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111.
A wideband uniplanar 180-degree hybrid ring coupler implemented in coplanar and slot transmission lines is described. An equivalent circuit of the device is developed. The device is analyzed on a computer and its characteristics are optimized. Experimental results show that the inphase and antiphase power division losses are <1.5 dB and the port-to-port isolation is >20 dB over frequency bands ranging from 4 to 12 GHz. The measured characteristics are in good agreement with the calculated ones. 相似文献
112.
In this article, we present an investigation of the structural development of poly(ethylene terephthalate) (PET) during uniaxial stretching above the glass‐transition temperature; this followed a statistical design of experiment approach to determine the influence of the stretching variables on the structural development. Amorphous PET was submitted to a stretching program with variations in the stretching temperature (Tst), stretching rate ( $\dot {\varepsilon}_{st}$ ), and stretching ratio (λst). Stretched samples were rapidly quenched and characterized by wide‐angle X‐ray scattering, optical birefringence, and differential scanning calorimetry. The relevance and influence of the stretching variables on the obtained parameters (phase fraction, phase orientation, and thermal parameters) were analyzed. The strain‐induced crystallinity was controlled by Tst, λst, and the interactions between them. Mesophase development was not dependant on Tst but on the interactions between $\dot {\varepsilon}_{st}$ and λst. The molecular orientation was proportionally dependent on Tst, λst, and their interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
113.
Vladislav Todorov 《Mathematics and computers in simulation》2011,81(7):1397-1408
The article presents a general classification of the models being developed in the area of sustainability arguing that the existing models represent the historical conceptualisation of sustainability starting from environmental constraints and moving towards economic valuation and social behaviour and policies. Coupled with computer power, sophisticated models with a varying levels of complexity have also been developed (static/dynamic; local/global; specific/general). However as any model is a simplification of the complex reality, the main purpose of any sustainability modelling (and the newly emerging area of sustainometrics) should be to allow dynamic representation, including the co-evolution of the sustainability systems and the role of humans as sustainability guardians. 相似文献
114.
A. Gray I. Bethune R. Kenway L. Smith M. Guest C. Kitchen P. Calleja A. Korzynski S. Rankin M. Ashworth A. Porter I. Todorov M. Plummer E. Jones L. Steenman-Clark B. Ralston C. Laughton 《Computer Physics Communications》2012,183(3):520-529
A suite of application benchmarks, designed to be broadly representative of UK HPC usage, has been developed to stress a broad range of architectural features of large scale parallel HPC resources. A generic methodology to investigate application performance and scaling characteristics has been defined, resulting in a detailed understanding of the performance of these applications. This methodology is transferable to other applications and systems: it is of practical value to developers and users who are aiming for optimal utilisation of HPC resources. An understanding of the performance characteristics of a range of large-scale HPC resources has been obtained using low-level synthetic benchmarks. A relatively simple, qualitative mechanism to assess and predict application performance on current and future architectures using synthetic benchmark results together with application performance analysis results is explored. 相似文献
115.
Svetoslav D. Todorov Hervé PrévostMartine Lebois Xavier DoussetJean Guy LeBlanc Bernadette D.G.M. Franco 《Food research international (Ottawa, Ont.)》2011,44(5):1351-1363
Strain ST16PA, isolated from papaya was identified as Lactobacillus plantarum based on biochemical tests, PCR with species-specific primers and 16S rDNA sequencing. L. plantarum ST16PA produces a 6.5 kDa bacteriocin, active against different species from genera Enterobacter, Enterococcus, Lactobacillus, Pseudomonas, Streptococcus and Staphylococcus and different serotypes of Listeria spp. The peptide is inactivated by proteolytic enzymes, but not when treated with ??-amylase, catalase, lipase, Triton X-100, SDS, Tween 20, Tween 80, urea, NaCl and EDTA. However, presence of 1% Triton X-114 deactivates the bacteriocin. No change in activity was recorded after 2 h at pH values between 2.0 and 12.0, and after treatment at 100 °C for 120 min or 121 °C for 20 min. The mode of activity against Lactobacillus sakei ATCC 15521, Enterococcus faecalis ATCC 19443 and Listeria innocua 2030C was bactericidal, resulting in cell lysis and enzyme-leakage. No significant differences in cell growth and bacteriocin production were observed when strain ST16Pa was cultured in MRS broth at 26 °C and 30 °C for 24 h (25 600 AU/ml). However, even though strain ST16PA grows well in MRS broth at 15 °C and 37 °C, a reduction of bacteriocin production was observed (400 AU/ml and 1600 AU/ml, respectively). In addition, effect of MRS medium components, different initial pH and additions of glycerol or vitamins to the media on bacteriocin ST16Pa production was studied.Peptide ST16PA adsorbs (400 AU/ml) to producer cells. However, bacteriocin ST16Pa was adsorbed at 50% to cells of L. innocua 2030C and at 75% to L. sakei ATCC 15521 and E. faecalis ATCC 19433 when experiments were conducted at 30 °C and pH 6.5. Adsorption of bacteriocin ST16Pa to target cells at different temperatures, pH and in presence of potassium sorbate, sodium nitrate, sodium chloride, ascorbic acid, Tween 80 and Tween 20 were also studied. To the best of our knowledge, this is the first report on detection of L. plantarum in papaya. 相似文献
116.
In this paper, we combine the methods of geostatistics and multi-attribute reservoir parameter prediction (the multi-attribute transform) for the integration of seismic and well log data, and illustrate this new procedure with a case study involving the prediction of porosity at the Blackfoot oilfield, central Alberta. The objectives of the survey were to delineate incised, valley-fill sediments within the Early Cretaceous Glauconitic Formation at this field and to distinguish between sand-fill and shale-fill. The input consisted of twelve porosity logs together with a 3D seismic volume and the inversion of this volume. Although an excellent correlation was found between porosity and the initial inverted acoustic impedance volume, the combination of traditional geostatistics and the multi-attribute transform produced an improved final result.
Our approach uses well logs to "train" the multi-attribute transform algorithm. We first extract average porosity values over the depth zone of interest, and compare these values to average seismic attributes over the same zone. Cross-validation is used to show which attributes are significant. We then apply the results of the training and cross-validation to data slices derived from both the seismic data cube and the inverted cube to produce an initial porosity map. Finally, we improve the fit between the well-log values and the porosity map using cokriging. 相似文献
Our approach uses well logs to "train" the multi-attribute transform algorithm. We first extract average porosity values over the depth zone of interest, and compare these values to average seismic attributes over the same zone. Cross-validation is used to show which attributes are significant. We then apply the results of the training and cross-validation to data slices derived from both the seismic data cube and the inverted cube to produce an initial porosity map. Finally, we improve the fit between the well-log values and the porosity map using cokriging. 相似文献
117.
Modern methods of encoding information into digital form include error check digits that are functions of the other information digits. When digital information is transmitted, the values of the error check digits can be computed from the information digits to determine whether the information has been received accurately. These error correcting codes make it possible to detect and correct common errors in transmission. The sequence of bases in DNA is also a digital code consisting of four symbols: A, C, G, and T. Does DNA also contain an error correcting code? Such a code would allow repair enzymes to protect the fidelity of nonreplicating DNA and increase the accuracy of replication. If a linear block error correcting code is present in DNA then some bases would be a linear function of the other bases in each set of bases. We developed an efficient procedure to determine whether such an error correcting code is present in the base sequence. We illustrate the use of this procedure by using it to analyze the lac operon and the gene for cytochrome c. These genes do not appear to contain such a simple error correcting code. 相似文献
118.
A cross-sectional study covering four adjoining villages in Haryana during 1993 was carried out among 8595 subjects to find out cases having seizures or paralysis. The prevalence of seizures (n = 69) was found to be 8.03 per 1000 population. Out of 69 seizures, 48(69%) were true seizures and 21(31%) were febrile seizures. The prevalence of seizures was highest (14.05 per 1000) in the age group of > 1-4 years. Of 40 males with seizures, 22(55%) had epileptic seizures and 18(45%) had febrile seizures. Of the 29 females, 26(89%) had epileptic seizures and 3(11%) had febrile seizures. There were 25 cases of pseudoseizures. The prevalence of paralysis (n = 60) was 6.98 per 1000. Of these, 38 cases (63%) were due to poliomyelitis which is the highest so far the paralysis is concerned. Of 60 cases, 34 occurred among males and 26 among females. The prevalence of paralysis was highest (12.42 per 1000) among 0-1 year age group. As the prevalence of seizures is sufficiently high in rural areas, the primary health care doctors should be trained in counselling and therapy of seizures. As regarding paralysis due to poliomyelitis the recent success of pulse polio immunisations is commendable and which in near future is expected to eradicate poliomyelitis. 相似文献
119.
120.
The design and characteristics of a balanced active high electron-mobility transistor (HEMT) mixer operating in the 4.5-10-GHz frequency band are described in this paper. It consists of two parts implemented as independent hybrid circuits, namely, an microwave part fabricated by using a uniplanar technology and comprising a 180° hybrid ring coupler, HEMTs, and input-output matching circuits, and a low-frequency part consisting of an L-C balun and a low-pass filter built of discrete elements. The design of the microwave part of the mixer ensures a high degree of isolation between the signal and local-oscillator (LO) inputs within a wide frequency band at low IF. The measurements show a conversion gain of 5-7 dB, noise figure of 5-7.5 dB, and isolation between the signal and LO ports greater than 20 dB within the 4.5-10-GHz range 相似文献