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441.
Annie Cuyt Oliver Salazar Celis Maryna Lukach 《Multidimensional Systems and Signal Processing》2014,25(3):447-471
It is well-known that IIR filters can have a much lower order than FIR filters with the same performance. On the downside is that the implementation of an IIR filter is an iterative procedure while that of an FIR filter is a one-shot computation. But in higher dimensions IIR filters are definitely more attractive. We offer a technique where the filter’s performance specifications, stability constraints, its convergence speed and a protection against possible adverse effects of perturbations are all included in the design from the start. The technique only needs an off-the-shelf LP solver because the filter is obtained as a Chebyshev center of a convex polytope. The method deals with general non-causal non-separable filters. 相似文献
442.
Annie Waldherr 《The Journal of communication》2014,64(5):852-873
The study investigates fundamental mechanisms generating issue‐attention cycles in news coverage with a social simulation approach. An agent‐based computer model is developed, which integrates the main drivers of news waves as identified by empirical research. By simulating the model many times under varying conditions, the interaction of the factors to generate the typical issue‐attention cycle can be observed. Results suggest that the momentum of news waves is mainly driven by the adaptive reporting behavior of journalists. Sponsors actively supporting issues by initiating events are not necessary to generate issue‐attention cycles, but change their typical dynamics. Comparing simulated time series to two empirical cases yields that the model produces more realistic patterns of media attention when issue sponsors are introduced. 相似文献
443.
The phenolic acid and polysaccharide composition of cell walls of bran layers of mature wheat (Triticum aestivum L. cv. Avalon) grains 总被引:1,自引:0,他引:1
Mary L Parker Annie Ng Keith W Waldron 《Journal of the science of food and agriculture》2005,85(15):2539-2547
The purpose of this study was to examine the carbohydrate and phenolic‐ester composition of cell walls in wheat bran layers. Four defined layers of wheat bran were separated manually from mature grains of wheat (Triticum aestivum L. cv. Avalon) to give samples of beeswing bran (outer pericarp), cross cells, testa + nucellar epidermis and aleurone cells. The cell‐wall material from each layer, and from a sample of intact bran, was analysed for carbohydrates and wall‐bound esterified phenolic acids. The cell‐wall material of intact bran was rich in arabinose and xylose with significant quantities of glucose and uronic acid and a relatively small amount of galactose and mannose. The varying ratios of arabinose:xylose in cell walls of isolated bran layers indicated that the heteroxylans had tissue‐specific substitution patterns. HPLC analysis of phenolic acids identified significant amounts of esterified ferulic acid and 8‐8′‐ (aryltetralin form), 5‐8′‐, 5‐5′‐, 8‐0‐4′‐ and 5‐8′‐(benzofuran form)‐dehydrodiferulic acids in the isolated cell walls. Ferulic acid was highly concentrated in the aleurone layer, whereas dehydrodiferulates were concentrated in the beeswing bran and cross cells. The role of phenolic cross‐linking is discussed in relation to the architecture of the cell walls of wheat bran and to processing implications. Copyright © 2005 Society of Chemical Industry 相似文献
444.
Aim
To analyze the demographics, risk factors, clinical and microbiological characteristics of cases of bilateral simultaneous infective keratitis.Methods
In this retrospective case series, patients with clinical evidence of bilateral simultaneous infective keratitis were identified from January 1, 2011 to August 31, 2016. Demographics, risk factors, clinical and microbiological characteristics, and treatment outcomes were analyzed.Results
Five patients (ten eyes) with bilateral simultaneous infective keratitis were identified. The mean age was 32.8 years (SD, ± 8.8; range, 24–44). All the patients were disposable soft contact lens wearers before presentation. The average size of the infiltrate was 4.76 mm2 (SD ± 9.0; range, 0.2–31.34). A total of 4 types of bacteria were isolated, with Pseudomonas aeruginosa being the most frequently isolated bacteria involving 5 eyes of four patients. Infection resolved with medical treatment in 9 eyes, 1 patient required therapeutic corneal transplantation for impending corneal perforation. The average time taken for infection to resolve was 6.7 days (SD ± 4.5; range, 2–16).Conclusions
In this case series, the most common risk factor of bilateral simultaneous microbial keratitis was use of soft disposable contact lens and the most commonly isolated bacteria was Pseudomonas aeruginosa. Bilateral simultaneous infective keratitis is uncommon and is a serious complication of contact lens use in immunocompetent adult patients. 相似文献445.
446.
The displacement based finite element model of a general third-order beam theory is developed to study the quasi-static behavior of viscoelastic rectangular orthotropic beams. The mechanical properties are considered to be linear viscoelastic in nature with a scope to undergo von Kármán nonlinear geometric deformations. A differential constitutive law is developed for an orthotropic linear viscoelastic beam under the assumptions of plane-stress. The fully discretized finite element equations are obtained by approximating the convolution integrals using a trapezoidal rule. A two-point recurrence scheme is developed that necessitates storage of data from the previous time step only, and not from the entire deformation history. Full integration is used to evaluate all the stiffness terms using spectral/hp lagrange polynomials. The Newton iterative scheme is employed to enhance the rate of convergence of the nonlinear finite element equations. Numerical examples are presented to study the viscoelastic phenomena like creep, cyclic creep and recovery for thick and thin beams using classical mechanical analogues like generalized n-parameter Kelvin-Voigt solids and Maxwell solids. 相似文献
447.
Bethany Palen Ethan T. Iverson Matthew G. Rabaey Shaik Merkatur Hakim Marjuban Carolyn T. Long Thomas J. Kolibaba Annie Benson Homero Castaneda-Lopez Jaime C. Grunlan 《大分子材料与工程》2023,308(5):2200561
Dielectric materials that can withstand high voltages are of great interest due to the growing need for high-performance insulation systems in electronics. Polymer nanocomposites have gained popularity as electrical insulators due to their processability, high operating voltage, and tortuous paths for current flow created by the nanoparticles in the polymer matrix. The dielectric breakdown strength of a relatively thick multilayer thin film containing polyethylenimine (PEI) and vermiculite clay (VMT), thickened with tris(hydroxymethyl)aminomethane (tris), is evaluated as a function of bilayers (BL) deposited. The resulting nanobrick wall structure of this clay-based assembly is ideal for protective insulation. An 8 BL PEI+tris/VMT film achieves a dielectric breakdown strength of 245 kV mm−1, with a thickness of 5 µm. With increasing bilayers, the breakdown strength gradually decreases, but 20 BL of PEI+tris/VMT achieves a breakdown voltage of 2.36 kV. This nanoplatelet-based system is the first “thick growing” layer-by-layer deposited film to be used as an insulating layer. Its unusually high breakdown strength can be useful for the protection of various high voltage electronics. 相似文献
448.
Tony G. Feric Sara T. Hamilton Byung Hee Ko Gahyun Annie Lee Sumit Verma Feng Jiao Ah-Hyung Alissa Park 《Advanced functional materials》2023,33(13):2210017
Coupling renewable energy with the electrochemical conversion of CO2 to chemicals and fuels has been proposed as a strategy to achieve a new circular carbon economy and help mitigate the effects of anthropogenic CO2 emissions. Liquid-like Nanoparticle Organic Hybrid Materials (NOHMs) are composed of polymers tethered to nanoparticles and are previously explored as CO2 capture materials and electrolyte additives. In this study, two types of aqueous NOHM-based electrolytes are prepared to explore the effect of CO2 binding energy (i.e., chemisorption versus physisorption) on CO2 electroreduction over a silver nanoparticle catalyst for syngas production. Poly(ethylenimine) (PEI) and Jeffamine M2070 (HPE) are ionically tethered to SiO2 nanoparticles to form the amine-containing NOHM-I-PEI and ether-containing NOHM-I-HPE, respectively. At less negative cathode potentials, PEI and NOHM-I-PEI-based electrolytes produce CO at higher rates than 0.1 molal. KHCO3 due to favorable catalyst-electrolyte interactions. Whereas at more negative potentials, H2 production is favored because of the carbamate electrochemical inactivity. Conversely, HPE and NOHM-I-HPE-based electrolytes display poor CO2 reduction performance at less negative potentials. At more negative potentials, their performance approached that of 0.1 molal. KHCO3, highlighting how the polymer functional groups of NOHMs can be strategically selected to produce value-added products from CO2 with highly tunable compositions. 相似文献
449.
A Princy E Annie Rathnakumari S Masilla Moses Kennedy 《Journal of the American Ceramic Society》2023,106(9):5364-5380
A novel vanadate host Ca2LiMg2V3O12 (CLMV) and the Eu3+-doped samples were synthesized via a solid-state reaction method. The phase formation and the morphological analysis were studied in detail. The Rietveld refinement result shows that the host belongs to cubic space group Ia-3d (230) with lattice parameter, a = 12.3948 Å, V = 1904.23 Å3, and Z = 8. The diffuse reflectance spectroscopy measurement estimated the bandgap of the host and the CLMV:0.05Eu3+ phosphors. The host exhibits a broad absorption band (peak at 345 nm) ranging from 240 to 380 nm, which is attributed to the charge transfer in the O2−–V5+ complex. Under near UV excitation (λexc = 345 nm), the host gives a broad emission band covering the visible region from 400 to 730 nm and the emission is in the bluish–green region of the CIE diagram. When the host is doped with the Eu3+ ions and excited at 345 nm, the emission spectrum depicts the superimposition of the characteristic emission bands (red emission) of the Eu3+ ions corresponding to the f–f transitions over the broad emission band of the host. The calculated color coordinates (9600 to 2280 K) demonstrated the color tuning ability of the phosphor as the dopant concentration is increased in the host. This is because the VO43− group plays the sensitiser role and partially transfers energy with the Eu3+ ions. When the same set of phosphors were excited at the dominant characteristic excitation band (λexc = 394 nm) of the Eu3+, the characteristic emission bands of the Eu3+ in the orange–red region were observed. As the electric dipole transition of the Eu3+ was found to be dominant, the prepared phosphors possessed high color purity (CP). The energy transfer mechanism and the lifetime values were also presented. The temperature-dependent PL studies showed good thermal stability of the optimum sample. Various radiative transition properties were analyzed by the Judd–Ofelt theory. The photometric results reveal the color tuning ability and CP of the CLMV:xEu3+ phosphors. 相似文献
450.
Rosnadiya Rosli Othman Othman Nurhidayu Haji Harudin Mohd Zieauddin Kufian Annie Maria Mahat Faridah Sonsudin Izlina Supa'at Zurina Osman 《International Journal of Applied Ceramic Technology》2023,20(4):2371-2381
Magnesium ion battery is an alternative for secondary battery instead of lithium ion battery due to its advantages of low cost, safety and environment friendly. Magnesium (Mg) is safer compared to lithium (Li) where it has high stability in contact of air and prevent the formation of dendrites during electrochemical cycling. The cathode materials of un-doped MgMn2O4 and Al-doped MgMn2-xAlxO4, x = .01, .02, .03 were prepared using self-propagating combustion method with triethanolamine fuel as a reducing agent. All samples (powder form) were annealed at 700˚C in 6 h based on the thermogravimetric analysis results. The samples were been characterized using X ray diffraction, field emission electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy to study structural and morphological properties of the samples. Electrochemical properties of linear sweep voltammetry, cyclic voltammetry, and charge-discharge capacity were performed in 1 M Magnesium Trifluoromethanesulfonate (MgTf2) with ratio 1:1 of ethylene carbonate: dimethyl ether electrolyte. The discharge capacity of magnesium ion cells using Al-doped cathode material showed the improvement of 68% compared to the un-doped sample. 相似文献