Accelerated Laboratory Tests

International Nuclear Information System (INIS)

Cambier, S.M.; Frankel, G.S.

2014-01-01

In a previous paper, it was demonstrated that the measurement of cathodic delamination by the Scanning Kelvin Probe can assess the interface stability of poly(vinyl butyral) (PVB) coated steel after field exposure. This technique was utilized to characterize the degradation of the polymer/metal interface in several outdoor climates. In this paper, the effects of environmental factors on the interface degradation were investigated in the laboratory. The mechanisms measured in the field were reproduced to provide input in the development of an appropriate accelerated test for PVB coated steel. The ASTM B117 and G154 standardized tests were investigated individually and sequentially. The interface stability improved after 24 h of ASTM G154 exposure. After 144 h of exposure to ASTM G154 exposure, polymer oxidation took place simultaneously with interface degradation. The condensation phase of the ASTM G154 test was responsible for the interface improvement while the ultraviolet radiation triggered the interface degradation. Pre-exposure to ASTM G154 delayed wet de-adhesion during ASTM B117 exposure. After wet de-adhesion caused by 6 h of ASTM B117, exposure to ASTM G154 for 24 h increased the interface stability. The effects of ultraviolet radiation, relative humidity, temperature and environment on interface degradation were investigated in a special chamber. Humidity was the primary factor found to influence the interface improvement during G154 exposure. A wet/dry salt fog cycle with irradiation by an ultraviolet or filtered xenon arc lamp around room temperature was suggested to reproduce the competition between the interface improvement and the interface degradation that takes place in the field

The Source Equivalence Acceleration Method

International Nuclear Information System (INIS)

Everson, Matthew S.; Forget, Benoit

2015-01-01

Highlights: • We present a new acceleration method, the Source Equivalence Acceleration Method. • SEAM forms an equivalent coarse group problem for any spatial method. • Equivalence is also formed across different spatial methods and angular quadratures. • Testing is conducted using OpenMOC and performance is compared with CMFD. • Results show that SEAM is preferable for very expensive transport calculations. - Abstract: Fine-group whole-core reactor analysis remains one of the long sought goals of the reactor physics community. Such a detailed analysis is typically too computationally expensive to be realized on anything except the largest of supercomputers. Recondensation using the Discrete Generalized Multigroup (DGM) method, though, offers a relatively cheap alternative to solving the fine group transport problem. DGM, however, suffered from inconsistencies when applied to high-order spatial methods. While an exact spatial recondensation method was developed and provided full spatial consistency with the fine group problem, this approach substantially increased memory requirements for realistic problems. The method described in this paper, called the Source Equivalence Acceleration Method (SEAM), forms a coarse-group problem which preserves the fine-group problem even when using higher order spatial methods. SEAM allows recondensation to converge to the fine-group solution with minimal memory requirements and little additional overhead. This method also provides for consistency when using different spatial methods and angular quadratures between the coarse group and fine group problems. SEAM was implemented in OpenMOC, a 2D MOC code developed at MIT, and its performance tested against Coarse Mesh Finite Difference (CMFD) acceleration on the C5G7 benchmark problem and on a 361 group version of the problem. For extremely expensive transport calculations, SEAM was able to outperform CMFD, resulting in speed-ups of 20–45 relative to the normal power

Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

2015-01-01

An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, which are the two main environmental stress factors that promote potential-induced degradation (PID). This model was derived...

Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

2015-01-01

An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, the two main environmental stress factors that promote potential-induced degradation. This model was derived from module pow...

Systems and methods for the magnetic insulation of accelerator electrodes in electrostatic accelerators

Science.gov (United States)

Grisham, Larry R

2013-12-17

The present invention provides systems and methods for the magnetic insulation of accelerator electrodes in electrostatic accelerators. Advantageously, the systems and methods of the present invention improve the practically obtainable performance of these electrostatic accelerators by addressing, among other things, voltage holding problems and conditioning issues. The problems and issues are addressed by flowing electric currents along these accelerator electrodes to produce magnetic fields that envelope the accelerator electrodes and their support structures, so as to prevent very low energy electrons from leaving the surfaces of the accelerator electrodes and subsequently picking up energy from the surrounding electric field. In various applications, this magnetic insulation must only produce modest gains in voltage holding capability to represent a significant achievement.

Lasers and new methods of particle acceleration

International Nuclear Information System (INIS)

Parsa, Z.

1998-02-01

There has been a great progress in development of high power laser technology. Harnessing their potential for particle accelerators is a challenge and of great interest for development of future high energy colliders. The author discusses some of the advances and new methods of acceleration including plasma-based accelerators. The exponential increase in sophistication and power of all aspects of accelerator development and operation that has been demonstrated has been remarkable. This success has been driven by the inherent interest to gain new and deeper understanding of the universe around us. With the limitations of the conventional technology it may not be possible to meet the requirements of the future accelerators with demands for higher and higher energies and luminosities. It is believed that using the existing technology one can build a linear collider with about 1 TeV center of mass energy. However, it would be very difficult (or impossible) to build linear colliders with energies much above one or two TeV without a new method of acceleration. Laser driven high gradient accelerators are becoming more realistic and is expected to provide an alternative, (more compact, and more economical), to conventional accelerators in the future. The author discusses some of the new methods of particle acceleration, including laser and particle beam driven plasma based accelerators, near and far field accelerators. He also discusses the enhanced IFEL (Inverse Free Electron Laser) and NAIBEA (Nonlinear Amplification of Inverse-Beamstrahlung Electron Acceleration) schemes, laser driven photo-injector and the high energy physics requirements

Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions

Science.gov (United States)

Sun, Bo; Ye, Tianyuan; Feng, Qiang; Yao, Jinghua; Wei, Mumeng

2015-01-01

This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu2O film increased gradually. Its corrosion product was Cu2(OH)3Cl, which increased in quantity over time. Cl− was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss), degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e., dissolved oxygen (DO) and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet. PMID:28793549

Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions.

Science.gov (United States)

Sun, Bo; Ye, Tianyuan; Feng, Qiang; Yao, Jinghua; Wei, Mumeng

2015-09-10

This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu₂O film increased gradually. Its corrosion product was Cu₂(OH)₃Cl, which increased in quantity over time. Cl - was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss), degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e. , dissolved oxygen (DO) and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet.

Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions

Directory of Open Access Journals (Sweden)

Bo Sun

2015-09-01

Full Text Available This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu2O film increased gradually. Its corrosion product was Cu2(OH3Cl, which increased in quantity over time. Cl− was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss, degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e., dissolved oxygen (DO and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet.

Accelerated reliability demonstration under competing failure modes

International Nuclear Information System (INIS)

Luo, Wei; Zhang, Chun-hua; Chen, Xun; Tan, Yuan-yuan

2015-01-01

The conventional reliability demonstration tests are difficult to apply to products with competing failure modes due to the complexity of the lifetime models. This paper develops a testing methodology based on the reliability target allocation for reliability demonstration under competing failure modes at accelerated conditions. The specified reliability at mission time and the risk caused by sampling of the reliability target for products are allocated for each failure mode. The risk caused by degradation measurement fitting of the target for a product involving performance degradation is equally allocated to each degradation failure mode. According to the allocated targets, the accelerated life reliability demonstration test (ALRDT) plans for the failure modes are designed. The accelerated degradation reliability demonstration test plans and the associated ALRDT plans for the degradation failure modes are also designed. Next, the test plan and the decision rules for the products are designed. Additionally, the effects of the discreteness of sample size and accepted number of failures for failure modes on the actual risks caused by sampling for the products are investigated. - Highlights: • Accelerated reliability demonstration under competing failure modes is studied. • The method is based on the reliability target allocation involving the risks. • The test plan for the products is based on the plans for all the failure modes. • Both failure mode and degradation failure modes are considered. • The error of actual risks caused by sampling for the products is small enough

A statistical comparison of accelerated concrete testing methods

OpenAIRE

Denny Meyer

1997-01-01

Accelerated curing results, obtained after only 24 hours, are used to predict the 28 day strength of concrete. Various accelerated curing methods are available. Two of these methods are compared in relation to the accuracy of their predictions and the stability of the relationship between their 24 hour and 28 day concrete strength. The results suggest that Warm Water accelerated curing is preferable to Hot Water accelerated curing of concrete. In addition, some other methods for improving the...

Optimal Constant-Stress Accelerated Degradation Test Plans Using Nonlinear Generalized Wiener Process

Directory of Open Access Journals (Sweden)

Zhen Chen

2016-01-01

Full Text Available Accelerated degradation test (ADT has been widely used to assess highly reliable products’ lifetime. To conduct an ADT, an appropriate degradation model and test plan should be determined in advance. Although many historical studies have proposed quite a few models, there is still room for improvement. Hence we propose a Nonlinear Generalized Wiener Process (NGWP model with consideration of the effects of stress level, product-to-product variability, and measurement errors for a higher estimation accuracy and a wider range of use. Then under the constraints of sample size, test duration, and test cost, the plans of constant-stress ADT (CSADT with multiple stress levels based on the NGWP are designed by minimizing the asymptotic variance of the reliability estimation of the products under normal operation conditions. An optimization algorithm is developed to determine the optimal stress levels, the number of units allocated to each level, inspection frequency, and measurement times simultaneously. In addition, a comparison based on degradation data of LEDs is made to show better goodness-of-fit of the NGWP than that of other models. Finally, optimal two-level and three-level CSADT plans under various constraints and a detailed sensitivity analysis are demonstrated through examples in this paper.

Optical characterization of voltage-accelerated degradation in CH3NH3PbI3 perovskite solar cells.

Science.gov (United States)

Handa, Taketo; Tex, David M; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

2016-05-16

We investigate the performance degradation mechanism of CH3NH3PbI3 perovskite solar cells under bias voltage in air and nitrogen atmospheres using photoluminescence and electroluminescence techniques. When applying forward bias, the power conversion efficiency of the solar cells decreased significantly in air, but showed no degradation in nitrogen atmosphere. Time-resolved photoluminescence measurements on these devices revealed that the application of forward bias in air accelerates the generation of non-radiative recombination centers in the perovskite layer buried in the device. We found a negative correlation between the electroluminescence intensity and the injected current intensity in air. The irreversible change of the perovskite grain surface in air initiates the degradation of the perovskite solar cells.

Environmental aging in polycrystalline-Si photovoltaic modules: comparison of chamber-based accelerated degradation studies with field-test data

Science.gov (United States)

Lai, T.; Biggie, R.; Brooks, A.; Potter, B. G.; Simmons-Potter, K.

2015-09-01

Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following

Delayless acceleration measurement method for motion control applications

Energy Technology Data Exchange (ETDEWEB)

Vaeliviita, S.; Ovaska, S.J. [Helsinki University of Technology, Otaniemi (Finland). Institute of Intelligent Power Electronics

1997-12-31

Delayless and accurate sensing of angular acceleration can improve the performance of motion control in motor drives. Acceleration control is, however, seldom implemented in practical drive systems due to prohibitively high costs or unsatisfactory results of most acceleration measurement methods. In this paper we propose an efficient and accurate acceleration measurement method based on direct differentiation of the corresponding velocity signal. Polynomial predictive filtering is used to smooth the resulting noisy signal without delay. This type of prediction is justified by noticing that a low-degree polynomial can usually be fitted into the primary acceleration curve. No additional hardware is required to implement the procedure if the velocity signal is already available. The performance of the acceleration measurement method is evaluated by applying it to a demanding motion control application. (orig.) 12 refs.

Evaluation of a new method of RF power coupling to acceleration cavity of charged particles accelerators

Directory of Open Access Journals (Sweden)

A M Poursaleh

2017-08-01

Full Text Available In this paper, the feasibility studty of a new method of RF power coupling to acceleration cavity of charged particles accelerator will be evaluated. In this method a slit is created around the accelerator cavity, and RF power amplifier modules is connected directly to the acceleration cavity. In fact, in this design, the cavity in addition to acting as an acceleration cavity, acts as a RF power combiner. The benefits of this method are avoiding the use of RF vacuum tubes, transmission lines, high power combiner and coupler. In this research, cylindrical and coaxial cavities were studied, and a small sample coaxial cavity is build by this method. The results of the resarch showed that compact, economical and safe RF accelerators can be achieved by the proposed method

Method of degrading pollutants in soil

Science.gov (United States)

Hazen, Terry C.; Lopez-De-Victoria, Geralyne

1994-01-01

A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant.

A statistical comparison of accelerated concrete testing methods

Directory of Open Access Journals (Sweden)

Denny Meyer

1997-01-01

Full Text Available Accelerated curing results, obtained after only 24 hours, are used to predict the 28 day strength of concrete. Various accelerated curing methods are available. Two of these methods are compared in relation to the accuracy of their predictions and the stability of the relationship between their 24 hour and 28 day concrete strength. The results suggest that Warm Water accelerated curing is preferable to Hot Water accelerated curing of concrete. In addition, some other methods for improving the accuracy of predictions of 28 day strengths are suggested. In particular the frequency at which it is necessary to recalibrate the prediction equation is considered.

Acceleration transforms and statistical kinetic models

International Nuclear Information System (INIS)

LuValle, M.J.; Welsher, T.L.; Svoboda, K.

1988-01-01

For a restricted class of problems a mathematical model of microscopic degradation processes, statistical kinetics, is developed and linked through acceleration transforms to the information which can be obtained from a system in which the only observable sign of degradation is sudden and catastrophic failure. The acceleration transforms were developed in accelerated life testing applications as a tool for extrapolating from the observable results of an accelerated life test to the dynamics of the underlying degradation processes. A particular concern of a physicist attempting to interpreted the results of an analysis based on acceleration transforms is determining the physical species involved in the degradation process. These species may be (a) relatively abundant or (b) relatively rare. The main results of this paper are a theorem showing that for an important subclass of statistical kinetic models, acceleration transforms cannot be used to distinguish between cases a and b, and an example showing that in some cases falling outside the restrictions of the theorem, cases a and b can be distinguished by their acceleration transforms

Method of degrading pollutants in soil

Science.gov (United States)

Hazen, T.C.; Lopez-De-Victoria, G.

1994-07-05

Disclosed are a method and system for enhancing the motility of microorganisms. This is accomplished by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant. 5 figures.

Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.

Science.gov (United States)

Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

2013-09-01

In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2 days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2 days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Neutron Transport Methods for Accelerator-Driven Systems

International Nuclear Information System (INIS)

Nicholas Tsoulfanidis; Elmer Lewis

2005-01-01

The objective of this project has been to develop computational methods that will enable more effective analysis of Accelerator Driven Systems (ADS). The work is centered at the University of Missouri at Rolla, with a subcontract at Northwestern University, and close cooperation with the Nuclear Engineering Division at Argonne National Laboratory. The work has fallen into three categories. First, the treatment of the source for neutrons originating from the spallation target which drives the neutronics calculations of the ADS. Second, the generalization of the nodal variational method to treat the R-Z geometry configurations frequently needed for scoping calculations in Accelerator Driven Systems. Third, the treatment of void regions within variational nodal methods as needed to treat the accelerator beam tube

Method of radiation degradation of PTFE under vacuum conditions

Energy Technology Data Exchange (ETDEWEB)

Korenev, Sergey E-mail: sergey_korenev@steris.com

2004-10-01

A new method of radiation degradation of Polytetrafluoroethylene (PTFE) under vacuum conditions is considered in this report. The combination of glow gas discharge and electrical surface discharge (on surface and inside PTFE) increases the efficiency of thermal-radiation degradation. The main mechanism of this degradation method consists of the breaking of C-C and C-F bonds. The vacuum conditions allow decreasing of the concentration of toxic compounds, such as a HF. Experimental results for degradation of PTFE are presented.

Method of radiation degradation of PTFE under vacuum conditions

Science.gov (United States)

Korenev, Sergey

2004-09-01

A new method of radiation degradation of Polytetrafluoroethylene (PTFE) under vacuum conditions is considered in this report. The combination of glow gas discharge and electrical surface discharge (on surface and inside PTFE) increases the efficiency of thermal-radiation degradation. The main mechanism of this degradation method consists of the breaking of C-C and C-F bonds. The vacuum conditions allow decreasing of the concentration of toxic compounds, such as a HF. Experimental results for degradation of PTFE are presented.

Thermal Efficiency Degradation Diagnosis Method Using Regression Model

International Nuclear Information System (INIS)

Jee, Chang Hyun; Heo, Gyun Young; Jang, Seok Won; Lee, In Cheol

2011-01-01

This paper proposes an idea for thermal efficiency degradation diagnosis in turbine cycles, which is based on turbine cycle simulation under abnormal conditions and a linear regression model. The correlation between the inputs for representing degradation conditions (normally unmeasured but intrinsic states) and the simulation outputs (normally measured but superficial states) was analyzed with the linear regression model. The regression models can inversely response an associated intrinsic state for a superficial state observed from a power plant. The diagnosis method proposed herein is classified into three processes, 1) simulations for degradation conditions to get measured states (referred as what-if method), 2) development of the linear model correlating intrinsic and superficial states, and 3) determination of an intrinsic state using the superficial states of current plant and the linear regression model (referred as inverse what-if method). The what-if method is to generate the outputs for the inputs including various root causes and/or boundary conditions whereas the inverse what-if method is the process of calculating the inverse matrix with the given superficial states, that is, component degradation modes. The method suggested in this paper was validated using the turbine cycle model for an operating power plant

Degradation model and application in life prediction of rotating-mechanism

International Nuclear Information System (INIS)

Zhou Yuhui

2009-01-01

The degradation data can provide additional information beyond that provided by the failure observations, both sets of observations need to be considered when doing inference on the statistical parameters of the product and system lifetime distributions. By the degradation model showing the wear out failure, the predicted results of mechanism life is more accurate. Strength is one of the important capabilities of the rotating mechanism. In this paper, the degradation data of strength are described as a stochastic process model. Accelerated tests expose the products to greater environmental stress levels so that we can obtain lifetime and degradation measurements in a more timely fashion. Using the Best Linear Unbiased Estimation (BLUE) Method, the parameters under the degradation path were estimated from the accelerated life test (ALT) data of the rotating mechanism. Based on solving the singularity of degradation equation, at any time the reliability is estimated by the using the strength-stress interference theory. So we can predict the life of the rotating mechanism. (authors)

Evolutionary optimization methods for accelerator design

Science.gov (United States)

Poklonskiy, Alexey A.

Many problems from the fields of accelerator physics and beam theory can be formulated as optimization problems and, as such, solved using optimization methods. Despite growing efficiency of the optimization methods, the adoption of modern optimization techniques in these fields is rather limited. Evolutionary Algorithms (EAs) form a relatively new and actively developed optimization methods family. They possess many attractive features such as: ease of the implementation, modest requirements on the objective function, a good tolerance to noise, robustness, and the ability to perform a global search efficiently. In this work we study the application of EAs to problems from accelerator physics and beam theory. We review the most commonly used methods of unconstrained optimization and describe the GATool, evolutionary algorithm and the software package, used in this work, in detail. Then we use a set of test problems to assess its performance in terms of computational resources, quality of the obtained result, and the tradeoff between them. We justify the choice of GATool as a heuristic method to generate cutoff values for the COSY-GO rigorous global optimization package for the COSY Infinity scientific computing package. We design the model of their mutual interaction and demonstrate that the quality of the result obtained by GATool increases as the information about the search domain is refined, which supports the usefulness of this model. We Giscuss GATool's performance on the problems suffering from static and dynamic noise and study useful strategies of GATool parameter tuning for these and other difficult problems. We review the challenges of constrained optimization with EAs and methods commonly used to overcome them. We describe REPA, a new constrained optimization method based on repairing, in exquisite detail, including the properties of its two repairing techniques: REFIND and REPROPT. We assess REPROPT's performance on the standard constrained

Generalized Coarse-Mesh Rebalance Method for Acceleration of Neutron Transport Calculations

International Nuclear Information System (INIS)

Yamamoto, Akio

2005-01-01

This paper proposes a new acceleration method for neutron transport calculations: the generalized coarse-mesh rebalance (GCMR) method. The GCMR method is a unified scheme of the traditional coarse-mesh rebalance (CMR) and the coarse-mesh finite difference (CMFD) acceleration methods. Namely, by using an appropriate acceleration factor, formulation of the GCMR method becomes identical to that of the CMR or CMFD method. This also indicates that the convergence property of the GCMR method can be controlled by the acceleration factor since the convergence properties of the CMR and CMFD methods are generally different. In order to evaluate the convergence property of the GCMR method, a linearized Fourier analysis was carried out for a one-group homogeneous medium, and the results clarified the relationship between the acceleration factor and the spectral radius. It was also shown that the spectral radius of the GCMR method is smaller than those of the CMR and CMFD methods. Furthermore, the Fourier analysis showed that when an appropriate acceleration factor was used, the spectral radius of the GCMR method did not exceed unity in this study, which was in contrast to the results of the CMR or the CMFD method. Application of the GCMR method to practical calculations will be easy when the CMFD acceleration is already adopted in a transport code. By multiplying a suitable acceleration factor to a coefficient (D FD ) of a finite difference formulation, one can improve the numerical instability of the CMFD acceleration method

Cyclotron method for heavy ion acceleration

International Nuclear Information System (INIS)

Gikal, B.N.; Gul'bekyan, G.G.; Kutner, V.B.; Oganesyan, R.Ts.

1984-01-01

Studies on heavy ion beams in a wide range of masses (up to uranium) and energies disclose essential potential opportunities for solution of both fundamental scientific and significant economical problems. A cyclotron method for heavy ion acceleration is considered. Development of low and medium energy heavy ion accelerators is revealed. The design of a complex comprising two isochronous cyclotrons which is planned to be constrdcted 1n the JINR is described. The cyclotron complex includes the U-400 and the U-400 M cyclotrons and it is intended for acceleration of both 35-20 MeV/nucleon superheavy ions such as Xe-U and 120 MeV/nucleon light ions. Certain systems of the accelerators are described. Prospects of the U-400 and the U-400 M development are displayed

Iterative acceleration methods for Monte Carlo and deterministic criticality calculations

Energy Technology Data Exchange (ETDEWEB)

Urbatsch, T.J.

1995-11-01

If you have ever given up on a nuclear criticality calculation and terminated it because it took so long to converge, you might find this thesis of interest. The author develops three methods for improving the fission source convergence in nuclear criticality calculations for physical systems with high dominance ratios for which convergence is slow. The Fission Matrix Acceleration Method and the Fission Diffusion Synthetic Acceleration (FDSA) Method are acceleration methods that speed fission source convergence for both Monte Carlo and deterministic methods. The third method is a hybrid Monte Carlo method that also converges for difficult problems where the unaccelerated Monte Carlo method fails. The author tested the feasibility of all three methods in a test bed consisting of idealized problems. He has successfully accelerated fission source convergence in both deterministic and Monte Carlo criticality calculations. By filtering statistical noise, he has incorporated deterministic attributes into the Monte Carlo calculations in order to speed their source convergence. He has used both the fission matrix and a diffusion approximation to perform unbiased accelerations. The Fission Matrix Acceleration method has been implemented in the production code MCNP and successfully applied to a real problem. When the unaccelerated calculations are unable to converge to the correct solution, they cannot be accelerated in an unbiased fashion. A Hybrid Monte Carlo method weds Monte Carlo and a modified diffusion calculation to overcome these deficiencies. The Hybrid method additionally possesses reduced statistical errors.

Iterative acceleration methods for Monte Carlo and deterministic criticality calculations

International Nuclear Information System (INIS)

Urbatsch, T.J.

1995-11-01

If you have ever given up on a nuclear criticality calculation and terminated it because it took so long to converge, you might find this thesis of interest. The author develops three methods for improving the fission source convergence in nuclear criticality calculations for physical systems with high dominance ratios for which convergence is slow. The Fission Matrix Acceleration Method and the Fission Diffusion Synthetic Acceleration (FDSA) Method are acceleration methods that speed fission source convergence for both Monte Carlo and deterministic methods. The third method is a hybrid Monte Carlo method that also converges for difficult problems where the unaccelerated Monte Carlo method fails. The author tested the feasibility of all three methods in a test bed consisting of idealized problems. He has successfully accelerated fission source convergence in both deterministic and Monte Carlo criticality calculations. By filtering statistical noise, he has incorporated deterministic attributes into the Monte Carlo calculations in order to speed their source convergence. He has used both the fission matrix and a diffusion approximation to perform unbiased accelerations. The Fission Matrix Acceleration method has been implemented in the production code MCNP and successfully applied to a real problem. When the unaccelerated calculations are unable to converge to the correct solution, they cannot be accelerated in an unbiased fashion. A Hybrid Monte Carlo method weds Monte Carlo and a modified diffusion calculation to overcome these deficiencies. The Hybrid method additionally possesses reduced statistical errors

Degradation of naphthalene and fluorene by radiolysis using accelerated electrons; Degradacion de naftaleno y fluoreno por radiolisis empleando electrones acelerados

Energy Technology Data Exchange (ETDEWEB)

Flores de Jesus, I

2003-07-01

The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

Degradation of naphthalene and fluorene by radiolysis using accelerated electrons; Degradacion de naftaleno y fluoreno por radiolisis empleando electrones acelerados

Energy Technology Data Exchange (ETDEWEB)

Flores de Jesus, I

2003-07-01

The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

Accelerated Stress-Corrosion Testing

Science.gov (United States)

1986-01-01

Test procedures for accelerated stress-corrosion testing of high-strength aluminum alloys faster and provide more quantitative information than traditional pass/fail tests. Method uses data from tests on specimen sets exposed to corrosive environment at several levels of applied static tensile stress for selected exposure times then subsequently tensile tested to failure. Method potentially applicable to other degrading phenomena (such as fatigue, corrosion fatigue, fretting, wear, and creep) that promote development and growth of cracklike flaws within material.

Degradation of acephate using combined ultrasonic and ozonation method

Directory of Open Access Journals (Sweden)

Bin Wang

2015-07-01

Full Text Available The degradation of acephate in aqueous solutions was investigated with the ultrasonic and ozonation methods, as well as a combination of both. An experimental facility was designed and operation parameters such as the ultrasonic power, temperature, and gas flow rate were strictly controlled at constant levels. The frequency of the ultrasonic wave was 160 kHz. The ultraviolet-visible (UV-Vis spectroscopic and Raman spectroscopic techniques were used in the experiment. The UV-Vis spectroscopic results show that ultrasonication and ozonation have a synergistic effect in the combined system. The degradation efficiency of acephate increases from 60.6% to 87.6% after the solution is irradiated by a 160 kHz ultrasonic wave for 60 min in the ozonation process, and it is higher with the combined method than the sum of the separated ultrasonic and ozonation methods. Raman spectra studies show that degradation via the combined ultrasonic/ozonation method is more thorough than photocatalysis. The oxidability of nitrogen atoms is promoted under ultrasonic waves. Changes of the inorganic ions and degradation pathway during the degradation process were investigated in this study. Most final products are innocuous to the environment.

Moments method in the theory of accelerators

International Nuclear Information System (INIS)

Perel'shtejn, Eh.A.

1984-01-01

The moments method is widely used for solution of different physical and calculation problems in the theory of accelerators, magnetic optics and dynamics of high-current beams. Techniques using moments of the second order-mean squape characteristics of charged particle beams is shown to be most developed. The moments method is suitable and sometimes even the only technique applicable for solution of computerized problems on optimization of accelerating structures, beam transport channels, matching and other systems with accout of a beam space charge

First muon acceleration using a radio-frequency accelerator

Directory of Open Access Journals (Sweden)

S. Bae

2018-05-01

Full Text Available Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu^{-}, which are bound states of positive muons (μ^{+} and two electrons, are generated from μ^{+}’s through the electron capture process in an aluminum degrader. The generated Mu^{-}’s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ. In the RFQ, the Mu^{-}’s are accelerated to 89 keV. The accelerated Mu^{-}’s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Statistical Bayesian method for reliability evaluation based on ADT data

Science.gov (United States)

Lu, Dawei; Wang, Lizhi; Sun, Yusheng; Wang, Xiaohong

2018-05-01

Accelerated degradation testing (ADT) is frequently conducted in the laboratory to predict the products’ reliability under normal operating conditions. Two kinds of methods, degradation path models and stochastic process models, are utilized to analyze degradation data and the latter one is the most popular method. However, some limitations like imprecise solution process and estimation result of degradation ratio still exist, which may affect the accuracy of the acceleration model and the extrapolation value. Moreover, the conducted solution of this problem, Bayesian method, lose key information when unifying the degradation data. In this paper, a new data processing and parameter inference method based on Bayesian method is proposed to handle degradation data and solve the problems above. First, Wiener process and acceleration model is chosen; Second, the initial values of degradation model and parameters of prior and posterior distribution under each level is calculated with updating and iteration of estimation values; Third, the lifetime and reliability values are estimated on the basis of the estimation parameters; Finally, a case study is provided to demonstrate the validity of the proposed method. The results illustrate that the proposed method is quite effective and accuracy in estimating the lifetime and reliability of a product.

Accelerated Test Method for Corrosion Protective Coatings Project

Science.gov (United States)

Falker, John; Zeitlin, Nancy; Calle, Luz

2015-01-01

This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as accurately and reliably as current long-term atmospheric exposure tests. This new accelerated test method will shorten the time needed to evaluate the corrosion protection performance of coatings for NASA's critical ground support structures. Lifetime prediction for spaceport structure coatings has a 5-year qualification cycle using atmospheric exposure. Current accelerated corrosion tests often provide false positives and negatives for coating performance, do not correlate to atmospheric corrosion exposure results, and do not correlate with atmospheric exposure timescales for lifetime prediction.

Acceleration techniques for the discrete ordinate method

International Nuclear Information System (INIS)

Efremenko, Dmitry; Doicu, Adrian; Loyola, Diego; Trautmann, Thomas

2013-01-01

In this paper we analyze several acceleration techniques for the discrete ordinate method with matrix exponential and the small-angle modification of the radiative transfer equation. These techniques include the left eigenvectors matrix approach for computing the inverse of the right eigenvectors matrix, the telescoping technique, and the method of false discrete ordinate. The numerical simulations have shown that on average, the relative speedup of the left eigenvector matrix approach and the telescoping technique are of about 15% and 30%, respectively. -- Highlights: ► We presented the left eigenvector matrix approach. ► We analyzed the method of false discrete ordinate. ► The telescoping technique is applied for matrix operator method. ► Considered techniques accelerate the computations by 20% in average.

Calreticulin-mutant proteins induce megakaryocytic signaling to transform hematopoietic cells and undergo accelerated degradation and Golgi-mediated secretion

Directory of Open Access Journals (Sweden)

Lijuan Han

2016-05-01

Full Text Available Abstract Background Somatic calreticulin (CALR, Janus kinase 2 (JAK2, and thrombopoietin receptor (MPL mutations essentially show mutual exclusion in myeloproliferative neoplasms (MPN, suggesting that they activate common oncogenic pathways. Recent data have shown that MPL function is essential for CALR mutant-driven MPN. However, the exact role and the mechanisms of action of CALR mutants have not been fully elucidated. Methods The murine myeloid cell line 32D and human HL60 cells overexpressing the most frequent CALR type 1 and type 2 frameshift mutants were generated to analyze the first steps of cellular transformation, in the presence and absence of MPL expression. Furthermore, mutant CALR protein stability and secretion were examined using brefeldin A, MG132, spautin-1, and tunicamycin treatment. Results The present study demonstrates that the expression of endogenous Mpl, CD41, and the key megakaryocytic transcription factor NF-E2 is stimulated by type 1 and type 2 CALR mutants, even in the absence of exogenous MPL. Mutant CALR expressing 32D cells spontaneously acquired cytokine independence, and this was associated with increased Mpl mRNA expression, CD41, and NF-E2 protein as well as constitutive activation of downstream signaling and response to JAK inhibitor treatment. Exogenous expression of MPL led to constitutive activation of STAT3 and 5, ERK1/2, and AKT, cytokine-independent growth, and reduction of apoptosis similar to the effects seen in the spontaneously outgrown cells. We observed low CALR-mutant protein amounts in cellular lysates of stably transduced cells, and this was due to accelerated protein degradation that occurred independently from the ubiquitin-proteasome system as well as autophagy. CALR-mutant degradation was attenuated by MPL expression. Interestingly, we found high levels of mutated CALR and loss of downstream signaling after blockage of the secretory pathway and protein glycosylation. Conclusions These

Methods for Delineating Degraded Land at Citarum Watershed, West Java, Indonesia

Directory of Open Access Journals (Sweden)

Suria Darma Tarigan

2012-09-01

Full Text Available Accurate information on the extent and spatial location of degraded lands is very important to plan their rehabilitation.So far, various institutions issue different estimation on the extent of degraded land in Indonesia led to big confusion for rehabilitation planning. Ministry of Forestry estimates around 30.2 million ha of degraded land both inside and outside forestry area throughout Indonesia based on data released in 2007. Ministry of Forestry implementes the socalled scoring method in delineating degraded land. Criteria used in the scoring methods are: land cover, slope steepness, erosion, and management. Scoring method applies different weight to each of those criteria. This study aimed to analyze accuracy of scoring method and to compare it to propose alternative methods in delineating degraded land such as: a Inconsistency of land use, and b Combination of Inconsistency of land use and scoring method. The accuracy of these methods were obtained by comparing to the field observation. The slope map was derived from SRTM 30 m, soil map was obtained from Soil Research Institute and land cover/land use from Ministry for Environment. Using GIS analysis, those maps were used to compose land capability classification (LCC and inconsistency of land use. The study showed that scoring method had 66% accuracy in delineating degraded land. When scoring method was combined with Inconsistency method the accuracy increased about 7%.

Determination of LEDs degradation with entropy generation rate

Science.gov (United States)

Cuadras, Angel; Yao, Jiaqiang; Quilez, Marcos

2017-10-01

We propose a method to assess the degradation and aging of light emitting diodes (LEDs) based on irreversible entropy generation rate. We degraded several LEDs and monitored their entropy generation rate ( S ˙ ) in accelerated tests. We compared the thermoelectrical results with the optical light emission evolution during degradation. We find a good relationship between aging and S ˙ (t), because S ˙ is both related to device parameters and optical performance. We propose a threshold of S ˙ (t) as a reliable damage indicator of LED end-of-life that can avoid the need to perform optical measurements to assess optical aging. The method lays beyond the typical statistical laws for lifetime prediction provided by manufacturers. We tested different LED colors and electrical stresses to validate the electrical LED model and we analyzed the degradation mechanisms of the devices.

Aging precursors and degradation effects of SiC-MOSFET modules under highly accelerated power cycling conditions

DEFF Research Database (Denmark)

Luo, Haoze; Iannuzzo, Francesco; Blaabjerg, Frede

2017-01-01

A highly accelerated power cycling test platform using current source converter for SiC-MOSFET power modules is proposed. The control principles of delta and average junction temperatures are introduced. By using isolated thermal fibers, the junction temperature (Tj) variations can be monitored...... and compared. As a result, the effects of degradation on the static and dynamic characteristics during conventional operation are discussed. Finally, the research results can help examine the failure precursors and then estimate the remaining useful lifetime of SiC MOSFET modules....

Cathodic Delamination Accelerated Life Test Method

National Research Council Canada - National Science Library

Ramotowski, Thomas S

2007-01-01

A method for conducting an accelerated life test of a polymer coated metallic sample includes placing the sample below the water surface in a test tank containing water and an oxygen containing gas...

A novel accelerated oxidative stability screening method for pharmaceutical solids.

Science.gov (United States)

Zhu, Donghua Alan; Zhang, Geoff G Z; George, Karen L S T; Zhou, Deliang

2011-08-01

Despite the fact that oxidation is the second most frequent degradation pathway for pharmaceuticals, means of evaluating the oxidative stability of pharmaceutical solids, especially effective stress testing, are still lacking. This paper describes a novel experimental method for peroxide-mediated oxidative stress testing on pharmaceutical solids. The method utilizes urea-hydrogen peroxide, a molecular complex that undergoes solid-state decomposition and releases hydrogen peroxide vapor at elevated temperatures (e.g., 30°C), as a source of peroxide. The experimental setting for this method is simple, convenient, and can be operated routinely in most laboratories. The fundamental parameter of the system, that is, hydrogen peroxide vapor pressure, was determined using a modified spectrophotometric method. The feasibility and utility of the proposed method in solid form selection have been demonstrated using various solid forms of ephedrine. No degradation was detected for ephedrine hydrochloride after exposure to the hydrogen peroxide vapor for 2 weeks, whereas both anhydrate and hemihydrate free base forms degraded rapidly under the test conditions. In addition, both the anhydrate and the hemihydrate free base degraded faster when exposed to hydrogen peroxide vapor at 30°C under dry condition than at 30°C/75% relative humidity (RH). A new degradation product was also observed under the drier condition. The proposed method provides more relevant screening conditions for solid dosage forms, and is useful in selecting optimal solid form(s), determining potential degradation products, and formulation screening during development. Copyright © 2011 Wiley-Liss, Inc.

Phase-of-flight method for setting the accelerating fields in the ion linear accelerator

International Nuclear Information System (INIS)

Dvortsov, S.V.; Lomize, L.G.

1983-01-01

For setting amplitudes and phases of accelerating fields in multiresonator ion accelerators presently Δt-procedure is used. The determination and setting of two unknown parameters of RF-field (amplitude and phase) in n-resonator is made according to the two increments of particle time-of-flight, measured experimentally: according to the change of the particle time-of-flight Δt 1 in the n-resonator, during the field switching in the resonator, and according to the change of Δt 2 of the time-of-flight in (n+1) resonator without RF-field with the switching of accelerating field in the n-resonator. When approaching the accelerator exit the particle energy increases, relative energy increment decreases and the accuracy of setting decreases. To enchance the accuracy of accelerating fields setting in a linear ion accelerator a phase-of-flight method is developed, in which for the setting of accelerating fields the measured time-of-flight increment Δt only in one resonator is used (the one in which the change of amplitude and phase is performed). Results of simulation of point bunch motion in the IYaI AN USSR linear accelerator are presented

A simple eigenfunction convergence acceleration method for Monte Carlo

International Nuclear Information System (INIS)

Booth, Thomas E.

2011-01-01

Monte Carlo transport codes typically use a power iteration method to obtain the fundamental eigenfunction. The standard convergence rate for the power iteration method is the ratio of the first two eigenvalues, that is, k_2/k_1. Modifications to the power method have accelerated the convergence by explicitly calculating the subdominant eigenfunctions as well as the fundamental. Calculating the subdominant eigenfunctions requires using particles of negative and positive weights and appropriately canceling the negative and positive weight particles. Incorporating both negative weights and a ± weight cancellation requires a significant change to current transport codes. This paper presents an alternative convergence acceleration method that does not require modifying the transport codes to deal with the problems associated with tracking and cancelling particles of ± weights. Instead, only positive weights are used in the acceleration method. (author)

Transport methods: general. 3. An Additive Angular-Dependent Re-balance Acceleration Method for Neutron Transport Equations

International Nuclear Information System (INIS)

Cho, Nam Zin; Park, Chang Je

2001-01-01

An additive angular-dependent re-balance (AADR) factor acceleration method is described to accelerate the source iteration of discrete ordinates transport calculation. The formulation of the AADR method follows that of the angular-dependent re-balance (ADR) method in that the re-balance factor is defined only on the cell interface and in that the low-order equation is derived by integrating the transport equation (high-order equation) over angular subspaces. But, the re-balance factor is applied additively. While the AADR method is similar to the boundary projection acceleration and the alpha-weighted linear acceleration, it is more general and does have distinct features. The method is easily extendible to DP N and low-order S N re-balancing, and it does not require consistent discretizations between the high- and low-order equations as in diffusion synthetic acceleration. We find by Fourier analysis and numerical results that the AADR method with a chosen form of weighting functions is unconditionally stable and very effective. There also exists an optimal weighting parameter that leads to the smallest spectral radius. The AADR acceleration method described in this paper is simple to implement, unconditionally stable, and very effective. It uses a physically based weighting function with an optimal parameter, leading to the best spectral radius of ρ<0.1865, compared to ρ<0.2247 of DSA. The application of the AADR acceleration method with the LMB scheme on a test problem shows encouraging results

An Adaptively Accelerated Bayesian Deblurring Method with Entropy Prior

Directory of Open Access Journals (Sweden)

Yong-Hoon Kim

2008-05-01

Full Text Available The development of an efficient adaptively accelerated iterative deblurring algorithm based on Bayesian statistical concept has been reported. Entropy of an image has been used as a “prior” distribution and instead of additive form, used in conventional acceleration methods an exponent form of relaxation constant has been used for acceleration. Thus the proposed method is called hereafter as adaptively accelerated maximum a posteriori with entropy prior (AAMAPE. Based on empirical observations in different experiments, the exponent is computed adaptively using first-order derivatives of the deblurred image from previous two iterations. This exponent improves speed of the AAMAPE method in early stages and ensures stability at later stages of iteration. In AAMAPE method, we also consider the constraint of the nonnegativity and flux conservation. The paper discusses the fundamental idea of the Bayesian image deblurring with the use of entropy as prior, and the analytical analysis of superresolution and the noise amplification characteristics of the proposed method. The experimental results show that the proposed AAMAPE method gives lower RMSE and higher SNR in 44% lesser iterations as compared to nonaccelerated maximum a posteriori with entropy prior (MAPE method. Moreover, AAMAPE followed by wavelet wiener filtering gives better result than the state-of-the-art methods.

High-power UV-LED degradation: Continuous and cycled working condition influence

Science.gov (United States)

Arques-Orobon, F. J.; Nuñez, N.; Vazquez, M.; Segura-Antunez, C.; González-Posadas, V.

2015-09-01

High-power (HP) UV-LEDs can replace UV lamps for real-time fluoro-sensing applications by allowing portable and autonomous systems. However, HP UV-LEDs are not a mature technology, and there are still open issues regarding their performance evolution over time. This paper presents a reliability study of 3 W UV-LEDs, with special focus on LED degradation for two working conditions: continuous and cycled (30 s ON and 30 s OFF). Accelerated life tests are developed to evaluate the influence of temperature and electrical working conditions in high-power LEDs degradation, being the predominant failure mechanism the degradation of the package. An analysis that includes dynamic thermal and optical HP UV-LED measurements has been performed. Static thermal and stress simulation analysis with the finite element method (FEM) identifies the causes of package degradation. Accelerated life test results prove that HP UV-LEDs working in cycled condition have a better performance than those working in continuous condition.

The Extrapolation-Accelerated Multilevel Aggregation Method in PageRank Computation

Directory of Open Access Journals (Sweden)

Bing-Yuan Pu

2013-01-01

Full Text Available An accelerated multilevel aggregation method is presented for calculating the stationary probability vector of an irreducible stochastic matrix in PageRank computation, where the vector extrapolation method is its accelerator. We show how to periodically combine the extrapolation method together with the multilevel aggregation method on the finest level for speeding up the PageRank computation. Detailed numerical results are given to illustrate the behavior of this method, and comparisons with the typical methods are also made.

Accelerated stability testing of organic photovoltaics using concentrated sunlight

DEFF Research Database (Denmark)

Katz, Eugene A.; Manor, Assaf; Mescheloff, Asaf

2012-01-01

We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported.......We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported....

Synthetic acceleration methods for linear transport problems with highly anisotropic scattering

International Nuclear Information System (INIS)

Khattab, K.M.

1989-01-01

One of the iterative methods which is used to solve the discretized transport equation is called the Source Iteration Method (SI). The SI method converges very slowly for problems with optically thick regions and scattering ratios (σ s /σ t ) near unity. The Diffusion-Synthetic Acceleration method (DSA) is one of the methods which has been devised to improve the convergence rate of the SI method. The DSA method is a good tool to accelerate the SI method, if the particle which is being dealt with is a neutron. This is because the scattering process for neutrons is not severely anisotropic. However, if the particle is a charged particle (electron), DSA becomes ineffective as an acceleration device because here the scattering process is severely anisotropic. To improve the DSA algorithm for electron transport, the author approaches the problem in two different ways in this thesis. He develops the first approach by accelerating more angular moments (φ 0 , φ 1 , φ 2 , φ 3 ,...) than is done in DSA; he calls this approach the Modified P N Synthetic Acceleration (MPSA) method. In the second approach he modifies the definition of the transport sweep, using the physics of the scattering; he calls this approach the Modified Diffusion Synthetic Acceleration (MDSA) method. In general, he has developed, analyzed, and implemented the MPSA and MDSA methods in this thesis and has shown that for a high order quadrature set and mesh widths about 1.0 cm, they are each about 34 times faster (clock time) than the DSA method. Also, he has found that the MDSA spectral radius decreases as the mesh size increases. This makes the MDSA method a better choice for large spatial meshes

Accelerated Test Method for Corrosion Protective Coatings

Data.gov (United States)

National Aeronautics and Space Administration — This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as...

Halide salts accelerate degradation of high explosives by zerovalent iron

International Nuclear Information System (INIS)

Kim, Jong Sung; Shea, Patrick J.; Yang, Jae E.; Kim, Jang-Eok

2007-01-01

Zerovalent iron (Fe 0 , ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe 0 (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24 h also restored ZVI reactivity, resulting in complete degradation within 8 h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl - and Br - was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br - was present in solution. - The addition of halide ions promotes the degradation of high explosives by zerovalent iron

Accelerated in-vitro release testing methods for extended-release parenteral dosage forms.

Science.gov (United States)

Shen, Jie; Burgess, Diane J

2012-07-01

This review highlights current methods and strategies for accelerated in-vitro drug release testing of extended-release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in-situ depot-forming systems and implants. Extended-release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, 'real-time' in-vitro release tests for these dosage forms are often run over a long time period. Accelerated in-vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in-vitro release methods using United States Pharmacopeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended-release parenteral dosage forms, along with the accelerated in-vitro release testing methods currently employed are discussed. Accelerated in-vitro release testing methods with good discriminatory ability are critical for quality control of extended-release parenteral products. Methods that can be used in the development of in-vitro-in-vivo correlation (IVIVC) are desirable; however, for complex parenteral products this may not always be achievable. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

Accelerated in vitro release testing methods for extended release parenteral dosage forms

Science.gov (United States)

Shen, Jie; Burgess, Diane J.

2012-01-01

Objectives This review highlights current methods and strategies for accelerated in vitro drug release testing of extended release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in situ depot-forming systems, and implants. Key findings Extended release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, “real-time” in vitro release tests for these dosage forms are often run over a long time period. Accelerated in vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in vitro release methods using United States Pharmacopoeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended release parenteral dosage forms, along with the accelerated in vitro release testing methods currently employed are discussed. Conclusions Accelerated in vitro release testing methods with good discriminatory ability are critical for quality control of extended release parenteral products. Methods that can be used in the development of in vitro-in vivo correlation (IVIVC) are desirable, however for complex parenteral products this may not always be achievable. PMID:22686344

Convergence analysis of CMADR acceleration for the method of characteristics

International Nuclear Information System (INIS)

Park, Young Ryong; Cho, Nam Zin

2005-01-01

As the nuclear reactor core becomes more complex, heterogeneous, and geometrically irregular, the method of characteristics (MOC) is gaining its wide use in the neutron transport calculations. However, the long computer times require good acceleration methods. In our previous paper, the concept of coarse-mesh angular dependent rebalance (CMADR) acceleration was described and applied to the MOC calculations. The method is based on angular dependent rebalance factors defined on the coarse-mesh boundaries; a coarse-mesh consists of several fine meshes that may be (1) heterogeneous and (2) of mixed geometries with irregular or unstructured mesh shapes. In addition, (3) the coarse-mesh boundaries may not coincide with the structural interfaces of the problem and can be chosen artificially for convenience. The CMADR acceleration method on the MOC scheme that enables the very desirable features (1), (2), and (3) above is new in the neutron transport literature to the best of the authors knowledge. In this paper, we analyze the convergence of CMADR acceleration for MOC calculation in x-y-z (infinite) geometry by using Fourier analysis

Linear electron accelerator body and method of its manufacture

International Nuclear Information System (INIS)

Landa, V.; Maresova, V.; Lucek, J.; Prusa, F.

1988-01-01

The accelerator body consists of a hollow casing made of a high electric conductivity metal. The inside is partitioned with a system of resonators. The resonator body is made of one piece of the same metal as the casing or a related one (e.g., copper -coper, silver-copper, copper-copper alloy). The accelerator body is manufactured using the cathodic process on the periphery of a system of metal partitions and negative models of resonator cavities fitted to a metal pin. The pin is then removed from the system and the soluble models of the cavities are dissolved in a solvent. The advantage of the design and the method of manufacture is that the result is a compact, perfectly tight body with a perfectly lustre surface. The casing wall can be very thin, which improves accelerator performance. The claimed method can also be used in manufacturing miniature accelerators. (E.J.). 1 fig

CMFD and GPU acceleration on method of characteristics for hexagonal cores

International Nuclear Information System (INIS)

Han, Yu; Jiang, Xiaofeng; Wang, Dezhong

2014-01-01

Highlights: • A merged hex-mesh CMFD method solved via tri-diagonal matrix inversion. • Alternative hardware acceleration of using inexpensive GPU. • A hex-core benchmark with solution to confirm two acceleration methods. - Abstract: Coarse Mesh Finite Difference (CMFD) has been widely adopted as an effective way to accelerate the source iteration of transport calculation. However in a core with hexagonal assemblies there are non-hexagonal meshes around the edges of assemblies, causing a problem for CMFD if the CMFD equations are still to be solved via tri-diagonal matrix inversion by simply scanning the whole core meshes in different directions. To solve this problem, we propose an unequal mesh CMFD formulation that combines the non-hexagonal cells on the boundary of neighboring assemblies into non-regular hexagonal cells. We also investigated the alternative hardware acceleration of using graphics processing units (GPU) with graphics card in a personal computer. The tool CUDA is employed, which is a parallel computing platform and programming model invented by the company NVIDIA for harnessing the power of GPU. To investigate and implement these two acceleration methods, a 2-D hexagonal core transport code using the method of characteristics (MOC) is developed. A hexagonal mini-core benchmark problem is established to confirm the accuracy of the MOC code and to assess the effectiveness of CMFD and GPU parallel acceleration. For this benchmark problem, the CMFD acceleration increases the speed 16 times while the GPU acceleration speeds it up 25 times. When used simultaneously, they provide a speed gain of 292 times

CMFD and GPU acceleration on method of characteristics for hexagonal cores

Energy Technology Data Exchange (ETDEWEB)

Han, Yu, E-mail: hanyu1203@gmail.com [School of Nuclear Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Jiang, Xiaofeng [Shanghai NuStar Nuclear Power Technology Co., Ltd., No. 81 South Qinzhou Road, XuJiaHui District, Shanghai 200000 (China); Wang, Dezhong [School of Nuclear Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China)

2014-12-15

Highlights: • A merged hex-mesh CMFD method solved via tri-diagonal matrix inversion. • Alternative hardware acceleration of using inexpensive GPU. • A hex-core benchmark with solution to confirm two acceleration methods. - Abstract: Coarse Mesh Finite Difference (CMFD) has been widely adopted as an effective way to accelerate the source iteration of transport calculation. However in a core with hexagonal assemblies there are non-hexagonal meshes around the edges of assemblies, causing a problem for CMFD if the CMFD equations are still to be solved via tri-diagonal matrix inversion by simply scanning the whole core meshes in different directions. To solve this problem, we propose an unequal mesh CMFD formulation that combines the non-hexagonal cells on the boundary of neighboring assemblies into non-regular hexagonal cells. We also investigated the alternative hardware acceleration of using graphics processing units (GPU) with graphics card in a personal computer. The tool CUDA is employed, which is a parallel computing platform and programming model invented by the company NVIDIA for harnessing the power of GPU. To investigate and implement these two acceleration methods, a 2-D hexagonal core transport code using the method of characteristics (MOC) is developed. A hexagonal mini-core benchmark problem is established to confirm the accuracy of the MOC code and to assess the effectiveness of CMFD and GPU parallel acceleration. For this benchmark problem, the CMFD acceleration increases the speed 16 times while the GPU acceleration speeds it up 25 times. When used simultaneously, they provide a speed gain of 292 times.

Accelerated H-LBP-based edge extraction method for digital radiography

Energy Technology Data Exchange (ETDEWEB)

Qiao, Shuang; Zhao, Chen-yi; Huang, Ji-peng [School of Physics, Northeast Normal University, Changchun 130024 (China); Sun, Jia-ning, E-mail: sunjn118@nenu.edu.cn [School of Mathematics and Statistics, Northeast Normal University, Changchun 130024 (China)

2015-01-11

With the goal of achieving real time and efficient edge extraction for digital radiography, an accelerated H-LBP-based edge extraction method (AH-LBP) is presented in this paper by improving the existing framework of local binary pattern with the H function (H-LBP). Since the proposed method avoids computationally expensive operations with no loss of quality, it possesses much lower computational complexity than H-LBP. Experimental results on real radiographies show desirable performance of our method. - Highlights: • An accelerated H-LBP method for edge extraction on digital radiography is proposed. • The novel AH-LBP relies on numerical analysis of the existing H-LBP method. • Aiming at accelerating, H-LBP is reformulated as a direct binary processing. • AH-LBP provides the same edge extraction result as H-LBP does. • AH-LBP has low computational complexity satisfying real time requirements.

Accelerated degradation and durability of concrete in cold climates.

Science.gov (United States)

2011-08-01

Degradation of aggregate in concrete can be caused by erosion or fracture, and both cementitious materials and aggregate age over time. : The specification requirements for the degradation of aggregates have been established for hot mix asphalt and f...

Degradation of Polypropylene Membranes Applied in Membrane Distillation Crystallizer

Directory of Open Access Journals (Sweden)

Marek Gryta

2016-03-01

Full Text Available The studies on the resistance to degradation of capillary polypropylene membranes assembled in a membrane crystallizer were performed. The supersaturation state of salt was achieved by evaporation of water from the NaCl saturated solutions using membrane distillation process. A high feed temperature (363 K was used in order to enhance the degradation effects and to shorten the test times. Salt crystallization was carried out by the application of batch or fluidized bed crystallizer. A significant membrane scaling was observed regardless of the method of realized crystallization. The SEM-EDS, DSC, and FTIR methods were used for investigations of polypropylene degradation. The salt crystallization onto the membrane surface accelerated polypropylene degradation. Due to a polymer degradation, the presence of carbonyl groups on the membranes’ surface was identified. Besides the changes in the chemical structure a significant mechanical damage of the membranes, mainly caused by the internal scaling, was also found. As a result, the membranes were severely damaged after 150 h of process operation. A high level of salt rejection was maintained despite damage to the external membrane surface.

GPU accelerated manifold correction method for spinning compact binaries

Science.gov (United States)

Ran, Chong-xi; Liu, Song; Zhong, Shuang-ying

2018-04-01

The graphics processing unit (GPU) acceleration of the manifold correction algorithm based on the compute unified device architecture (CUDA) technology is designed to simulate the dynamic evolution of the Post-Newtonian (PN) Hamiltonian formulation of spinning compact binaries. The feasibility and the efficiency of parallel computation on GPU have been confirmed by various numerical experiments. The numerical comparisons show that the accuracy on GPU execution of manifold corrections method has a good agreement with the execution of codes on merely central processing unit (CPU-based) method. The acceleration ability when the codes are implemented on GPU can increase enormously through the use of shared memory and register optimization techniques without additional hardware costs, implying that the speedup is nearly 13 times as compared with the codes executed on CPU for phase space scan (including 314 × 314 orbits). In addition, GPU-accelerated manifold correction method is used to numerically study how dynamics are affected by the spin-induced quadrupole-monopole interaction for black hole binary system.

New method to determine wools and hairs degradation

OpenAIRE

Marsal Amenós, Félix

2013-01-01

A new method is proposed, validated in the industrial practice, to determine possible bacterial and microbial degradation in textile wools and hairs. It is applied to wools of variable fineness between 18 and 34 microns and to alpaca fibers between 20 and 36 microns. It is based on a dynamometer test to determine tribocharge excision the slivers combed. The rheological behavior of degraded fiber slivers is quite different in the spinning process in addition to the major problems that appear i...

Fiscal 1994 survey report. Survey of factors causing degradation of phosphoric acid fuel cells; 1994 nendo rinsangata nenryo denchi no cell rekka yoin chosa hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-03-01

This survey aims to effectively promote studies for evaluating phosphoric acid fuel cell degradation. Data of time-dependent changes in voltage are collected from 58 plants now in operation (for 17,500 hours at the maximum). Half of them exhibit a degradation rate of 0.25-1%/1000 hours while degradation is abruptly accelerated midway in the other half. Causes for voltage drop are not known clearly. Since but a little systematically collected test data are available concerning the mechanism of cell degradation, it is decided that tests be conducted using small test model cells sharing the same specifications. Primary test conditions (combination of temperature, current, and pressure with test reference levels), performance evaluating methods (conditions of data collection), and methods of investigation by dismantling (items and frequency of investigations) are determined, and guidelines are provided for element tests for complementing the said test items and for studying their relations with the degradation mechanism. Based on acceleration-related factors to be obtained by common specification test cells, corporations involved will develop their own accelerated test methods. Small cells are fabricated for testing parameters, and model cells are specified. (NEDO)

Accelerated Aging in Electrolytic Capacitors for Prognostics

Science.gov (United States)

Celaya, Jose R.; Kulkarni, Chetan; Saha, Sankalita; Biswas, Gautam; Goebel, Kai Frank

2012-01-01

The focus of this work is the analysis of different degradation phenomena based on thermal overstress and electrical overstress accelerated aging systems and the use of accelerated aging techniques for prognostics algorithm development. Results on thermal overstress and electrical overstress experiments are presented. In addition, preliminary results toward the development of physics-based degradation models are presented focusing on the electrolyte evaporation failure mechanism. An empirical degradation model based on percentage capacitance loss under electrical overstress is presented and used in: (i) a Bayesian-based implementation of model-based prognostics using a discrete Kalman filter for health state estimation, and (ii) a dynamic system representation of the degradation model for forecasting and remaining useful life (RUL) estimation. A leave-one-out validation methodology is used to assess the validity of the methodology under the small sample size constrain. The results observed on the RUL estimation are consistent through the validation tests comparing relative accuracy and prediction error. It has been observed that the inaccuracy of the model to represent the change in degradation behavior observed at the end of the test data is consistent throughout the validation tests, indicating the need of a more detailed degradation model or the use of an algorithm that could estimate model parameters on-line. Based on the observed degradation process under different stress intensity with rest periods, the need for more sophisticated degradation models is further supported. The current degradation model does not represent the capacitance recovery over rest periods following an accelerated aging stress period.

Effect of Graphite Doped TiO_2 Nanoparticles on Smoke Degradation

International Nuclear Information System (INIS)

Roshasnorlyza Hazan; Mohamad Shahrizal Md Zain; Natrah Syafiqah Rosli

2016-01-01

Secondhand smoke affects in the same way as regular smoker. The best solution is to purify the air efficiently and effectively. In this study, we were successfully doped TiO_2 nanoparticle with graphite to accelerate the degradation of cigarette smoke. The graphite doped and undoped TiO_2 nanoparticles were prepared from synthetic rutile using alkaline fusion method and their photo catalytic activity were investigated under visible light irradiation. The photo catalytic activity of the TiO_2 nanoparticles was analyzed in terms of their particle size analysis, crystallization and optical band gap. TiO_2 nanoparticle act as photo catalyzer by utilization of light energy to excite electron-hole pairs in smoke degradation processes. With the aided from graphite in TiO_2 nanoparticles, the smoke degradation was accelerate up to 44.4 %. In this case, graphite helps to reduce optical band gap of TiO_2 nanoparticle, thus increasing excitation of electron from valence band to conduction band. (author)

A novel mechanochemical method for reconstructing the moisture-degraded HKUST-1.

Science.gov (United States)

Sun, Xuejiao; Li, Hao; Li, Yujie; Xu, Feng; Xiao, Jing; Xia, Qibin; Li, Yingwei; Li, Zhong

2015-07-11

A novel mechanochemical method was proposed to reconstruct quickly moisture-degraded HKUST-1. The degraded HKUST-1 can be restored within minutes. The reconstructed samples were characterized, and confirmed to have 95% surface area and 92% benzene capacity of the fresh HKUST-1. It is a simple and effective strategy for degraded MOF reconstruction.

Acceleration of Meshfree Radial Point Interpolation Method on Graphics Hardware

International Nuclear Information System (INIS)

Nakata, Susumu

2008-01-01

This article describes a parallel computational technique to accelerate radial point interpolation method (RPIM)-based meshfree method using graphics hardware. RPIM is one of the meshfree partial differential equation solvers that do not require the mesh structure of the analysis targets. In this paper, a technique for accelerating RPIM using graphics hardware is presented. In the method, the computation process is divided into small processes suitable for processing on the parallel architecture of the graphics hardware in a single instruction multiple data manner.

LOO: a low-order nonlinear transport scheme for acceleration of method of characteristics

International Nuclear Information System (INIS)

Li, Lulu; Smith, Kord; Forget, Benoit; Ferrer, Rodolfo

2015-01-01

This paper presents a new physics-based multi-grid nonlinear acceleration method: the low-order operator method, or LOO. LOO uses a coarse space-angle multi-group method of characteristics (MOC) neutron transport calculation to accelerate the fine space-angle MOC calculation. LOO is designed to capture more angular effects than diffusion-based acceleration methods through a transport-based low-order solver. LOO differs from existing transport-based acceleration schemes in that it emphasizes simplified coarse space-angle characteristics and preserves physics in quadrant phase-space. The details of the method, including the restriction step, the low-order iterative solver and the prolongation step are discussed in this work. LOO shows comparable convergence behavior to coarse mesh finite difference on several two-dimensional benchmark problems while not requiring any under-relaxation, making it a robust acceleration scheme. (author)

Algebraic collapsing acceleration of the characteristics method with anisotropic scattering

International Nuclear Information System (INIS)

Le Tellier, R.; Hebert, A.; Roy, R.

2004-01-01

In this paper, the characteristics solvers implemented in the lattice code Dragon are extended to allow a complete anisotropic treatment of the collision operator. An efficient synthetic acceleration method, called Algebraic Collapsing Acceleration (ACA), is presented. Tests show that this method can substantially speed up the convergence of scattering source iterations. The effect of boundary conditions, either specular or white reflections, on anisotropic scattering lattice-cell problems is also considered. (author)

The Effect of Different Delivery Conditions on the Accelerated Degradation of Structural Steel in the Coal Mine Environment / Wpływ Różnego Stanu Dostawy Na Przyspieszoną Degradację Stali Konstrukcyjnej W Środowisku Kopalnianym

Science.gov (United States)

Pawłowski, Bogdan; Bała, Piotr

2012-12-01

The main objective of this work was to determine the effect of different delivery conditions on the accelerated degradation of structural steels used for lifting beams (rails) of the monorail transport systems. Some of these rails, made of the same steel grade as others, undergoes accelerated corrosion in the coal mine environment. Corrosion degradation occurs much faster (more than two times faster), comparing to the same steel grade rails operated under the same conditions but with different microstructures. However, all the provided rails meet the requirements of appropriate standards for steel on the lifting beams of the monorail transport systems. The investigations were carried out on rails made of the same steel grade but with different microstructures and showed that the main factor influencing the accelerated corrosion degradation of tested steels is the delivery condition, so-called "as rolled" condition. The greatest resistance to the accelerated corrosion showed rails in the normalized or normalizing rolling condition.

Testing Method of Degrading Heavy Oil Pollution by Microorganisms

Science.gov (United States)

Wu, Qi; Zhao, Lin; Ma, Aijin

2018-01-01

With the development of human society, we are more and more relying on the petrochemical energy. The use of petrochemical energy not only brings us great convenience, but is also accompanied by a series of environmental pollution problems, especially oil pollution. Since it is impractical to restore all pollution problems, the proper use of some remedial measures, under the guidance of functional orientation, may be sufficient to minimize the risk of persistent and diffusing pollutants. In recent years, bioremediation technology has been gradually developed into a promising stage and has played a crucial role in the degradation of heavy oil pollution. Specially, microbes in the degradation of heavy oil have made a great contribution. This paper mainly summarizes the different kinds of microorganisms for degrading heavy oil and the detection method for degradation efficiency of heavy oil pollution.

A Novel Degradation Identification Method for Wind Turbine Pitch System

Science.gov (United States)

Guo, Hui-Dong

2018-04-01

It’s difficult for traditional threshold value method to identify degradation of operating equipment accurately. An novel degradation evaluation method suitable for wind turbine condition maintenance strategy implementation was proposed in this paper. Based on the analysis of typical variable-speed pitch-to-feather control principle and monitoring parameters for pitch system, a multi input multi output (MIMO) regression model was applied to pitch system, where wind speed, power generation regarding as input parameters, wheel rotation speed, pitch angle and motor driving currency for three blades as output parameters. Then, the difference between the on-line measurement and the calculated value from the MIMO regression model applying least square support vector machines (LSSVM) method was defined as the Observed Vector of the system. The Gaussian mixture model (GMM) was applied to fitting the distribution of the multi dimension Observed Vectors. Applying the model established, the Degradation Index was calculated using the SCADA data of a wind turbine damaged its pitch bearing retainer and rolling body, which illustrated the feasibility of the provided method.

Characteristic Experimentations of Degrader and Scatterer at MC-50 Cyclotron

CERN Document Server

Lee Seok Ki; Kim, Kye-Ryung; Lee, Hwa-Ryun; Park, Bum-Sik

2005-01-01

Building proton beam user facilities, especially deciding beam energy level, depends on the attached proton accelerator and users' needs. To adjust beam energy level, two methods are generally used. One is to directly adjust the beam in the accelerator. The other is to adjust beam energy after extracting from the accelerator. Degrader/Scatterer System has been installed in the MC-50 Cyclotron to adjust energy level of the beam used for various application fields. Its degrader and scatterer are made of Al foils and Au foils, respectively. Al thickness are 2, 1, 0.5, 0.3, 0.2, 0.1, 0.05, 0.03, 0.02, 0.01mm and Au thickness are 0.2, 0.1, 0.05, 0.03, 0.02, 0.01mm, respectively. In this study, suitable beam condition was adjusted through overlapping Al/Au foils of various thickness through simulation results. After that, LET(Linear Energy Transfer) value was indirectly acquired by measuring the bragg peak of the external beam through PMMA plastic Phantom and profile was measured by film dosimetry.

Analysis of accelerated degradation of a HT-PEM fuel cell caused by cell reversal in fuel starvation condition

DEFF Research Database (Denmark)

Zhou, Fan; Andreasen, Søren Juhl; Kær, Søren Knudsen

2015-01-01

This paper reports an accelerated degradation test of a high temperature PEM fuel cell under repeated H2 starvation condition. The H2 stoichiometry is cycled between 3.0 and 0.8 every 2 min during the test. The experimental results show that the polarity of the fuel cell is reversed under H2......, there is only a slight decrease in open circuit voltage of the fuel cell which implies the membrane is not affected by the test. The electrochemical impedance spectrum measurement shows that the H2 starvation can cause significant increase in the ohmic resistance and charge transfer resistance. By looking...... starvation condition, and the cell performance indicated by cell voltage at H2 stoichiometry of 3.0 declines from 0.59 V to 0.41 V in 19 cycles. Since CO2 is detected in anode exhaust under H2 starvation condition, carbon corrosion is believed to be the reason for the degradation in this test. After the test...

A Novel Method for Vertical Acceleration Noise Suppression of a Thrust-Vectored VTOL UAV.

Science.gov (United States)

Li, Huanyu; Wu, Linfeng; Li, Yingjie; Li, Chunwen; Li, Hangyu

2016-12-02

Acceleration is of great importance in motion control for unmanned aerial vehicles (UAVs), especially during the takeoff and landing stages. However, the measured acceleration is inevitably polluted by severe noise. Therefore, a proper noise suppression procedure is required. This paper presents a novel method to reduce the noise in the measured vertical acceleration for a thrust-vectored tail-sitter vertical takeoff and landing (VTOL) UAV. In the new procedure, a Kalman filter is first applied to estimate the UAV mass by using the information in the vertical thrust and measured acceleration. The UAV mass is then used to compute an estimate of UAV vertical acceleration. The estimated acceleration is finally fused with the measured acceleration to obtain the minimum variance estimate of vertical acceleration. By doing this, the new approach incorporates the thrust information into the acceleration estimate. The method is applied to the data measured in a VTOL UAV takeoff experiment. Two other denoising approaches developed by former researchers are also tested for comparison. The results demonstrate that the new method is able to suppress the acceleration noise substantially. It also maintains the real-time performance in the final estimated acceleration, which is not seen in the former denoising approaches. The acceleration treated with the new method can be readily used in the motion control applications for UAVs to achieve improved accuracy.

A Novel Method for Vertical Acceleration Noise Suppression of a Thrust-Vectored VTOL UAV

Directory of Open Access Journals (Sweden)

Huanyu Li

2016-12-01

Full Text Available Acceleration is of great importance in motion control for unmanned aerial vehicles (UAVs, especially during the takeoff and landing stages. However, the measured acceleration is inevitably polluted by severe noise. Therefore, a proper noise suppression procedure is required. This paper presents a novel method to reduce the noise in the measured vertical acceleration for a thrust-vectored tail-sitter vertical takeoff and landing (VTOL UAV. In the new procedure, a Kalman filter is first applied to estimate the UAV mass by using the information in the vertical thrust and measured acceleration. The UAV mass is then used to compute an estimate of UAV vertical acceleration. The estimated acceleration is finally fused with the measured acceleration to obtain the minimum variance estimate of vertical acceleration. By doing this, the new approach incorporates the thrust information into the acceleration estimate. The method is applied to the data measured in a VTOL UAV takeoff experiment. Two other denoising approaches developed by former researchers are also tested for comparison. The results demonstrate that the new method is able to suppress the acceleration noise substantially. It also maintains the real-time performance in the final estimated acceleration, which is not seen in the former denoising approaches. The acceleration treated with the new method can be readily used in the motion control applications for UAVs to achieve improved accuracy.

Acceleration methods for assembly-level transport calculations

International Nuclear Information System (INIS)

Adams, Marvin L.; Ramone, Gilles

1995-01-01

A family acceleration methods for the iterations that arise in assembly-level transport calculations is presented. A single iteration in these schemes consists of a transport sweep followed by a low-order calculation which is itself a simplified transport problem. It is shown that a previously-proposed method fitting this description is unstable in two and three dimensions. It is presented a family of methods and shown that some members are unconditionally stable. (author). 8 refs, 4 figs, 4 tabs

Fast multipole acceleration of the MEG/EEG boundary element method

International Nuclear Information System (INIS)

Kybic, Jan; Clerc, Maureen; Faugeras, Olivier; Keriven, Renaud; Papadopoulo, Theo

2005-01-01

The accurate solution of the forward electrostatic problem is an essential first step before solving the inverse problem of magneto- and electroencephalography (MEG/EEG). The symmetric Galerkin boundary element method is accurate but cannot be used for very large problems because of its computational complexity and memory requirements. We describe a fast multipole-based acceleration for the symmetric boundary element method (BEM). It creates a hierarchical structure of the elements and approximates far interactions using spherical harmonics expansions. The accelerated method is shown to be as accurate as the direct method, yet for large problems it is both faster and more economical in terms of memory consumption

Study on degrading graphene oxide in wastewater under different conditions for developing an efficient and economical degradation method.

Science.gov (United States)

Li, Ting; Zhang, Chao-Zhi; Gu, Chengyue

2017-12-01

With popular application of graphene and graphene oxide (GO), they have been discharged into water. Graphene and GO harm organisms. However, an efficient and economical method for removing graphene and GO in wastewater has seldom been reported. Graphene can be oxidized by hydrogen peroxide to give GO; therefore, degradation of graphene oxide is an important step in the procedure of removal of graphene from water. In this paper, GO degradation via photo-Fenton reaction under different conditions was carried out. Experimental results suggested that GO in wastewater can be efficiently and economically degraded into carbon dioxide and H 2 O when pH value is 3, concentration of H 2 O 2 and FeCl 3 are 35 mM and 5 ppm, respectively. Degradation mechanism of GO was suggested based on UV-vis absorption spectra, scanning electron microscopy, X-ray diffraction and liquid chromatography-mass spectra data of degradation intermediates. This paper suggests an efficient and economical degradation way of GO in wastewater.

Accelerated degradation of polyetheretherketone and its composites in the deep sea

Science.gov (United States)

Liu, Hao; Wang, Jianzhang; Jiang, Pengfei; Yan, Fengyuan

2018-04-01

The performance of polymer composites in seawater, under high hydrostatic pressure (typically few tens of MPa), for simulating exposures at great depths in seas and oceans, has been little studied. In this paper, polyetheretherketone (PEEK) and its composites reinforced by carbon fibres and glass fibres were prepared. The seawater environment with different seawater hydrostatic pressure ranging from normal pressure to 40 MPa was simulated with special equipment, in which the seawater absorption and wear behaviour of PEEK and PEEK-based composites were examined in situ. The effects of seawater hydrostatic pressure on the mechanical properties, wear resistance and microstructure of PEEK and its composites were focused on. The results showed that seawater absorption of PEEK and its composites were greatly accelerated by increased hydrostatic pressure in the deep sea. Affected by seawater absorption, both for neat PEEK and composites, the degradation on mechanical properties, wear resistance and crystallinity were induced, the degree of which was increasingly serious with the increase of hydrostatic pressure of seawater environment. There existed a good correlation in an identical form of exponential function between the wear rate and the seawater hydrostatic pressure. Moreover, the corresponding mechanisms of the effects of deep-sea hydrostatic pressure were also discussed.

Comparison of oxytetracycline degradation behavior in pig manure with different antibiotic addition methods.

Science.gov (United States)

Wang, Yan; Chen, Guixiu; Liang, Juanboo; Zou, Yongde; Wen, Xin; Liao, Xindi; Wu, Yinbao

2015-12-01

Using manure collected from swine fed with diet containing antibiotics and antibiotic-free swine manure spiked with antibiotics are the two common methods of studying the degradation behavior of veterinary antibiotic in manure in the environment. However, few studies had been conducted to co-compare these two different antibiotic addition methods. This study used oxytetracycline (OTC) as a model antibiotic to study antibiotic degradation behavior in manure under the above two OTC addition methods. In addition, the role of microorganisms present in the manure on degradation behavior was also examined. The results showed that degradation half-life of OTC in manure from swine fed OTC (9.04 days) was significantly shorter than that of the manure directly treated with OTC (9.65 days). Concentration of 4-epi-OTC in manure from swine fed OTC peaked earlier than that in manure spiked with OTC, and the degradation rates of 4-epi-OTC and α-apo-OTC in the manure from swine fed OTC were faster, but the peak concentrations were lower, than those in manure spiked with OTC. Bacterial diversity and relative abundance of Bacillus cereus data demonstrated that sterilization of the manure before experiment significantly decreased OTC degradation rate in both of the addition methods. Results of the present study demonstrated that the presence of the metabolites (especially 4-epi-OTC) and microorganisms had significant influence on OTC degradation.

An accelerated test method for efflorescence in clay bricks

International Nuclear Information System (INIS)

Beggan, John Edward

1998-01-01

An investigation into the creation of accelerated efflorescence in clay bricks was undertaken with a view to creating a viable test procedure for determining efflorescence potential. The testing programme incorporated ambient conditions similar to those which promote efflorescence growth in bricks in use. Theoretical investigations into the physical mechanism underlying the creation of efflorescence directed the attempts to accelerate the process. It was found that calcium sulphate efflorescence could not be sufficiently accelerated such that a useful efflorescence test procedure could be proposed. The inability to produce accelerated efflorescence in brick samples was attributed to limitations associated with time dependent salt diffusion in the efflorescence mechanism. The preliminary testing that was undertaken into the creation of efflorescence prompted the use of acid assisted methods to accelerate efflorescence. The acid assisted method that was adopted to provide a possible indication of efflorescence potential relies upon the transformation of low solubility calcium to a more soluble form. The movement of the transformed salt is then induced by cyclic temperature exposure at temperatures similar to those experienced in Spring. The appearance of the transformed calcium salt on the surface of the brick specimen provides an indication of the efflorescence potential. Brick piers constructed on an exposed site and monitored over a 12 month period provided information on the validity of the acid assisted test method. The efflorescence observed on the piers correlated well with that predicted by the acid assisted test, suggesting that the new test has the potential to accurately predict the efflorescence potential of clay bricks Relationships between other properties such as air permeability, sorptivity and tensile strength were investigated such that an alternative method of predicting efflorescence could be achieved. It was found that (within the bounds of the

VUV/UV light inducing accelerated phenol degradation with a low electric input† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6ra26043h Click here for additional data file.

Science.gov (United States)

Li, Mengkai; Wen, Dong

2017-01-01

This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4–6 min. The HO˙ and HO2˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H2O2 and Fe3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H2O2 or Fe3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants. PMID:28496972

Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

International Nuclear Information System (INIS)

Gao Jinzhang; Ma Dongping; Guo Xiao; Wang Aixiang; Fu Yan; Wu Jianlin; Yang Wu

2008-01-01

This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe 2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant k and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. mol -1 and the pre-exponential factor ko of 2.065x10 -1 min -1 were obtained, too. The determination of hydroxyl radical was carried out by using N,N-dimethyl-p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

Science.gov (United States)

Gao, Jinzhang; Ma, Dongping; Guo, Xiao; Wang, Aixiang; Fu, Yan; Wu, Jianlin; Yang, Wu

2008-08-01

This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant k and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. mol-1 and the pre-exponential factor ko of 2.065×10-1 min-1 were obtained, too. The determination of hydroxyl radical was carried out by using N,N-dimethyl-p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

Acceleration of Multidimensional Discrete Ordinates Methods Via Adjacent-Cell Preconditioners

International Nuclear Information System (INIS)

Azmy, Y.Y.

2000-01-01

The adjacent-cell preconditioner (AP) formalism originally derived in slab geometry is extended to multidimensional Cartesian geometry for generic fixed-weight, weighted diamond difference neutron transport methods. This is accomplished for the thick-cell regime (KAP) and thin-cell regime (NAP). A spectral analysis of the resulting acceleration schemes demonstrates their excellent spectral properties for model problem configurations, characterized by a uniform mesh of infinite extent and homogeneous material composition, each in its own cell-size regime. Thus, the spectral radius of KAP vanishes as the computational cell size approaches infinity, but it exceeds unity for very thin cells, thereby implying instability. In contrast, NAP is stable and robust for all cell sizes, but its spectral radius vanishes more slowly as the cell size increases. For this reason, and to avoid potential complication in the case of cells that are thin in one dimension and thick in another, NAP is adopted in the remainder of this work. The most important feature of AP for practical implementation in production level codes is that it is cell centered, reducing the size of the algebraic system comprising the acceleration stage compared to face-centered schemes. Boundary conditions for finite extent problems and a mixing formula across material and cell-size discontinuity are derived and used to implement NAP in a test code, AHOT, and a production code, TORT. Numerical testing for algebraically linear iterative schemes for the cases embodied in Burre's Suite of Test Problems demonstrates the high efficiency of the new method in reducing the number of iterations required to achieve convergence, especially for optically thick cells where acceleration is most needed. Also, for algebraically nonlinear (adaptive) methods, AP generally performs better than the partial current rebalance method in TORT and the diffusion synthetic acceleration method in TWODANT. Finally, application of the AP

In vitro Degradation of Butanediamine-Grafted Poly(DL-Lactic acids)

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The degradation of butanediamine-grafted poly(DL-lactic acid) polymers (BDPLAs) in vitro together with PDLLA and maleic anhydride-grafted poly(DL-lactic acid) polymers (MPLAs) was investigated by observation of the changes of the pH value of incubation media, and weight loss ratio during degradation duration of 12 weeks. The results reveal that the acidity of PDLLA degradation products was weakened or neutralized by grafting butanediamine onto PDLLA. A uniform degradation of BDPLAs was observed in comparison with an acidity-induced auto-accelerating degradation featured by PDLLA and MPLAs. The biodegradation behaviors of BDPLAs can be adjusted by controlling the content of BDA. BDPLAs might be a new derivative of PDLLA-based biodegradable materials for medical applications without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as that of PDLLA.

Development of the cybernetic methods in the new generation of superhigh-energy accelerators

International Nuclear Information System (INIS)

Vasil'ev, A.A.; Berezhnoj, V.A.

1985-01-01

The problems related to the use of cybernetic methods in case of the development of control systems for superhigh-energy accelerators, particularly for parameters control which determine betatron particle oscillations are discussed. It is pointed out that early in 1960-s the development of the 1 TeV cybernetic accelerating complex consisting of a linear accelerator - injector, booster and main accelerator has been started. The conclusion is drawn that with the increase of accelerator energy, increase of ring magnet perimeter and decrease of vacuum chaber aperture as well as owing to comlication of accelerating complexes complication of operational modes and increase of particle beams intensity the use of cybernetic methods and completely automated control systems created on their base becomes in future still more pressing

Results from the RACE [Ring ACceleration Experiment] Compact Torus Acceleration Experiment

International Nuclear Information System (INIS)

Hammer, J.H.; Hartman, C.W.; Eddleman, J.L.; Kusse, B.

1987-06-01

RACE (Ring ACceleration Experiment) is a proof-of-principle experiment aimed at demonstrating acceleration of magnetically confined compact torus plasma rings to directed kinetic energies well in excess of their magnetic and thermal energies. In the course of the first year of operation the following have been observed: successful formation of rings in the RACE geometry; acceleration of rings with large forces, F/sub accelerate/ ∼F/sub equilibrium/ without apparent degradation of the ring structure; peak velocities of ≅2.5 x 10 8 cm/sec; acceleration efficiency of >30% at speeds of 1.5 x 10 8 cm/sec inferred from trajectory and capacitor bank data; kinetic to magnetic energy ratios ∼10 were observed. Experiments in the near future will be aimed at confirmation of the mass/energy measurements by calorimetry and direct density measurements

Evaluating polymer degradation with complex mixtures using a simplified surface area method.

Science.gov (United States)

Steele, Kandace M; Pelham, Todd; Phalen, Robert N

2017-09-01

Chemical-resistant gloves, designed to protect workers from chemical hazards, are made from a variety of polymer materials such as plastic, rubber, and synthetic rubber. One material does not provide protection against all chemicals, thus proper polymer selection is critical. Standardized testing, such as chemical degradation tests, are used to aid in the selection process. The current methods of degradation ratings based on changes in weight or tensile properties can be expensive and data often do not exist for complex chemical mixtures. There are hundreds of thousands of chemical products on the market that do not have chemical resistance data for polymer selection. The method described in this study provides an inexpensive alternative to gravimetric analysis. This method uses surface area change to evaluate degradation of a polymer material. Degradation tests for 5 polymer types against 50 complex mixtures were conducted using both gravimetric and surface area methods. The percent change data were compared between the two methods. The resulting regression line was y = 0.48x + 0.019, in units of percent, and the Pearson correlation coefficient was r = 0.9537 (p ≤ 0.05), which indicated a strong correlation between percent weight change and percent surface area change. On average, the percent change for surface area was about half that of the weight change. Using this information, an equivalent rating system was developed for determining the chemical degradation of polymer gloves using surface area.

Sequential Isolation of Saturated, Aromatic, Resinic and Asphaltic Fractions Degrading Bacteria from Oil Contaminated Soil in South Sumatera

Directory of Open Access Journals (Sweden)

Pingkan Aditiawati

2012-04-01

Full Text Available Sequential isolation has been conducted to obtain isolates of saturated, aromatic, resin, and asphaltene fractions degrading bacteria from oil contaminated sites. Five soil samples were collected from South Sumatera. These were analyzed using soil extract medium enriched with oil recovery or Remaining-Oil recovery Degradated (ROD as sole carbon and energy sources according to the isolation stage. ROD at the end of every isolation stage analyzed oil fractions by use of the SARA analysis method. Six isolates of bacteria have been selected, one isolate was fraction saturates degrading bacteria that are Mycobacterium sp. T1H2D4-7 at degradation rate 0.0199 mgs/h with density 8.4x106 cfu/g from stage I. The isolate T2H1D2-4, identified as Pseudomonas sp. was fraction aromatics degrading bacteria at accelerate 0.0141 mgs/h with density 5.1x106 cfu/g are obtained at stage II. Two isolates namely Micrococcus sp. T3H2D4-2 and Pseudomonas sp. T1H1D5-5 were fraction resins degrading bacteria by accelerate 0.0088 mgs/h at density 5.6x106 cfu/g and 0.0089 mgs/h at density 5.7x106 cfu/g are obtained at stage III. Isolation of stage IV has been obtained two isolates Pseudomonas sp. T4H1D3-1and Pseudomonas sp. T4H3D5-4 were fraction asphaltenes degrading bacteria by accelerate 0.0057 mgs/h at density 5.6x106 cfu/g and accelerate 0.0058 mgs/h at density 5.7x106 cfu/g.

An accelerated test method of luminous flux depreciation for LED luminaires and lamps

International Nuclear Information System (INIS)

Qian, C.; Fan, X.J.; Fan, J.J.; Yuan, C.A.; Zhang, G.Q.

2016-01-01

Light Emitting Diode (LED) luminaires and lamps are energy-saving and environmental friendly alternatives to traditional lighting products. However, current luminous flux depreciation test at luminaire and lamp level requires a minimum of 6000 h testing, which is even longer than the product development cycle time. This paper develops an accelerated test method for luminous flux depreciation to reduce the test time within 2000 h at an elevated temperature. The method is based on lumen maintenance boundary curve, obtained from a collection of LED source lumen depreciation data, known as LM-80 data. The exponential decay model and Arrhenius acceleration relationship are used to determine the new threshold of lumen maintenance and acceleration factor. The proposed method has been verified by a number of simulation studies and experimental data for a wide range of LED luminaire and lamp types from both internal and external experiments. The qualification results obtained by the accelerated test method agree well with traditional 6000 h tests. - Highlights: • We develop an accelerated test method for LED luminaires and lamps. • The method is proposed based on a “Boundary Curve” concept. • The parameters of the boundary curve are extracted from LM-80 test reports. • Qualification results from the proposed method agree with ES requirements.

FDTD method using for electrodynamic simulation of resonator accelerating structures

International Nuclear Information System (INIS)

Vorogushin, M.F.; Svistunov, Yu.A.; Chetverikov, I.O.; Malyshev, V.N.; Malyukhov, M.V.

2000-01-01

The finite difference method in the time area (FDTD) makes it possible to model both stationary and nonstationary processes, originating by the beam and field interaction. Possibilities of the method by modeling the fields in the resonant accelerating structures are demonstrated. The possibility of considering the transition processes is important besides the solution of the problem on determination of frequencies and distribution in the space of the resonators oscillations proper types. The program presented makes it possible to obtain practical results for modeling accelerating structures on personal computers [ru

Degradation of biodegradable plastic mulch films in soil environment by phylloplane fungi isolated from gramineous plants.

Science.gov (United States)

Koitabashi, Motoo; Noguchi, Masako T; Sameshima-Yamashita, Yuka; Hiradate, Syuntaro; Suzuki, Ken; Yoshida, Shigenobu; Watanabe, Takashi; Shinozaki, Yukiko; Tsushima, Seiya; Kitamoto, Hiroko K

2012-08-02

To improve the biodegradation of biodegradable plastic (BP) mulch films, 1227 fungal strains were isolated from plant surface (phylloplane) and evaluated for BP-degrading ability. Among them, B47-9 a strain isolated from the leaf surface of barley showed the strongest ability to degrade poly-(butylene succinate-co-butylene adipate) (PBSA) and poly-(butylene succinate) (PBS) films. The strain grew on the surface of soil-mounted BP films, produced breaks along the direction of hyphal growth indicated that it secreted a BP-degrading enzyme, and has directly contributing to accelerating the degradation of film. Treatment with the culture filtrate decomposed 91.2 wt%, 23.7 wt%, and 14.6 wt% of PBSA, PBS, and commercially available BP polymer blended mulch film, respectively, on unsterlized soil within 6 days. The PCR-DGGE analysis of the transition of soil microbial community during film degradation revealed that the process was accompanied with drastic changes in the population of soil fungi and Acantamoeba spp., as well as the growth of inoculated strain B47-9. It has a potential for application in the development of an effective method for accelerating degradation of used plastics under actual field conditions.

Detecting chaos in particle accelerators through the frequency map analysis method.

Science.gov (United States)

Papaphilippou, Yannis

2014-06-01

The motion of beams in particle accelerators is dominated by a plethora of non-linear effects, which can enhance chaotic motion and limit their performance. The application of advanced non-linear dynamics methods for detecting and correcting these effects and thereby increasing the region of beam stability plays an essential role during the accelerator design phase but also their operation. After describing the nature of non-linear effects and their impact on performance parameters of different particle accelerator categories, the theory of non-linear particle motion is outlined. The recent developments on the methods employed for the analysis of chaotic beam motion are detailed. In particular, the ability of the frequency map analysis method to detect chaotic motion and guide the correction of non-linear effects is demonstrated in particle tracking simulations but also experimental data.

Development of laboratory acceleration test method for service life prediction of concrete structures

International Nuclear Information System (INIS)

Cho, M. S.; Song, Y. C.; Bang, K. S.; Lee, J. S.; Kim, D. K.

1999-01-01

Service life prediction of nuclear power plants depends on the application of history of structures, field inspection and test, the development of laboratory acceleration tests, their analysis method and predictive model. In this study, laboratory acceleration test method for service life prediction of concrete structures and application of experimental test results are introduced. This study is concerned with environmental condition of concrete structures and is to develop the acceleration test method for durability factors of concrete structures e.g. carbonation, sulfate attack, freeze-thaw cycles and shrinkage-expansion etc

Method for modeling the gradual physical degradation of a porous material

Energy Technology Data Exchange (ETDEWEB)

Flach, Greg [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-20

Cementitious and other engineered porous materials encountered in waste disposals may degrade over time due to one or more mechanisms. Physical degradation may take the form of cracking (fracturing) and/or altered (e.g. increased) porosity, depending on the material and underlying degradation mechanism. In most cases, the hydraulic properties of degrading materials are expected to evolve due to physical changes occurring over roughly the pore to decimeter scale, which is conducive to calculating equivalent or effective material properties. The exact morphology of a degrading material in its end-state may or may not be known. In the latter case, the fully-degraded condition can be assumed to be similar to a more-permeable material in the surrounding environment, such as backfill soil. Then the fully-degraded waste form or barrier material is hydraulically neutral with respect to its surroundings, constituting neither a barrier to nor conduit for moisture flow and solute transport. Unless the degradation mechanism is abrupt, a gradual transition between the intact initial and fully-degraded final states is desired. Linear interpolation through time is one method for smoothly blending hydraulic properties between those of an intact matrix and those of a soil or other surrogate for the end-state.

Method for modeling the gradual physical degradation of a porous material

International Nuclear Information System (INIS)

Flach, Greg

2017-01-01

Cementitious and other engineered porous materials encountered in waste disposals may degrade over time due to one or more mechanisms. Physical degradation may take the form of cracking (fracturing) and/or altered (e.g. increased) porosity, depending on the material and underlying degradation mechanism. In most cases, the hydraulic properties of degrading materials are expected to evolve due to physical changes occurring over roughly the pore to decimeter scale, which is conducive to calculating equivalent or effective material properties. The exact morphology of a degrading material in its end-state may or may not be known. In the latter case, the fully-degraded condition can be assumed to be similar to a more-permeable material in the surrounding environment, such as backfill soil. Then the fully-degraded waste form or barrier material is hydraulically neutral with respect to its surroundings, constituting neither a barrier to nor conduit for moisture flow and solute transport. Unless the degradation mechanism is abrupt, a gradual transition between the intact initial and fully-degraded final states is desired. Linear interpolation through time is one method for smoothly blending hydraulic properties between those of an intact matrix and those of a soil or other surrogate for the end-state.

Analysis of the applicability of acceleration methods for a triangular prism geometry nodal diffusion code

International Nuclear Information System (INIS)

Fujimura, Toichiro; Okumura, Keisuke

2002-11-01

A prototype version of a diffusion code has been developed to analyze the hexagonal core as reduced moderation reactor and the applicability of some acceleration methods have been investigated to accelerate the convergence of the iterative solution method. The hexagonal core is divided into regular triangular prisms in the three-dimensional code MOSRA-Prism and a polynomial expansion nodal method is applied to approximate the neutron flux distribution by a cubic polynomial. The multi-group diffusion equation is solved iteratively with ordinal inner and outer iterations and the effectiveness of acceleration methods is ascertained by applying an adaptive acceleration method and a neutron source extrapolation method, respectively. The formulation of the polynomial expansion nodal method is outlined in the report and the local and global effectiveness of the acceleration methods is discussed with various sample calculations. A new general expression of vacuum boundary condition, derived in the formulation is also described. (author)

Automated Data Collection for Determining Statistical Distributions of Module Power Undergoing Potential-Induced Degradation

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu

We propose a method for increasing the frequency of data collection and reducing the time and cost of accelerated lifetime testing of photovoltaic modules undergoing potential-induced degradation (PID). This consists of in-situ measurements of dark current-voltage curves of the modules at elevate...

Spectral analysis of an algebraic collapsing acceleration for the characteristics method

International Nuclear Information System (INIS)

Le Tellier, R.; Hebert, A.

2005-01-01

A spectral analysis of a diffusion synthetic acceleration called Algebraic Collapsing Acceleration (ACA) was carried out in the context of the characteristics method to solve the neutron transport equation. Two analysis were performed in order to assess the ACA performances. Both a standard Fourier analysis in a periodic and infinite slab-geometry and a direct spectral analysis for a finite slab-geometry were investigated. In order to evaluate its performance, ACA was compared with two competing techniques used to accelerate the convergence of the characteristics method, the Self-Collision Re-balancing technique and the Asymptotic Synthetic Acceleration. In the restricted framework of 1-dimensional slab-geometries, we conclude that ACA offers a good compromise between the reduction of the spectral radius of the iterative matrix and the resources to construct, store and solve the corrective system. A comparison on a monoenergetic 2-dimensional benchmark was performed and tends to confirm these conclusions. (authors)

Degradation of polyethylene microplastics in seawater: Insights into the environmental degradation of polymers.

Science.gov (United States)

Da Costa, João P; Nunes, Ana R; Santos, Patrícia S M; Girão, Ana V; Duarte, Armando C; Rocha-Santos, Teresa

2018-04-06

Microplastic contamination of aquatic environments has become an increasingly alarming problem. These, defined as particles degradation of this material. These results highlight the importance of determining the mechanisms of degradation of microplastics in marine settings and what the implications may be for the environment. Overall, the herein presented results show that a relatively short period of time of accelerated exposure can yield quantifiable chemical and physical impacts on the structural and morphological characteristics of PE pellets.

An ultrasonic-accelerated oxidation method for determining the oxidative stability of biodiesel.

Science.gov (United States)

Avila Orozco, Francisco D; Sousa, Antonio C; Domini, Claudia E; Ugulino Araujo, Mario Cesar; Fernández Band, Beatriz S

2013-05-01

Biodiesel is considered an alternative energy because it is produced from fats and vegetable oils by means of transesterification. Furthermore, it consists of fatty acid alkyl esters (FAAS) which have a great influence on biodiesel fuel properties and in the storage lifetime of biodiesel itself. The biodiesel storage stability is directly related to the oxidative stability parameter (Induction Time - IT) which is determined by means of the Rancimat® method. This method uses condutimetric monitoring and induces the degradation of FAAS by heating the sample at a constant temperature. The European Committee for Standardization established a standard (EN 14214) to determine the oxidative stability of biodiesel, which requires it to reach a minimum induction period of 6h as tested by Rancimat® method at 110°C. In this research, we aimed at developing a fast and simple alternative method to determine the induction time (IT) based on the FAAS ultrasonic-accelerated oxidation. The sonodegradation of biodiesel samples was induced by means of an ultrasonic homogenizer fitted with an immersible horn at 480Watts of power and 20 duty cycles. The UV-Vis spectrometry was used to monitor the FAAS sonodegradation by measuring the absorbance at 270nm every 2. Biodiesel samples from different feedstock were studied in this work. In all cases, IT was established as the inflection point of the absorbance versus time curve. The induction time values of all biodiesel samples determined using the proposed method was in accordance with those measured through the Rancimat® reference method by showing a R(2)=0.998. Copyright © 2012 Elsevier B.V. All rights reserved.

Diffusion-synthetic acceleration methods for discrete-ordinates problems

International Nuclear Information System (INIS)

Larsen, E.W.

1984-01-01

The diffusion-synthetic acceleration (DSA) method is an iterative procedure for obtaining numerical solutions of discrete-ordinates problems. The DSA method is operationally more complicated than the standard source-iteration (SI) method, but if encoded properly it converges much more rapidly, especially for problems with diffusion-like regions. In this article we describe the basic ideas behind the DSA method and give a (roughly chronological) review of its long development. We conclude with a discussion which covers additional topics, including some remaining open problems an the status of current efforts aimed at solving these problems

Method for pulse to pulse dose reproducibility applied to electron linear accelerators

International Nuclear Information System (INIS)

Ighigeanu, D.; Martin, D.; Oproiu, C.; Cirstea, E.; Craciun, G.

2002-01-01

An original method for obtaining programmed beam single shots and pulse trains with programmed pulse number, pulse repetition frequency, pulse duration and pulse dose is presented. It is particularly useful for automatic control of absorbed dose rate level, irradiation process control as well as in pulse radiolysis studies, single pulse dose measurement or for research experiments where pulse-to-pulse dose reproducibility is required. This method is applied to the electron linear accelerators, ALIN-10 of 6.23 MeV and 82 W and ALID-7, of 5.5 MeV and 670 W, built in NILPRP. In order to implement this method, the accelerator triggering system (ATS) consists of two branches: the gun branch and the magnetron branch. ATS, which synchronizes all the system units, delivers trigger pulses at a programmed repetition rate (up to 250 pulses/s) to the gun (80 kV, 10 A and 4 ms) and magnetron (45 kV, 100 A, and 4 ms).The accelerated electron beam existence is determined by the electron gun and magnetron pulses overlapping. The method consists in controlling the overlapping of pulses in order to deliver the beam in the desired sequence. This control is implemented by a discrete pulse position modulation of gun and/or magnetron pulses. The instabilities of the gun and magnetron transient regimes are avoided by operating the accelerator with no accelerated beam for a certain time. At the operator 'beam start' command, the ATS controls electron gun and magnetron pulses overlapping and the linac beam is generated. The pulse-to-pulse absorbed dose variation is thus considerably reduced. Programmed absorbed dose, irradiation time, beam pulse number or other external events may interrupt the coincidence between the gun and magnetron pulses. Slow absorbed dose variation is compensated by the control of the pulse duration and repetition frequency. Two methods are reported in the electron linear accelerators' development for obtaining the pulse to pulse dose reproducibility: the method

Planetary method to measure the neutrons spectrum in lineal accelerators of medical use

International Nuclear Information System (INIS)

Vega C, H. R.; Benites R, J. L.

2014-08-01

A novel procedure to measure the neutrons spectrum originated in a lineal accelerator of medical use has been developed. The method uses a passive spectrometer of Bonner spheres. The main advantage of the method is that only requires of a single shot of the accelerator. When this is used around a lineal accelerator is necessary to operate it under the same conditions so many times like the spheres that contain the spectrometer, activity that consumes enough time. The developed procedure consists on situating all the spheres of the spectrometer at the same time and to realize the reading making a single shot. With this method the photo neutrons spectrum produced by a lineal accelerator Varian ix of 15 MV to 100 cm of the isocenter was determined, with the spectrum is determined the total flow and the ambient dose equivalent. (Author)

EPICOR-II resin characterization and proposed methods for degradation analysis. Rev. 1

International Nuclear Information System (INIS)

Doyle, J.D.; McConnell, J.W. Jr.; Sanders, R.D. Sr.

1984-06-01

One goal of the EPICOR-II Research and Disposition Program is the examination of the EPICOR-II organic ion-exchange resins for physical and chemical degradation. This report summarizes preliminary information necessary for the evaluation of the resins for degradation. Degradation of the synthetic organic ion-exchange resins should be efficiently and accurately measurable by using the baseline data provided by the nonirradiated resin characterization. The degradation threshold is about 10 8 rads, approximately the same dose rate the resins will have received by the examination date. If degradation has not occurred at the first examination point, later examinations will detect resin degradation using the same analytical methods. The results from the characterization tests will yield practical and useful data on the actual effects of radiation on commercial synthetic organic ion-exchange resins. 10 references, 12 figures

Linear multifrequency-grey acceleration recast for preconditioned Krylov iterations

International Nuclear Information System (INIS)

Morel, Jim E.; Brian Yang, T.-Y.; Warsa, James S.

2007-01-01

The linear multifrequency-grey acceleration (LMFGA) technique is used to accelerate the iterative convergence of multigroup thermal radiation diffusion calculations in high energy density simulations. Although it is effective and efficient in one-dimensional calculations, the LMFGA method has recently been observed to significantly degrade under certain conditions in multidimensional calculations with large discontinuities in material properties. To address this deficiency, we recast the LMFGA method in terms of a preconditioned system that is solved with a Krylov method (LMFGK). Results are presented demonstrating that the new LMFGK method always requires fewer iterations than the original LMFGA method. The reduction in iteration count increases with both the size of the time step and the inhomogeneity of the problem. However, for reasons later explained, the LMFGK method can cost more per iteration than the LMFGA method, resulting in lower but comparable efficiency in problems with small time steps and weak inhomogeneities. In problems with large time steps and strong inhomogeneities, the LMFGK method is significantly more efficient than the LMFGA method

Method for accelerated aging under combined environmental stress conditions

International Nuclear Information System (INIS)

Gillen, K.T.

1979-01-01

An accelerated aging method which can be used to simulate aging in combined stress environment situations is described. It is shown how the assumptions of the method can be tested experimentally. Aging data for a chloroprene cable jacketing material in single and combined radiation and temperature environments are analyzed and it is shown that these data offer evidence for the validity of the method

Comparison of efficiency degradation in polycrystalline-Si and CdTe thin-film PV modules via accelerated lifecycle testing

Science.gov (United States)

Lai, T.; Potter, B. G.; Simmons-Potter, K.

2017-08-01

Thin-film solar cells normally have the shortest energy payback time due to their simpler mass-production process compared to polycrystalline-Si photovoltaic (PV) modules, despite the fact that crystalline-Si-based technology typically has a longer total lifetime and a higher initial power conversion efficiency. For both types of modules, significant aging occurs during the first two years of usage with slower long-term aging over the module lifetime. The PV lifetime and the return-on-investment for local PV system installations rely on long-term device performance. Understanding the efficiency degradation behavior under a given set of environmental conditions is, therefore, a primary goal for experimental research and economic analysis. In the present work, in-situ measurements of key electrical characteristics (J, V, Pmax, etc.) in polycrystalline-Si and CdTe thin-film PV modules have been analyzed. The modules were subjected to identical environmental conditions, representative of southern Arizona, in a full-scale, industrial-standard, environmental degradation chamber, equipped with a single-sun irradiance source, temperature, and humidity controls, and operating an accelerated lifecycle test (ALT) sequence. Initial results highlight differences in module performance with environmental conditions, including temperature de-rating effects, for the two technologies. Notably, the thin-film CdTe PV module was shown to be approximately 15% less sensitive to ambient temperature variation. After exposure to a seven-month equivalent compressed night-day weather cycling regimen the efficiency degradation rates of both PV technology types were obtained and will be discussed.

A new method of measuring gravitational acceleration in an undergraduate laboratory program

Science.gov (United States)

Wang, Qiaochu; Wang, Chang; Xiao, Yunhuan; Schulte, Jurgen; Shi, Qingfan

2018-01-01

This paper presents a high accuracy method to measure gravitational acceleration in an undergraduate laboratory program. The experiment is based on water in a cylindrical vessel rotating about its vertical axis at a constant speed. The water surface forms a paraboloid whose focal length is related to rotational period and gravitational acceleration. This experimental setup avoids classical source errors in determining the local value of gravitational acceleration, so prevalent in the common simple pendulum and inclined plane experiments. The presented method combines multiple physics concepts such as kinematics, classical mechanics and geometric optics, offering the opportunity for lateral as well as project-based learning.

Fluctuation Flooding Method (FFM) for accelerating conformational transitions of proteins

Science.gov (United States)

Harada, Ryuhei; Takano, Yu; Shigeta, Yasuteru

2014-03-01

A powerful conformational sampling method for accelerating structural transitions of proteins, "Fluctuation Flooding Method (FFM)," is proposed. In FFM, cycles of the following steps enhance the transitions: (i) extractions of largely fluctuating snapshots along anisotropic modes obtained from trajectories of multiple independent molecular dynamics (MD) simulations and (ii) conformational re-sampling of the snapshots via re-generations of initial velocities when re-starting MD simulations. In an application to bacteriophage T4 lysozyme, FFM successfully accelerated the open-closed transition with the 6 ns simulation starting solely from the open state, although the 1-μs canonical MD simulation failed to sample such a rare event.

Methods for Evaluating the Biodegradability of Environmentally Degradable Polymers

NARCIS (Netherlands)

Zee, van der M.

2014-01-01

This chapter presents an overview of the current knowledge on experimental methods for monitoring the biodegradability of polymeric materials. The focus is, in particular, on the biodegradation of materials under environmental conditions. Examples of in vivo degradation of polymers used in

Acceleration methods and models in Sn calculations

International Nuclear Information System (INIS)

Sbaffoni, M.M.; Abbate, M.J.

1984-01-01

In some neutron transport problems solved by the discrete ordinate method, it is relatively common to observe some particularities as, for example, negative fluxes generation, slow and insecure convergences and solution instabilities. The commonly used models for neutron flux calculation and acceleration methods included in the most used codes were analyzed, in face of their use in problems characterized by a strong upscattering effect. Some special conclusions derived from this analysis are presented as well as a new method to perform the upscattering scaling for solving the before mentioned problems in this kind of cases. This method has been included in the DOT3.5 code (two dimensional discrete ordinates radiation transport code) generating a new version of wider application. (Author) [es

A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition.

Science.gov (United States)

Souri, E; Aghdami, A Negahban; Adib, N

2014-01-01

An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r(2)>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms.

Synthetic acceleration methods for linear transport problems with highly anisotropic scattering

International Nuclear Information System (INIS)

Khattab, K.M.; Larsen, E.W.

1992-01-01

The diffusion synthetic acceleration (DSA) algorithm effectively accelerates the iterative solution of transport problems with isotropic or mildly anisotropic scattering. However, DSA loses its effectiveness for transport problems that have strongly anisotropic scattering. Two generalizations of DSA are proposed, which, for highly anisotropic scattering problems, converge at least an order of magnitude (clock time) faster than the DSA method. These two methods are developed, the results of Fourier analysis that theoretically predict their efficiency are described, and numerical results that verify the theoretical predictions are presented. (author). 10 refs., 7 figs., 5 tabs

Synthetic acceleration methods for linear transport problems with highly anisotropic scattering

International Nuclear Information System (INIS)

Khattab, K.M.; Larsen, E.W.

1991-01-01

This paper reports on the diffusion synthetic acceleration (DSA) algorithm that effectively accelerates the iterative solution of transport problems with isotropic or mildly anisotropic scattering. However, DSA loses its effectiveness for transport problems that have strongly anisotropic scattering. Two generalizations of DSA are proposed, which, for highly anisotropic scattering problems, converge at least an order of magnitude (clock time) faster than the DSA method. These two methods are developed, the results of Fourier analyses that theoretically predict their efficiency are described, and numerical results that verify the theoretical predictions are presented

Method for accelerated leaching of solidified waste

International Nuclear Information System (INIS)

Fuhrmann, M.; Heiser, J.H.; Pietrzak, R.F.; Franz, E.M.; Colombo, P.

1990-11-01

An accelerated leach test method has been developed to determine the maximum leachability of solidified waste. The approach we have taken is to use a semi-dynamic leach test; that is, the leachant is sampled and replaced periodically. Parameters such as temperature, leachant volume, and specimen size are used to obtain releases that are accelerated relative to other standard leach tests and to the leaching of full-scale waste forms. The data obtained with this test can be used to model releases from waste forms, or to extrapolate from laboratory-scale to full-scale waste forms if diffusion is the dominant leaching mechanism. Diffusion can be confirmed as the leaching mechanism by using a computerized mathematical model for diffusion from a finite cylinder. We have written a computer program containing several models including diffusion to accompany this test. The program and a Users' Guide that gives screen-by-screen instructions on the use of the program are available from the authors. 14 refs., 4 figs., 1 tab

Degradation of photovoltaic backsheet materials under multi-factor accelerated UV light exposures

Science.gov (United States)

Klinke, Addison G.; Gok, Abdulkerim; Ifeanyi, Silas I.; French, Roger H.; Bruckman, Laura S.

2017-08-01

Long term outdoor durability of photovoltaic (PV) module backsheets is critical to a module's power output over its lifetime. The use of uoropolymer-based backsheets or the addition of stabilizers to polyethylene-terephthalate (PET) and polyamide (PA) type backsheets can help extend their lifetime. This study presents the performance of 21 backsheets made of 8 different material combinations under ASTM G154 Cycle 4 accelerated light exposures. The backsheets were subjected to 4000 hours of high irradiance UVA light at a peak intensity of 1.55 W=m2 at 340 nm at 70°C with and without a condensing humidity cycle at 50°C. Backsheets were evaluated, with repeated measurements, using various evaluation techniques to identify and assess potential signs of degradation. These evaluations included the yellowness index (YI), CIE color space coordinates, and gloss at 20, 60, and 85°. The temporal evolution of the relative color change ΔE was statistically analyzed to develop a stress-response model which used the UVA light dose to predict color change. It was found that the PVF/PET/E backsheet performed the best while PET/PET/E and THV/PET/EVA backsheets performed the worst. Additionally, substantial variation in color change response, attributable to key manufacturing differences, was observed within a given material type.

New diffusion-sythetic acceleration methods for the SN equations with corner balance spatial differencing

International Nuclear Information System (INIS)

Wareing, T.A.

1993-01-01

New methods are presented for diffusion-synthetic accelerating the S N equations in slab and x-y geometries with the corner balance spatial differencing scheme. With the standard diffusion-synthetic acceleration method, the discretized diffusion problem is derived from the discretized S N problem to insure stability through consistent differencing. The major difference between our new methods and standard diffusion-synthetic acceleration is that the discretized diffusion problem is derived from a discretization of the P 1 equations, independently of the discretized S N problem. We present theoretical and numerical results to show that these new methods are unconditionally efficient in slab and x-y geometries with rectangular spatial meshes and isotropic scattering. (orig.)

Compact multi-energy electron linear accelerators

International Nuclear Information System (INIS)

Tanabe, E.; Hamm, R.W.

1985-01-01

Two distinctly different concepts that have been developed for compact multi-energy, single-section, standing-wave electron linear accelerator structures are presented. These new concepts, which utilize (a) variable nearest neighbor couplings and (b) accelerating field phase switching, provide the capability of continuously varying the electron output energy from the accelerator without degrading the energy spectrum. These techniques also provide the means for continuously varying the energy spectrum while maintaining a given average electron energy, and have been tested successfully with several accelerators of length from 0.1 m to 1.9 m. Theoretical amd experimental results from these accelerators, and demonstrated applications of these techniques to medical and industrial linear accelerator technology will be described. In addition, possible new applications available to research and industry from these techniques are presented. (orig.)

Accelerated stress testing of terrestrial solar cells

Science.gov (United States)

Lathrop, J. W.; Hawkins, D. C.; Prince, J. L.; Walker, H. A.

1982-01-01

The development of an accelerated test schedule for terrestrial solar cells is described. This schedule, based on anticipated failure modes deduced from a consideration of IC failure mechanisms, involves bias-temperature testing, humidity testing (including both 85-85 and pressure cooker stress), and thermal-cycle thermal-shock testing. Results are described for 12 different unencapsulated cell types. Both gradual electrical degradation and sudden catastrophic mechanical change were observed. These effects can be used to discriminate between cell types and technologies relative to their reliability attributes. Consideration is given to identifying laboratory failure modes which might lead to severe degradation in the field through second quadrant operation. Test results indicate that the ability of most cell types to withstand accelerated stress testing depends more on the manufacturer's design, processing, and worksmanship than on the particular metallization system. Preliminary tests comparing accelerated test results on encapsulated and unencapsulated cells are described.

Activation of chromatin degradation by a protein factor of thymocyte cytoplasm of irradiated mice

International Nuclear Information System (INIS)

Soldatenkov, V.A.; Filippovich, I.V.

1986-01-01

A cytoplasmic thymocyte fraction isolated 1 h after irradiation of mice accelerates chromatin degradation in isolated nuclei. Treatment of the cytoplasmic fraction by heat and injection of cycloheximide to mice prevent the acceleration of DNA degradation. The analysis of the chromatin degradation products and the kinetics of this process at acid and alkaline pH shows that activation of DNA degradation in thymocytes by a factor obtained from the irradiated cell cytoplasm is specific for a Ca 2+ , Mg 2+ -dependent enzyme. The time- and dose-dependent parameters of the appearance in the thymocyte cytoplasm of the factor influencing degradation of chromatin are in a good agreement with both the time of the onset of its postirradiation degradation and the dose dependence of this process

A hybrid degradation tendency measurement method for mechanical equipment based on moving window and Grey–Markov model

International Nuclear Information System (INIS)

Jiang, Wei; Zhou, Jianzhong; Zheng, Yang; Liu, Han

2017-01-01

Accurate degradation tendency measurement is vital for the secure operation of mechanical equipment. However, the existing techniques and methodologies for degradation measurement still face challenges, such as lack of appropriate degradation indicator, insufficient accuracy, and poor capability to track the data fluctuation. To solve these problems, a hybrid degradation tendency measurement method for mechanical equipment based on a moving window and Grey–Markov model is proposed in this paper. In the proposed method, a 1D normalized degradation index based on multi-feature fusion is designed to assess the extent of degradation. Subsequently, the moving window algorithm is integrated with the Grey–Markov model for the dynamic update of the model. Two key parameters, namely the step size and the number of states, contribute to the adaptive modeling and multi-step prediction. Finally, three types of combination prediction models are established to measure the degradation trend of equipment. The effectiveness of the proposed method is validated with a case study on the health monitoring of turbine engines. Experimental results show that the proposed method has better performance, in terms of both measuring accuracy and data fluctuation tracing, in comparison with other conventional methods. (paper)

A hybrid degradation tendency measurement method for mechanical equipment based on moving window and Grey-Markov model

Science.gov (United States)

Jiang, Wei; Zhou, Jianzhong; Zheng, Yang; Liu, Han

2017-11-01

Accurate degradation tendency measurement is vital for the secure operation of mechanical equipment. However, the existing techniques and methodologies for degradation measurement still face challenges, such as lack of appropriate degradation indicator, insufficient accuracy, and poor capability to track the data fluctuation. To solve these problems, a hybrid degradation tendency measurement method for mechanical equipment based on a moving window and Grey-Markov model is proposed in this paper. In the proposed method, a 1D normalized degradation index based on multi-feature fusion is designed to assess the extent of degradation. Subsequently, the moving window algorithm is integrated with the Grey-Markov model for the dynamic update of the model. Two key parameters, namely the step size and the number of states, contribute to the adaptive modeling and multi-step prediction. Finally, three types of combination prediction models are established to measure the degradation trend of equipment. The effectiveness of the proposed method is validated with a case study on the health monitoring of turbine engines. Experimental results show that the proposed method has better performance, in terms of both measuring accuracy and data fluctuation tracing, in comparison with other conventional methods.

Degradation Behavior and Accelerated Weathering of Composite Boards Produced from Waste Tetra Pak® Packaging Materials

Directory of Open Access Journals (Sweden)

Nural Yilgo

2014-06-01

Full Text Available Manufacturing panels from Tetra Pak® (TP packaging material might be an alternative to conventional wood-based panels. This study evaluated some chemical and physical properties as well as biological, weathering, and fire performance of panels with and without zinc borate (ZnB by using shredded TP packaging cartons. Such packaging material, a worldwide well-known multilayer beverage packaging system, is composed of cellulose, low-density polyethylene (LDPE, and aluminum (Al. Panels produced from waste TP packaging material were also examined by FT-IR to understand the fungal deterioration and extent of degradation after accelerated weathering. Before FT-IR investigations, panel specimens were ground under nitrogen atmosphere due to non-uniformity of the composite material. The FT-IR results showed that fungal degradation occurred in the natural polymer of the panel matrix. Although the natural polymer is mostly composed of cellulose, there were also small amounts of polyoses and lignin. It was seen that especially polyose and lignin bands in FT-IR spectra were affected more than cellulose bands by fungal attack. No changes were observed by the fungi in the plastic component (LDPE of the matrix; however, LDPE seemed more sensitive to weathering than cellulose. Incorporation of ZnB at loading level of 1% (w/w did not contribute fire performance of the panels when compared to control panel specimens, while a loading level of 10% improved fire performance considering test parameters such as mass loss, ignition time and peak heat release rate.

High-field dipoles for future accelerators

International Nuclear Information System (INIS)

Wipf, S.L.

1984-09-01

This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators

Early detection of materials degradation

Science.gov (United States)

Meyendorf, Norbert

2017-02-01

Lightweight components for transportation and aerospace applications are designed for an estimated lifecycle, taking expected mechanical and environmental loads into account. The main reason for catastrophic failure of components within the expected lifecycle are material inhomogeneities, like pores and inclusions as origin for fatigue cracks, that have not been detected by NDE. However, material degradation by designed or unexpected loading conditions or environmental impacts can accelerate the crack initiation or growth. Conventional NDE methods are usually able to detect cracks that are formed at the end of the degradation process, but methods for early detection of fatigue, creep, and corrosion are still a matter of research. For conventional materials ultrasonic, electromagnetic, or thermographic methods have been demonstrated as promising. Other approaches are focused to surface damage by using optical methods or characterization of the residual surface stresses that can significantly affect the creation of fatigue cracks. For conventional metallic materials, material models for nucleation and propagation of damage have been successfully applied for several years. Material microstructure/property relations are well established and the effect of loading conditions on the component life can be simulated. For advanced materials, for example carbon matrix composites or ceramic matrix composites, the processes of nucleation and propagation of damage is still not fully understood. For these materials NDE methods can not only be used for the periodic inspections, but can significantly contribute to the material scientific knowledge to understand and model the behavior of composite materials.

Diffusion-synthetic acceleration methods for the discrete-ordinates equations

International Nuclear Information System (INIS)

Larsen, E.W.

1983-01-01

The diffusion-synthetic acceleration (DSA) method is an iterative procedure for obtaining numerical solutions of discrete-ordinates problems. The DSA method is operationally more complicated than the standard source-iteration (SI) method, but if encoded properly it converges much more rapidly, especially for problems with diffusion-like regions. In this article we describe the basic ideas beind the DSA method and give a (roughly chronological) review of its long development. We conclude with a discussion which covers additional topics, including some remaining open problems and the status of current efforts aimed at solving these problems

Accelerated degradation of polyetheretherketone and its composites in the deep sea.

Science.gov (United States)

Liu, Hao; Wang, Jianzhang; Jiang, Pengfei; Yan, Fengyuan

2018-04-01

The performance of polymer composites in seawater, under high hydrostatic pressure (typically few tens of MPa), for simulating exposures at great depths in seas and oceans, has been little studied. In this paper, polyetheretherketone (PEEK) and its composites reinforced by carbon fibres and glass fibres were prepared. The seawater environment with different seawater hydrostatic pressure ranging from normal pressure to 40 MPa was simulated with special equipment, in which the seawater absorption and wear behaviour of PEEK and PEEK-based composites were examined in situ . The effects of seawater hydrostatic pressure on the mechanical properties, wear resistance and microstructure of PEEK and its composites were focused on. The results showed that seawater absorption of PEEK and its composites were greatly accelerated by increased hydrostatic pressure in the deep sea. Affected by seawater absorption, both for neat PEEK and composites, the degradation on mechanical properties, wear resistance and crystallinity were induced, the degree of which was increasingly serious with the increase of hydrostatic pressure of seawater environment. There existed a good correlation in an identical form of exponential function between the wear rate and the seawater hydrostatic pressure. Moreover, the corresponding mechanisms of the effects of deep-sea hydrostatic pressure were also discussed.

Methods of Phase and Power Control in Magnetron Transmitters for Superconducting Accelerators

Energy Technology Data Exchange (ETDEWEB)

Kazadevich, G. [MUONS Inc., Batavia; Johnson, R. [MUONS Inc., Batavia; Neubauer, M. [MUONS Inc., Batavia; Lebedev, V. [Fermilab; Schappert, W. [Fermilab; Yakovlev, V. [Fermilab

2017-05-01

Various methods of phase and power control in magnetron RF sources of superconducting accelerators intended for ADS-class projects were recently developed and studied with conventional 2.45 GHz, 1 kW, CW magnetrons operating in pulsed and CW regimes. Magnetron transmitters excited by a resonant (injection-locking) phasemodulated signal can provide phase and power control with the rates required for precise stabilization of phase and amplitude of the accelerating field in Superconducting RF (SRF) cavities of the intensity-frontier accelerators. An innovative technique that can significantly increase the magnetron transmitter efficiency at the widerange power control required for superconducting accelerators was developed and verified with the 2.45 GHz magnetrons operating in CW and pulsed regimes. High efficiency magnetron transmitters of this type can significantly reduce the capital and operation costs of the ADSclass accelerator projects.

Production of isometric forces during sustained acceleration.

Science.gov (United States)

Sand, D P; Girgenrath, M; Bock, O; Pongratz, H

2003-06-01

The operation of high-performance aircraft requires pilots to apply finely graded forces on controls. Since they are often exposed to high levels of acceleration in flight, we investigated to what extent this ability is degraded in such an environment. Twelve healthy non-pilot volunteers were seated in the gondola of a centrifuge and their performance was tested at normal gravity (1 G) and while exposed to sustained forces of 1.5 G and 3 G oriented from head to foot (+Gz). Using an isometric joystick, they attempted to produce force vectors with specific lengths and directions commanded in random order by a visual display. Acceleration had substantial effects on the magnitude of produced force. Compared with 1 G, maximum produced force was about 2 N higher at 1.5 G and about 10 N higher at 3 G. The size of this effect was constant across the different magnitudes, but varied with the direction of the prescribed force. Acceleration degrades control of force production. This finding may indicate that the motor system misinterprets the unusual gravitoinertial environment and/or that proprioceptive feedback is degraded due to increased muscle tone. The production of excessive isometric force could affect the safe operation of high-performance aircraft.

Stability-indicating UPLC method for determining related substances and degradants in dronedarone.

Science.gov (United States)

Pydimarry, Surya Prakash Rao; Cholleti, Vijay Kumar; Vangala, Ranga Reddy

2014-08-01

A simple, sensitive and reproducible method was developed on ultra-performance liquid chromatography coupled with photodiode array detection for the quantitative determination of dronedarone hydrochloride (DRO) in drug substance and pharmaceutical dosage forms. The method is applicable for the quantification of related substances and assays of drug substances. Chromatographic separation was achieved on Acquity UPLC BEH C8 100 mm, 2.1 mm and 1.7 µm columns, using gradient elution within a short run time of 10.0 min. The eluted compounds were monitored at 288 nm, the flow rate was 0.5 mL/min and the column oven temperature was maintained at 40°C. The resolution of DRO and 11 impurities (potentials and by-products) was greater than 2.0 for all pairs of components. The high correlation coefficient value (>0.9995) indicates the clear correlations between the concentrations of investigated compound and their peak areas within the test ranges. The repeatability and intermediate precision, expressed by the relative standard deviation, were less than 2.5%. The accuracy and validity of the method were further ascertained by performing recovery studies via a spike method. The accuracy of the method, expressed as relative error, was satisfactory. No interference was observed from concomitant substances normally added to the tablets. DRO was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. DRO was found to degrade significantly in acid and base stress conditions and to remain stable in thermal, photolytic degradation, oxidative and hydrolytic conditions. The degradation products were well resolved from primary peak and its impurities, proving that the method is stability indicating. The developed method was validated as per International Conference on Harmonization guidelines with respect to specificity, limit of detection, limit of quantification, linearity, accuracy, precision, solution stability and robustness

Beam-Based Error Identification and Correction Methods for Particle Accelerators

CERN Document Server

AUTHOR|(SzGeCERN)692826; Tomas, Rogelio; Nilsson, Thomas

2014-06-10

Modern particle accelerators have tight tolerances on the acceptable deviation from their desired machine parameters. The control of the parameters is of crucial importance for safe machine operation and performance. This thesis focuses on beam-based methods and algorithms to identify and correct errors in particle accelerators. The optics measurements and corrections of the Large Hadron Collider (LHC), which resulted in an unprecedented low β-beat for a hadron collider is described. The transverse coupling is another parameter which is of importance to control. Improvement in the reconstruction of the coupling from turn-by-turn data has resulted in a significant decrease of the measurement uncertainty. An automatic coupling correction method, which is based on the injected beam oscillations, has been successfully used in normal operation of the LHC. Furthermore, a new method to measure and correct chromatic coupling that was applied to the LHC, is described. It resulted in a decrease of the chromatic coupli...

Radiation damage calculations for the LANSCE degrader

International Nuclear Information System (INIS)

Ferguson, P.D.; Sommer, W.F.; Dudziak, D.J.; Wechsler, M.S.; Barnett, M.H.; Corzine, R.K.

1998-01-01

The A-6 water degrader at the Los Alamos Neutron Science Center (LANSCE) linear proton accelerator has an outer shell of Inconel 718. The degrader was irradiated by 800-MeV protons during 1988--1993 to an exposure of 5.3 ampere-hours (A h). As described in Ref. 1, material from the Inconel is currently being cut into specimens for microhardness, three-point bending, ball punch, microscopy, and corrosion tests. This paper is devoted to calculations of radiation damage, particularly displacement and He production, sustained by the degrader Inconel

Automated Data Collection for Determining Statistical Distributions of Module Power Undergoing Potential-Induced Degradation: Preprint

Energy Technology Data Exchange (ETDEWEB)

Hacke, P.; Spataru, S.

2014-08-01

We propose a method for increasing the frequency of data collection and reducing the time and cost of accelerated lifetime testing of photovoltaic modules undergoing potential-induced degradation (PID). This consists of in-situ measurements of dark current-voltage curves of the modules at elevated stress temperature, their use to determine the maximum power at 25 degrees C standard test conditions (STC), and distribution statistics for determining degradation rates as a function of stress level. The semi-continuous data obtained by this method clearly show degradation curves of the maximum power, including an incubation phase, rates and extent of degradation, precise time to failure, and partial recovery. Stress tests were performed on crystalline silicon modules at 85% relative humidity and 60 degrees C, 72 degrees C, and 85 degrees C. Activation energy for the mean time to failure (1% relative) of 0.85 eV was determined and a mean time to failure of 8,000 h at 25 degrees C and 85% relative humidity is predicted. No clear trend in maximum degradation as a function of stress temperature was observed.

A quality control method for detecting energy changes of medical accelerators

International Nuclear Information System (INIS)

McGinley, P.H.

2000-01-01

A description is presented of a simple and sensitive method for detecting a change in the energy of the electrons bombarding the target of medical accelerators. This technique is useful for x-ray beams with end point energy in the range of 15.7 to 25 MeV. The method is based on the photoactivation of 16 O and 14 N in a small sample of ammonium nitrate. It was found that the ratio of the activity induced in the oxygen divided by that produced in the nitrogen can be used as a quality control technique to detect a change in the energy of the electrons that bombard the target of the accelerator. An electron energy change of the order of 0.2 MeV can be determined using this method. (author)

SSC accelerator availability allocation

International Nuclear Information System (INIS)

Dixon, K.T.; Franciscovich, J.

1991-03-01

Superconducting Super Collider (SSC) operational availability is an area of major concern, judged by the Central Design Group to present such risk that use of modern engineering tools would be essential to program success. Experience has shown that as accelerator beam availability falls below about 80%, efficiency of physics experiments degrades rapidly due to inability to maintain adequate coincident accelerator and detector operation. For this reason, the SSC availability goal has been set at 80%, even though the Fermi National Accelerator Laboratory accelerator, with a fraction of the SSC's complexity, has only recently approached that level. This paper describes the allocation of the top-level goal to part-level reliability and maintainability requirements, and it gives the results of parameter sensitivity studies designed to help identify the best approach to achieve the needed system availability within funding and schedule constraints. 1 ref., 12 figs., 4 tabs

Preliminary experimental study on the deterioration of cementitious materials by an acceleration method

International Nuclear Information System (INIS)

Saito, H.; Nakane, S.; Ikari, S.; Fujiwara, A.

1992-01-01

Development of a deterioration model for cementitious materials is important in assessing long-term integrity of nuclear waste repositories. The authors preliminarily examined a new test method for acceleration of aging of mortar specimens by application of electrical potential gradients and observed whether the method could throw light on the deterioration process of cementitious materials under repository conditions. As a result, it was concluded that the application of a potential gradient to a mortar specimen might be useful as an accelerated test method for assessing the deterioration behavior of cementitious materials due to leaching. (orig.)

Scalable fast multipole accelerated vortex methods

KAUST Repository

Hu, Qi

2014-05-01

The fast multipole method (FMM) is often used to accelerate the calculation of particle interactions in particle-based methods to simulate incompressible flows. To evaluate the most time-consuming kernels - the Biot-Savart equation and stretching term of the vorticity equation, we mathematically reformulated it so that only two Laplace scalar potentials are used instead of six. This automatically ensuring divergence-free far-field computation. Based on this formulation, we developed a new FMM-based vortex method on heterogeneous architectures, which distributed the work between multicore CPUs and GPUs to best utilize the hardware resources and achieve excellent scalability. The algorithm uses new data structures which can dynamically manage inter-node communication and load balance efficiently, with only a small parallel construction overhead. This algorithm can scale to large-sized clusters showing both strong and weak scalability. Careful error and timing trade-off analysis are also performed for the cutoff functions induced by the vortex particle method. Our implementation can perform one time step of the velocity+stretching calculation for one billion particles on 32 nodes in 55.9 seconds, which yields 49.12 Tflop/s.

Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui, E-mail: sgzhou@soil.gd.cn

2015-08-15

Highlights: • Paddy soil contaminated with benzoate incubated with hematite and magnetite. • Iron oxides addition enhanced methanogenic benzoate degradation by 25–53%. • The facilitated syntrophy might involve direct interspecies electron transfer. • Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved. - Abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH{sub 4} production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

Estimating grass and grass silage degradation characteristics by in situ and in vitro gas production methods

Directory of Open Access Journals (Sweden)

Danijel Karolyi

2010-01-01

Full Text Available Fermentation characteristics of grass and grass silage at different maturities were studied using in situ and in vitro gas production methods. In situ data determined difference between grass and silage. Degradable fraction decreased as grass matured while the undegradable fraction increased. Rate of degradation (kd was slower for silage than fresh grass. Gas production method (GP data showed that fermentation of degradable fraction was different between stage of maturity in both grass and silage. Other data did not show any difference with the exception for the rate of GP of soluble and undegradable fraction. The in situ degradation characteristics were estimated from GP characteristics. The degradable and undegradable fractions could be estimated by multiple relationships. Using the three-phases model for gas production kd and fermentable organic matter could be estimated from the same parameters. The only in situ parameter that could not be estimated with GP parameters was the soluble fraction. The GP method and the three phases model provided to be an alternative to the in situ method for animal feed evaluations.

The generalized PN synthetic acceleration method for linear transport problems with highly anisotropic scattering

International Nuclear Information System (INIS)

Khattab, K.M.

1997-01-01

The diffusion synthetic acceleration (DSA) method has been known to be an effective tool for accelerating the iterative solution of transport equations with isotropic or mildly anisotropic scattering. However, the DSA method is not effective for transport equations that have strongly anisotropic scattering. A generalization of the modified DSA (MDSA) method is proposed that converges (clock time) faster than the MDSA method. This method is developed, the results of a Fourier analysis that theoretically predicts its efficiency are described, and numerical results that verify the theoretical prediction are presented

Photo-oxidative degradation of TiO{sub 2}/polypropylene films

Energy Technology Data Exchange (ETDEWEB)

García-Montelongo, X.L. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael70@yahoo.com.mx [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Vázquez-Rodríguez, S. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Torres-Martínez, Leticia M. [Facultad de Ingeniería Civil, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico)

2014-03-01

Graphical abstract: - Highlights: • Photo-oxidative degradation of polypropylene is accelerated by TiO{sub 2} incorporation. • Weight loss, FTIR, SEM and GPC shown high degree of degradation of polypropylene. • A mechanism of the photo-degradation of polypropylene by TiO{sub 2} is proposed. - Abstract: Photo-oxidative degradation of polypropylene films with TiO{sub 2} nanoparticles incorporated was studied in a chamber of weathering with Xenon lamps as irradiation source. TiO{sub 2} powder with crystalline structure of anatase was synthesized by thermal treatments at 400 and 500 °C starting from a precursor material obtained by sol–gel method. Composites of TiO{sub 2}/polypropylene were prepared with 0.1, 0.5 and 1.0 wt% of TiO{sub 2}. The mixture of components was performed using a twin screw extruder, the resulting material was pelletized by mechanical fragmenting and then hot-pressed in order to form polypropylene films with TiO{sub 2} dispersed homogeneously. Photo-oxidative degradation process was followed by visual inspection, weight loss of films, scanning electron microscopy (SEM), infrared spectroscopy with Fourier transformed (FTIR), and gel permeation chromatography (GPC)

Estimation of Shelf Life “Halua Kenari” Using Accelerated Shelf Life Testing (ASLT) Method Arrhenius Model at Small and Medium Enterprises at Sitaro Archipelago

OpenAIRE

Pongajow, Novke J; Djarkasi, Gregoria S. S; Mandey, Lucia C

2015-01-01

The halua kenari is one of the signature product from North Sulawesi especially Minahasa and Siau. Fat and oil oxidation processes lead to taste and flavor dislike and degradation of nutrition and functional characteristics. Beside chemical composition, halua kenari degradation accelerated by improper handling and packing during transportation, distribution, and storage by consumer and seller. The aims of this research is to predict shelf life of halua kenari production of Small And Medium E...

Acceleration and parallelization calculation of EFEN-SP_3 method

International Nuclear Information System (INIS)

Yang Wen; Zheng Youqi; Wu Hongchun; Cao Liangzhi; Li Yunzhao

2013-01-01

Due to the fact that the exponential function expansion nodal-SP_3 (EFEN-SP_3) method needs further improvement in computational efficiency to routinely carry out PWR whole core pin-by-pin calculation, the coarse mesh acceleration and spatial parallelization were investigated in this paper. The coarse mesh acceleration was built by considering discontinuity factor on each coarse mesh interface and preserving neutron balance within each coarse mesh in space, angle and energy. The spatial parallelization based on MPI was implemented by guaranteeing load balancing and minimizing communications cost to fully take advantage of the modern computing and storage abilities. Numerical results based on a commercial nuclear power reactor demonstrate an speedup ratio of about 40 for the coarse mesh acceleration and a parallel efficiency of higher than 60% with 40 CPUs for the spatial parallelization. With these two improvements, the EFEN code can complete a PWR whole core pin-by-pin calculation with 289 × 289 × 218 meshes and 4 energy groups within 100 s by using 48 CPUs (2.40 GHz frequency). (authors)

Evaluation of HDPE and LDPE degradation by fungus, implemented by statistical optimization

Science.gov (United States)

Ojha, Nupur; Pradhan, Neha; Singh, Surjit; Barla, Anil; Shrivastava, Anamika; Khatua, Pradip; Rai, Vivek; Bose, Sutapa

2017-01-01

Plastic in any form is a nuisance to the well-being of the environment. The ‘pestilence’ caused by it is mainly due to its non-degradable nature. With the industrial boom and the population explosion, the usage of plastic products has increased. A steady increase has been observed in the use of plastic products, and this has accelerated the pollution. Several attempts have been made to curb the problem at large by resorting to both chemical and biological methods. Chemical methods have only resulted in furthering the pollution by releasing toxic gases into the atmosphere; whereas; biological methods have been found to be eco-friendly however they are not cost effective. This paves the way for the current study where fungal isolates have been used to degrade polyethylene sheets (HDPE, LDPE). Two potential fungal strains, namely, Penicillium oxalicum NS4 (KU559906) and Penicillium chrysogenum NS10 (KU559907) had been isolated and identified to have plastic degrading abilities. Further, the growth medium for the strains was optimized with the help of RSM. The plastic sheets were subjected to treatment with microbial culture for 90 days. The extent of degradation was analyzed by, FE-SEM, AFM and FTIR. Morphological changes in the plastic sheet were determined.

Evaluation of HDPE and LDPE degradation by fungus, implemented by statistical optimization.

Science.gov (United States)

Ojha, Nupur; Pradhan, Neha; Singh, Surjit; Barla, Anil; Shrivastava, Anamika; Khatua, Pradip; Rai, Vivek; Bose, Sutapa

2017-01-04

Plastic in any form is a nuisance to the well-being of the environment. The 'pestilence' caused by it is mainly due to its non-degradable nature. With the industrial boom and the population explosion, the usage of plastic products has increased. A steady increase has been observed in the use of plastic products, and this has accelerated the pollution. Several attempts have been made to curb the problem at large by resorting to both chemical and biological methods. Chemical methods have only resulted in furthering the pollution by releasing toxic gases into the atmosphere; whereas; biological methods have been found to be eco-friendly however they are not cost effective. This paves the way for the current study where fungal isolates have been used to degrade polyethylene sheets (HDPE, LDPE). Two potential fungal strains, namely, Penicillium oxalicum NS4 (KU559906) and Penicillium chrysogenum NS10 (KU559907) had been isolated and identified to have plastic degrading abilities. Further, the growth medium for the strains was optimized with the help of RSM. The plastic sheets were subjected to treatment with microbial culture for 90 days. The extent of degradation was analyzed by, FE-SEM, AFM and FTIR. Morphological changes in the plastic sheet were determined.

Accelerated in vitro release testing of implantable PLGA microsphere/PVA hydrogel composite coatings.

Science.gov (United States)

Shen, Jie; Burgess, Diane J

2012-01-17

Dexamethasone loaded poly(lactic-co-glycolic acid) (PLGA) microsphere/PVA hydrogel composites have been investigated as an outer drug-eluting coating for implantable devices such as glucose sensors to counter negative tissue responses to implants. The objective of this study was to develop a discriminatory, accelerated in vitro release testing method for this drug-eluting coating using United States Pharmacopeia (USP) apparatus 4. Polymer degradation and drug release kinetics were investigated under "real-time" and accelerated conditions (i.e. extreme pH, hydro-alcoholic solutions and elevated temperatures). Compared to "real-time" conditions, the initial burst and lag phases were similar using hydro-alcoholic solutions and extreme pH conditions, while the secondary apparent zero-order release phase was slightly accelerated. Elevated temperatures resulted in a significant acceleration of dexamethasone release. The accelerated release data were able to predict "real-time" release when applying the Arrhenius equation. Microsphere batches with faster and slower release profiles were investigated under "real-time" and elevated temperature (60°C) conditions to determine the discriminatory ability of the method. The results demonstrated both the feasibility and the discriminatory ability of this USP apparatus 4 method for in vitro release testing of drug loaded PLGA microsphere/PVA hydrogel composites. This method may be appropriate for similar drug/device combination products and drug delivery systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Degradation Analysis of NBR and Epichlorohydrin Rubber by New Micro Analysis Method

Science.gov (United States)

Katoh, Hisao; Kamoto, Ritsu; Murata, Jun

The degradation analysis of NBR and Epichlorohydrin rubber was carried out by infrared micro spectroscopy (μ-IR) and micro sampling mass spectrometry (μ-MS) which gives information on the scission and crosslinking of rubber molecules. Samples were prepared by three different treatments, heat as well as ultra violet (UV) and electron beam (EB) irradiations. It was found for NBR vulcanizates that the heat treatment induced the oxidation, scission and crosslinking of rubber molecules. By the UV treatment, chain scission and crosslinking accompanied by a slight oxidation were induced. The EB treatment enhanced the crosslinking, however, the extent of oxidation was negligible. For Epichlorohydrin rubber vulcanizates, the heat treatment accelerated chain scission rather than crosslinking. On the other hand, the oxidation and crosslinking were induced by the UV and EB treatments.

Simplified MPN method for enumeration of soil naphthalene degraders using gaseous substrate.

Science.gov (United States)

Wallenius, Kaisa; Lappi, Kaisa; Mikkonen, Anu; Wickström, Annika; Vaalama, Anu; Lehtinen, Taru; Suominen, Leena

2012-02-01

We describe a simplified microplate most-probable-number (MPN) procedure to quantify the bacterial naphthalene degrader population in soil samples. In this method, the sole substrate naphthalene is dosed passively via gaseous phase to liquid medium and the detection of growth is based on the automated measurement of turbidity using an absorbance reader. The performance of the new method was evaluated by comparison with a recently introduced method in which the substrate is dissolved in inert silicone oil and added individually to each well, and the results are scored visually using a respiration indicator dye. Oil-contaminated industrial soil showed slightly but significantly higher MPN estimate with our method than with the reference method. This suggests that gaseous naphthalene was dissolved in an adequate concentration to support the growth of naphthalene degraders without being too toxic. The dosing of substrate via gaseous phase notably reduced the work load and risk of contamination. The result scoring by absorbance measurement was objective and more reliable than measurement with indicator dye, and it also enabled further analysis of cultures. Several bacterial genera were identified by cloning and sequencing of 16S rRNA genes from the MPN wells incubated in the presence of gaseous naphthalene. In addition, the applicability of the simplified MPN method was demonstrated by a significant positive correlation between the level of oil contamination and the number of naphthalene degraders detected in soil.

Degradation of pollutants and elimination of pathogens of waste water by adsorption of accelerated electrons

International Nuclear Information System (INIS)

Martinez M, I.

1991-10-01

This report presents a position of the pollutants degradation of the industrial residual waters, it intends a method that consists on making pass residual water, treated biologically by a packed column with activated carbon. The carbon retains the pollutants and the water goes out with a purity that allows the reuse. In simultaneous form to the adsorption of pollutants are made pass electrons through the column of carbon, the electrons will destroy to the polluting adsorbed in the carbon; the pollutants degrade until CO 2 that escapes as gas. The active sites of the carbon are empty and clever to be occupied by other pollutants. This process is continuous and it is repeated while water is passing by the column and electrons through this. (Author)

Non-Maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in Non-Inertial Frames

International Nuclear Information System (INIS)

Khan, Salman; Khan, Niaz Ali; Khan, M.K.

2014-01-01

The π-tangle is used to study the behavior of entanglement of a nonmaximal tripartite state of both Dirac and scalar fields in accelerated frame. For Dirac fields, the degree of degradation with acceleration of both one-tangle of accelerated observer and π-tangle, for the same initial entanglement, is different by just interchanging the values of probability amplitudes. A fraction of both one-tangles and the π-tangle always survives for any choice of acceleration and the degree of initial entanglement. For scalar field, the one-tangle of accelerated observer depends on the choice of values of probability amplitudes and it vanishes in the range of infinite acceleration, whereas for π-tangle this is not always true. The dependence of π-tangle on probability amplitudes varies with acceleration. In the lower range of acceleration, its behavior changes by switching between the values of probability amplitudes and for larger values of acceleration this dependence on probability amplitudes vanishes. Interestingly, unlike bipartite entanglement, the degradation of π-tangle against acceleration in the case of scalar fields is slower than for Dirac fields. (general)

Use of the preconditioned conjugate gradient method to accelerate S/sub n/ iterations

International Nuclear Information System (INIS)

Derstine, K.L.; Gelbard, E.M.

1985-01-01

It is well known that specially tailored diffusion difference equations are required in the synthetic method. The tailoring process is not trivial, and for some S/sub n/ schemes (e.g., in hexagonal geometry) tailored diffusion operators are not available. The need for alternative acceleration methods has been noted by Larsen who has, in fact, proposed two alternatives. The proposed methods, however, do not converge to the S/sub n/ solution, and their accuracy is still largely unknown. Los Alamos acceleration methods are required to converge for any mesh, no matter how coarse. Since negative flux-fix ups (normally involved when mesh widths are large) may impede convergence, it is not clear that such a strict condition is really practical. Here a lesser objective is chosen. The authors wish to develop an acceleration method useful for a wide (though finite) range of mesh widths, but to avoid the use of special diffusion difference equations. It is shown that the conjugate gradient (CG) method, with the standard box-centered (BC) diffusion equation as a preconditioner, yields an algorithm that, for fixed-source problems with isotropic scattering, is mechanically very similar to the synthetic method; but, in two-dimensional test problems in various geometries, the CG method is substantially more stable

Novel methods in the Particle-In-Cell accelerator Code-Framework Warp

Energy Technology Data Exchange (ETDEWEB)

Vay, J-L [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Grote, D. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cohen, R. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Friedman, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2012-12-26

The Particle-In-Cell (PIC) Code-Framework Warp is being developed by the Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) to guide the development of accelerators that can deliver beams suitable for high-energy density experiments and implosion of inertial fusion capsules. It is also applied in various areas outside the Heavy Ion Fusion program to the study and design of existing and next-generation high-energy accelerators, including the study of electron cloud effects and laser wakefield acceleration for example. This study presents an overview of Warp's capabilities, summarizing recent original numerical methods that were developed by the HIFS-VNL (including PIC with adaptive mesh refinement, a large-timestep 'drift-Lorentz' mover for arbitrarily magnetized species, a relativistic Lorentz invariant leapfrog particle pusher, simulations in Lorentz-boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride-based digital filtering), with special emphasis on the description of the mesh refinement capability. In addition, selected examples of the applications of the methods to the abovementioned fields are given.

A comparative study of accelerated tests to simulate atmospheric corrosion

International Nuclear Information System (INIS)

Assis, Sergio Luiz de

2000-01-01

In this study, specimens coated with five organic coating systems were exposed to accelerated tests for periods up to 2000 hours, and also to weathering for two years and six months. The accelerated tests consisted of the salt spray test, according to ASTM B-117; Prohesion (ASTM G 85-98 annex 5A); Prohesion combined with cyclic exposure to UV-A radiation and condensation; 'Prohchuva' a test described by ASTM G 85-98 using a salt spray with composition that simulated the acid rain of Sao Paulo, but one thousand times more concentrated, and 'Prohchuva' combined with cyclic exposure to UV-A radiation and condensation. The coated specimens were exposed with and without incision to expose the substrate. The onset and progress of corrosion at and of the exposed metallic surface, besides coating degradation, were followed by visual observation, and photographs were taken. The coating systems were classified according to the extent of corrosion protection given to the substrate, using a method based on ASTM standards D-610, D-714, D-1654 and D-3359. The rankings of the coatings obtained from accelerated tests and weathering were compared and contrasted with classification of the same systems obtained from literature, for specimens exposed to an industrial atmosphere. Coating degradation was strongly dependent on the test, and could be attributed to differences in test conditions. The best correlation between accelerated test and weathering was found for the test Prohesion alternated with cycles of exposure to UV-A radiation and condensation. (author)

An FDTD method with FFT-accelerated exact absorbing boundary conditions

KAUST Repository

Sirenko, Kostyantyn

2011-07-01

An accurate and efficient finite-difference time-domain (FDTD) method for analyzing axially symmetric structures is presented. The method achieves its accuracy and efficiency using exact absorbing conditions (EACs) for terminating the computation domain and a blocked-FFT based scheme for accelerating the computation of the temporal convolutions present in non-local EACs. The method is shown to be especially useful in characterization of long-duration resonant wave interactions. © 2011 IEEE.

Research on degradation of vacuum O-rings under gamma radiation

CERN Document Server

Ino, H; Saitô, Y; Kubo, T; Kinsho, M

2003-01-01

The high-intensity proton accelerator being constructed by JAERI and KEK will generates greater beam power than conventional accelerators. The radiation emission due to beam losses will therefore increase. Since vacuum O-rings installed in the accelerator will be degraded badly by the radiation, there is need to find an O-ring that has more resistant to radiation. To find an O-ring that has better radiation resistant than that of the fluororubber used for conventional accelerators in general, some O-rings which are expected to have enough resistant to the radiation were irradiated, and estimated a degradation by measurement of outgassing rate, hardness, permeation time of helium gas, and an outward observation. Most of the O-rings were irradiated in an oxygen free atmosphere and in the air. The irradiations were carried out at room temperature in Co-60 gamma irradiation facility until a dose of 1 MGy was reached. The radiation resistance of PURE-RUBBER O-ring showed somewhat better than that of the fluororubb...

Accelerating the degradation of green plant waste with chemical decomposition agents.

Science.gov (United States)

Kejun, Sun; Juntao, Zhang; Ying, Chen; Zongwen, Liao; Lin, Ruan; Cong, Liu

2011-10-01

Degradation of green plant waste is often difficult, and excess maturity times are typically required. In this study, we used lignin, cellulose and hemicellulose assays; scanning electron microscopy; infrared spectrum analysis and X-ray diffraction analysis to investigate the effects of chemical decomposition agents on the lignocellulose content of green plant waste, its structure and major functional groups and the mechanism of accelerated degradation. Our results showed that adding chemical decomposition agents to Ficus microcarpa var. pusillifolia sawdust reduced the contents of lignin by 0.53%-11.48% and the contents of cellulose by 2.86%-7.71%, and increased the contents of hemicellulose by 2.92%-33.63% after 24 h. With increasing quantities of alkaline residue and sodium lignosulphonate, the lignin content decreased. Scanning electron microscopy showed that, after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, lignocellulose tube wall thickness increased significantlyIncreases of 29.41%, 3.53% and 34.71% were observed after treatment with NaOH, alkaline residue and sodium lignosulphonate, respectively. Infrared spectroscopy showed that CO and aromatic skeleton stretching absorption peaks were weakened and the C-H vibrational absorption peak from out-of-plane in positions 2 and 6 (S units) (890-900 cm(-1)) was strengthened after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, indicating a reduction in lignin content. Several absorption peaks [i.e., C-H deformations (asymmetry in methyl groups, -CH(3)- and -CH(2)-) (1450-1460 cm(-1)); Aliphatic C-H stretching in methyl and phenol OH (1370-1380 cm(-1)); CO stretching (cellulose and hemicellulose) (1040-1060 cm(-1))] that indicate the presence of a chemical bond between lignin and cellulose was reduced, indicating that the chemical bond between lignin and cellulose had been partially broken. X-ray diffraction analysis showed that Na

Method for determination of methyl tert-butyl ether and its degradation products in water

Science.gov (United States)

Church, C.D.; Isabelle, L.M.; Pankow, J.F.; Rose, D.L.; Tratnyek, P.G.

1997-01-01

An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method

Activation of persulfate/copper by hydroxylamine via accelerating the cupric/cuprous redox couple.

Science.gov (United States)

Zhou, Peng; Zhang, Jing; Liang, Juan; Zhang, Yongli; Liu, Ya; Liu, Bei

2016-01-01

Cuprous copper [Cu(I)] reacts with sodium persulfate (PDS) to generate sulfate radical SO4(-)•, but it has been seldom investigated owing to its instability and difficulty in dissolving it. This study proposes a new method to regenerate Cu(I) from cupric copper [Cu(II)] by addition of hydroxylamine (HA) to induce the continuous production of radicals through active PDS, and investigates the resulting enhanced methyl orange (MO) degradation efficiency and mechanism in the new system. HA accelerated the degradation of MO markedly in the pH range from 6.0 to 8.0 in the HA/Cu(II)/PDS process. Both SO4(-)• and hydroxyl radicals (•OH) were considered as the primary reactive radicals in the process. The MO degradation in the HA/Cu(II)/PDS process can be divided into three stages: the fast stage, the transitory stage, and the low stage. MO degradation was enhanced with increased dosage of PDS. Although high dosage of HA could accelerate the transformation of the Cu(II)/Cu(I) cycle to produce more reactive radicals, excess HA can quench the reactive radicals. This study indicates that through a copper-redox cycling mechanism by HA, the production of SO4(-)• and •OH can be strongly enhanced, and the effective pH range can be expanded to neutral conditions.

An accelerated stress testing program for determining the reliability sensitivity of silicon solar cells to encapsulation and metallization systems

Science.gov (United States)

Lathrop, J. W.; Davis, C. W.; Royal, E.

1982-01-01

The use of accelerated testing methods in a program to determine the reliability attributes of terrestrial silicon solar cells is discussed. Different failure modes are to be expected when cells with and without encapsulation are subjected to accelerated testing and separate test schedules for each are described. Unencapsulated test cells having slight variations in metallization are used to illustrate how accelerated testing can highlight different diffusion related failure mechanisms. The usefulness of accelerated testing when applied to encapsulated cells is illustrated by results showing that moisture related degradation may be many times worse with some forms of encapsulation than with no encapsulation at all.

Life estimation I and C cable insulation materials based on accelerated life testing accelerated life testing

International Nuclear Information System (INIS)

Santhosh, T.V.; Ramteke, P.K.; Shrestha, N.B.; Ahirwar, A.K.; Gopika, V.

2016-01-01

Accelerated Iife tests are becoming increasingly popular in today's industry due to the need for obtaining life data quickly and reliably. Life testing of products under higher stress levels without introducing additional failure modes can provide significant savings of both time and money. Correct analysis of data gathered via such accelerated life testing will yield parameters and other information for the product's life under use stress conditions. To be of practical use in assessing the operational behaviour of cables in NPPs, laboratory ageing aims to mimic the type of degradation observed under operational conditions. Conditions of testing therefore need to be carefully chosen to ensure that the degradation mechanism occurring in the accelerated tests are similar to those which occur in service. This paper presents the results of an investigation in which the elongation-at-break (EAB) measurements were carried on a typical control cable to predict the mean life at service conditions. A low voltage polyvinyl chloride (PVC) insulated and PVC sheathed control cable, used in NPP instrumentation and control (I and C) applications, was subjected thermal ageing at three elevated temperatures

Evaluation of HDPE and LDPE degradation by fungus, implemented by statistical optimization

OpenAIRE

Ojha, Nupur; Pradhan, Neha; Singh, Surjit; Barla, Anil; Shrivastava, Anamika; Khatua, Pradip; Rai, Vivek; Bose, Sutapa

2017-01-01

Plastic in any form is a nuisance to the well-being of the environment. The ?pestilence? caused by it is mainly due to its non-degradable nature. With the industrial boom and the population explosion, the usage of plastic products has increased. A steady increase has been observed in the use of plastic products, and this has accelerated the pollution. Several attempts have been made to curb the problem at large by resorting to both chemical and biological methods. Chemical methods have only r...

The generalized PN synthetic acceleration method for linear transport problems with highly anisotropic scattering

International Nuclear Information System (INIS)

Khattab, K.M.

1998-01-01

The diffusion synthetic acceleration (DSA) method has been known to be an effective tool for accelerating the iterative solution of transport equations with isotopic or mildly anisotropic scattering. However, the DSA method is not effective for transport equations that have strongly anisotropic scattering. A generalization of the modified DSA (MDSA) methods is proposed. This method converges (Clock time) faster than the MDSA method. It is developed, the results of a Fourier analysis that theoretically predicts its efficiency are described, and numerical results that verify the theoretical prediction are presented. (author). 9 refs., 2 tabs., 5 figs

Catalyst Degradation Under Potential Cycling as an Accelerated Stress Test for PBI-Based High-Temperature PEM Fuel Cells - Effect of Humidification

DEFF Research Database (Denmark)

Søndergaard, Tonny; Cleemann, Lars Nilausen; Zhong, Lijie

2018-01-01

In the present work, high-temperature polymer electrolyte membrane fuel cells were subjected to accelerated stress tests of 30,000 potential cycles between 0.6 and 1.0 V at 160 textdegreeC (133 h cycling time). The effect that humidity has on the catalyst durability was studied by testing either...... with or without humidification of the nitrogen that was used as cathode gas during cycling segments. Pronounced degradation was seen from the polarization curves in both cases, though permanent only in the humidified case. In the unhumidified case, the performance loss was more or less recoverable following 24 h...

Using Uncertainty Analysis to Guide the Development of Accelerated Stress Tests (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Kempe, M.

2014-03-01

Extrapolation of accelerated testing to the long-term results expected in the field has uncertainty associated with the acceleration factors and the range of possible stresses in the field. When multiple stresses (such as temperature and humidity) can be used to increase the acceleration, the uncertainty may be reduced according to which stress factors are used to accelerate the degradation.

Review of Acceleration Methods for Seismic Analysis of Through-Wall Cracked Piping from the Viewpoint of Linear Elastic Fracture Mechanics

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Sung; Kim, Yong Woo [Sunchon National University, Suncheon (Korea, Republic of)

2014-10-15

Two acceleration methods, an effective force method (or inertia method) and a large mass method, have been applied for performing time history seismic analysis. The acceleration methods for uncracked structures have been verified via previous studies. However, no study has identified the validity of these acceleration methods for cracked piping. In this study, the validity of the acceleration methods for through-wall cracked piping is assessed via time history implicit dynamic elastic seismic analysis from the viewpoint of linear elastic fracture mechanics. As a result, it is identified that both acceleration methods show the same results for cracked piping if a large mass magnitude and maximum time increment are adequately selected.

Review of Acceleration Methods for Seismic Analysis of Through-Wall Cracked Piping from the Viewpoint of Linear Elastic Fracture Mechanics

International Nuclear Information System (INIS)

Kim, Jong Sung; Kim, Yong Woo

2014-01-01

Two acceleration methods, an effective force method (or inertia method) and a large mass method, have been applied for performing time history seismic analysis. The acceleration methods for uncracked structures have been verified via previous studies. However, no study has identified the validity of these acceleration methods for cracked piping. In this study, the validity of the acceleration methods for through-wall cracked piping is assessed via time history implicit dynamic elastic seismic analysis from the viewpoint of linear elastic fracture mechanics. As a result, it is identified that both acceleration methods show the same results for cracked piping if a large mass magnitude and maximum time increment are adequately selected

Development and evaluation of accelerated drug release testing methods for a matrix-type intravaginal ring.

Science.gov (United States)

Externbrink, Anna; Eggenreich, Karin; Eder, Simone; Mohr, Stefan; Nickisch, Klaus; Klein, Sandra

2017-01-01

Accelerated drug release testing is a valuable quality control tool for long-acting non-oral extended release formulations. Currently, several intravaginal ring candidates designed for the long-term delivery of steroids or anti-infective drugs are being in the developing pipeline. The present article addresses the demand for accelerated drug release methods for these formulations. We describe the development and evaluation of accelerated release methods for a steroid releasing matrix-type intravaginal ring. The drug release properties of the formulation were evaluated under real-time and accelerated test conditions. Under real-time test conditions drug release from the intravaginal ring was strongly affected by the steroid solubility in the release medium. Under sufficient sink conditions that were provided in release media containing surfactants drug release was Fickian diffusion driven. Both temperature and hydro-organic dissolution media were successfully employed to accelerate drug release from the formulation. Drug release could be further increased by combining the temperature effect with the application of a hydro-organic release medium. The formulation continued to exhibit a diffusion controlled release kinetic under the investigated accelerated conditions. Moreover, the accelerated methods were able to differentiate between different prototypes of the intravaginal ring that exhibited different release profiles under real-time test conditions. Overall, the results of the present study indicate that both temperature and hydro-organic release media are valid parameters for accelerating drug release from the intravaginal ring. Variation of either a single or both parameters yielded release profiles that correlated well with real-time release. Copyright © 2016 Elsevier B.V. All rights reserved.

Degradation diagnosing method for low voltage electric wire and cable in nuclear facility

International Nuclear Information System (INIS)

Kamimura, Seiji; Seki, Ikuo; Yagyu, Hideki; Onishi, Takao; Kusama, Yasuo.

1991-01-01

A considerable skill is required for a visual inspection method which has been used most widely for determining the degradation of low voltage electric wires and cables used mostly in facilities such as nuclear power plants. It is extremely difficult to determine the degradation accurately and appropriately even for skilled inspectors because of individual difference. Then, a small amount of organic insulation materials is taken as a sample from insulators or sheath materials actually disposed. The pyrolytic temperature of the sample is measured by thermal gravimetric analysis to determine the extent of the degradation of the electric wire and cable based on the relationship between the degradation and the elongation. Since there is a close relationship between the temperature at which the measured weight of the sample is reduced by 5% and the degradation behavior of the mechanical property, analysis can be conducted effectively by an extremely small amount of the sample. Since the insulation degradation of relatively low voltage electric wires and cables can be determined in a non-destructive manner at high accuracy, the lifetime can be forecasted. (N.H.)

Monitoring Low-Cycle Fatigue Material-Degradation by Ultrasonic Methods

Directory of Open Access Journals (Sweden)

R. Himawan

2010-08-01

Full Text Available Any system consisting of structural material often undergoes fatigue, which is caused by dynamic load cycle. As a structural system, nuclear power plant is very likely to have low-cycle fatigue at many of its components. Taking into account the importance of monitoring low-cycle fatigue on structural components to prevent them from getting failure, the authors have conducted a work to monitor material degradation caused by low-cycle fatigue by using ultrasonic method. An alloy of Cu-40Zn was used as a test specimen. Ultrasonic water immersion procedure was employed in this ultrasonic test. The probe used is a focusing type and has frequency as high as 15 MHz. The specimen area tested is in the middle part divided into 14 points × 23 points. The results, which were frequency spectrums, were analyzed using two parameters: frequency spectrum peak intensity and attenuation function gradient. The analysis indicates that peak intensity increases at the beginning of load cycle and then decreases. Meanwhile, gradient of attenuation function is lower at the beginning of fatigue process, and then consistently gets higher. It concludes that low-fatigue material degradation can be monitored by using ultrasonic method.

Environmental impact assessment methods of the radiation generated by the runing medical linear accelerator

International Nuclear Information System (INIS)

Yin haihua; Yao Zhigang

2014-01-01

This article describes the environmental impact assessment methods of the radiation generated by the runing. medical linear accelerator. The material and thickness of shielding wall and protective doors of the linear accelerator were already knew, therefore we can evaluate the radiation by the runing. medical linear accelerator whether or not in the normal range of national standard by calculating the annual effective radiation dose of the surrounding personnel suffered. (authors)

Study of variables for accelerating lifetime testing of SOFCs

DEFF Research Database (Denmark)

Ploner, Alexandra; Hagen, Anke; Hauch, Anne

Solid oxide fuel cell (SOFC) applications require lifetimes of several years on the system level. A big challenge is to proof/confirm/demonstrate such exceptionally long lifetimes.Accelerated or compressed testing are possible methods. Activities in this area have been carried out without arriving...... at different current load cycling profiles revealed a strong deviation between predicted and measured lifetime [3].In this study, we present a detailed analysis of durability results for degradation mechanisms of single SOFC components as function of operating conditions. Electrochemical impedance data...

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

Science.gov (United States)

Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

2017-07-01

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

CMADR acceleration and its convergence analysis of the method of characteristics for neutron transport calculation

International Nuclear Information System (INIS)

Young, Ryong Park; Nam, Zin Cho

2005-01-01

As the nuclear reactor core becomes more complex, heterogeneous, and geometrically irregular, the method of characteristics (MOC) is gaining its wide use in the neutron transport calculations. However, the long computing times require good acceleration methods. In this paper, the concept of coarse-mesh angular dependent re-balance (CMADR) acceleration is described and applied to the MOC calculation in x-y-z (z-infinite, uniform) geometry. The method is based on the angular dependent re-balance factors defined only on the coarse-mesh boundaries; a coarse-mesh consists of several fine meshes that may be heterogeneous and of mixed geometries with irregular or unstructured mesh shapes. In addition, the coarse-mesh boundaries may not coincide with the structural interfaces of the problem and can be chosen artificially for convenience. CMADR acceleration is tested on several test problems and the results show that CMADR is very effective in reducing the number of iterations and computing times of MOC calculations. Fourier analysis is also provided to investigate convergence of the CMADR method analytically and the results show that CMADR acceleration is unconditionally stable. (authors)

Abiotic degradation of plastic films

Science.gov (United States)

Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

2017-01-01

Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

Formulation of nonlinear chromaticity in circular accelerators by canonical perturbation method

International Nuclear Information System (INIS)

Takao, Masaru

2005-01-01

The formulation of nonlinear chromaticity in circular accelerators based on the canonical perturbation method is presented. Since the canonical perturbation method directly relates the tune shift to the perturbation Hamiltonian, it greatly simplifies the calculation of the nonlinear chromaticity. The obtained integral representation for nonlinear chromaticity can be systematically extended to higher orders

Monte Carlo method for calculating the radiation skyshine produced by electron accelerators

Energy Technology Data Exchange (ETDEWEB)

Kong Chaocheng [Department of Engineering Physics, Tsinghua University Beijing 100084 (China)]. E-mail: kongchaocheng@tsinghua.org.cn; Li Quanfeng [Department of Engineering Physics, Tsinghua University Beijing 100084 (China); Chen Huaibi [Department of Engineering Physics, Tsinghua University Beijing 100084 (China); Du Taibin [Department of Engineering Physics, Tsinghua University Beijing 100084 (China); Cheng Cheng [Department of Engineering Physics, Tsinghua University Beijing 100084 (China); Tang Chuanxiang [Department of Engineering Physics, Tsinghua University Beijing 100084 (China); Zhu Li [Laboratory of Radiation and Environmental Protection, Tsinghua University, Beijing 100084 (China); Zhang Hui [Laboratory of Radiation and Environmental Protection, Tsinghua University, Beijing 100084 (China); Pei Zhigang [Laboratory of Radiation and Environmental Protection, Tsinghua University, Beijing 100084 (China); Ming Shenjin [Laboratory of Radiation and Environmental Protection, Tsinghua University, Beijing 100084 (China)

2005-06-01

Using the MCNP4C Monte Carlo code, the X-ray skyshine produced by 9 MeV, 15 MeV and 21 MeV electron linear accelerators were calculated respectively with a new two-step method combined with the split and roulette variance reduction technique. Results of the Monte Carlo simulation, the empirical formulas used for skyshine calculation and the dose measurements were analyzed and compared. In conclusion, the skyshine dose measurements agreed reasonably with the results computed by the Monte Carlo method, but deviated from computational results given by empirical formulas. The effect on skyshine dose caused by different structures of accelerator head is also discussed in this paper.

Method of phorbol ester degradation in Jatropha curcas L. seed cake using rice bran lipase.

Science.gov (United States)

Hidayat, Chusnul; Hastuti, Pudji; Wardhani, Avita Kusuma; Nadia, Lana Santika

2014-03-01

A novel enzymatic degradation of phorbol esters (PE) in the jatropha seed cake was developed using lipase. Cihera rice bran lipase had the highest ability to hydrolyze PE, and reduced PE to a safe level after 8 h of incubation. Enzymatic degradation may be a promising method for PE degradation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Comparing joint kinematics and center of mass acceleration as feedback for control of standing balance by functional neuromuscular stimulation

Directory of Open Access Journals (Sweden)

Nataraj Raviraj

2012-05-01

Full Text Available Abstract Background The purpose of this study was to determine the comparative effectiveness of feedback control systems for maintaining standing balance based on joint kinematics or total body center of mass (COM acceleration, and assess their clinical practicality for standing neuroprostheses after spinal cord injury (SCI. Methods In simulation, controller performance was measured according to the upper extremity effort required to stabilize a three-dimensional model of bipedal standing against a variety of postural disturbances. Three cases were investigated: proportional-derivative control based on joint kinematics alone, COM acceleration feedback alone, and combined joint kinematics and COM acceleration feedback. Additionally, pilot data was collected during external perturbations of an individual with SCI standing with functional neuromuscular stimulation (FNS, and the resulting joint kinematics and COM acceleration data was analyzed. Results Compared to the baseline case of maximal constant muscle excitations, the three control systems reduced the mean upper extremity loading by 51%, 43% and 56%, respectively against external force-pulse perturbations. Controller robustness was defined as the degradation in performance with increasing levels of input errors expected with clinical deployment of sensor-based feedback. At error levels typical for body-mounted inertial sensors, performance degradation due to sensor noise and placement were negligible. However, at typical tracking error levels, performance could degrade as much as 86% for joint kinematics feedback and 35% for COM acceleration feedback. Pilot data indicated that COM acceleration could be estimated with a few well-placed sensors and efficiently captures information related to movement synergies observed during perturbed bipedal standing following SCI. Conclusions Overall, COM acceleration feedback may be a more feasible solution for control of standing with FNS given its

Acceleration methods for multi-physics compressible flow

Science.gov (United States)

Peles, Oren; Turkel, Eli

2018-04-01

In this work we investigate the Runge-Kutta (RK)/Implicit smoother scheme as a convergence accelerator for complex multi-physics flow problems including turbulent, reactive and also two-phase flows. The flows considered are subsonic, transonic and supersonic flows in complex geometries, and also can be either steady or unsteady flows. All of these problems are considered to be a very stiff. We then introduce an acceleration method for the compressible Navier-Stokes equations. We start with the multigrid method for pure subsonic flow, including reactive flows. We then add the Rossow-Swanson-Turkel RK/Implicit smoother that enables performing all these complex flow simulations with a reasonable CFL number. We next discuss the RK/Implicit smoother for time dependent problem and also for low Mach numbers. The preconditioner includes an intrinsic low Mach number treatment inside the smoother operator. We also develop a modified Roe scheme with a corresponding flux Jacobian matrix. We then give the extension of the method for real gas and reactive flow. Reactive flows are governed by a system of inhomogeneous Navier-Stokes equations with very stiff source terms. The extension of the RK/Implicit smoother requires an approximation of the source term Jacobian. The properties of the Jacobian are very important for the stability of the method. We discuss what the chemical physics theory of chemical kinetics tells about the mathematical properties of the Jacobian matrix. We focus on the implication of the Le-Chatelier's principle on the sign of the diagonal entries of the Jacobian. We present the implementation of the method for turbulent flow. We use a two RANS turbulent model - one equation model - Spalart-Allmaras and a two-equation model - k-ω SST model. The last extension is for two-phase flows with a gas as a main phase and Eulerian representation of a dispersed particles phase (EDP). We present some examples for such flow computations inside a ballistic evaluation

Accelerating Rate Calorimetry Tests of Lithium-Ion Cells Before and After Storage Degradation at High Temperature

Directory of Open Access Journals (Sweden)

Mendoza-Hernandez Omar Samuel

2017-01-01

Full Text Available Understanding the behavior of Li-ion cells during thermal runaway is critical to evaluate the safety of these energy storage devices under outstanding conditions. Li-ion cells possess a high energy density and are used to store and supply energy to many aerospace applications. Incidents related to the overheating or thermal runaway of these cells can cause catastrophic damages that could end up costly space missions; therefore, thermal studies of Li-ion cells are very important for ensuring safety and reliability of space missions. This work evaluates the thermal behavior of Li-ion cells before and after storage degradation at high temperature using accelerating rate calorimeter (ARC equipment to analyze the thermal behavior of Li-ion cells under adiabatic conditions. Onset temperature points of self-heating and thermal runaway reactions are obtained. The onset points are used to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge. The results obtained can be useful to develop accurate thermo-electrochemical models of Li-ion cells.

Method of correcting eddy current magnetic fields in particle accelerator vacuum chambers

Science.gov (United States)

Danby, Gordon T.; Jackson, John W.

1991-01-01

A method for correcting magnetic field aberrations produced by eddy currents induced in a particle accelerator vacuum chamber housing is provided wherein correction windings are attached to selected positions on the housing and the windings are energized by transformer action from secondary coils, which coils are inductively coupled to the poles of electro-magnets that are powered to confine the charged particle beam within a desired orbit as the charged particles are accelerated through the vacuum chamber by a particle-driving rf field. The power inductively coupled to the secondary coils varies as a function of variations in the power supplied by the particle-accelerating rf field to a beam of particles accelerated through the vacuum chamber, so the current in the energized correction coils is effective to cancel eddy current flux fields that would otherwise be induced in the vacuum chamber by power variations in the particle beam.

Different Spectrophotometric Methods for Simultaneous Determination of Trelagliptin and Its Acid Degradation Product

Science.gov (United States)

Hassan, Mostafa A.; Zaghary, Wafaa A.

2018-01-01

New spectrophotometric and chemometric methods were carried out for the simultaneous assay of trelagliptin (TRG) and its acid degradation product (TAD) and applied successfully as a stability indicating assay to recently approved Zafatek® tablets. TAD was monitored using TLC to ensure complete degradation. Furthermore, HPLC was used to confirm dealing with one major acid degradation product. The proposed methods were developed by manipulating zero-order, first-derivative, and ratio spectra of TRG and TAD using simultaneous equation, first-derivative, and mean-centering methods, respectively. Using Spectra Manager II and Minitab v.14 software, the absorbance at 274 nm–260.4 nm, amplitudes at 260.4 nm–274.0 nm, and mean-centered values at 287.6 nm–257.2 nm were measured against methanol as a blank for TRG and TAD, respectively. Linearity and the other validation parameters were acceptable at concentration ranges of 5–50 μg/mL and 2.5–25 μg/mL for TRG and TAD, respectively. Using one-way analysis of variance (ANOVA), the optimized methods were compared and proved to be accurate for the simultaneous assay of TRG and TAD. PMID:29629213

An acceleration technique for 2D MOC based on Krylov subspace and domain decomposition methods

International Nuclear Information System (INIS)

Zhang Hongbo; Wu Hongchun; Cao Liangzhi

2011-01-01

Highlights: → We convert MOC into linear system solved by GMRES as an acceleration method. → We use domain decomposition method to overcome the inefficiency on large matrices. → Parallel technology is applied and a matched ray tracing system is developed. → Results show good efficiency even in large-scale and strong scattering problems. → The emphasis is that the technique is geometry-flexible. - Abstract: The method of characteristics (MOC) has great geometrical flexibility but poor computational efficiency in neutron transport calculations. The generalized minimal residual (GMRES) method, a type of Krylov subspace method, is utilized to accelerate a 2D generalized geometry characteristics solver AutoMOC. In this technique, a form of linear algebraic equation system for angular flux moments and boundary fluxes is derived to replace the conventional characteristics sweep (i.e. inner iteration) scheme, and then the GMRES method is implemented as an efficient linear system solver. This acceleration method is proved to be reliable in theory and simple for implementation. Furthermore, as introducing no restriction in geometry treatment, it is suitable for acceleration of an arbitrary geometry MOC solver. However, it is observed that the speedup decreases when the matrix becomes larger. The spatial domain decomposition method and multiprocessing parallel technology are then employed to overcome the problem. The calculation domain is partitioned into several sub-domains. For each of them, a smaller matrix is established and solved by GMRES; and the adjacent sub-domains are coupled by 'inner-edges', where the trajectory mismatches are considered adequately. Moreover, a matched ray tracing system is developed on the basis of AutoCAD, which allows a user to define the sub-domains on demand conveniently. Numerical results demonstrate that the acceleration techniques are efficient without loss of accuracy, even in the case of large-scale and strong scattering

Stability analysis of CMFD acceleration for the wavelet expansion method of neutron transport equation

International Nuclear Information System (INIS)

Zheng Youqi; Wu Hongchun; Cao Liangzhi

2013-01-01

This paper describes the stability analysis for the coarse mesh finite difference (CMFD) acceleration used in the wavelet expansion method. The nonlinear CMFD acceleration scheme is transformed by linearization and the Fourier ansatz is introduced into the linearized formulae. The spectral radius is defined as the stability criterion, which is the least upper bound (LUB) of the largest eigenvalue of Fourier analysis matrix. The stability analysis considers the effect of mesh size (spectral length), coarse mesh division and scattering ratio. The results show that for the wavelet expansion method, the CMFD acceleration is conditionally stable. The small size of fine mesh brings stability and fast convergent. With the increase of the mesh size, the stability becomes worse. The scattering ratio does not impact the stability obviously. It makes the CMFD acceleration highly efficient in the strong scattering case. The results of Fourier analysis are verified by the numerical tests based on a homogeneous slab problem.

Retrieve polarization aberration from image degradation: a new measurement method in DUV lithography

Science.gov (United States)

Xiang, Zhongbo; Li, Yanqiu

2017-10-01

Detailed knowledge of polarization aberration (PA) of projection lens in higher-NA DUV lithographic imaging is necessary due to its impact to imaging degradations, and precise measurement of PA is conductive to computational lithography techniques such as RET and OPC. Current in situ measurement method of PA thorough the detection of degradations of aerial images need to do linear approximation and apply the assumption of 3-beam/2-beam interference condition. The former approximation neglects the coupling effect of the PA coefficients, which would significantly influence the accuracy of PA retrieving. The latter assumption restricts the feasible pitch of test masks in higher-NA system, conflicts with the Kirhhoff diffraction model of test mask used in retrieving model, and introduces 3D mask effect as a source of retrieving error. In this paper, a new in situ measurement method of PA is proposed. It establishes the analytical quadratic relation between the PA coefficients and the degradations of aerial images of one-dimensional dense lines in coherent illumination through vector aerial imaging, which does not rely on the assumption of 3-beam/2- beam interference and linear approximation. In this case, the retrieval of PA from image degradation can be convert from the nonlinear system of m-quadratic equations to a multi-objective quadratic optimization problem, and finally be solved by nonlinear least square method. Some preliminary simulation results are given to demonstrate the correctness and accuracy of the new PA retrieving model.

Methods for locating ground faults and insulation degradation condition in energy conversion systems

Science.gov (United States)

Agamy, Mohamed; Elasser, Ahmed; Galbraith, Anthony William; Harfman Todorovic, Maja

2015-08-11

Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

Solar photo-ozonation: A novel treatment method for the degradation of water pollutants

International Nuclear Information System (INIS)

Chávez, Ana M.; Rey, Ana; Beltrán, Fernando J.; Álvarez, Pedro M.

2016-01-01

Highlights: • Aqueous ozone decomposition is accelerated by solar radiation. • Hydrogen peroxide is identifies as a main intermediate of decomposition of aqueous ozone under solar irradiation. • Solar photo-ozonation leads to higher Rct ratios than single ozonation. • Solar photo-ozonation is a promising AOP for the degradation of water pollutants. - Abstract: The decomposition of aqueous ozone by UV–vis radiation has been investigated with focus on the impact of ozone photolysis on the degradation of water pollutants during solar ozonation processes. The apparent first-order rate constants of the decomposition of ozone (k_o_b_s) have been determined at various pHs in the 4–9 range using radiation of different wavelengths in the UV–vis range. It was found that UVA–visible radiation (λ > 320 nm) highly enhanced ozone decomposition, especially at pH 4, for which k_o_b_s was three-folded with respect to the process in the absence of radiation. Hydrogen peroxide was identified as a main intermediate of ozone photo-decomposition at pH 4. Experiments of degradation of oxalic acid by ozone showed that solar irradiation brings about an increase in the hydroxyl radical to ozone exposures ratio (R_c_t). Finally, photo-ozonation (λ > 300 nm) was shown advantageous over single ozonation in the mineralization of a selection of emerging contaminants (metoprolol, ibuprofen, N,N-diethyl-meta-toluamide and clofibric acid) in both ultrapure water and a synthetic secondary effluent. Thus, TOC removal in 2-h treatments increased from 10 to 25% in the absence of radiation to about 50% in the presence of radiation.

Solar photo-ozonation: A novel treatment method for the degradation of water pollutants

Energy Technology Data Exchange (ETDEWEB)

Chávez, Ana M.; Rey, Ana; Beltrán, Fernando J.; Álvarez, Pedro M., E-mail: pmalvare@unex.es

2016-11-05

Highlights: • Aqueous ozone decomposition is accelerated by solar radiation. • Hydrogen peroxide is identifies as a main intermediate of decomposition of aqueous ozone under solar irradiation. • Solar photo-ozonation leads to higher Rct ratios than single ozonation. • Solar photo-ozonation is a promising AOP for the degradation of water pollutants. - Abstract: The decomposition of aqueous ozone by UV–vis radiation has been investigated with focus on the impact of ozone photolysis on the degradation of water pollutants during solar ozonation processes. The apparent first-order rate constants of the decomposition of ozone (k{sub obs}) have been determined at various pHs in the 4–9 range using radiation of different wavelengths in the UV–vis range. It was found that UVA–visible radiation (λ > 320 nm) highly enhanced ozone decomposition, especially at pH 4, for which k{sub obs} was three-folded with respect to the process in the absence of radiation. Hydrogen peroxide was identified as a main intermediate of ozone photo-decomposition at pH 4. Experiments of degradation of oxalic acid by ozone showed that solar irradiation brings about an increase in the hydroxyl radical to ozone exposures ratio (R{sub ct}). Finally, photo-ozonation (λ > 300 nm) was shown advantageous over single ozonation in the mineralization of a selection of emerging contaminants (metoprolol, ibuprofen, N,N-diethyl-meta-toluamide and clofibric acid) in both ultrapure water and a synthetic secondary effluent. Thus, TOC removal in 2-h treatments increased from 10 to 25% in the absence of radiation to about 50% in the presence of radiation.

Critical analysis of industrial electron accelerators

Energy Technology Data Exchange (ETDEWEB)

Korenev, S. E-mail: sergey_korenev@steris.com

2004-10-01

The critical analysis of electron linacs for industrial applications (degradation of PTFE, curing of composites, modification of materials, sterilization and others) is considered in this report. Main physical requirements for industrial electron accelerators consist in the variations of beam parameters, such as kinetic energy and beam power. Questions for regulation of these beam parameters are considered. The level of absorbed dose in the irradiated product and throughput determines the main parameters of electron accelerator. The type of ideal electron linac for industrial applications is discussed.

Critical analysis of industrial electron accelerators

Science.gov (United States)

Korenev, S.

2004-09-01

The critical analysis of electron linacs for industrial applications (degradation of PTFE, curing of composites, modification of materials, sterlization and others) is considered in this report. Main physical requirements for industrial electron accelerators consist in the variations of beam parameters, such as kinetic energy and beam power. Questions for regulation of these beam parameters are considered. The level of absorbed dose in the irradiated product and throughput determines the main parameters of electron accelerator. The type of ideal electron linac for industrial applications is discussed.

Critical analysis of industrial electron accelerators

International Nuclear Information System (INIS)

Korenev, S.

2004-01-01

The critical analysis of electron linacs for industrial applications (degradation of PTFE, curing of composites, modification of materials, sterilization and others) is considered in this report. Main physical requirements for industrial electron accelerators consist in the variations of beam parameters, such as kinetic energy and beam power. Questions for regulation of these beam parameters are considered. The level of absorbed dose in the irradiated product and throughput determines the main parameters of electron accelerator. The type of ideal electron linac for industrial applications is discussed

Accelerated Compressed Sensing Based CT Image Reconstruction.

Science.gov (United States)

Hashemi, SayedMasoud; Beheshti, Soosan; Gill, Patrick R; Paul, Narinder S; Cobbold, Richard S C

2015-01-01

In X-ray computed tomography (CT) an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS) enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization.

Accelerated Compressed Sensing Based CT Image Reconstruction

Directory of Open Access Journals (Sweden)

SayedMasoud Hashemi

2015-01-01

Full Text Available In X-ray computed tomography (CT an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization.

Influence of Fermentation Methods on Neutral Detergent Fiber Degradation Parameters

DEFF Research Database (Denmark)

Bossen, D; Mertens, D R; Weisbjerg, M R

2008-01-01

The effect of 3 fermentation methods, in situ (IS) in 4 lactating cows (average pH of 5.8), in vitro (IVn) with media pH of 6.8, or in vitro (IVa) with media pH adjusted to 6.0 using citric acid, on fiber degradation parameters was studied using feeds ground to different particle sizes. Corn silage...

Fourier analysis of parallel block-Jacobi splitting with transport synthetic acceleration in two-dimensional geometry

International Nuclear Information System (INIS)

Rosa, M.; Warsa, J. S.; Chang, J. H.

2007-01-01

A Fourier analysis is conducted in two-dimensional (2D) Cartesian geometry for the discrete-ordinates (SN) approximation of the neutron transport problem solved with Richardson iteration (Source Iteration) and Richardson iteration preconditioned with Transport Synthetic Acceleration (TSA), using the Parallel Block-Jacobi (PBJ) algorithm. The results for the un-accelerated algorithm show that convergence of PBJ can degrade, leading in particular to stagnation of GMRES(m) in problems containing optically thin sub-domains. The results for the accelerated algorithm indicate that TSA can be used to efficiently precondition an iterative method in the optically thin case when implemented in the 'modified' version MTSA, in which only the scattering in the low order equations is reduced by some non-negative factor β<1. (authors)

A grey diffusion acceleration method for time-dependent radiative transfer calculations: analysis and application

International Nuclear Information System (INIS)

Nowak, P.F.

1993-01-01

A grey diffusion acceleration method is presented and is shown by Fourier analysis and test calculations to be effective in accelerating radiative transfer calculations. The spectral radius is bounded by 0.9 for the continuous equations, but is significantly smaller for the discretized equations, especially in the optically thick regimes characteristic to radiation transport problems. The GDA method is more efficient than the multigroup DSA method because its slightly higher iteration count is more than offset by the much lower cost per iteration. A wide range of test calculations confirm the efficiency of GDA compared to multifrequency DSA. (orig.)

Analysis on the capacity degradation mechanism of a series lithium-ion power battery pack based on inconsistency of capacity

International Nuclear Information System (INIS)

Wang Zhen-Po; Liu Peng; Wang Li-Fang

2013-01-01

The lithium-ion battery has been widely used as an energy source. Charge rate, discharge rate, and operating temperature are very important factors for the capacity degradations of power batteries and battery packs. Firstly, in this paper we make use of an accelerated life test and a statistical analysis method to establish the capacity accelerated degradation model under three constant stress parameters according to the degradation data, which are charge rate, discharge rate, and operating temperature, and then we propose a capacity degradation model according to the current residual capacity of a Li-ion cell under dynamic stress parameters. Secondly, we analyze the charge and discharge process of a series power battery pack and interpret the correlation between the capacity degradations of the battery pack and its charge/discharge rate. According to this cycling condition, we establish a capacity degradation model of a series power battery pack under inconsistent capacity of cells, and analyze the degradation mechanism with capacity variance and operating temperature difference. The comparative analysis of test results shows that the inconsistent operating temperatures of cells in the series power battery pack are the main cause of its degradation; when the difference between inconsistent temperatures is narrowed by 5 °C, the cycle life can be improved by more than 50%. Therefore, it effectively improves the cycle life of the series battery pack to reasonably assemble the batteries according to their capacities and to narrow the differences in operating temperature among cells. (interdisciplinary physics and related areas of science and technology)

ESTIMACIÓN DE LA DEGRADABILIDAD EFECTIVA EN EL RUMEN MEDIANTE MÉTODOS NUMÉRICOS ESTIMATION OF EFFECTIVE DEGRADABILITY IN RUMEN TROUGH NUMERICAL METHODS

Directory of Open Access Journals (Sweden)

Héctor Jairo Correa Cardona

2008-12-01

Full Text Available La estimación correcta de la degradabilidad ruminal efectiva en el rumen (DE de las distintas fracciones nutricionales de los alimentos es fundamental para el desarrollo de programas eficientes de alimentación para rumiantes. La propuesta clásica para estimar la degradabilidad efectiva en el rumen de la fracción potencialmente degradable (DEb=bKd/(Kd+Kp, no es correcta ya que se basa en la presunción de que las constantes de la cinética de la degradabilidad (Kd y del pasaje ruminal (Kp representan la velocidad de fermentación y de pasaje ruminal, respectivamente cuando estas realmente representan la relación constante entre la aceleración y la velocidad de degradación y de pasaje. Se presenta, entonces, una nueva propuesta coherente con las bases matemáticas de la cinética de la degradación y el pasaje ruminal de la fracción potencialmente degradable en el rumen (b que requiere el uso de métodos numéricos para despejar el tiempo “t” de la expresión 1 = e-kd*t + e-kp*t, que al reemplazarlo en la expresión b*e-kd*t, permite calcular la DEb. La estimación de la DEb por este método permite obtener datos confiables y coherentes con las bases matemáticas de la cinética de la degradación y el pasaje ruminal de las fracciones nutricionales.A correct estimation of effective degradability in rumen of nutritional fractions of feedstuff is basic to develop efficient feed programs to ruminants. However, the classic proposal to estimate the effective degradability in rumen of potentially degradable fraction (EDb=bKd/(Kd+Kp, is not correct since it is based on the presumption that the constants of the kinetics of the ruminal degradability (Kd and passage (Kp represent the speed of the ruminal fermentation and passage, respectively, when these really represent the constant relationship between the acceleration and speed of degradation and of passage. In this paper is then proposed a new mathematical procedure coherent with the

Accelerated gradient methods for total-variation-based CT image reconstruction

Energy Technology Data Exchange (ETDEWEB)

Joergensen, Jakob H.; Hansen, Per Christian [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Informatics and Mathematical Modeling; Jensen, Tobias L.; Jensen, Soeren H. [Aalborg Univ. (Denmark). Dept. of Electronic Systems; Sidky, Emil Y.; Pan, Xiaochuan [Chicago Univ., Chicago, IL (United States). Dept. of Radiology

2011-07-01

Total-variation (TV)-based CT image reconstruction has shown experimentally to be capable of producing accurate reconstructions from sparse-view data. In particular TV-based reconstruction is well suited for images with piecewise nearly constant regions. Computationally, however, TV-based reconstruction is demanding, especially for 3D imaging, and the reconstruction from clinical data sets is far from being close to real-time. This is undesirable from a clinical perspective, and thus there is an incentive to accelerate the solution of the underlying optimization problem. The TV reconstruction can in principle be found by any optimization method, but in practice the large scale of the systems arising in CT image reconstruction preclude the use of memory-intensive methods such as Newton's method. The simple gradient method has much lower memory requirements, but exhibits prohibitively slow convergence. In the present work we address the question of how to reduce the number of gradient method iterations needed to achieve a high-accuracy TV reconstruction. We consider the use of two accelerated gradient-based methods, GPBB and UPN, to solve the 3D-TV minimization problem in CT image reconstruction. The former incorporates several heuristics from the optimization literature such as Barzilai-Borwein (BB) step size selection and nonmonotone line search. The latter uses a cleverly chosen sequence of auxiliary points to achieve a better convergence rate. The methods are memory efficient and equipped with a stopping criterion to ensure that the TV reconstruction has indeed been found. An implementation of the methods (in C with interface to Matlab) is available for download from http://www2.imm.dtu.dk/~pch/TVReg/. We compare the proposed methods with the standard gradient method, applied to a 3D test problem with synthetic few-view data. We find experimentally that for realistic parameters the proposed methods significantly outperform the standard gradient method. (orig.)

Factors influencing hydroquinone degradation in aqueous solution using a modified microelectrolysis method.

Science.gov (United States)

Li, Tong; Li, Tingting; Xiong, Houfeng; Zou, Donglei

2015-01-01

The discharge of hydroquinone (HQ), an important chemical raw material, to natural waters poses different ecological threats to aquatic organisms. In this study, we investigated the removal performance of traditional and modified microelectrolysis methods in aqueous solutions. The traditional microelectrolysis packing was modified by adding manganese (Mn), zinc (Zn), and copper (Cu) powder as additives. The factors affecting the removal performance of HQ, such as catalytic metal type, mass fraction of additive, reaction time, and initial pH, were examined. The results showed that the Mn modified packing exhibited the best performance compared to Zn and Cu powder. The removal rate of HQ using Mn modified packing can reach 94% after 4 h. In addition, 9% of Mn packing has a higher removal rate than other mass fractions. The acidic solution pH shows a more favorable degradation than a neutral and alkaline solution. The intermediates of HQ degradation by modified microelectrolysis were identified and then the pathway of HQ degradation was proposed. Our result indicates that Mn as catalytic metal holds promising potential to enhance HQ removal in water using the microelectrolysis method.

Accelerated thermal and radiative ageing of hydrogenated NBR for DRC

International Nuclear Information System (INIS)

Mares, G.; Notingher, P.

1996-01-01

The accelerated thermal and gamma radiation ageing of HNBR carbon black-T80 has been studied by measuring the residual deformation under constant deflection -- DRC, in air, using a relevant equation for the relaxation phenomena. The residual deformation under constant deflection during the process of accelerated ageing is increasing but the structure of polymer answers in the proper manner to the mechanical stress. The degradation equations were obtained, using Alfrey model for the relaxation polymer subject to compression and an Arrhenius dependence for the chemical reaction rate. The inverted relaxation time for the thermal degradation is depending on the chemical reaction rate and the dose rate of gamma radiation

On accelerated flow of MHD powell-eyring fluid via homotopy analysis method

Science.gov (United States)

Salah, Faisal; Viswanathan, K. K.; Aziz, Zainal Abdul

2017-09-01

The aim of this article is to obtain the approximate analytical solution for incompressible magnetohydrodynamic (MHD) flow for Powell-Eyring fluid induced by an accelerated plate. Both constant and variable accelerated cases are investigated. Approximate analytical solution in each case is obtained by using the Homotopy Analysis Method (HAM). The resulting nonlinear analysis is carried out to generate the series solution. Finally, Graphical outcomes of different values of the material constants parameters on the velocity flow field are discussed and analyzed.

A novel approach for supercapacitors degradation characterization

Science.gov (United States)

Oz, Alon; Gelman, Danny; Goren, Emanuelle; Shomrat, Neta; Baltianski, Sioma; Tsur, Yoed

2017-07-01

A novel approach to analyze electrochemical impedance spectroscopy (EIS), based on evolutionary programming, has been utilized to characterize supercapacitors operation mechanism and degradation processes. This approach poses the ability of achieving a comprehensive study of supercapacitors via solely AC measurements. Commercial supercapacitors were examined during accelerated degradation. The microstructure of the electrode-electrolyte interface changes upon degradation; electrolyte parasitic reactions yield the formation of precipitates on the porous surface, which limit the access of the electrolyte ions to the active area and thus reduces performance. EIS analysis using Impedance Spectroscopy Genetic Programming (ISGP) technique enables identifying how the changing microstructure is affecting the operation mechanism of supercapacitors, in terms of each process effective capacitance and time constant. The most affected process is the transport of electrolyte ions at the porous electrode. Their access to the whole active area is hindered, which is shown in our analysis by the decrease of the capacitance gained in the transport and the longer time it takes to penetrate the entire pores depth. Early failure detection is also demonstrated, in a way not readily possible via conventional indicators. ISGP advanced analysis method has been verified using conventional and proven techniques: cyclic voltammetry and post mortem measurements.

[Establishment and evaluation of an in vitro method for neutrophil extracellular trap generation and degradation].

Science.gov (United States)

Li, Jinlong; Zhang, Yidan; Zhou, Xin; Ji, Wenjie; Zhao, Jihong; Wei, Luqing; Li, Yuming

2014-09-01

To evaluate a novel method for in vitro generation and degradation of neutrophil extracellular traps (NETs), which are a newly recognized structure that is involved in the pathogenesis of autoimmune diseases and thrombosis. Neutrophils from peripheral blood of healthy donors were obtained by Ficoll-Histopaque gradient separation. NET release was initiated by phorbol myristate acetate (PMA) and validated by immunofluorescence staining and agarose gel electrophoresis. NETs degraded by DNase I and healthy human plasma were quantified by fluorescence spectrometry after staining with PicoGreen. HE staining showed that the purity of neutrophils was up to 95% after Ficoll-Histopaque gradient separation. NET immunofluorescent staining revealed that the network structure was mainly composed of DNA and histones, with molecular length more than 10 kb as demonstrated by agarose gel electrophoresis. Moreover, both DNase and healthy human plasma could induce the degradation of NETs, in varying degrees. This work established an efficient method for in vitro generation and degradation of human NETs.

A tuning method for nonuniform traveling-wave accelerating structures

International Nuclear Information System (INIS)

Gong Cunkui; Zheng Shuxin; Shao Jiahang; Jia Xiaoyu; Chen Huaibi

2013-01-01

The tuning method of uniform traveling-wave structures based on non-resonant perturbation field distribution measurement has been widely used in tuning both constant-impedance and constant-gradient structures. In this paper, the method of tuning nonuniform structures is proposed on the basis of the above theory. The internal reflection coefficient of each cell is obtained from analyzing the normalized voltage distribution. A numerical simulation of tuning process according to the coupled cavity chain theory has been done and the result shows each cell is in right phase advance after tuning. The method will be used in the tuning of a disk-loaded traveling-wave structure being developed at the Accelerator Laboratory, Tsinghua University. (authors)

Degradation properties of the electrostatic assembly PDLLA/CS/CHS nerve conduit

Energy Technology Data Exchange (ETDEWEB)

Xu Haixing [School of Chemical Engineering, Wuhan University of Technology, Wuhan 430070 (China); Yan Yuhua; Wan Tao; Li Shipu, E-mail: yanyuhua8@126.co [Biomedical Materials and Engineering Research Center, Wuhan University of Technology, Wuhan 430070 (China)

2009-08-15

A poly(d,l-lactic acid)/chondroitin sulfate/chitosan (PDLLA/CS/CHS) nerve conduit for repairing nerve defects was prepared by electrostatic assembly and the thermally induced phase separation technique. The hydrophilic characteristics of the PDLLA/CS/CHS assembly nerve conduits were improved markedly. The degradation behavior of the nerve conduit with various assembly layers was evaluated by a pH change, weight loss rate and molecular weight change. The pH of the solution of the nerve conduit could be effectively adjusted by varying the layer numbers and overcoming the acidity-caused auto-acceleration of PDLLA; the nerve conduit can retain its integrity in a phosphate buffer solution after being degraded for 3 months. After such a conduit was implanted in the rat for 3 months, obvious degradation occurred, but the regenerated nerve was integrated and it grew successfully from the proximal to distal nerve stump. All these results implied that the degradation rate of the prepared conduit can adapt to the regeneration of the peripheral nerve, which might be a new derivative of PDLLA-based biodegradable materials for repairing nerve injuries without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as shown by PDLLA.

Accelerated DNA Methylation Age: Associations with PTSD and Neural Integrity

Science.gov (United States)

Wolf, Erika J.; Logue, Mark W.; Hayes, Jasmeet P.; Sadeh, Naomi; Schichman, Steven A.; Stone, Annjanette; Salat, David H.; Milberg, William; McGlinchey, Regina; Miller, Mark W.

2015-01-01

Background Accumulating evidence suggests that post traumatic stress disorder (PTSD) may accelerate cellular aging and lead to premature morbidity and neurocognitive decline. Methods This study evaluated associations between PTSD and DNA methylation (DNAm) age using recently developed algorithms of cellular age by Horvath (2013) and Hannum et al. (2013). These estimates reflect accelerated aging when they exceed chronological age. We also examined if accelerated cellular age manifested in degraded neural integrity, indexed via diffusion tensor imaging. Results Among 281 male and female veterans of the conflicts in Iraq and Afghanistan, DNAm age was strongly related to chronological age (rs ~.88). Lifetime PTSD severity was associated with Hannum DNAm age estimates residualized for chronological age (β = .13, p= .032). Advanced DNAm age was associated with reduced integrity in the genu of the corpus callosum (β = −.17, p= .009) and indirectly linked to poorer working memory performance via this region (indirect β = − .05, p= .029). Horvath DNAm age estimates were not associated with PTSD or neural integrity. Conclusions Results provide novel support for PTSD-related accelerated aging in DNAm and extend the evidence base of known DNAm age correlates to the domains of neural integrity and cognition. PMID:26447678

Fate of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX) on soil following accelerant-based fire and liquid decontamination.

Science.gov (United States)

Gravett, M R; Hopkins, F B; Self, A J; Webb, A J; Timperley, C M; Riches, J R

2014-08-01

In the event of alleged use of organophosphorus nerve agents, all kinds of environmental samples can be received for analysis. These might include decontaminated and charred matter collected from the site of a suspected chemical attack. In other scenarios, such matter might be sampled to confirm the site of a chemical weapon test or clandestine laboratory decontaminated and burned to prevent discovery. To provide an analytical capability for these contingencies, we present a preliminary investigation of the effect of accelerant-based fire and liquid decontamination on soil contaminated with the nerve agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX). The objectives were (a) to determine if VX or its degradation products were detectable in soil after an accelerant-based fire promoted by aviation fuel, including following decontamination with Decontamination Solution 2 (DS2) or aqueous sodium hypochlorite, (b) to develop analytical methods to support forensic analysis of accelerant-soaked, decontaminated and charred soil and (c) to inform the design of future experiments of this type to improve analytical fidelity. Our results show for the first time that modern analytical techniques can be used to identify residual VX and its degradation products in contaminated soil after an accelerant-based fire and after chemical decontamination and then fire. Comparison of the gas chromatography-mass spectrometry (GC-MS) profiles of VX and its impurities/degradation products from contaminated burnt soil, and burnt soil spiked with VX, indicated that the fire resulted in the production of diethyl methylphosphonate and O,S-diethyl methylphosphonothiolate (by an unknown mechanism). Other products identified were indicative of chemical decontamination, and some of these provided evidence of the decontaminant used, for example, ethyl 2-methoxyethyl methylphosphonate and bis(2-methoxyethyl) methylphosphonate following decontamination with DS2. Sample preparation

Method for Impeding Degradation of Porous Silicon Structures

Science.gov (United States)

Vilentchouk, Biana Godin; Ferrari, Mauro

2011-01-01

This invention relates to surface modification of porosified silicon (pSi) structures with poly(alkylene) glycols for the purpose of controlled degradation of the silicon matrix and tailored release of encapsulated substances for biomedical applications. The pSi structures are currently used in diverse biomedical applications including bio-molecular screening, optical bio-sensoring, and drug delivery by means of injectable/orally administered carriers and implantable devices. The size of the pores and the surface chemistry of the pSi structure can be controlled during the microfabrication process and thereafter. A fine regulation of the degradation kinetics of mesoporous silicon structures is of fundamental importance. Polyethylene glycols (PEGs) represent the major category of surface modifying agents used in classical drug delivery systems and in pharmaceutical dosage forms. PEGylation enables avoidance of RES uptake, thus prolonging circulation time of intravenously injectable nanovectors. PEG molecules demonstrate little toxicity and immunogenicity, and are cleared from the body through the urine (molecular weight, MW less than 30 kDa) or in the feces (MW greater than 30kDa). The invention focuses on the possibility of finely tuning the degradation kinetics of the pSi nanovectors and other structures through surface conjugation of PEGs with various backbone lengths/MWs. To prove the concept, pSi nanovectors were covalently conjugated to seven PEGs with MW from 245 to 5,000 Da and their degradation kinetics in physiologically relevant media (phosphate buffer saline, PBS pH7.4, and fetal bovine serum) was assessed by the elemental analysis of the Si using inductive coupled plasma atomic emission spectroscopy (ICP-AES). The conjugation of the PEG with lowest MW to the nanovectors surface did not induce any change in the degradation kinetics in serum, but inhibited degradation and consequently the release of orthosilicic acid into buffer. When PEGs with the longer

Laboratory Test Methods to Determine the Degradation of Plastics in Marine Environmental Conditions

OpenAIRE

Tosin, Maurizio; Weber, Miriam; Siotto, Michela; Lott, Christian; Degli Innocenti, Francesco

2012-01-01

In this technology report, three test methods were developed to characterize the degradation of plastic in marine environment. The aim was to outline a test methodology to measure the physical and biological degradation in different habitats where plastic waste can deposit when littered in the sea. Previously, research has focused mainly on the conditions encountered by plastic items when floating in the sea water (pelagic domain). However, this is just one of the possible habitats that plast...

Epsilon topological accelerating algorithms for difference method for initial-value problems

International Nuclear Information System (INIS)

Hristea, V.; Posirca, M.

1992-01-01

Linear and nonlinear parabolic equations can be solved by discretization methods which lead to linear and nonlinear algebraic systems. The iterative methods (e.g. Gauss - Seidel) show a very slow convergence and instability in the case of nonlinear equations. This paper proposes an ε topological algorithm for accelerating slow iterative methods used in the thermohydraulic code COBRA and the dynamic code ADEP. The results show an executing time approximately ten times lower than original algorithms. (Author)

Degradation characteristics of 2,4-dichlorophenoxyacetic acid in electro-biological system

Energy Technology Data Exchange (ETDEWEB)

Zhang, JingLi, E-mail: jinglizhangczp@126.com [Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Cao, ZhanPing; Zhang, HongWei [School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Zhao, LianMei [Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Sun, XuDong; Mei, Feng [School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

2013-11-15

Highlights: • The 2,4-D reductive degradation was studied in an electro-biological system. • The electric auxiliary accelerates 2,4-D microbial degradation. • A electron transfer is achieved between the electrode, bacteria and the pollutants. • The paper provides a promising way for the degradation of persistent organics. -- Abstract: The reductive degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in an electro-biological system, a biological system and an electric catalytic system, respectively. Electrochemical characteristics were monitored by cyclic voltammetry and the intermediate products of 2,4-D degradation were determined by high speed liquid chromatography (HPLC). The results showed that all 2,4-D degradations in the three systems conformed to the kinetics characteristics of one-order reaction, and the degradation kinetics constants were 28.74 × 10{sup −2} h{sup −1}, 19.73 × 10{sup −2} h{sup −1} and 3.54 × 10{sup −2} h{sup −1}, respectively. The kinetics constant in the electro-biological system was higher than the sum in the other two systems by 19%. The electrochemical assistance provided the electrons and accelerated the electron transfer rate in the microbial degradation of 2,4-D. The degradation resulted from the microbial reduction strengthened by the electrochemical assistance. The electron transfer existed between the electrode, cytochrome, NAD and the pollutants. A long-range electron transfer process could be achieved on the multi-phase interfaces between the electrode, bacteria and the pollutants.

Controlling Radiation Degradation of Natural Polymers for Industrial and Agricultural application

International Nuclear Information System (INIS)

Hegazy, E.A.; AbdEl-Rehim, H

2008-01-01

Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. The addition of some additives such as potassium per-sulfate (KPS), ammonium per-sulfate (APS), or H 2O2 to natural polymers such as chitosan and Na-alginate during irradiation process accelerates their degradation. The highest degradation rate of polysaccharides obtained when APS was used. The end product of irradiated chitosan, and Na-alginate may be used as food additive or benefited in agricultural purposes. The prepared crosslinked copolymers possessed high and fast swelling properties in simulated urine media and the swelling ratios of CMC-Na /PAAm gels in urine are acceptable for diaper application. (author)

Comparative efficacy of multimodal digital methods in assessing trail/resource degradation

Science.gov (United States)

Logan O. Park

2014-01-01

Outdoor recreation can cause both positive and negative impacts on associated forest ecosystems. Forest recreation trails localize negative impacts to a controlled spatial extent while providing recreation access beyond developed areas and transportation networks. Current methods for assessing extent and severity of trail and proximal resource degradation require...

Methods for the visualization and analysis of extracellular matrix protein structure and degradation.

Science.gov (United States)

Leonard, Annemarie K; Loughran, Elizabeth A; Klymenko, Yuliya; Liu, Yueying; Kim, Oleg; Asem, Marwa; McAbee, Kevin; Ravosa, Matthew J; Stack, M Sharon

2018-01-01

This chapter highlights methods for visualization and analysis of extracellular matrix (ECM) proteins, with particular emphasis on collagen type I, the most abundant protein in mammals. Protocols described range from advanced imaging of complex in vivo matrices to simple biochemical analysis of individual ECM proteins. The first section of this chapter describes common methods to image ECM components and includes protocols for second harmonic generation, scanning electron microscopy, and several histological methods of ECM localization and degradation analysis, including immunohistochemistry, Trichrome staining, and in situ zymography. The second section of this chapter details both a common transwell invasion assay and a novel live imaging method to investigate cellular behavior with respect to collagen and other ECM proteins of interest. The final section consists of common electrophoresis-based biochemical methods that are used in analysis of ECM proteins. Use of the methods described herein will enable researchers to gain a greater understanding of the role of ECM structure and degradation in development and matrix-related diseases such as cancer and connective tissue disorders. © 2018 Elsevier Inc. All rights reserved.

A new non-degradative method to purify glycogen.

Science.gov (United States)

Tan, Xinle; Sullivan, Mitchell A; Gao, Fei; Li, Shihan; Schulz, Benjamin L; Gilbert, Robert G

2016-08-20

Liver glycogen, a complex branched glucose polymer containing a small amount of protein, is important for maintaining glucose homeostasis (blood-sugar control) in humans. It has recently been found that glycogen molecular structure is impaired in diabetes. Isolating the carbohydrate polymer and any intrinsically-attached protein(s) is an essential prerequisite for studying this structural impairment. This requires an effective, non-degradative and efficient purification method to exclude the many other proteins present in liver. Proteins and glycogen have different ranges of molecular sizes. Despite the plethora of proteins that might still be present in significant abundance after other isolation techniques, SEC (size exclusion chromatography, also known as GPC), which separates by molecular size, should separate those extraneous to glycogen from glycogen with any intrinsically associated protein(s). A novel purification method is developed for this, based on preparative SEC following sucrose gradient centrifugation. Proteomics is used to show that the new method compares favourably with current methods in the literature. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method

Directory of Open Access Journals (Sweden)

Md. Sarowar Jahan

2014-01-01

Full Text Available A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH. For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8 and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS, 150 × 4.6 mm, 5 μm, Phenomenex Inc. column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient ( R 2 values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient ( R 2 > 0.995. The percent recoveries for two drugs were found within the acceptance limit of (97.0-103.0%. Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5-20%, according to the guideline of ICH, while paracetamol showed <20% degradation in oxidation and basic condition.

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method.

Science.gov (United States)

Jahan, Md Sarowar; Islam, Md Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R (2)) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R (2) > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0-103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5-20%, according to the guideline of ICH), while paracetamol showed degradation in oxidation and basic condition.

An efficient and environment-friendly method of removing graphene oxide in wastewater and its degradation mechanisms.

Science.gov (United States)

Zhang, Chao-Zhi; Li, Ting; Yuan, Yang; Xu, Jianqiang

2016-06-01

Graphene and graphene oxide (GO) have already existed in air, water and soil due to their popular application in functional materials. However, degradation of graphene and GO in wastewater has not been reported. Degradation of GO plays a key role in the elimination of graphene and GO in wastewater due to graphene being easily oxidized to GO. In this paper, GO was completely degraded to give CO2 by Photo-Fenton. The degradation intermediates were determined by UV-vis absorption spectra, elemental analysis (EA), fourier transform infrared (FT-IR) and liquid chromatography-mass spectrometry (LC-MS). Experimental results showed that graphene oxide was completely degraded to give CO2 after 28 days. Based on UV, FT-IR, LC-MS spectra and EA data of these degradation intermediates, the degradation mechanisms of GO were supposed. This paper suggests an efficient and environment-friendly method to degrade GO and graphene. Copyright © 2016 Elsevier Ltd. All rights reserved.

Accelerated aging tests on ENEA-ASE solar coating for receiver tube suitable to operate up to 550 °C

Science.gov (United States)

Antonaia, A.; D'Angelo, A.; Esposito, S.; Addonizio, M. L.; Castaldo, A.; Ferrara, M.; Guglielmo, A.; Maccari, A.

2016-05-01

A patented solar coating for evacuated receiver, based on innovative graded WN-AlN cermet layer, has been optically designed and optimized to operate at high temperature with high performance and high thermal stability. This solar coating, being designed to operate in solar field with molten salt as heat transfer fluid, has to be thermally stable up to the maximum temperature of 550 °C. With the aim of determining degradation behaviour and lifetime prediction of the solar coating, we chose to monitor the variation of the solar absorptance αs after each thermal annealing cycle carried out at accelerated temperatures under vacuum. This prediction method was coupled with a preliminary Differential Thermal Analysis (DTA) in order to give evidence for any chemical-physical coating modification in the temperature range of interest before performing accelerated aging tests. In the accelerated aging tests we assumed that the temperature dependence of the degradation processes could be described by Arrhenius behaviour and we hypothesized that a linear correlation occurs between optical parameter variation rate (specifically, Δαs/Δt) and degradation process rate. Starting from Δαs/Δt values evaluated at 650 and 690 °C, Arrhenius plot gave an activation energy of 325 kJ mol-1 for the degradation phenomenon, where the prediction on the coating degradation gave a solar absorptance decrease of only 1.65 % after 25 years at 550 °C. This very low αs decrease gave evidence for an excellent stability of our solar coating, also when employed at the maximum temperature (550 °C) of a solar field operating with molten salt as heat transfer fluid.

Photocatalytic degradation of textile dyestuffs using TiO{sub 2} nanotubes prepared by sonoelectrochemical method

Energy Technology Data Exchange (ETDEWEB)

Tekin, Derya, E-mail: deryatekin@atauni.edu.tr

2014-11-01

Highlights: • TiO{sub 2} nanotubes prepared by electrochemical and sonoelectrochemical method. • More regular TiO{sub 2} nanotubes diameters prepared by sonoelectrochemical method. • Obtained nanotubes were used in the photocatalytic degradation of Orange G dye. • TiO{sub 2} nanotubes prepared by sonoelectrochemical method showed 10% faster degradation of Orange G dye compared with the one by electrochemical method. - Abstract: TiO{sub 2} nanotubes were prepared by anodization of Ti plates by conventional electrochemical technique as well as by an emerging sonoelectrochemical technique. Scanning electron miscroscope (SEM) analysis showed that ultrasound assisted anodization yielded more ordered and controllable TiO{sub 2} tube banks with higher tube diameter. The photocatalytical activities of TiO{sub 2} nanotubes were tested in the photocatalytical degradation of Orange G dye. The results showed that sonoelectrochemically prepared TiO{sub 2} tubes exhibited 10% higher photocatalytic performance than the electrochemical prepared ones, and more than 18% higher activity than the other TiO{sub 2} samples.

Evaluation of the electrode performance for PAFC by using acid absorption, acceleration and ac-impedance measurement

Energy Technology Data Exchange (ETDEWEB)

Kim, Chang-Soo; Song, Rak-Hyun; Choi, Byung-Woo [Korea Institute of Energy Research, Taejon (Korea, Republic of)] [and others

1996-12-31

In PAFC, the degradation on cathode electrode caused by carbon corrosion, platinum dissolution and growth is especially severe. An acceleration test is a good technique for evaluating the degradation of electrode performance, because it does not need long time. Coleman et al used thermal cycling and on-off cycling as an acceleration test. Song et al showed that hydrogen shortage decreased the electrode performance more rapidly than that of air shortage in gas shortage test. Honji et al reported that the rate of coarsening of Pt particle is rapid in open circuit potential and this is one of major causes on the performance degradation of electrode. The cathode performance has been studied by using acid absorption, acceleration and ac-impedance measurements as functions of the polytetrafluoroethylene (PTFE) contents and sintering temperatures of the electrode.

Application of the personnel photographic monitoring method to determine equivalent radiation dose beyond proton accelerator shielding

International Nuclear Information System (INIS)

Gel'fand, E.K.; Komochkov, M.M.; Man'ko, B.V.; Salatskaya, M.I.; Sychev, B.S.

1980-01-01

Calculations of regularities to form radiation dose beyond proton accelerator shielding are carried out. Numerical data on photographic monitoring dosemeter in radiation fields investigated are obtained. It was shown how to determine the total equivalent dose of radiation fields beyond proton accelerator shielding by means of the photographic monitoring method by introduction into the procedure of considering nuclear emulsions of division of particle tracks into the black and grey ones. A comparison of experimental and calculational data has shown the applicability of the used calculation method for modelling dose radiation characteristics beyond proton accelerator shielding [ru

Glass fibres reinforced polyester composites degradation monitoring by surface analysis

Energy Technology Data Exchange (ETDEWEB)

Croitoru, Catalin [“Transilvania” University of Brasov, Materials Engineering and Welding Department, Eroilor 29 Str., 500036 Brasov (Romania); Patachia, Silvia, E-mail: st.patachia@unitbv.ro [“Transilvania” University of Brasov, Product Design Environment and Mechatronics Department, Eroilor 29 Str., 500036 Brasov (Romania); Papancea, Adina [“Transilvania” University of Brasov, Product Design Environment and Mechatronics Department, Eroilor 29 Str., 500036 Brasov (Romania); Baltes, Liana; Tierean, Mircea [“Transilvania” University of Brasov, Materials Engineering and Welding Department, Eroilor 29 Str., 500036 Brasov (Romania)

2015-12-15

Highlights: • Glass fibre-reinforced polyester composites surface analysis by photographic method. • The composites are submitted to accelerated ageing by UV irradiation at 254 nm. • The UV irradiation promotes differences in the surface chemistry of the composites. • MB dye is differently adsorbed on surfaces with different degradation degrees. • Good correlation between the colouring degree and surface chemistry. - Abstract: The paper presents a novel method for quantification of the modifications that occur on the surface of different types of gel-coated glass fibre-reinforced polyester composites under artificial UV-ageing at 254 nm. The method implies the adsorption of an ionic dye, namely methylene blue, on the UV-aged composite, and computing the CIELab colour space parameters from the photographic image of the coloured composite's surface. The method significantly enhances the colour differences between the irradiated composites and the reference, in contrast with the non-coloured ones. The colour modifications that occur represent a good indicative of the surface degradation, alteration of surface hydrophily and roughness of the composite and are in good correlation with the ATR-FTIR spectroscopy and optical microscopy results. The proposed method is easier, faster and cheaper than the traditional ones.

Functional and RNA-sequencing analysis revealed expression of a novel stay-green gene from Zoysia japonica (ZjSGR caused chlorophyll degradation and accelerated senescence in Arabidopsis

Directory of Open Access Journals (Sweden)

Ke Teng

2016-12-01

Full Text Available Senescence is not only an important developmental process, but also a responsive regulation to abiotic and biotic stress for plants. Stay-green protein plays crucial roles in plant senescence and chlorophyll degradation. However, the underlying mechanisms were not well studied, particularly in non-model plants. In this study, a novel stay-green gene, ZjSGR, was isolated from Zoysia japonica. Subcellular localization result demonstrated that ZjSGR was localized in the chloroplasts. Quantitative real-time PCR results together with promoter activity determination using transgenic Arabidopsis confirmed that ZjSGR could be induced by darkness, ABA and MeJA. Its expression levels could also be up-regulated by natural senescence, but suppressed by SA treatments. Overexpression of ZjSGR in Arabidopsis resulted in a rapid yellowing phenotype; complementary experiments proved that ZjSGR was a functional homologue of AtNYE1 from Arabidopsis thaliana. Overexpression of ZjSGR accelerated chlorophyll degradation and impaired photosynthesis in Arabidopsis. Transmission electron microscopy observation revealed that overexpression of ZjSGR decomposed the chloroplasts structure. RNA sequencing analysis showed that ZjSGR could play multiple roles in senescence and chlorophyll degradation by regulating hormone signal transduction and the expression of a large number of senescence and environmental stress related genes. Our study provides a better understanding of the roles of SGRs, and new insight into the senescence and chlorophyll degradation mechanisms in plants.

Radiation degradation of silk protein

International Nuclear Information System (INIS)

Pewlong, W.; Sudatis, B.; Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu

2000-01-01

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl 2 /C 2 H 5 OH/H 2 O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

Radiation degradation of silk protein

Energy Technology Data Exchange (ETDEWEB)

Pewlong, W; Sudatis, B [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2000-03-01

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

A Theoretical Model for Metal Corrosion Degradation

Directory of Open Access Journals (Sweden)

David V. Svintradze

2010-01-01

Full Text Available Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitting corrosion behavior was derived from solid-state physics and some solutions and simulations are presented and discussed.

The impact of external optical feedback on the degradation behavior of high-power diode lasers

DEFF Research Database (Denmark)

Hempel, Martin; Chi, Mingjun; Petersen, Paul Michael

2013-01-01

The impact of external feedback on high-power diode laser degradation is studied. For this purpose early stages of gradual degradation are prepared by accelerated aging of 808-nm-emitting AlGaAs-based devices. While the quantum well that actually experiences the highest total optical load remains...... unaffected, severe impact is observed to the cladding layers and the waveguide. Consequently hardening of diode lasers for operation under external optical feedback must necessarily involve claddings and waveguide, into which the quantum well is embedded.......The impact of external feedback on high-power diode laser degradation is studied. For this purpose early stages of gradual degradation are prepared by accelerated aging of 808-nm-emitting AlGaAs-based devices. While the quantum well that actually experiences the highest total optical load remains...

Limitations and Strengths of the Fourier Transform Method to Detect Accelerating Targets

National Research Council Canada - National Science Library

Thayaparan, Thayananthan

2000-01-01

.... In using a Pulse Doppler Radar to detect a non-accelerating target in additive white Gaussian noise and to estimate its radial velocity, the Fourier method provides an output signal-to-noise ratio (SNR...

Nondestructive Examination (NDE) Detection and Characterization of Degradation Precursors, Technical Progress Report for FY 2012

Energy Technology Data Exchange (ETDEWEB)

Ramuhalli, P.; Meyer, R.M.; Fricke, J.M.; Prowant, M.S.; Coble, J.B.; Griffin, J.W.; Pitman, S.G.; Dahl, M.E.; Kafentzis, T.A.; Roosendaal, T.J.

2012-09-01

The overall objective of this project was to investigate the effectiveness of nondestructive examination (NDE) technology in detecting material degradation precursors by initiating and growing cracks in selected materials and using NDE methods to measure crack precursors prior to the onset of cracking. Nuclear reactor components are subject to stresses over time that are not precisely known and that make the life expectancy of components difficult to determine. To prevent future issues with the operation of these plants because of unforeseen failure of components, NDE technology is needed that can be used to identify and quantify precursors to macroscopic degradation of materials. Some of the NDE methods being researched as possible solutions to the precursor detection problem are magnetic Barkhausen noise, nonlinear ultrasonics, acoustic emission, eddy current measurements, and guided wave technology. In FY12, the objective was to complete preliminary assessment of advanced NDE techniques for sensitivity to degradation precursors, using prototypical degradation mechanisms in laboratory-scale measurements. This present document reports on the deliverable that meets the following milestone: M3LW-12OR0402143 – Report detailing an initial demonstration on samples from the crack-initiation tests will be provided (demonstrating acceleration of the work).

Radiation-thermal transformation of degraded oils

International Nuclear Information System (INIS)

Guliyeva, N.G.; Aliyeva, S.F.

2010-01-01

Full text :In order to elucidate the role of radiation in the process of oil degradation in the environment, and to identify opportunities for application of radiation-chemical technology to clean oil-contaminated soil were studied some regularities of radiation-chemical transformations of oil samples taken from wells, as well as after long-term presence on the surface of the water and soil. The most high radiation resistances of oil are samples taken from surface water. This is due to structural changes in the process of oil degradation, namely an increase in their part of the radiation-resistant resins and aspartames. This is due to evaporation of light hydrocarbons and heavy destructive transformations under the influence of oxygen, microorganisms, as well as components of the surface layer of soil. This phenomenon is explained by the specificity of action of the beam of accelerated electrons, namely the possible heating of the reaction zone due to inhibition of the electron. In this case the acceleration of diffusion processes results in an increase in the yield of gases.

A probabilistic degradation model for the estimation of the remaining life distribution of feeders

International Nuclear Information System (INIS)

Yuan, X.-X.; Pandey, M.D.; Bickel, G.A.

2006-01-01

Wall thinning due to flow accelerated corrosion (FAC) is a pervasive form of degradation in the outlet feeder pipes of the primary heat transport system of CANDU reactors. The prediction of the end-of-life of a feeder from wall thickness measurement data is confounded by the sampling and temporal uncertainties associated with the FAC degradation phenomenon. Traditional regression-based statistical methods deal with only the sampling uncertainties, leaving the temporal uncertainties unresolved. This paper presents an advanced probabilistic model, which is able to integrate the temporal uncertainties into the prediction of lifetime. In particular, a random gamma process model is proposed to model the FAC process and it is calibrated with a set of wall thickness measurements using the method of maximum likelihood. This information can be used to establish an optimum strategy for inspection and replacement of feeders. (author)

Accelerated perturbation-resilient block-iterative projection methods with application to image reconstruction.

Science.gov (United States)

Nikazad, T; Davidi, R; Herman, G T

2012-03-01

We study the convergence of a class of accelerated perturbation-resilient block-iterative projection methods for solving systems of linear equations. We prove convergence to a fixed point of an operator even in the presence of summable perturbations of the iterates, irrespective of the consistency of the linear system. For a consistent system, the limit point is a solution of the system. In the inconsistent case, the symmetric version of our method converges to a weighted least squares solution. Perturbation resilience is utilized to approximate the minimum of a convex functional subject to the equations. A main contribution, as compared to previously published approaches to achieving similar aims, is a more than an order of magnitude speed-up, as demonstrated by applying the methods to problems of image reconstruction from projections. In addition, the accelerated algorithms are illustrated to be better, in a strict sense provided by the method of statistical hypothesis testing, than their unaccelerated versions for the task of detecting small tumors in the brain from X-ray CT projection data.

Degradation of polyethylene induced by plasma in oxidizing atmospheres

International Nuclear Information System (INIS)

Colin, E.; Olayo, M.G.; Cruz, G.J.

2002-01-01

The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

Simulation of isothermal multi-phase fuel-coolant interaction using MPS method with GPU acceleration

Energy Technology Data Exchange (ETDEWEB)

Gou, W.; Zhang, S.; Zheng, Y. [Zhejiang Univ., Hangzhou (China). Center for Engineering and Scientific Computation

2016-07-15

The energetic fuel-coolant interaction (FCI) has been one of the primary safety concerns in nuclear power plants. Graphical processing unit (GPU) implementation of the moving particle semi-implicit (MPS) method is presented and used to simulate the fuel coolant interaction problem. The governing equations are discretized with the particle interaction model of MPS. Detailed implementation on single-GPU is introduced. The three-dimensional broken dam is simulated to verify the developed GPU acceleration MPS method. The proposed GPU acceleration algorithm and developed code are then used to simulate the FCI problem. As a summary of results, the developed GPU-MPS method showed a good agreement with the experimental observation and theoretical prediction.

Probing electron acceleration and x-ray emission in laser-plasma accelerators

International Nuclear Information System (INIS)

Thaury, C.; Ta Phuoc, K.; Corde, S.; Brijesh, P.; Lambert, G.; Malka, V.; Mangles, S. P. D.; Bloom, M. S.; Kneip, S.

2013-01-01

While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam, is focused on the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion, which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction length to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied

Evaluation of an in vitro faecal degradation method for early assessment of the impact of colonic degradation on colonic absorption in humans.

Science.gov (United States)

Tannergren, Christer; Borde, Anders; Boreström, Cecilia; Abrahamsson, Bertil; Lindahl, Anders

2014-06-16

The objective of this study was to develop and evaluate an in vitro method to investigate bacterial-mediated luminal degradation of drugs in colon in humans. This would be a valuable tool for the assessment of drug candidates during early drug development, especially for compounds intended to be developed as oral extended release formulations. Freshly prepared faecal homogenate from healthy human volunteers (n=3-18), dog (n=6) and rat (colon and caecal content, n=3) was homogenised with 3.8 parts (w/w) physiological saline under anaerobical conditions. Four model compounds (almokalant, budesonide, ximelagatran and metoprolol) were then incubated (n=3-18) separately in the human faecal homogenate for up to 120min at 37°C. In addition, ximelagatran was also incubated in the faecal or colonic content from dog and rat. The mean (±SD) in vitro half-life for almokalant, budesonide and ximelagatran was 39±1, 68±21 and 26±12min, respectively, in the human faecal homogenate. Metoprolol was found to be stable in the in vitro model. The in vitro degradation data was then compared to literature data on fraction absorbed after direct colon administration in humans. The percentage of drug remaining after 60min of in vitro incubation correlated (R(2)=0.90) with the fraction absorbed from colon in humans. The mean in vitro half-life of ximelagatran was similar in human faeces (26±12min) and rat colon content (34±31min), but significantly (pdegradation in vivo was rapidly degraded in the faecal homogenates as well as quantitatively since a correlation was established between percentage degraded in vitro at 60min and fraction absorbed in the colon for the model drugs, which have no other absorption limiting properties. Also, the method is easy to use from a technical point of view, which suggests that the method is suitable for use in early assessment of colonic absorption of extended release formulation candidates. Further improvement of the confidence in the use of the

Chiral separation and enantioselective degradation of vinclozolin in soils.

Science.gov (United States)

Liu, Hui; Liu, Donghui; Shen, Zhigang; Sun, Mingjing; Zhou, Zhiqiang; Wang, Peng

2014-03-01

Vinclozolin is a chiral fungicide with potential environmental problems. The chiral separation of the enantiomers and enantioselective degradation in soil were investigated in this work. The enantiomers were separated by high-performance liquid chromatography (HPLC) on Chiralpak IA, IB, and AZ-H chiral columns under normal phase and the influence of the mobile phase composition on the separation was also studied. Complete resolutions were obtained on all three chiral columns under optimized conditions with the same elution order of (+)/(-). The residual analysis of the enantiomers in soil was conducted using accelerate solvent extraction followed by HPLC determination. The recoveries of the enantiomers ranged from 85.7-105.7% with relative standard deviation (SD) of 0.12-3.83%, and the limit of detection (LOD) of the method was 0.013 µg/g. The results showed that the degradations of vinclozolin enantiomers in the soils followed first-order kinetics. Preferential degradation of the (-)-enantiomer was observed only in one soil with the largest |ES| value of 0.047, and no obvious enantioselective degradation was observed in other soils. It was found that the persistence of vinclozolin in soil was related to pH values based on the half-lives. The two enantiomers disappeared about 8 times faster in basic soils than that in neutral or acidic soils. © 2014 Wiley Periodicals, Inc.

Sonodegradation of cyanidin-3-glucosylrutinoside: degradation kinetic analysis and its impact on antioxidant capacity in vitro.

Science.gov (United States)

Sun, Jianxia; Li, Xinghua; Lin, Xinyu; Mei, Zhouxiong; Li, Yitao; Ding, Lijun; Bai, Weibin

2017-03-01

As an alternative preservation method for thermal treatment, ultrasound comprises a novel non-thermal processing technology that can significantly avoid undesirable nutritional changes. However, the recent literature indicates that anthocyanin degradation occurs when ultrasound is applied in juice at high amplitude parameters. Such work has mainly focussed on the effect of ultrasound on stability, the antioxidant capacity of cyanidin-3-glucosylrutinoside (Cy-3-glc-rut) and the correlation between anthocyanin degradation and ·OH generation in a simulated system. The spectral intensities of Cy-3-glc-rut at 518 and 282 nm decreased with increasing ultrasound power and treatment time. The degradation of Cy-3-glc-rut was consistent with first-order reaction kinetics (r 2  > 0.9000) and there was a good linear correlation between anthocyanin degradation and hydroxyl radical formation induced by ultrasound (r 2  = 0.9258). Moreover, a decrease in the antioxidant activity of Cy-3-glc-rut after ultrasound evaluated by the 1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power methods was observed. Overall, the results of the present study show that ultrasound will accelerate the degradation of Cy-3-glc-rut with the growth of power over time. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Radiation degradation of silk

Energy Technology Data Exchange (ETDEWEB)

Ishida, Kazushige; Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2001-03-01

Silk fibroin powder was prepared from irradiated silk fibroin fiber by means of only physical treatment. Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1000 kGy was pulverized by using a ball mill. Unirradiated silk fibroin fiber was not pulverized at all. But the more irradiation was increased, the more the conversion efficiency from fiber to powder was increased. The conversion efficiency of silk fibroin fiber irradiated 1000 kGy in oxygen was 94%. Silk fibroin powder shows remarkable solubility, which dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin which did not treat with chemicals gets solubility only being pulverized. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk fibroin powder was analyzed. The more irradiation dose up, the more glycine or alanine degraded, but degradation fraction reached bounds about 50%. Other amino acids were degraded only 20% even at the maximum. To consider crystal construction of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve silk fibroin powder. (author)

Potential for photocatalytic degradation of the potassic diclofenac using scandium and silver modified titanium dioxide thin films

International Nuclear Information System (INIS)

Ciola, R.A.; Oliveira, C.T.; Lopes, S.A.; Cavalheiro, A.A.

2011-01-01

The potential for photocatalytic degradation of the potassic diclofenac drug was investigated using titanium dioxide thin films modified with two modifier types, scandium and silver, both prepared by Sol-Gel method. It was demonstrated by UVVis spectroscopy analysis of the solutions containing the drug, under UV-A light irradiation that the degradation efficiency of the titanium dioxide photocatalyst is dependent of the semiconductor nature and that the scandium accelerates the first step of the degradation when compared to the silver. This result seems to be related to the redox potential of the electron-hole pair, once the scandium modifying sample generates a p type semiconductor that reduces the band gap. The extra holes attract more strongly the chorine ion present in diclofenac and leading to the releasing more easily. However, after the first byproducts degradation the following steps are not facilitated, making the silver modifying more advantageous. (author)

Laser-driven ion acceleration: methods, challenges and prospects

Science.gov (United States)

Badziak, J.

2018-01-01

The recent development of laser technology has resulted in the construction of short-pulse lasers capable of generating fs light pulses with PW powers and intensities exceeding 1021 W/cm2, and has laid the basis for the multi-PW lasers, just being built in Europe, that will produce fs pulses of ultra-relativistic intensities ~ 1023 - 1024 W/cm2. The interaction of such an intense laser pulse with a dense target can result in the generation of collimated beams of ions of multi-MeV to GeV energies of sub-ps time durations and of extremely high beam intensities and ion fluencies, barely attainable with conventional RF-driven accelerators. Ion beams with such unique features have the potential for application in various fields of scientific research as well as in medical and technological developments. This paper provides a brief review of state-of-the art in laser-driven ion acceleration, with a focus on basic ion acceleration mechanisms and the production of ultra-intense ion beams. The challenges facing laser-driven ion acceleration studies, in particular those connected with potential applications of laser-accelerated ion beams, are also discussed.

Acceleration of 14C beams in electrostatic accelerators

International Nuclear Information System (INIS)

Rowton, L.J.; Tesmer, J.R.

1981-01-01

Operational problems in the production and acceleration of 14 C beams for nuclear structure research in Los Alamos National Laboratory's Van de Graaff accelerators are discussed. Methods for the control of contamination in ion sources, accelerators and personnel are described. Sputter source target fabrication techniques and the relative beam production efficiencies of various types of bound particulate carbon sputter source targets are presented

Ant colony method to control variance reduction techniques in the Monte Carlo simulation of clinical electron linear accelerators

International Nuclear Information System (INIS)

Garcia-Pareja, S.; Vilches, M.; Lallena, A.M.

2007-01-01

The ant colony method is used to control the application of variance reduction techniques to the simulation of clinical electron linear accelerators of use in cancer therapy. In particular, splitting and Russian roulette, two standard variance reduction methods, are considered. The approach can be applied to any accelerator in a straightforward way and permits, in addition, to investigate the 'hot' regions of the accelerator, an information which is basic to develop a source model for this therapy tool

High power accelerator for environmental application

International Nuclear Information System (INIS)

Han, B.; Kim, J.K.; Kim, Y.R.; Kim, S.M.

2011-01-01

The problems of environmental damage and degradation of natural resources are receiving increasing attention throughout the world. The increased population, higher living standards, increased urbanization and enhanced industrial activities of humankind are all leading to degradation of the environment. Increasing urbanization has been accompanied by significant environmental pollution, given the seriousness of the situation and future risk of crises, there is an urgent need to develop the efficient technologies including economical treatment methods. Therefore, cost-effective treatment of the stack gases, wastewater and sludge containing refractory pollutant with electron beam is actively studied in EB TECH Co. Electron beam treatment of such hazardous wastes is caused by the decomposition of pollutants as a result of their reactions with highly reactive species formed from radiolysis. However, to have advantages over existing processes, the electron beam process should have cost-effective and reliable in operation. Therefore high power accelerators (400kW~1MW) are developed for environmental application and they show the decrease in the cost of construction and operation of electron beam plant. In other way to reduce the cost for treatment, radical reactions accompanied by the other processes are introduced, and the synergistic effect upon the use of combined methods such as electron beam treatment with catalytic system, biological treatment and physico-chemical adsorption and others also show the improvement of the effect of electron beam treatment. (author)

High power accelerator for environmental application

Energy Technology Data Exchange (ETDEWEB)

Han, B.; Kim, J. K.; Kim, Y. R.; Kim, S. M. [EB-TECH Co., Ltd., Yuseong-gu Daejeon (Korea, Republic of)

2011-07-01

The problems of environmental damage and degradation of natural resources are receiving increasing attention throughout the world. The increased population, higher living standards, increased urbanization and enhanced industrial activities of humankind are all leading to degradation of the environment. Increasing urbanization has been accompanied by significant environmental pollution, given the seriousness of the situation and future risk of crises, there is an urgent need to develop the efficient technologies including economical treatment methods. Therefore, cost-effective treatment of the stack gases, wastewater and sludge containing refractory pollutant with electron beam is actively studied in EB TECH Co. Electron beam treatment of such hazardous wastes is caused by the decomposition of pollutants as a result of their reactions with highly reactive species formed from radiolysis. However, to have advantages over existing processes, the electron beam process should have cost-effective and reliable in operation. Therefore high power accelerators (400kW~1MW) are developed for environmental application and they show the decrease in the cost of construction and operation of electron beam plant. In other way to reduce the cost for treatment, radical reactions accompanied by the other processes are introduced, and the synergistic effect upon the use of combined methods such as electron beam treatment with catalytic system, biological treatment and physico-chemical adsorption and others also show the improvement of the effect of electron beam treatment. (author)

Degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid nanocomposite in simulated body fluid

International Nuclear Information System (INIS)

Liuyun, Jiang; Chengdong, Xiong; Lixin, Jiang; Lijuan, Xu

2013-01-01

Graphical abstract: In this manuscript, we initiated a systematic study to investigate the effect of HA on thermal properties, inner structure, reduction of mechanical strength, surface morphology and the surface deposit of n-HA/PLGA composite with respect to the soaking time. The results showed that n-HA played an important role in improving the degradation behavior of n-HA/PLGA composite, which can accelerate the degradation of n-HA/PLGA composite and endow it with bioactivity, after n-HA was detached from PLGA during the degradation, so that n-HA/PLGA composite may have a more promising prospect of the clinical application than pure PLGA as bone fracture internal fixation materials, and the results would be of reference significance to predict the in vivo degradation and biological properties. - Highlights: • Effect of n-HA on degradation behavior of n-HA/PLGA composite was investigated. • Degradation behaviors of n-HA/PLGA and PLGA were carried out in SBF for 6 months. • Viscosity, thermal properties, inner structure and bending strength were tested. • n-HA can accelerate the degradation and endows it with bioactivity. - Abstract: To investigate the effect of hydroxyapatite(HA) on the degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid (HA/PLGA) nanocomposite, the degradation experiment of n-HA/PLGA composite and pure PLGA were carried out by soaking in simulated body fluid(SBF) at 37 °C for 1, 2, 4 and 6 months. The change of intrinsic viscosity, thermal properties, inner structure, bending strength reduction, surface morphology and the surface deposit of n-HA/PLGA composite and pure PLGA with respect to the soaking time were investigated by means of UbbeloHde Viscometer, differential scanning calorimeter (DSC), scanning electron microscope(SEM), electromechanical universal tester, a conventional camera and X-ray diffraction (XRD). The results showed that n-HA played an important role in improving the degradation behavior of n

Multi-GPU Accelerated Admittance Method for High-Resolution Human Exposure Evaluation.

Science.gov (United States)

Xiong, Zubiao; Feng, Shi; Kautz, Richard; Chandra, Sandeep; Altunyurt, Nevin; Chen, Ji

2015-12-01

A multi-graphics processing unit (GPU) accelerated admittance method solver is presented for solving the induced electric field in high-resolution anatomical models of human body when exposed to external low-frequency magnetic fields. In the solver, the anatomical model is discretized as a three-dimensional network of admittances. The conjugate orthogonal conjugate gradient (COCG) iterative algorithm is employed to take advantage of the symmetric property of the complex-valued linear system of equations. Compared against the widely used biconjugate gradient stabilized method, the COCG algorithm can reduce the solving time by 3.5 times and reduce the storage requirement by about 40%. The iterative algorithm is then accelerated further by using multiple NVIDIA GPUs. The computations and data transfers between GPUs are overlapped in time by using asynchronous concurrent execution design. The communication overhead is well hidden so that the acceleration is nearly linear with the number of GPU cards. Numerical examples show that our GPU implementation running on four NVIDIA Tesla K20c cards can reach 90 times faster than the CPU implementation running on eight CPU cores (two Intel Xeon E5-2603 processors). The implemented solver is able to solve large dimensional problems efficiently. A whole adult body discretized in 1-mm resolution can be solved in just several minutes. The high efficiency achieved makes it practical to investigate human exposure involving a large number of cases with a high resolution that meets the requirements of international dosimetry guidelines.

Investigations on the Chemical Degradation of Silver Gelatine Prints

OpenAIRE

Maha Ahmed ALI; Mona Fouad ALI; Mohammed Osama SAKER; Abdel Azez El Bayoumi ABDEL ALEEM; Khaled Ibrahim EL NAGAR

2012-01-01

Photographs are considered composite objects with complex chemical and physical structures. Therefore they are more prone to damage as compared to other objects. Chemical degradation is by far the most common decay form found among photographic collections. This study investigates the chemical degradation of silver gelatin prints (DOP) and the reaction of the image, silver, gelatin, and paper to accelerated aging, to the action of light, and oxidizing gases, in terms of their physical and che...

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

Science.gov (United States)

van Tilborg, J.; Barber, S. K.; Benedetti, C.; Schroeder, C. B.; Isono, F.; Tsai, H.-E.; Geddes, C. G. R.; Leemans, W. P.

2018-05-01

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this manuscript, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam. An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.

Microstructural degradation mechanisms during creep in strength enhanced high Cr ferritic steels and their evaluation by hardness measurement

International Nuclear Information System (INIS)

Ghassemi Armaki, Hassan; Chen, Ruiping; Kano, Satoshi; Maruyama, Kouichi; Hasegawa, Yasushi; Igarashi, Masaaki

2011-01-01

Graphical abstract: Effect of static recovery on the acceleration of subgrain coarsening during creep plastic deformation. Display Omitted Highlights: → Short-term 'H' and long-term 'L' creep regions have different creep characteristics. → Strain-induced recovery of subgrains proceeds in the both creep regions 'H' and 'L'. → In region ''L', two additional degradation mechanisms accelerate creep failure. → Thermal coarsening of precipitates and subgrains appear during long-term creep ''L'. → In region 'L', strain-induced coarsening of precipitates accelerates creep failure. - Abstract: There are two creep regions with different creep characteristics: short-term creep region 'H', where precipitates and subgrains are thermally stable, and long-term creep region 'L', where thermal coarsening of precipitates and subgrains appear. In region 'H', the normalized subgrain size (λ-λ 0 )/(λ * -λ 0 ) has a linear relation with creep strain and its slope is 10ε -1 . But, region L is the time range in which the static recovery and the strain-induced recovery progress simultaneously. In this region, the static recovery accelerates the strain-induced recovery, and subgrain size is larger than that line which neglects the contribution of the static recovery. In region 'L', the Δλ/Δλ * -strain present a linear relation with a slope 35ε -1 . There is a linear relation between hardness and subgrain size. Hardness drop, H 0 - H, as a function of Larson-Miller parameter can be a good measure method for assessment of hardness drop and consequently degradation of microstructure. Hardness drop shows an identical slope in creep region 'H', whereas hardness drop due to thermal aging and creep in region 'L' show together a similar slope. In region 'H', degradation of microstructure is mainly due to recovery of subgrains controlled by creep plastic deformation, and precipitates do not have a major role. However, in creep region 'L', there are three degradation mechanisms

Ant colony method to control variance reduction techniques in the Monte Carlo simulation of clinical electron linear accelerators

Energy Technology Data Exchange (ETDEWEB)

Garcia-Pareja, S. [Servicio de Radiofisica Hospitalaria, Hospital Regional Universitario ' Carlos Haya' , Avda. Carlos Haya, s/n, E-29010 Malaga (Spain)], E-mail: garciapareja@gmail.com; Vilches, M. [Servicio de Fisica y Proteccion Radiologica, Hospital Regional Universitario ' Virgen de las Nieves' , Avda. de las Fuerzas Armadas, 2, E-18014 Granada (Spain); Lallena, A.M. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)

2007-09-21

The ant colony method is used to control the application of variance reduction techniques to the simulation of clinical electron linear accelerators of use in cancer therapy. In particular, splitting and Russian roulette, two standard variance reduction methods, are considered. The approach can be applied to any accelerator in a straightforward way and permits, in addition, to investigate the 'hot' regions of the accelerator, an information which is basic to develop a source model for this therapy tool.

A transport synthetic acceleration method for transport iterations

International Nuclear Information System (INIS)

Ramone, G.L.; Adams, M.L.

1997-01-01

A family of transport synthetic acceleration (TSA) methods for iteratively solving within group scattering problems is presented. A single iteration in these schemes consists of a transport sweep followed by a low-order calculation, which itself is a simplified transport problem. The method for isotropic-scattering problems in X-Y geometry is described. The Fourier analysis of a model problem for equations with no spatial discretization shows that a previously proposed TSA method is unstable in two dimensions but that the modifications make it stable and rapidly convergent. The same procedure for discretized transport equations, using the step characteristic and two bilinear discontinuous methods, shows that discretization enhances TSA performance. A conjugate gradient algorithm for the low-order problem is described, a crude quadrature set for the low-order problem is proposed, and the number of low-order iterations per high-order sweep is limited to a relatively small value. These features lead to simple and efficient improvements to the method. TSA is tested on a series of problems, and a set of parameters is proposed for which the method behaves especially well. TSA achieves a substantial reduction in computational cost over source iteration, regardless of discretization parameters or material properties, and this reduction increases with the difficulty of the problem

Coupling between chemical degradation and mechanical behaviour of leached concrete; Couplage degradation chimique - comportement en compression du beton

Energy Technology Data Exchange (ETDEWEB)

Nguyen, V H

2005-10-15

This work is in the context of the long term behavior of concrete employed in radioactive waste disposal. The objective is to study the coupled chemo-mechanical modelling of concrete. In the first part of this contribution, experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. An accelerated method has been chosen to perform this leaching process by using an ammonium nitrate solution. In the second part, we present a coupled phenomenological chemo-mechanical model that represents the degradation of concrete materials. On one hand, the chemical behavior is described by the simplified calcium leaching approach of cement paste and mortar. Then a homogenization approach using the asymptotic development is presented to take into account the influence of the presence of aggregates in concrete. And on the other hand, the mechanical part of the modelling is given. Here continuum damage mechanics is used to describe the mechanical degradation of concrete. The growth of inelastic strains observed during the mechanical tests is describes by means of a plastic like model. The model is established on the basis of the thermodynamics of irreversible processes framework. The coupled nonlinear problem at hand is addressed within the context of the finite element method. Finally, numerical simulations are compared with the experimental results for validation. (author)

A model-based radiography restoration method based on simple scatter-degradation scheme for improving image visibility

Science.gov (United States)

Kim, K.; Kang, S.; Cho, H.; Kang, W.; Seo, C.; Park, C.; Lee, D.; Lim, H.; Lee, H.; Kim, G.; Park, S.; Park, J.; Kim, W.; Jeon, D.; Woo, T.; Oh, J.

2018-02-01

In conventional planar radiography, image visibility is often limited mainly due to the superimposition of the object structure under investigation and the artifacts caused by scattered x-rays and noise. Several methods, including computed tomography (CT) as a multiplanar imaging modality, air-gap and grid techniques for the reduction of scatters, phase-contrast imaging as another image-contrast modality, etc., have extensively been investigated in attempt to overcome these difficulties. However, those methods typically require higher x-ray doses or special equipment. In this work, as another approach, we propose a new model-based radiography restoration method based on simple scatter-degradation scheme where the intensity of scattered x-rays and the transmission function of a given object are estimated from a single x-ray image to restore the original degraded image. We implemented the proposed algorithm and performed an experiment to demonstrate its viability. Our results indicate that the degradation of image characteristics by scattered x-rays and noise was effectively recovered by using the proposed method, which improves the image visibility in radiography considerably.

Light and current induced degradation in p-type multi-crystalline cells and development of an inspection method and a stabilization method

Energy Technology Data Exchange (ETDEWEB)

Broek, K.M.; Bennett, I.J.; Jansen, M.J.; Borg, Van der N.J.C.M.; Eerenstein, W. [ECN Solar Energy, Petten (Netherlands)

2012-09-15

Stable solar cells are needed for durability testing of different combinations of module materials. In such a test, significant power losses in full-size modules with multi-crystalline cells after thermal cycling have been observed. This has been related to degradation of the solar cells used and it appeared that this was caused by current induced degradation. This phenomenon is not limited to boron doped Cz-Si, but can also occur in p-type multi-crystalline silicon. Work was done to develop an incoming inspection method for new batches of cells. Also, stabilisation procedures for modules containing cells that are sensitive to degradation have been determined.

A thin film degradation study of a fluorinated polyether liquid lubricant using an HPLC method

Science.gov (United States)

Morales, W.

1986-01-01

A High Pressure Liquid Chromatography (HPLC) separation method was developed to study and analyze a fluorinated polyether fluid which is promising liquid lubricant for future applications. This HPLC separation method was used in a preliminary study investigating the catalytic effect of various metal, metal alloy, and ceramic engineering materials on the degradation of this fluid in a dry air atmosphere at 345 C. Using a 440 C stainless steel as a reference catalytic material it was found that a titanium alloy and a chromium plated material degraded the fluorinated polyether fluid substantially more than the reference material.

High power ring methods and accelerator driven subcritical reactor application

Energy Technology Data Exchange (ETDEWEB)

Tahar, Malek Haj [Univ. of Grenoble (France)

2016-08-07

High power proton accelerators allow providing, by spallation reaction, the neutron fluxes necessary in the synthesis of fissile material, starting from Uranium 238 or Thorium 232. This is the basis of the concept of sub-critical operation of a reactor, for energy production or nuclear waste transmutation, with the objective of achieving cleaner, safer and more efficient process than today’s technologies allow. Designing, building and operating a proton accelerator in the 500-1000 MeV energy range, CW regime, MW power class still remains a challenge nowadays. There is a limited number of installations at present achieving beam characteristics in that class, e.g., PSI in Villigen, 590 MeV CW beam from a cyclotron, SNS in Oakland, 1 GeV pulsed beam from a linear accelerator, in addition to projects as the ESS in Europe, a 5 MW beam from a linear accelerator. Furthermore, coupling an accelerator to a sub-critical nuclear reactor is a challenging proposition: some of the key issues/requirements are the design of a spallation target to withstand high power densities as well as ensure the safety of the installation. These two domains are the grounds of the PhD work: the focus is on the high power ring methods in the frame of the KURRI FFAG collaboration in Japan: upgrade of the installation towards high intensity is crucial to demonstrate the high beam power capability of FFAG. Thus, modeling of the beam dynamics and benchmarking of different codes was undertaken to validate the simulation results. Experimental results revealed some major losses that need to be understood and eventually overcome. By developing analytical models that account for the field defects, one identified major sources of imperfection in the design of scaling FFAG that explain the important tune variations resulting in the crossing of several betatron resonances. A new formula is derived to compute the tunes and properties established that characterize the effect of the field imperfections on the

Shelf life prediction of apple brownies using accelerated method

Science.gov (United States)

Pulungan, M. H.; Sukmana, A. D.; Dewi, I. A.

2018-03-01

The aim of this research was to determine shelf life of apple brownies. Shelf life was determined with Accelerated Shelf Life Testing method and Arrhenius equation. Experiment was conducted at 25, 35, and 45°C for 30 days. Every five days, the sample was analysed for free fatty acid (FFA), water activity (Aw), and organoleptic acceptance (flavour, aroma, and texture). The shelf life of the apple brownies based on FFA were 110, 54, and 28 days at temperature of 25, 35, and 45°C, respectively.

An accelerated training method for back propagation networks

Science.gov (United States)

Shelton, Robert O. (Inventor)

1993-01-01

The principal objective is to provide a training procedure for a feed forward, back propagation neural network which greatly accelerates the training process. A set of orthogonal singular vectors are determined from the input matrix such that the standard deviations of the projections of the input vectors along these singular vectors, as a set, are substantially maximized, thus providing an optimal means of presenting the input data. Novelty exists in the method of extracting from the set of input data, a set of features which can serve to represent the input data in a simplified manner, thus greatly reducing the time/expense to training the system.

Correction of longitudinal errors in accelerators for heavy-ion fusion

International Nuclear Information System (INIS)

Sharp, W.M.; Callahan, D.A.; Barnard, J.J.; Langdon, A.B.; Fessenden, T.J.

1993-01-01

Longitudinal space-charge waves develop on a heavy-ion inertial-fusion pulse from initial mismatches or from inappropriately timed or shaped accelerating voltages. Without correction, waves moving backward along the beam can grow due to the interaction with their resistivity retarded image fields, eventually degrading the longitudinal emittance. A simple correction algorithm is presented here that uses a time-dependent axial electric field to reverse the direction of backward-moving waves. The image fields then damp these forward-moving waves. The method is demonstrated by fluid simulations of an idealized inertial-fusion driver, and practical problems in implementing the algorithm are discussed

Analytical methods for toxic gases from thermal degradation of polymers

Science.gov (United States)

Hsu, M.-T. S.

1977-01-01

Toxic gases evolved from the thermal oxidative degradation of synthetic or natural polymers in small laboratory chambers or in large scale fire tests are measured by several different analytical methods. Gas detector tubes are used for fast on-site detection of suspect toxic gases. The infrared spectroscopic method is an excellent qualitative and quantitative analysis for some toxic gases. Permanent gases such as carbon monoxide, carbon dioxide, methane and ethylene, can be quantitatively determined by gas chromatography. Highly toxic and corrosive gases such as nitrogen oxides, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and sulfur dioxide should be passed into a scrubbing solution for subsequent analysis by either specific ion electrodes or spectrophotometric methods. Low-concentration toxic organic vapors can be concentrated in a cold trap and then analyzed by gas chromatography and mass spectrometry. The limitations of different methods are discussed.

A chain-of-states acceleration method for the efficient location of minimum energy paths

Energy Technology Data Exchange (ETDEWEB)

Hernández, E. R., E-mail: Eduardo.Hernandez@csic.es; Herrero, C. P. [Instituto de Ciencia de Materiales de Madrid (ICMM–CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Soler, J. M. [Departamento de Física de la Materia Condensada and IFIMAC, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

2015-11-14

We describe a robust and efficient chain-of-states method for computing Minimum Energy Paths (MEPs) associated to barrier-crossing events in poly-atomic systems, which we call the acceleration method. The path is parametrized in terms of a continuous variable t ∈ [0, 1] that plays the role of time. In contrast to previous chain-of-states algorithms such as the nudged elastic band or string methods, where the positions of the states in the chain are taken as variational parameters in the search for the MEP, our strategy is to formulate the problem in terms of the second derivatives of the coordinates with respect to t, i.e., the state accelerations. We show this to result in a very simple and efficient method for determining the MEP. We describe the application of the method to a series of test cases, including two low-dimensional problems and the Stone-Wales transformation in C{sub 60}.

A chain-of-states acceleration method for the efficient location of minimum energy paths

International Nuclear Information System (INIS)

Hernández, E. R.; Herrero, C. P.; Soler, J. M.

2015-01-01

We describe a robust and efficient chain-of-states method for computing Minimum Energy Paths (MEPs) associated to barrier-crossing events in poly-atomic systems, which we call the acceleration method. The path is parametrized in terms of a continuous variable t ∈ [0, 1] that plays the role of time. In contrast to previous chain-of-states algorithms such as the nudged elastic band or string methods, where the positions of the states in the chain are taken as variational parameters in the search for the MEP, our strategy is to formulate the problem in terms of the second derivatives of the coordinates with respect to t, i.e., the state accelerations. We show this to result in a very simple and efficient method for determining the MEP. We describe the application of the method to a series of test cases, including two low-dimensional problems and the Stone-Wales transformation in C 60

Electrostatic accelerators

CERN Document Server

Hinterberger, F

2006-01-01

The principle of electrostatic accelerators is presented. We consider Cockcroft– Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We sketch possible applications and the progress in the development of electrostatic accelerators.

Accelerating the life of transistors

International Nuclear Information System (INIS)

Qi Haochun; Lü Changzhi; Zhang Xiaoling; Xie Xuesong

2013-01-01

Choosing small and medium power switching transistors of the NPN type in a 3DK set as the study object, the test of accelerating life is conducted in constant temperature and humidity, and then the data are statistically analyzed with software developed by ourselves. According to degradations of such sensitive parameters as the reverse leakage current of transistors, the lifetime order of transistors is about more than 10 4 at 100 °C and 100% relative humidity (RH) conditions. By corrosion fracture of transistor outer leads and other failure modes, with the failure truncated testing, the average lifetime rank of transistors in different distributions is extrapolated about 10 3 . Failure mechanism analyses of degradation of electrical parameters, outer lead fracture and other reasons that affect transistor lifetime are conducted. The findings show that the impact of external stress of outer leads on transistor reliability is more serious than that of parameter degradation. (semiconductor devices)

Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

Science.gov (United States)

Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

2016-12-01

Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10 -3 and 12.4 × 10 -3  min -1 , respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

The Use of Conditional Probability Integral Transformation Method for Testing Accelerated Failure Time Models

Directory of Open Access Journals (Sweden)

Abdalla Ahmed Abdel-Ghaly

2016-06-01

Full Text Available This paper suggests the use of the conditional probability integral transformation (CPIT method as a goodness of fit (GOF technique in the field of accelerated life testing (ALT, specifically for validating the underlying distributional assumption in accelerated failure time (AFT model. The method is based on transforming the data into independent and identically distributed (i.i.d Uniform (0, 1 random variables and then applying the modified Watson statistic to test the uniformity of the transformed random variables. This technique is used to validate each of the exponential, Weibull and lognormal distributions' assumptions in AFT model under constant stress and complete sampling. The performance of the CPIT method is investigated via a simulation study. It is concluded that this method performs well in case of exponential and lognormal distributions. Finally, a real life example is provided to illustrate the application of the proposed procedure.

[6]-Shogaol Inhibits α-MSH-Induced Melanogenesis through the Acceleration of ERK and PI3K/Akt-Mediated MITF Degradation

Directory of Open Access Journals (Sweden)

Huey-Chun Huang

2014-01-01

Full Text Available [6]-Shogaol is the main biologically active component of ginger. Previous reports showed that [6]-shogaol has several pharmacological characteristics, such as antioxidative, anti-inflammatory, antimicrobial, and anticarcinogenic properties. However, the effects of [6]-shogaol on melanogenesis remain to be elucidated. The study aimed to evaluate the potential skin whitening mechanisms of [6]-shogaol. The effects of [6]-shogaol on cell viability, melanin content, tyrosinase activity, and the expression of the tyrosinase and microphthalmia-associated transcription factor (MITF were measured. The results revealed that [6]-shogaol effectively suppresses tyrosinase activity and the amount of melanin and that those effects are more pronounced than those of arbutin. It was also found that [6]-shogaol decreased the protein expression levels of tyrosinase-related protein 1 (TRP-1 and microphthalmia-associated transcriptional factor (MITF. In addition, the MITF mRNA levels were also effectively decreased in the presence of 20 μM [6]-shogaol. The degradation of MITF protein was inhibited by the MEK 1-inhibitor (U0126 or phosphatidylinositol-3-kinase inhibitor (PI3K inhibitor (LY294002. Further immunofluorescence staining assay implied the involvement of the proteasome in the downregulation of MITF by [6]-shogaol. Our confocal assay results also confirmed that [6]-shogaol inhibited α-melanocyte stimulating hormone- (α-MSH- induced melanogenesis through the acceleration of extracellular responsive kinase (ERK and phosphatidylinositol-3-kinase- (PI3K/Akt- mediated MITF degradation.

Microcantilever sensors for fast analysis of enzymatic degradation of poly (D, L-lactide)

DEFF Research Database (Denmark)

Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

2015-01-01

of the biodegradation rate of PDLLA with a minute amount of sample and without the need of thermal and chemical acceleration. The degradation rate of the polymer has been estimated by multilayer cantilever theory and model simulation. A bulk degradation rate of 0.24 μg mm-2 hour-1 is estimated which agrees well...

Accelerator mass spectrometry at the Rossendorf 5 MV tandem accelerator

International Nuclear Information System (INIS)

Friedrich, M.; Buerger, W.; Curian, H.; Hartmann, B.; Hentschel, E.; Matthes, H.; Probst, W.; Seidel, M.; Turuc, S.; Hebert, D.; Rothe, T.; Stolz, W.

1992-01-01

The Rossendorf electrostatic accelerators (5 MV tandem accelerator and single ended 2 MV van de Graaff accelerator) are already used for ion beam analysis. The existing methods (RBS, PIXE, ERDA, NRA, nuclear microprobe and external beam) will be completed by introduction of Accelerator Mass Spectrometry (AMS). A short description of the Rossendorf AMS system is given and first experimental results are presented. (R.P.) 4 refs.; 6 figs

An improved method for statistical analysis of raw accelerator mass spectrometry data

International Nuclear Information System (INIS)

Gutjahr, A.; Phillips, F.; Kubik, P.W.; Elmore, D.

1987-01-01

Hierarchical statistical analysis is an appropriate method for statistical treatment of raw accelerator mass spectrometry (AMS) data. Using Monte Carlo simulations we show that this method yields more accurate estimates of isotope ratios and analytical uncertainty than the generally used propagation of errors approach. The hierarchical analysis is also useful in design of experiments because it can be used to identify sources of variability. 8 refs., 2 figs

Influence of the formation- and passivation rate of boron-oxygen defects for mitigating carrier-induced degradation in silicon within a hydrogen-based model

International Nuclear Information System (INIS)

Hallam, Brett; Abbott, Malcolm; Nampalli, Nitin; Hamer, Phill; Wenham, Stuart

2016-01-01

A three-state model is used to explore the influence of defect formation- and passivation rates of carrier-induced degradation related to boron-oxygen complexes in boron-doped p-type silicon solar cells within a hydrogen-based model. The model highlights that the inability to effectively mitigate carrier-induced degradation at elevated temperatures in previous studies is due to the limited availability of defects for hydrogen passivation, rather than being limited by the defect passivation rate. An acceleration of the defect formation rate is also observed to increase both the effectiveness and speed of carrier-induced degradation mitigation, whereas increases in the passivation rate do not lead to a substantial acceleration of the hydrogen passivation process. For high-throughput mitigation of such carrier-induced degradation on finished solar cell devices, two key factors were found to be required, high-injection conditions (such as by using high intensity illumination) to enable an acceleration of defect formation whilst simultaneously enabling a rapid passivation of the formed defects, and a high temperature to accelerate both defect formation and defect passivation whilst still ensuring an effective mitigation of carrier-induced degradation

Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

International Nuclear Information System (INIS)

Leech, Dina M.; Snyder, Matthew T.; Wetzel, Robert G.

2009-01-01

Nanomolar concentrations of steroid hormones such as 17β-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17β-estradiol demonstrated modest photodegradation (∼ 26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased (∼ 40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone

Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

Energy Technology Data Exchange (ETDEWEB)

Leech, Dina M. [Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557 (United States)], E-mail: dmleech@email.unc.edu; Snyder, Matthew T.; Wetzel, Robert G. [Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States)

2009-03-01

Nanomolar concentrations of steroid hormones such as 17{beta}-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17{beta}-estradiol demonstrated modest photodegradation ({approx} 26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased ({approx} 40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone.

A degradation-based sorting method for lithium-ion battery reuse.

Directory of Open Access Journals (Sweden)

Hao Chen

Full Text Available In a world where millions of people are dependent on batteries to provide them with convenient and portable energy, battery recycling is of the utmost importance. In this paper, we developed a new method to sort 18650 Lithium-ion batteries in large quantities and in real time for harvesting used cells with enough capacity for battery reuse. Internal resistance and capacity tests were conducted as a basis for comparison with a novel degradation-based method based on X-ray radiographic scanning and digital image contrast computation. The test results indicate that the sorting accuracy of the test cells is about 79% and the execution time of our algorithm is at a level of 200 milliseconds, making our method a potential real-time solution for reusing the remaining capacity in good used cells.

Quality control methods for linear accelerator radiation and mechanical axes alignment.

Science.gov (United States)

Létourneau, Daniel; Keller, Harald; Becker, Nathan; Amin, Md Nurul; Norrlinger, Bernhard; Jaffray, David A

2018-06-01

The delivery accuracy of highly conformal dose distributions generated using intensity modulation and collimator, gantry, and couch degrees of freedom is directly affected by the quality of the alignment between the radiation beam and the mechanical axes of a linear accelerator. For this purpose, quality control (QC) guidelines recommend a tolerance of ±1 mm for the coincidence of the radiation and mechanical isocenters. Traditional QC methods for assessment of radiation and mechanical axes alignment (based on pointer alignment) are time consuming and complex tasks that provide limited accuracy. In this work, an automated test suite based on an analytical model of the linear accelerator motions was developed to streamline the QC of radiation and mechanical axes alignment. The proposed method used the automated analysis of megavoltage images of two simple task-specific phantoms acquired at different linear accelerator settings to determine the coincidence of the radiation and mechanical isocenters. The sensitivity and accuracy of the test suite were validated by introducing actual misalignments on a linear accelerator between the radiation axis and the mechanical axes using both beam steering and mechanical adjustments of the gantry and couch. The validation demonstrated that the new QC method can detect sub-millimeter misalignment between the radiation axis and the three mechanical axes of rotation. A displacement of the radiation source of 0.2 mm using beam steering parameters was easily detectable with the proposed collimator rotation axis test. Mechanical misalignments of the gantry and couch rotation axes of the same magnitude (0.2 mm) were also detectable using the new gantry and couch rotation axis tests. For the couch rotation axis, the phantom and test design allow detection of both translational and tilt misalignments with the radiation beam axis. For the collimator rotation axis, the test can isolate the misalignment between the beam radiation axis

Comparative study of modified polypropylene nanocomposites under environment and accelerated ageing conditions

International Nuclear Information System (INIS)

Komatsu, Luiz Gustavo Hiroki

2016-01-01

The understanding of degradation mechanism action on the polymer nanocomposites in face of weathering (UV light, heat, acid rain, among others), is the key for development of new additives and new applications. In this work the nanocomposite synthesis was carried in molten state, using twin-screw extruder. The polymer matrix was the HMS-PP (high melt polypropylene) synthesized by gamma irradiation and the nanometric inorganic component was the montmorillonite clay. For better compatibilization between the matrix and clay, it were used maleic anhydride as coupling agent. For environment and in oven accelerated aging assays, the dumbbell samples were prepared under hot pressing. The characterization of clay addition effects and aging effects on the nanocomposites, required the use of techniques of Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Fourier Transformed Infrared Spectroscopy (FT-IR), Xray Fluorescence (WDXRF), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and mechanical properties. Samples with 0.1; 1; 3; 5; 10 % of clay were tested. The sample with 5% of clay showed better stability on the environmental assay and accelerated aging in oven assay. On the other hand, the sample with higher percent of clay (10%), was more degraded under on environmental aging than under accelerated aging in stove. In this case, became more resistant until 56 days of assay. On the studied concentrations (less than ≤ 3%) of clay, it can be seen an equilibrium between barrier effect and metallic ions action accelerating the degradative process. (author)

Thermostable Alginate degrading enzymes and their methods of use

NARCIS (Netherlands)

Hreggvidsson, Gudmundur Oli; Jonsson, Oskar W.J.; Bjornsdottir, Bryndis; Fridjonsson, Hedinn O; Altenbuchner, Josef; Watzlawick, Hildegard; Dobruchowska, Justyna; Kamerling, Johannis

2015-01-01

The present invention relates to the identification, production and use of thermostable alginate lyase enzymes that can be used to partially degrade alginate to yield oligosaccharides or to give complete degradation of alginate to yield (unsaturated) mono-uronates.

Accelerators for Fusion Materials Testing

Science.gov (United States)

Knaster, Juan; Okumura, Yoshikazu

Fusion materials research is a worldwide endeavor as old as the parallel one working toward the long term stable confinement of ignited plasma. In a fusion reactor, the preservation of the required minimum thermomechanical properties of the in-vessel components exposed to the severe irradiation and heat flux conditions is an indispensable factor for safe operation; it is also an essential goal for the economic viability of fusion. Energy from fusion power will be extracted from the 14 MeV neutron freed as a product of the deuterium-tritium fusion reactions; thus, this kinetic energy must be absorbed and efficiently evacuated and electricity eventually generated by the conventional methods of a thermal power plant. Worldwide technological efforts to understand the degradation of materials exposed to 14 MeV neutron fluxes >1018 m-2s-1, as expected in future fusion power plants, have been intense over the last four decades. Existing neutron sources can reach suitable dpa (“displacement-per-atom”, the figure of merit to assess materials degradation from being exposed to neutron irradiation), but the differences in the neutron spectrum of fission reactors and spallation sources do not allow one to unravel the physics and to anticipate the degradation of materials exposed to fusion neutrons. Fusion irradiation conditions can be achieved through Li (d, xn) nuclear reactions with suitable deuteron beam current and energy, and an adequate flowing lithium screen. This idea triggered in the late 1970s at Los Alamos National Laboratory (LANL) a campaign working toward the feasibility of continuous wave (CW) high current linacs framed by the Fusion Materials Irradiation Test (FMIT) project. These efforts continued with the Low Energy Demonstrating Accelerator (LEDA) (a validating prototype of the canceled Accelerator Production of Tritium (APT) project), which was proposed in 2002 to the fusion community as a 6.7MeV, 100mA CW beam injector for a Li (d, xn) source to bridge

Bio stimulation for the Enhanced Degradation of Herbicides in Soil

International Nuclear Information System (INIS)

Kanissery, R.G; Sims, G.K

2011-01-01

Cleanup of herbicide-contaminated soils has been a dire environmental concern since the advent of industrial era. Although microorganisms are excellent degraders of herbicide compounds in the soil, some reparation may need to be brought about, in order to stimulate them to degrade the herbicide at a faster rate in a confined time frame. Bio stimulation through the appropriate utilization of organic amendments and nutrients can accelerate the degradation of herbicides in the soil. However, effective use of bio stimulants requires thorough comprehension of the global redox cycle during the microbial degradation of the herbicide molecules in the soil. In this paper, we present the prospects of using bio stimulation as a powerful remediation strategy for the rapid cleanup of herbicide-polluted soils.

Application of normal form methods to the analysis of resonances in particle accelerators

International Nuclear Information System (INIS)

Davies, W.G.

1992-01-01

The transformation to normal form in a Lie-algebraic framework provides a very powerful method for identifying and analysing non-linear behaviour and resonances in particle accelerators. The basic ideas are presented and illustrated. (author). 4 refs

Direct ubiquitin independent recognition and degradation of a folded protein by the eukaryotic proteasomes-origin of intrinsic degradation signals.

Directory of Open Access Journals (Sweden)

Amit Kumar Singh Gautam

Full Text Available Eukaryotic 26S proteasomes are structurally organized to recognize, unfold and degrade globular proteins. However, all existing model substrates of the 26S proteasome in addition to ubiquitin or adaptor proteins require unstructured regions in the form of fusion tags for efficient degradation. We report for the first time that purified 26S proteasome can directly recognize and degrade apomyoglobin, a globular protein, in the absence of ubiquitin, extrinsic degradation tags or adaptor proteins. Despite a high affinity interaction, absence of a ligand and presence of only helices/loops that follow the degradation signal, apomyoglobin is degraded slowly by the proteasome. A short floppy F-helix exposed upon ligand removal and in conformational equilibrium with a disordered structure is mandatory for recognition and initiation of degradation. Holomyoglobin, in which the helix is buried, is neither recognized nor degraded. Exposure of the floppy F-helix seems to sensitize the proteasome and primes the substrate for degradation. Using peptide panning and competition experiments we speculate that initial encounters through the floppy helix and additional strong interactions with N-terminal helices anchors apomyoglobin to the proteasome. Stabilizing helical structure in the floppy F-helix slows down degradation. Destabilization of adjacent helices accelerates degradation. Unfolding seems to follow the mechanism of helix unraveling rather than global unfolding. Our findings while confirming the requirement for unstructured regions in degradation offers the following new insights: a origin and identification of an intrinsic degradation signal in the substrate, b identification of sequences in the native substrate that are likely to be responsible for direct interactions with the proteasome, and c identification of critical rate limiting steps like exposure of the intrinsic degron and destabilization of an unfolding intermediate that are presumably

Radiation degradation of silk protein

Energy Technology Data Exchange (ETDEWEB)

Wachiraporn Pewlong; Boonya Sudatis [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2000-09-01

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated in the dose range up to 2500 kGy using an electron beam accelerator to apply the radiation degradation technique as a means to solubilize fibroin. The tensile strength of irradiated fibroin fiber decreased with increasing dose and the presence of oxygen in the irradiation atmosphere enhanced the degradation. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: calcium chloride solution (CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O = 1 : 2 : 8 in mole ratio), hydrochloric acid (0.5N) and distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water-soluble protein was extracted by distilled water. (author)

Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data

Energy Technology Data Exchange (ETDEWEB)

Patterson, Timothy [Research Engineer; Motupally, Sathya [Research Engineer

2012-06-01

UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells. This in-depth investigation will focused on critical fuel cell components (e.g. membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. UTC had access to MEA materials that had accrued significant load time under real-world conditions in PureMotion® 120 power plant used in transit buses. These materials are referred to as end-of-life (EOL) components in the rest of this document. Advanced characterization techniques were used to evaluate degradation mode progress using these critical cell components extracted from both bus power plants and corresponding materials tested using the DOE AST’s. These techniques were applied to samples at beginning-of-life (BOL) to serve as a baseline. These comparisons advised the progress of the various failure modes that these critical components were subjected to, such as membrane degradation, catalyst support corrosion, platinum group metal dissolution, and others. Gaps in the existing ASTs predicted the degradation observed in the field in terms of these modes were outlined. Using the gaps, new AST’s were recommended and tested to better reflect the degradation modes seen in field operation. Also, BOL components were degraded in a test vehicle at UTC designed to accelerate the bus field operation.

Stability indicating spectrophotometric and spectrodensitometric methods for the determination of diatrizoate sodium in presence of its degradation product

Science.gov (United States)

Abd El-Rahman, Mohamed K.; Riad, Safaa M.; Abdel Gawad, Sherif A.; Fawaz, Esraa M.; Shehata, Mostafa A.

2015-02-01

Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2 nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24 μg/mL with mean percentage recovery 99.95 ± 0.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227 nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.99 ± 1.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238 nm over a concentration range of 4-20 μg/spot, with mean percentage recovery 99.88 ± 0.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

Efficient Homodifunctional Bimolecular Ring-Closure Method for Cyclic Polymers by Combining RAFT and Self-Accelerating Click Reaction.

Science.gov (United States)

Qu, Lin; Sun, Peng; Wu, Ying; Zhang, Ke; Liu, Zhengping

2017-08-01

An efficient metal-free homodifunctional bimolecular ring-closure method is developed for the formation of cyclic polymers by combining reversible addition-fragmentation chain transfer (RAFT) polymerization and self-accelerating click reaction. In this approach, α,ω-homodifunctional linear polymers with azide terminals are prepared by RAFT polymerization and postmodification of polymer chain end groups. By virtue of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DBA) as small linkers, well-defined cyclic polymers are then prepared using the self-accelerating double strain-promoted azide-alkyne click (DSPAAC) reaction to ring-close the azide end-functionalized homodifunctional linear polymer precursors. Due to the self-accelerating property of DSPAAC ring-closing reaction, this novel method eliminates the requirement of equimolar amounts of telechelic polymers and small linkers in traditional bimolecular ring-closure methods. It facilitates this method to efficiently and conveniently produce varied pure cyclic polymers by employing an excess molar amount of DBA small linkers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

DEFF Research Database (Denmark)

Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng

2013-01-01

Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditions...... of the polymer. Fuel cell durability tests with contaminations of ferrous ions did show considerable performance degradation, however, primarily due to the catalyst deterioration rather than the membrane degradation........ In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer...

Photocatalytic Degradation of Malachite Green Using Nano-sized cerium-iron Oxide

Directory of Open Access Journals (Sweden)

K. L. Ameta

2014-05-01

Full Text Available Nano-sized cerium-iron oxide nanoparticles has been synthesized, characterized and explored as an efficient photocatalyst for the photocatalytic degradation of malachite green. The effects of different variables on degradation of dye were optimized such as the pH of the dye solution, dye concentration, amount of photocatalyst and light intensity. About 91% degradation of dye of 2×10-5 M concentration was observed after 2 hours at 8.5 pH and 600 Wm-2 light intensity. The reason for the high catalytic activity of the synthesized nanoparticles is ascribed to the high surface area which determines the active sites of the catalyst and accelerates the photocatalytic degradation.

Robust PV Degradation Methodology and Application

Energy Technology Data Exchange (ETDEWEB)

Jordan, Dirk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deline, Christopher A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Sarah [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kimball, Greg [SunPower; Anderson, Mike [SunPower

2017-11-15

The degradation rate plays an important role in predicting and assessing the long-term energy generation of PV systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this manuscript, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year (YOY) rate calculation. We show the method to provide reliable degradation rate estimates even in the case of sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.

Degradation Characterization of Thermal Interface Greases

Energy Technology Data Exchange (ETDEWEB)

Major, Joshua [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Paret, Paul P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Blackman, Gregory [DuPont; Wong, Arnold [DuPont; Meth, Jeffery [DuPont

2018-02-12

Thermal interface materials (TIMs) are used in power electronics packaging to minimize thermal resistance between the heat generating component and the heat sink. Thermal greases are one such class. The conformability and thin bond line thickness (BLT) of these TIMs can potentially provide low thermal resistance throughout the operation lifetime of a component. However, their performance degrades over time due to pump-out and dry-out during thermal and power cycling. The reliability performance of greases through operational cycling needs to be quantified to develop new materials with superior properties. NREL, in collaboration with DuPont, has performed thermal and reliability characterization of several commercially available thermal greases. Initial bulk and contact thermal resistance of grease samples were measured, and then the thermal degradation that occurred due to pump-out and dry-out during temperature cycling was monitored. The thermal resistances of five different grease materials were evaluated using NREL's steady-state thermal resistance tester based on the ASTM test method D5470. Greases were then applied, utilizing a 2.5 cm x 2.5 cm stencil, between invar and aluminum plates to compare the thermomechanical performance of the materials in a representative test fixture. Scanning Acoustic microscopy, thermal, and compositional analyses were performed periodically during thermal cycling from -40 degrees C to 125 degrees C. Completion of this characterization has allowed for a comprehensive evaluation of thermal greases both for their initial bulk and contact thermal performance, as well as their degradation mechanisms under accelerated thermal cycling conditions.

Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing.

Science.gov (United States)

Goiato, Marcelo Coelho; Santos, Daniela Micheline dos; Souza, Josiene Firmino; Moreno, Amália; Pesqueira, Aldiéris Alves

2010-12-01

Esthetics and durability of materials used to fabricate artificial eyes has been an important issue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin. This study assessed the color stability of acrylic resins used to fabricate sclera in three basic shades (N1, N2 and N3) when subjected to accelerated aging, mechanical and chemical polishing. Specimens of each resin were fabricated and submitted to mechanical and chemical polishing. Chromatic analysis was performed before and after accelerated aging through ultraviolet reflection spectrophotometry. All specimens revealed color alteration following polishing and accelerated aging. The resins presented statistically significant chromatic alteration (p<0.01) between the periods of 252 and 1008 h. Both polishing methods presented no significant difference between the values of color derivatives of resins.

Electrostatic accelerators

OpenAIRE

Hinterberger, F

2006-01-01

The principle of electrostatic accelerators is presented. We consider Cockcroft– Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We ...

Status of peatland degradation and development in Sumatra and Kalimantan.

Science.gov (United States)

Miettinen, Jukka; Liew, Soo Chin

2010-01-01

Peatlands cover around 13 Mha in Sumatra and Kalimantan, Indonesia. Human activities have rapidly increased in the peatland ecosystems during the last two decades, invariably degrading them and making them vulnerable to fires. This causes high carbon emissions that contribute to global climate change. For this article, we used 94 high resolution (10-20 m) satellite images to map the status of peatland degradation and development in Sumatra and Kalimantan using visual image interpretation. The results reveal that less than 4% of the peatland areas remain covered by pristine peatswamp forests (PSFs), while 37% are covered by PSFs with varying degree of degradation. Furthermore, over 20% is considered to be unmanaged degraded landscape, occupied by ferns, shrubs and secondary growth. This alarming extent of degradation makes peatlands vulnerable to accelerated peat decomposition and catastrophic fire episodes that will have global consequences. With on-going degradation and development the existence of the entire tropical peatland ecosystem in this region is in great danger.

Stability-indicating UPLC method for determination of Valsartan and their degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms.

Science.gov (United States)

Krishnaiah, Ch; Reddy, A Raghupathi; Kumar, Ramesh; Mukkanti, K

2010-11-02

A simple, precise, accurate stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the quantitative determination of purity of Valsartan drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. The method was developed using Waters Aquity BEH C18 (100 mm x 2.1 mm, 1.7 microm) column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 225 nm, the run time was within 9.5 min, which Valsartan and its seven impurities were well separated. Valsartan was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Valsartan was found to degrade significantly in acid and oxidative stress conditions and stable in base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per international conference on harmonization (ICH) guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of Valsartan in pharmaceutical dosage forms.

An improved method to accurately calibrate the gantry angle indicators of the radiotherapy linear accelerators

International Nuclear Information System (INIS)

Chang Liyun; Ho, S.-Y.; Du, Y.-C.; Lin, C.-M.; Chen Tainsong

2007-01-01

The calibration of the gantry angle indicator is an important and basic quality assurance (QA) item for the radiotherapy linear accelerator. In this study, we propose a new and practical method, which uses only the digital level, V-film, and general solid phantoms. By taking the star shot only, we can accurately calculate the true gantry angle according to the geometry of the film setup. The results on our machine showed that the gantry angle was shifted by -0.11 deg. compared with the digital indicator, and the standard deviation was within 0.05 deg. This method can also be used for the simulator. In conclusion, this proposed method could be adopted as an annual QA item for mechanical QA of the accelerator

High power accelerators and wastewater treatment

International Nuclear Information System (INIS)

Han, B.; Kim, J.K.; Kim, Y.R.; Kim, S.M.; Makaov, I.E.; Ponomarev, A.V.

2006-01-01

The problems of environmental damage and degradation of natural resources are receiving increasing attention throughout the world. The increased population, higher living standards, increased urbanization and enhanced industrial activities of humankind are all leading to degradation of the environment. Increasing urbanization has been accompanied by significant water pollution. Given the seriousness of the situation and future risk of crises, there is an urgent need to develop the water-efficient technologies including economical treatment methods of wastewater and polluted water. Therefore, cost-effective treatment of the municipal and industrial wastewater containing refractory pollutant with electron beam is actively studied in EB TECH Co.. Electron beam treatment of wastewater is caused by the decomposition of pollutants as a result of their reactions with highly reactive species formed from water radiolysis (hydrated electron, OH free radical and H atom). However, to have advantages over existing processes, the electron beam process should have cost-effective and reliable in operation. Therefore high power accelerators (400kW∼1MW) are developed for environmental application and they show the decrease in the cost of construction and operation of electron beam plant. In other way to reduce the cost for wastewater treatment, radical reactions accompanied by the other processes are introduced, and the synergistic effect upon the use of combined methods such as electron beam treatment with ozonation, biological treatment and physico-chemical adsorption and others also show the improvement of the effect of electron beam treatment for the wastewater purification. (author)

Stability-indicating methods for the determination of racecadotril in the presence of its degradation products.

Science.gov (United States)

Mohamed, Afaf O; Fouad, Manal M; Hasan, Mona M; Abdel Razeq, Sawsan A; Elsherif, Zeinab A

2009-12-01

Three stability-indicating methods were developed for the determination of racecadotril (RCT) in the presence of its alkaline degradation products. The first was an HPLC method in which efficient chromatographic separation was achieved on a C18 analytical column and a mobile phase of acetonitrile-methanol-water-acetic acid (52:28:20:0.1, v/v/v/v). Linearity was obtained in the range of 4-40 microg/mL with mean accuracy of 99.5 +/- 0.88%. The second method was a densitometric evaluation of thin-layer chromatograms of the drug using a mobile phase of isopropanol-ammonia (33%)-n-hexane (9:0.5:20, v/v/v). The chromatograms were scanned at 232 nm, a wavelength at which RCT can be readily separated from its degradation products and determined in the range of 2-20 microg per spot with mean accuracy of 99.5 +/- 0.56%. The third method is based on the use of first-derivative spectrophotometry (D1) at 240 nm, and the drug was determined in the range of 5-40 microg/mL with mean accuracy of 99.2 +/- 1.02%. The three methods provided satisfactory recovery of the intact drug (100.8 +/- 0.82, 100.4 +/- 0.55, and 99.9 +/- 0.72%, respectively) in the presence of up to 90% of its degradation products. Determination was also successful when analyzing RCT in a formulation in the form of acetorphan packets. Results were statistically analyzed and found to be in accordance with those given by a reported method.

Accelerated lifetime test of vibration isolator made of Metal Rubber material

Science.gov (United States)

Ao, Hongrui; Ma, Yong; Wang, Xianbiao; Chen, Jianye; Jiang, Hongyuan

2017-01-01

The Metal Rubber material (MR) is a kind of material with nonlinear damping characteristics for its application in the field of aerospace, petrochemical industry and so on. The study on the lifetime of MR material is impendent to its application in engineering. Based on the dynamic characteristic of MR, the accelerated lifetime experiments of vibration isolators made of MR working under random vibration load were conducted. The effects of structural parameters of MR components on the lifetime of isolators were studied and modelled with the fitting curves of degradation data. The lifetime prediction methods were proposed based on the models.

Degradation of diuron in aqueous solution by dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Feng Jingwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China); Zheng Zheng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)], E-mail: zzheng@nju.edu.cn; Sun Yabing; Luan Jingfei; Wang Zhen; Wang Lianhong; Feng Jianfang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)

2008-06-15

Degradation of diuron in aqueous solution was conducted in a dielectric barrier discharge (DBD) reactor and the proposed degradation mechanism was investigated in detail. The factors that affect the degradation of diuron were examined. The degradation efficiency of diuron and the removal of total organic carbon (TOC) increased with increasing input power, and the degradation of diuron by DBD fitted first-order kinetics. Both strong acidic and alkaline solution conditions could improve diuron degradation efficiency and TOC removal rate. Degradation of diuron could be accelerated or inhibited in the presence of H{sub 2}O{sub 2} depending on the dosage. The degradation efficiency increased dramatically with adding Fe{sup 2+}. The removal of TOC and the amount of the detected Cl{sup -}, NO{sub 3}{sup -} and NH{sub 4}{sup +} were increased in the presence of Fe{sup 2+}. The concentrations of oxalic and acetic acids were almost the same in the absence and presence of Fe{sup 2+}, but high concentration of formic acid was accumulated in the presence of Fe{sup 2+}. The main degradation pathway of diuron by DBD involved a series of dechlorination-hydroxylation, dealkylation and oxidative opening of the aromatic ring processes.

Accelerators of atomic particles

International Nuclear Information System (INIS)

Sarancev, V.

1975-01-01

A brief survey is presented of accelerators and methods of accelerating elementary particles. The principle of collective accelerating of elementary particles is clarified and the problems are discussed of its realization. (B.S.)

Recovering of images degraded by atmosphere

Science.gov (United States)

Lin, Guang; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

2017-08-01

Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.

Degradation of tropoelastin and skin elastin by neprilysin

DEFF Research Database (Denmark)

Mora Huertas, Angela C.; Schmelzer, Christian E. H.; Luise, Chiara

2018-01-01

was to investigate the degradation of fibrillar skin elastin by neprilysin and the influence of the donor's age on the degradation process using mass spectrometry and bioinformatics approaches. The results showed that cleavage by neprilysin is dependent on previous damage of elastin. While neprilysin does not cleave...... young and intact skin elastin well, it degrades elastin fibers from older donors, which may further promote aging processes. With regards to the cleavage behavior of neprilysin, a strong preference for Gly at P1 was found, while Gly, Ala and Val were well accepted at P1' upon cleavage of tropoelastin...... and skin elastin. The results of the study indicate that the progressive release of bioactive elastin peptides by neprilysin upon skin aging may enhance local tissue damage and accelerate extracellular matrix aging processes....

Effect of processing method on accelerated weathering of wood-flour/HDPE composites

Science.gov (United States)

Nicole M. Stark; Laurent M. Matuana; Craig M. Clemons

2003-01-01

Wood-plastic lumber is promoted as a low maintenance high-durability product. When exposed to accelerated weathering, however, wood-plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood-plastic composites lead to different surface characteristics, which can influence weathering, In this study, 50...

The Experimental Stand for Research of Wakefield Method of Charged Particles Acceleration

International Nuclear Information System (INIS)

Kiselev, V.A.; Linnik, A.F.; Onishchenko, I.N.; Onishchenko, N.I.; Sotnikov, G.V.; Uskov, V.V.

2006-01-01

The experimental installation and diagnostic equipment with motivation to use for various researches of wakefield method of charged particles acceleration both in plasma and in dielectric structure has been described. The main parameters of a sequence of short relativistic electron bunch and values of physical characteristics of slow-down structures have been presented

A Selective High Performance Liquid Chromatographic Method to Follow the Hydrolytic Degradation of Nicardipine Hydrochloride

Directory of Open Access Journals (Sweden)

K. E. Ibrahim

2010-01-01

Full Text Available A simple, stability indicating, reverse phase high performance liquid chromatographic method was developed and validated for determination of nicardipine hydrochloride (NC in the presence of its degradation products. The chromatographic separation was performed on Hypersil, BDS-C18, 30 cm × 3.9 mm id, at ambient temperature with UV-detection at 254 nm. A mixture of 20% (v/v aqueous 0.01 M sodium acetate∕acetic acid buffer (pH 4.5 and 80% acetonitrile was used as the mobile phase at a flow rate of 1.5 mL min-1, losartan was used as internal standard. The calibration curve is linear over the concentration range 5-40 μg mL-1, with a regression coefficient of 0.9984 and the % recovery was 99.78±0.17. The method was used to investigate the kinetics of alkaline, acids induced degradation, effect of buffer concentration and temperature. The degradation followed first-order kinetics. The rate constant, half-life time, and activation energy were calculated

Neuroprotective mechanism of Kai Xin San: upregulation of hippocampal insulin-degrading enzyme protein expression and acceleration of amyloid-beta degradation

Directory of Open Access Journals (Sweden)

Na Wang

2017-01-01

Full Text Available Kai Xin San is a Chinese herbal formula composed of Radix Ginseng , Poria , Radix Polygalae and Acorus Tatarinowii Rhizome . It has been used in China for many years for treating amnesia. Kai Xin San ameliorates amyloid-β (Aβ-induced cognitive dysfunction and is neuroprotective in vivo , but its precise mechanism remains unclear. Expression of insulin-degrading enzyme (IDE, which degrades Aβ, is strongly correlated with cognitive function. Here, we injected rats with exogenous Aβ42 (200 μM, 5 μL into the hippocampus and subsequently administered Kai Xin San (0.54 or 1.08 g/kg/d intragastrically for 21 consecutive days. Hematoxylin-eosin and Nissl staining revealed that Kai Xin San protected neurons against Aβ-induced damage. Furthermore, enzyme-linked immunosorbent assay, western blot and polymerase chain reaction results showed that Kai Xin San decreased Aβ42 protein levels and increased expression of IDE protein, but not mRNA, in the hippocampus. Our findings reveal that Kai Xin San facilitates hippocampal Aβ degradation and increases IDE expression, which leads, at least in part, to the alleviation of hippocampal neuron injury in rats.

Beam transient analyses of Accelerator Driven Subcritical Reactors based on neutron transport method

Energy Technology Data Exchange (ETDEWEB)

He, Mingtao; Wu, Hongchun [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Wang, Kunpeng [Nuclear and Radiation Safety Center, PO Box 8088, Beijing 100082 (China); Li, Xunzhao; Zhou, Shengcheng [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China)

2015-12-15

Highlights: • A transport-based kinetics code for Accelerator Driven Subcritical Reactors is developed. • The performance of different kinetics methods adapted to the ADSR is investigated. • The impacts of neutronic parameters deteriorating with fuel depletion are investigated. - Abstract: The Accelerator Driven Subcritical Reactor (ADSR) is almost external source dominated since there is no additional reactivity control mechanism in most designs. This paper focuses on beam-induced transients with an in-house developed dynamic analysis code. The performance of different kinetics methods adapted to the ADSR is investigated, including the point kinetics approximation and space–time kinetics methods. Then, the transient responds of beam trip and beam overpower are calculated and analyzed for an ADSR design dedicated for minor actinides transmutation. The impacts of some safety-related neutronics parameters deteriorating with fuel depletion are also investigated. The results show that the power distribution varying with burnup leads to large differences in temperature responds during transients, while the impacts of kinetic parameters and feedback coefficients are not very obvious. Classification: Core physic.

An accelerated method for the detection of Extended-Spectrum B- Lactamases in urinary isolates of Escherichia Coli and Klebsiella pneumoniae

International Nuclear Information System (INIS)

Kader, Abdulrahman A.; Kumar, A.; Krishna, A.; Zaman, M.N.

2006-01-01

We prospectively studied an accelerated phenotypic method by incorporating the double disk synergy test in the standard Kirby-Bauer disk diffusion susceptibility testing, to evaluate a protocol for the rapid detection of extended of extended-spectrum B-lactamases (ESBL) in urinary isolates of Escherichia coli (E. coli) and Klebsiella, pneumoniae (K. pneumoniae). All ESBL-positive isolates were confirmed by the standard Clinical Laboratory Standards Institute (CLSI) confirmatory disk diffusion method. Between November 2004 and December 2005, a total of 6988 urine specimens were analyzed of which 776 (11%) showed significant growth. They included E. coli in 577 cases (74%) and K. pneumoniae in 199 (25.6%). Of these, 63 E. coli (8%) and 15 K. pneumoniae (7.5%) were positive for ESBL by the accelerated and CLSI methods. Compared to the standard CLSI method, the accelerated method reduced the ESBL detection time from two days to one day. We conclude that the accelerated ESBL detection technique used by us in this study is a reliable and rapid method for detecting ESBL in urinary isolates of E. coli and K. pneumoniae. (author)

Accelerated laboratory weathering of acrylic lens materials

Science.gov (United States)

Arndt, Thomas; Richter, Steffen; Kogler, René; Pasierb, Mike; Walby, Christopher

2015-09-01

Flat samples from various poly(methyl methacrylate) (PMMA) formulations were subjected to outdoor weathering in Arizona and Florida, EMMAQUA® accelerated outdoor weathering, and two accelerated laboratory weathering procedures at 3 Sun irradiance which, imitate dry (Arizona) and wet (Florida) conditions. The main mode of degradation is yellowing and not the generation of haze for any weathering procedure within the investigated radiant exposure. Higher UV absorber concentrations lead to smaller changes in optical properties and in the resulting relative concentrator photovoltaic (CPV) module efficiencies. Comparison of sample properties after various weathering procedures reveals that the influence of weathering factors other than radiant exposure depends on the sample as well.

Reliability assessment using degradation models: bayesian and classical approaches

Directory of Open Access Journals (Sweden)

Marta Afonso Freitas

2010-04-01

Full Text Available Traditionally, reliability assessment of devices has been based on (accelerated life tests. However, for highly reliable products, little information about reliability is provided by life tests in which few or no failures are typically observed. Since most failures arise from a degradation mechanism at work for which there are characteristics that degrade over time, one alternative is monitor the device for a period of time and assess its reliability from the changes in performance (degradation observed during that period. The goal of this article is to illustrate how degradation data can be modeled and analyzed by using "classical" and Bayesian approaches. Four methods of data analysis based on classical inference are presented. Next we show how Bayesian methods can also be used to provide a natural approach to analyzing degradation data. The approaches are applied to a real data set regarding train wheels degradation.Tradicionalmente, o acesso à confiabilidade de dispositivos tem sido baseado em testes de vida (acelerados. Entretanto, para produtos altamente confiáveis, pouca informação a respeito de sua confiabilidade é fornecida por testes de vida no quais poucas ou nenhumas falhas são observadas. Uma vez que boa parte das falhas é induzida por mecanismos de degradação, uma alternativa é monitorar o dispositivo por um período de tempo e acessar sua confiabilidade através das mudanças em desempenho (degradação observadas durante aquele período. O objetivo deste artigo é ilustrar como dados de degradação podem ser modelados e analisados utilizando-se abordagens "clássicas" e Bayesiana. Quatro métodos de análise de dados baseados em inferência clássica são apresentados. A seguir, mostramos como os métodos Bayesianos podem também ser aplicados para proporcionar uma abordagem natural à análise de dados de degradação. As abordagens são aplicadas a um banco de dados real relacionado à degradação de rodas de trens.

The fingerprint method for characterization of radioactive waste in hadron accelerators

CERN Document Server

Magistris, M

2008-01-01

Beam losses are responsible for material activation in most of the components of particle accelerators. The activation is caused by several nuclear processes and varies with the irradiation history and the characteristics of the material (namely chemical composition and size). Once at the end of their operational lifetime, these materials require radiological characterization. The radionuclide inventory depends on the particle spectrum, the irradiation history and the chemical composition of the material. As long as these factors are known and the material cross-sections are available, the induced radioactivity can be calculated analytically. However, these factors vary widely among different items of waste and sometimes they are only partially known. The European Laboratory for Particle Physics (CERN, Geneva) has been operating accelerators for high-energy physics for 50 years. Different methods for the evaluation of the radionuclide inventory are currently under investigation at CERN, including the so-calle...

Steam Generator Analysis Tools and Modeling of Degradation Mechanisms

International Nuclear Information System (INIS)

Yetisir, M.; Pietralik, J.; Tapping, R.L.

2004-01-01

The degradation of steam generators (SGs) has a significant effect on nuclear heat transport system effectiveness and the lifetime and overall efficiency of a nuclear power plant. Hence, quantification of the effects of degradation mechanisms is an integral part of a SG degradation management strategy. Numerical analysis tools such as THIRST, a 3-dimensional (3D) thermal hydraulics code for recirculating SGs; SLUDGE, a 3D sludge prediction code; CHECWORKS a flow-accelerated corrosion prediction code for nuclear piping, PIPO-FE, a SG tube vibration code; and VIBIC and H3DMAP, 3D non-linear finite-element codes to predict SG tube fretting wear can be used to assess the impacts of various maintenance activities on SG thermal performance. These tools are also found to be invaluable at the design stage to influence the design by determining margins or by helping the designers minimize or avoid known degradation mechanisms. In this paper, the aforementioned numerical tools and their application to degradation mechanisms in CANDU recirculating SGs are described. In addition, the following degradation mechanisms are identified and their effect on SG thermal efficiency and lifetime are quantified: primary-side fouling, secondary-side fouling, fretting wear, and flow-accelerated corrosion (FAC). Primary-side tube inner diameter fouling has been a major contributor to SG thermal degradation. Using the results of thermalhydraulic analysis and field data, fouling margins are calculated. Individual effects of primary- and secondary-side fouling are separated through analyses, which allow station operators to decide what type of maintenance activity to perform and when to perform the maintenance activity. Prediction of the fretting-wear rate of tubes allows designers to decide on the number and locations of support plates and U-bend supports. The prediction of FAC rates for SG internals allows designers to select proper materials, and allows operators to adjust the SG maintenance

Chemical degradation of an uncrosslinked pure fluororubber in an alkaline environment

DEFF Research Database (Denmark)

Mitra, S.; Ghanbari-Siahkali, A.; Kingshott, P.

2004-01-01

after prolonged exposure (e.g., 12 weeks). The molecular mechanisms of the chemical degradation processes at the surface were evaluated with X-ray photoelectron spectroscopy and attenuated total reflectance/Fourier transform infrared spectroscopy. The results revealed that the early degradation...... proceeded primarily via dehydrofluorination reactions, creating double bonds in the rubber backbone. This further accelerated the degradation after longer exposure times. Furthermore, the resulting double bonds underwent nucleophilic attack by an aqueous NaOH solution to form several oxygenated species. All...... these species ultimately recombined to form crosslinks, as evidenced by the increase in the gel fraction and surface hardness (Shore A). The pronounced effect of chemical degradation through a reduction in the thermal stability of the pure FKM rubber upon exposure was also evident from thermogravimetric...

Validation of Finite-Element Models of Persistent-Current Effects in Nb3Sn Accelerator Magnets

International Nuclear Information System (INIS)

Wang, X.; Ambrosio, G.; Chlachidze, G.; Collings, E. W.; Dietderich, D. R.; DiMarco, J.; Felice, H.; Ghosh, A. K.; Godeke, A.; Gourlay, S. A.; Marchevsky, M.; Prestemon, S. O.; Sabbi, G.; Sumption, M. D.; Velev, G. V.; Xu, X.; Zlobin, A. V.

2015-01-01

Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, in particular at low field where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reproduced well with the critical-state model. However, this approach becomes less accurate for the calculation of the persistent-current effects observed in Nb 3 Sn accelerator magnets. Here a finite-element method based on the measured strand magnetization is validated against three state-of-art Nb3Sn accelerator magnets featuring different subelement diameters, critical currents, magnet designs and measurement temperatures. The temperature dependence of the persistent-current effects is reproduced. Based on the validated model, the impact of conductor design on the persistent current effects is discussed. The performance, limitations and possible improvements of the approach are also discussed

Particle beam accelerator

International Nuclear Information System (INIS)

Turner, N.L.

1982-01-01

A particle beam accelerator is described which has several electrodes that are selectively short circuited together synchronously with changes in the magnitude of a DC voltage applied to the accelerator. By this method a substantially constant voltage gradient is maintained along the length of the unshortened electrodes despite variations in the energy applied to the beam by the accelerator. The invention has particular application to accelerating ion beams that are implanted into semiconductor wafers. (U.K.)

Accelerator and radiation physics

CERN Document Server

Basu, Samita; Nandy, Maitreyee

2013-01-01

"Accelerator and radiation physics" encompasses radiation shielding design and strategies for hadron therapy accelerators, neutron facilities and laser based accelerators. A fascinating article describes detailed transport theory and its application to radiation transport. Detailed information on planning and design of a very high energy proton accelerator can be obtained from the article on radiological safety of J-PARC. Besides safety for proton accelerators, the book provides information on radiological safety issues for electron synchrotron and prevention and preparedness for radiological emergencies. Different methods for neutron dosimetry including LET based monitoring, time of flight spectrometry, track detectors are documented alongwith newly measured experimental data on radiation interaction with dyes, polymers, bones and other materials. Design of deuteron accelerator, shielding in beam line hutches in synchrotron and 14 MeV neutron generator, various radiation detection methods, their characteriza...

Development of an asymmetric multiple-position neutron source (AMPNS) method to monitor the criticality of a degraded reactor core

International Nuclear Information System (INIS)

Kim, S.S.; Levine, S.H.

1985-01-01

An analytical/experimental method has been developed to monitor the subcritical reactivity and unfold the k/sub infinity/ distribution of a degraded reactor core. The method uses several fixed neutron detectors and a Cf-252 neutron source placed sequentially in multiple positions in the core. Therefore, it is called the Asymmetric Multiple Position Neutron Source (AMPNS) method. The AMPNS method employs nucleonic codes to analyze the neutron multiplication of a Cf-252 neutron source. An optimization program, GPM, is utilized to unfold the k/sub infinity/ distribution of the degraded core, in which the desired performance measure minimizes the error between the calculated and the measured count rates of the degraded reactor core. The analytical/experimental approach is validated by performing experiments using the Penn State Breazeale TRIGA Reactor (PSBR). A significant result of this study is that it provides a method to monitor the criticality of a damaged core during the recovery period

Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

International Nuclear Information System (INIS)

Dong Dianbo; Li Peijun; Li Xiaojun; Zhao Qing; Zhang Yinqiu; Jia Chunyun; Li Peng

2010-01-01

Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO 2 under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO 2 (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25 h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO 2 accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36 h, corresponding to the TiO 2 amounts from 0% to 4%, respectively. The effects of H 2 O 2 , light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H 2 O 2 , light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO 2 was an advisable choice for the treatments of PAHs polluted soil in the future.

Clearance measurements on activated parts of accelerators by combined methods; Verfahrenskombinierte Freigabemessung aktivierter Beschleunigerteile

Energy Technology Data Exchange (ETDEWEB)

Jansen, S.; Friedemann, S. [VKTA, Dresden (Germany); Enghardt, W. [Technische Univ. Dresden (Germany). OncoRay

2016-07-01

The process of clearance of radioactive materials according to paragraph 29 StrlSchV contents the comparison of activity to mass and surface of the material. To avoid a borderless assessment of activity of activation it is often necessary to use combined measurement methods: For clearance of collimators of a medical proton accelerator (energy range up to 200 MeV) it needs to know the nuclide composition. The energetical and geometrical calibration was fixed by experiments. The clearance based on measurements of activity distribution, gammaspectroscopy verification of nuclide composition and gamma-counting detectors. Parts of medical electron-accelerators achieved its clearance by combination of abovementioned methods and in-situ-gammaspectroscopy. Activated und contaminated lead stones achieved its clearance by measurements of fluence, laboratory evaluation of samples, in-situ-gammaspectroscopy and wipe tests.

Degradation of Tetracyclines in Pig Manure by Composting with Rice Straw

Science.gov (United States)

Chai, Rushan; Huang, Lidong; Li, Lingling; Gielen, Gerty; Wang, Hailong; Zhang, Yongsong

2016-01-01

A holistic approach was followed for utilizing tetracyclines (TCs)-contaminated pig manure, by composting this with rice straw in a greenhouse for CO2 fertilization and composted residue application. After composting, the composted residues can be applied to cropland as a supplemental source of synthetic fertilizers. The objective of this study was to determine the effect of pig manure-rice straw composting on the degradation of TCs in pig manure. The results showed that greenhouse composting significantly accelerated the degradation of TCs. Contents (150 mg·kg−1) of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) in the composting feedstock could be completely removed within 42 days for OTC and TC, and 14 days for CTC. However, in the control samples incubated at 25 °C in the dark, concentrations of OTC, TC and CTC only decreased 64.7%, 66.7% and 73.3%, respectively, after 49 days. The degradation rates of TCs in the composting feedstock were in the order of CTC > TC > OTC. During the composting process, CTC dissipated rapidly with the time required for 50% degradation (DT50) and 90% degradation (DT90) of 2.4 and 7.9 days, but OTC was more persistent with DT50 and DT90 values of 5.5 and 18.4 days. On the basis of the results obtained in this study, it could be concluded that pig manure-rice straw composting in a greenhouse can help to accelerate the degradation of TCs in pig manure and make composted residues safer for field application. This technology could be an acceptable practice for greenhouse farmers to utilize TCs-contaminated pig manure. PMID:26927136

Acceleration of the nodal program FERM

International Nuclear Information System (INIS)

Nakata, H.

1985-01-01

Acceleration of the nodal FERM was tried by three acceleration schemes. Results of the calculations showed the best acceleration with the Tchebyshev method where the savings in the computing time were of the order of 50%. Acceleration with the Assymptotic Source Extrapoltation Method and with the Coarse-Mesh Rebalancing Method did not result in any improvement on the global computational time, although a reduction in the number of outer iterations was observed. (Author) [pt

An efficient fermentation method for the degradation of cyanogenic glycosides in flaxseed.

Science.gov (United States)

Wu, C-F; Xu, X-M; Huang, S-H; Deng, M-C; Feng, A-J; Peng, J; Yuan, J-P; Wang, J-H

2012-01-01

Recently, flaxseed has become increasingly popular in the health food market because it contains a considerable amount of specific beneficial nutrients such as lignans and omega-3 fatty acids. However, the presence of cyanogenic glycosides (CGs) in flaxseed severely limits the exploitation of its health benefits and nutritive value. We, therefore, developed an effective fermentation method, optimised by response surface methodology (RSM), for degrading CGs with an enzymatic preparation that includes 12.5% β-glucosidase and 8.9% cyanide hydratase. These optimised conditions resulted in a maximum CG degradation level of 99.3%, reducing the concentration of cyanide in the flaxseed power from 1.156 to 0.015 mg g(-1) after 48 h of fermentation. The avoidance of steam heat to evaporate hydrocyanic acid (HCN) results in lower energy consumption and no environmental pollution. In addition, the detoxified flaxseed retained the beneficial nutrients, lignans and fatty acids at the same level as untreated flaxseed, and this method could provide a new means of removing CGs from other edible plants, such as cassava, almond and sorghum by simultaneously expressing cyanide hydratase and β-glucosidase.

New method to extract radial acceleration of target from short-duration signal at low SNR

Institute of Scientific and Technical Information of China (English)

2008-01-01

In order to extract target radial acceleration from radar echo signal at low SNR (signal-to-noise), this paper employed FRFT (fractional Fourier transformation) to analyze short-duration radar echo and studied the relations between signal convergence peaks in matched transformation domain and signal duration and modu- lated frequency of signal. When signal duration is specified, the method of multi- plying sampled signal by the known frequency modulated signal to alter modulated frequency was presented, which generated the new signal with larger convergence peaks than the initial signal in matched transformation domain. Thus, it could successfully estimate the radial acceleration of radar target at low SNR. Simulations were conducted to show the feasibility and effectiveness of the method.

Effect of Rapid Chilling on Beef Quality and Cytoskeletal Protein Degradation in of Chinese Yellow Crossbred Bulls

Directory of Open Access Journals (Sweden)

Yanwei Mao

2012-08-01

Full Text Available The objective of this study was to investigate the effect of rapid chilling (RC on beef quality and the degradation of cytoskeletal proteins. Twenty Chinese Yellow crossbred bulls were selected and randomly divided into two groups. RC and conventional chilling (CC were applied to left and right sides of the carcasses respectively after slaughtering. To determine whether electrical stimulation (ES treatment can alleviate the potential hazard of RC on meat quality, ES was applied to one group. The effects of RC and ES were determined by meat color, shear force and cytoskeletal protein degradation postmortem (PM. The results showed that RC decreased beef tenderness at 1 d and 3 d postmortem, but had no detrimental effect on meat color. Western blotting showed that RC decreased the degradation rate of desmin and troponin-T, but the effects weakened gradually as postmortem aging extended. Degradation rates of both desmin and troponin-T were accelerated by ES. The combination of RC and ES could improve beef color, accelerate degradation rate of cytoskeletal protein and improve beef tenderness.

Envelope method for determination of the ion linear accelerator acceptance

International Nuclear Information System (INIS)

Sharshanov, A.A.; Goncharenko, I.I.; Revutskij, E.I.

1974-01-01

The acceptance defined by the slit u 2 2 in space u, ν, z (u=coordinate of the accelerated particle in the direction perpendicular to the accelerator axis, ν=ratio of the transverse particle velocity component to the longitudinal component, z=accelerator axis, a=dimensions of slit) represents a convex curvilinear polygon with centre of symmetry at the origin of the co-ordinates. The sides of the polygon are sections of ellipses and straight lines, the ellipses being part of an envelope to the set of proto-types of all cross-sections of the slit in planes z=3, where 0<=xi<=z and z is the length of the accelerator, and the straight lines are tangents to the ends of the envelope. In the paper the equations of the ellipses forming the sides of the polygon are written using an elementary variable matrix of the accelerator structure, and the co-ordinates of the polygon apexes are found. A numerical value is derived for the area of the polygon for one transverse co-ordinate of the particular accelerator, the pre-stripping section of the LUMZI-10. (author)

Electrical and Photo-Induced Degradation of ZnO Layers in Organic Photovoltaics

DEFF Research Database (Denmark)

Manor, Assaf; Katz, Eugene A.; Tromholt, Thomas

2011-01-01

minutes) does not affect the short-circuit current of the device. However, a significant degradation of V-OC and FF has been recorded by measurements of the cell current-voltage curves with a variation of light intensity, for the devices before and after the treatment. The same degradation was found......We present the case of degradation of organic solar cells by sunlight concentrated to a moderate level (similar to 4 suns). This concentration level is not enough for sufficient acceleration of the photobleaching or trap-generation in the photoactive layer and therefore such short treatment (100...

Investigation of Material Performance Degradation for High-Strength Aluminum Alloy Using Acoustic Emission Method

Directory of Open Access Journals (Sweden)

Yibo Ai

2015-02-01

Full Text Available Structural materials damages are always in the form of micro-defects or cracks. Traditional or conventional methods such as micro and macro examination, tensile, bend, impact and hardness tests can be used to detect the micro damage or defects. However, these tests are destructive in nature and not in real-time, thus a non-destructive and real-time monitoring and characterization of the material damage is needed. This study is focused on the application of a non-destructive and real-time acoustic emission (AE method to study material performance degradation of a high-strength aluminum alloy of high-speed train gearbox shell. By applying data relative analysis and interpretation of AE signals, the characteristic parameters of materials performance were achieved and the failure criteria of the characteristic parameters for the material tensile damage process were established. The results show that the AE method and signal analysis can be used to accomplish the non-destructive and real-time detection of the material performance degradation process of the high-strength aluminum alloy. This technique can be extended to other engineering materials.

Degradation of chlorpyrifos in tropical rice soils.

Science.gov (United States)

Das, Subhasis; Adhya, Tapan K

2015-04-01

Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridinol) phosphorothioate] is used worldwide as an agricultural insecticide against a broad spectrum of insect pests of economically important crops including rice, and soil application to control termites. The insecticide mostly undergoes hydrolysis to diethyl thiophosphoric acid (DETP) and 3,5,6-trichloro-2-pyridinol (TCP), and negligible amounts of other intermediate products. In a laboratory-cum-greenhouse study, chlorpyrifos, applied at a rate of 10 mg kg(-1) soil to five tropical rice soils of wide physico-chemical variability, degraded with a half-life ranging from 27.07 to 3.82 days. TCP was the major metabolite under both non-flooded and flooded conditions. Chlorpyrifos degradation had significant negative relationship with electrical conductivity (EC), cation exchange capacity (CEC), clay and sand contents of the soils under non-flooded conditions. Results indicate that degradation of chlorpyrifos was accelerated with increase in its application frequency, across the representative rice soils. Management regimes including moisture content and presence or absence of rice plants also influenced the process. Biotic factors also play an important role in the degradation of chlorpyrifos as demonstrated by its convincing degradation in mineral salts medium inoculated with non-sterile soil suspension. Copyright © 2015 Elsevier Ltd. All rights reserved.

Acceleration of the FERM nodal program

International Nuclear Information System (INIS)

Nakata, H.

1985-01-01

It was tested three acceleration methods trying to reduce the number of outer iterations in the FERM nodal program. The results obtained indicated that the Chebychev polynomial acceleration method with variable degree results in a economy of 50% in the computer time. Otherwise, the acceleration method by source asymptotic extrapolation or by zonal rebalance did not result in economy of the global computer time, however some acceleration had been verified in outer iterations. (M.C.K.) [pt

Biochar accelerates organic matter degradation and enhances N mineralisation during composting of poultry manure without a relevant impact on gas emissions.

Science.gov (United States)

Sánchez-García, M; Alburquerque, J A; Sánchez-Monedero, M A; Roig, A; Cayuela, M L

2015-09-01

A composting study was performed to assess the impact of biochar addition to a mixture of poultry manure and barley straw. Two treatments: control (78% poultry manure + 22% barley straw, dry weight) and the same mixture amended with biochar (3% dry weight), were composted in duplicated windrows during 19 weeks. Typical monitoring parameters and gaseous emissions (CO2, CO, CH4, N2O and H2S) were evaluated during the process as well as the agronomical quality of the end-products. Biochar accelerated organic matter degradation and ammonium formation during the thermophilic phase and enhanced nitrification during the maturation phase. Our results suggest that biochar, as composting additive, improved the physical properties of the mixture by preventing the formation of clumps larger than 70 mm. It favoured microbiological activity without a relevant impact on N losses and gaseous emissions. It was estimated that biochar addition at 3% could reduce the composting time by 20%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation Characterization of Thermal Interface Greases: Preprint

Energy Technology Data Exchange (ETDEWEB)

DeVoto, Douglas J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Major, Joshua [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Paret, Paul P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Blackman, G. S. [DuPont Experimental Station; Wong, A. [DuPont Experimental Station; Meth, J. S. [DuPont Experimental Station

2017-08-03

Thermal interface materials (TIMs) are used in power electronics packaging to minimize thermal resistance between the heat generating component and the heat sink. Thermal greases are one such class. The conformability and thin bond line thickness (BLT) of these TIMs can potentially provide low thermal resistance throughout the operation lifetime of a component. However, their performance degrades over time due to pump-out and dry-out during thermal and power cycling. The reliability performance of greases through operational cycling needs to be quantified to develop new materials with superior properties. NREL, in collaboration with DuPont, has performed thermal and reliability characterization of several commercially available thermal greases. Initial bulk and contact thermal resistance of grease samples were measured, and then the thermal degradation that occurred due to pump-out and dry-out during temperature cycling was monitored. The thermal resistances of five different grease materials were evaluated using NREL's steady-state thermal resistance tester based on the ASTM test method D5470. Greases were then applied, utilizing a 2.5 cm x 2.5 cm stencil, between invar and aluminum plates to compare the thermomechanical performance of the materials in a representative test fixture. Scanning Acoustic microscopy, thermal, and compositional analyses were performed periodically during thermal cycling from -40 degrees Celcius to 125 degrees Celcius. Completion of this characterization has allowed for a comprehensive evaluation of thermal greases both for their initial bulk and contact thermal performance, as well as their degradation mechanisms under accelerated thermal cycling conditions.

Acceleration of monte Carlo solution by conjugate gradient method

International Nuclear Information System (INIS)

Toshihisa, Yamamoto

2005-01-01

The conjugate gradient method (CG) was applied to accelerate Monte Carlo solutions in fixed source problems. The equilibrium model based formulation enables to use CG scheme as well as initial guess to maximize computational performance. This method is available to arbitrary geometry provided that the neutron source distribution in each subregion can be regarded as flat. Even if it is not the case, the method can still be used as a powerful tool to provide an initial guess very close to the converged solution. The major difference of Monte Carlo CG to deterministic CG is that residual error is estimated using Monte Carlo sampling, thus statistical error exists in the residual. This leads to a flow diagram specific to Monte Carlo-CG. Three pre-conditioners were proposed for CG scheme and the performance was compared with a simple 1-D slab heterogeneous test problem. One of them, Sparse-M option, showed an excellent performance in convergence. The performance per unit cost was improved by four times in the test problem. Although direct estimation of efficiency of the method is impossible mainly because of the strong problem-dependence of the optimized pre-conditioner in CG, the method seems to have efficient potential as a fast solution algorithm for Monte Carlo calculations. (author)

Mass spectrometric comparison of swift heavy ion-induced and anaerobic thermal degradation of polymers

Science.gov (United States)

Lima, V.; Hossain, U. H.; Walbert, T.; Seidl, T.; Ensinger, W.

2018-03-01

The study of polymers irradiated by highly energetic ions and the resulting radiation-induced degradation is of major importance for space and particle accelerator applications. The mechanism of ion-induced molecular fragmentation of polyethylene, polyethyleneimine and polyamide was investigated by means of mass spectrometry and infrared spectroscopy. The results show that the introduction of nitrogen and oxygen into the polymer influences the stability rendering aliphatic polymers with heteroatoms less stable. A comparison to thermal decomposition data from literature reveals that ion-induced degradation is different in its bond fracture mechanism. While thermal degradation starts at the weakest bond, which is usually the carbon-heteroatom bond, energetic ion irradiation leads in the first step to scission of all types of bonds creating smaller molecular fragments. This is due to the localized extreme energy input under non-equilibrium conditions when the ions transfer kinetic energy onto electrons. These findings are of relevance for the choice of polymers for long-term application in both space and accelerator facilities.

High modulus biodegradable polyurethanes for applications in cardiovascular stents: Evaluation of in-vitro degradation and cell viability

Directory of Open Access Journals (Sweden)

Melissa eSagarito

2015-05-01

Full Text Available We have recently reported the mechanical properties and hydrolytic degradation behaviour of a series of NovoSorb™ [1] biodegradable polyurethanes (PUs prepared by varying the hard segment (HS weight percentage from 60-100. In this study the in-vitro degradation behaviour of the PUs with and without extracellular matrix (ECM coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C conditions to allow complete degradation. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of Human Umbilical Vein Endothelial Cells (HUVEC were examined.The results showed that for most PUs in the series the degradation medium turned acidic and the extent of this was dependent on the HS percentage. As the HS decreased, a drop in pH was observed, suggesting that the by-products of soft segment (SS degradation causing the solution to be acidic. Most of the samples were completely eroded by 18 weeks, except PU containing more than 70% HS which only showed partial degradation with no significant change in appearance. The cytotoxicity tests on HUVEC cells of the aqueous extracts obtained after 18 weeks incubation showed that toxicity was dependent on 3 factors: dose, percentage of HS and degradation time. HUVEC growth is similar to but not identical to that observed with tissue culture polystyrene (TCPS standard. The results from this in-vitro cytotoxicity study suggest that the mixture of degradation products formed during the accelerated degradation of this PU series are not toxic to cells under the experimental conditions used.

Recent progress in particle accelerators

International Nuclear Information System (INIS)

Cole, F.T.; Mills, F.E.

1988-01-01

Many accelerators have also been built for medical radiography and therapy. Electron accelerators for this application are available commercially, using the electrons directly or bremsstrahlung photons. Neutrons produced by accelerator beams have also been used for therapy with considerable success, and several proton accelerators built for physics research have been adapted for direct therapy with protons. The first proton accelerator specifically for therapy is now being built. Separate from what might be called conventional accelerator technology, an entirely new field utilizing very highly pulsed power has been developed, and beams of short pulses of thousands or millions of amperes peak current in the MeV energy range are now available. These beams have important applications in high-energy particle acceleration, controlled fusion, industrial treatment of materials, and possibly in food preservation. All of these accelerators make use of external fields of acceleration. There is also vigorous research into new methods of acceleration, in many schemes making use of the intense accelerating fields, generated by laser beams or by plasma states of matter. This research has not as yet made traditional kinds of accelerators outmoded, but many workers hope that early in the next century there will be practical new acceleration methods making use of these very high fields. These developments are discussed in detail

Method for the mechanical axis alignment of the linear induction accelerator

International Nuclear Information System (INIS)

Li Hong; China Academy of Engineering Physics, Mianyang; Yao Jin; Liu Yunlong; Zhang Linwen; Deng Jianjun

2004-01-01

Accurate mechanical axis alignment is a basic requirement for assembling a linear induction accelerator (LIA). The total length of an LIA is usually over thirty or fifty meters, and it consists of many induction cells. By using a laser tracker a new method of mechanical axis alignment for LIA is established to achieve the high accuracy. This paper introduces the method and gives implementation step and point position measure errors of the mechanical axis alignment. During the alignment process a 55 m-long alignment control survey net is built, and the theoretic revision of the coordinate of the control survey net is presented. (authors)

Acceleration of polarized proton in high energy accelerators

International Nuclear Information System (INIS)

Lee, S.Y.

1991-01-01

In low to medium energy accelerators, betatron tune jumps and vertical orbit harmonic correction methods have been used to overcome the intrinsic and imperfection resonances. At high energy accelerators, snakes are needed to preserve polarization. The author analyzes the effects of snake resonances, snake imperfections, and overlapping resonances on spin depolarization. He discusses also results of recent snake experiments at the IUCF Cooler Ring. The snake can overcome various kinds of spin depolarization resonances. These experiments pointed out further that partial snake can be used to cure the imperfection resonances in low to medium energy accelerators

Linear accelerator accelerating module to suppress back-acceleration of field-emitted particles

Science.gov (United States)

Benson, Stephen V.; Marhauser, Frank; Douglas, David R.; Ament, Lucas J. P.

2017-12-05

A method for the suppression of upstream-directed field emission in RF accelerators. The method is not restricted to a certain number of cavity cells, but requires similar operating field levels in all cavities to efficiently annihilate the once accumulated energy. Such a field balance is desirable to minimize dynamic RF losses, but not necessarily achievable in reality depending on individual cavity performance, such as early Q.sub.0-drop or quench field. The method enables a significant energy reduction for upstream-directed electrons within a relatively short distance. As a result of the suppression of upstream-directed field emission, electrons will impact surfaces at rather low energies leading to reduction of dark current and less issues with heating and damage of accelerator components as well as radiation levels including neutron generation and thus radio-activation.

Optics of beam recirculation in the CEBAF [Continuous Electron Beam Accelerator Facility] cw linac

International Nuclear Information System (INIS)

Douglas, D.R.

1986-01-01

The use of recirculation in linear accelerator designs requires beam transport systems that will not degrade beam quality. We present a design for the transport lines to be used during recirculation in the CEBAF accelerator. These beam lines are designed to avoid beam degradation through synchrotron radiation excitation or betatron motion mismatch, are insensitive to errors commonly encountered during beam transport, and are optimized for electron beams with energies of 0.5 to 6.0 GeV. Optically, they are linearly isochronous second order achromats based on a ''missing magnet'' FODO structure. We give lattice specifications for, and results of analytic estimates and numerical simulations of the performance of, the beam transport system

A GPU-accelerated semi-implicit fractional-step method for numerical solutions of incompressible Navier-Stokes equations

Science.gov (United States)

Ha, Sanghyun; Park, Junshin; You, Donghyun

2018-01-01

Utility of the computational power of Graphics Processing Units (GPUs) is elaborated for solutions of incompressible Navier-Stokes equations which are integrated using a semi-implicit fractional-step method. The Alternating Direction Implicit (ADI) and the Fourier-transform-based direct solution methods used in the semi-implicit fractional-step method take advantage of multiple tridiagonal matrices whose inversion is known as the major bottleneck for acceleration on a typical multi-core machine. A novel implementation of the semi-implicit fractional-step method designed for GPU acceleration of the incompressible Navier-Stokes equations is presented. Aspects of the programing model of Compute Unified Device Architecture (CUDA), which are critical to the bandwidth-bound nature of the present method are discussed in detail. A data layout for efficient use of CUDA libraries is proposed for acceleration of tridiagonal matrix inversion and fast Fourier transform. OpenMP is employed for concurrent collection of turbulence statistics on a CPU while the Navier-Stokes equations are computed on a GPU. Performance of the present method using CUDA is assessed by comparing the speed of solving three tridiagonal matrices using ADI with the speed of solving one heptadiagonal matrix using a conjugate gradient method. An overall speedup of 20 times is achieved using a Tesla K40 GPU in comparison with a single-core Xeon E5-2660 v3 CPU in simulations of turbulent boundary-layer flow over a flat plate conducted on over 134 million grids. Enhanced performance of 48 times speedup is reached for the same problem using a Tesla P100 GPU.

Rate of antioxidant degradation and color variations in dehydrated apples as related to water activity.

Science.gov (United States)

Lavelli, Vera; Vantaggi, Claudia

2009-06-10

Dehydrated apples were studied to evaluate the effects of water activity on the stability of their antioxidants and color. Apples were freeze-dried, ground, then equilibrated, and stored at eight water activity levels, ranging from 0.058 to 0.747, at 40 degrees C. Their contents of hydroxycinnamic acids, dihydrochalcones, catechin, epicatechin, polymeric flavan-3-ols, and hydroxymethylfurfural, their antioxidant activity values, and their Hunter colorimetric parameters were analyzed at different storage times. Antioxidant degradation followed pseudo-first-order kinetics and was accelerated by increasing the water activity. The order of antioxidant stability in the products at water activity levels below 0.316 was catechin, epicatechin, and ascorbic acid acid acid; however, in the products at water activity levels above 0.316, the degradation of all antioxidants was very fast. The hydroxymethylfurfural formation rate increased exponentially during storage, especially at high water activity levels. The antioxidant activity of the dehydrated apples decreased during storage, consistent with antioxidant loss. The variations of the colorimetric parameters, namely, lightness (L*), redness (a*), and yellowness (b*), followed pseudo-zero-order kinetics and were accelerated by increasing water activity. All analytical indices indicated that the dehydrated apples were stable at water activity levels below 0.316, with the degradation rate accelerating upon exposure to higher relative humidities. Above 0.316, a small increase in water activity of the product would sharply increase the degradation rate constants for both antioxidant and color variations.

YEREVAN: Acceleration workshop

International Nuclear Information System (INIS)

Anon.

1989-01-01

Sponsored by the Yerevan Physics Institute in Armenia, a Workshop on New Methods of Charged Particle Acceleration in October near the Nor Amberd Cosmic Ray Station attracted participants from most major accelerator centres in the USSR and further afield

Application of the DSA preconditioned GMRES formalism to the method of characteristics - First results

International Nuclear Information System (INIS)

Le Tellier, R.; Hebert, A.

2004-01-01

The method of characteristics is well known for its slow convergence; consequently, as it is often done for SN methods, the Generalized Minimal Residual approach (GMRES) has been investigated for its practical implementation and its high reliability. GMRES is one of the most effective Krylov iterative methods to solve large linear systems. Moreover, the system has been 'left preconditioned' with the Algebraic Collapsing Acceleration (ACA) a variant of the Diffusion Synthetic Acceleration (DSA) based on I. Suslov's former works. This paper presents the first numerical results of these methods in 2D geometries with material discontinuities. Indeed, previous investigations have shown a degraded effectiveness of Diffusion Synthetic Accelerations with this kind of geometries. Results are presented for 9 x 9 Cartesian assemblies in terms of the speed of convergence of the inner iterations (fixed source) of the method of characteristics. It shows a significant improvement on the convergence rate. (authors)

A Precision-Positioning Method for a High-Acceleration Low-Load Mechanism Based on Optimal Spatial and Temporal Distribution of Inertial Energy

Directory of Open Access Journals (Sweden)