COMPOSITION OPERATORS ON UNIFORM ALGEBRAS AND THE PSEUDOHYPERBOLIC METRIC

Galindo, P.,Gamelin, T.W.,Lindstrom, M. Korean Mathematical Society 2004 대한수학회지 Vol.41 No.1

Let A be a uniform algebra, and let $\phi$ be a self-map of the spectrum $M_A$ of A that induces a composition operator $C_{\phi}$, on A. It is shown that the image of $M_A$ under some iterate ${\phi}^n$ of \phi is hyperbolically bounded if and only if \phi has a finite number of attracting cycles to which the iterates of $\phi$ converge. On the other hand, the image of the spectrum of A under $\phi$ is not hyperbolically bounded if and only if there is a subspace of $A^{**}$ "almost" isometric to ${\ell}_{\infty}$ on which ${C_{\phi}}^{**}$ "almost" an isometry. A corollary of these characterizations is that if $C_{\phi}$ is weakly compact, and if the spectrum of A is connected, then $\phi$ has a unique fixed point, to which the iterates of $\phi$ converge. The corresponding theorem for compact composition operators was proved in 1980 by H. Kamowitz [17].

ANALYSIS OF GAS-DYNAMIC EFFECTS IN COMPACT EXHAUST SYSTEMS OF SMALL TWO-STROKE ENGINES

Galindo, J.,Serrano, J.R.,Climent, H.,Tiseira, A. The Korean Society of Automotive Engineers 2007 International journal of automotive technology Vol.8 No.4

This article describes a methodology based on experiments and 1D modeling work related to the exhaust system analysis of a small two-stroke engine. The primary goal of this work was to understand how the design criteria of a compact exhaust system influenced the exhaust port pressure, since its evolution controls not only engine performance but also exhaust emissions. On the experimental side, a fully instrumented 50cc two-stroke engine was used to check the behavior of three different exhaust systems. A problem related to instantaneous pressure measurements in unsteady, hot flow was detected and solved during the study. To build the 1D model of the three exhaust systems, experimental information on the steady flow and the impulse test rigs was obtained under controlled conditions in specific facilities. Accurate comparisons between measured and calculated exhaust port instantaneous pressures were obtained from the following different exhaust system configurations: a straight duct, a tapered pipe and the three compact exhaust systems. The last step in the method used this model to analyze the pressure waves inside the exhaust system and detect the influence of the geometric parameters. The results should lead to improvements in the design process of complex compact exhaust systems in two-stroke engines.

Analysis of Gas-Dynamic Effects in Compact Exhaust Systems of Small Two-Stroke Engines

J. GALINDO,J. R. SERRANO,H. CLIMENT,A. TISEIRA 한국자동차공학회 2007 International journal of automotive technology Vol.8 No.4

This article describes a methodology based on experiments and 1D modeling work related to the exhaust system analysis of a small two-stroke engine. The primary goal of this work was to understand how the design criteria of a compact exhaust system influenced the exhaust port pressure, since its evolution controls not only engine performance but also exhaust emissions. On the experimental side, a fully instrumented 50cc two-stroke engine was used to check the behavior of three different exhaust systems. A problem related to instantaneous pressure measurements in unsteady, hot flow was detected and solved during the study. To build the 1D model of the three exhaust systems, experimental information on the steady flow and the impulse test rigs was obtained under controlled conditions in specific facilities. Accurate comparisons between measured and calculated exhaust port instantaneous pressures were obtained from the following different exhaust system configurations: a straight duct, a tapered pipe and the three compact exhaust systems. The last step in the method used this model to analyze the pressure waves inside the exhaust system and detect the influence of the geometric parameters. The results should lead to improvements in the design process of complex compact exhaust systems in two-stroke engines.

Renal denervation: back on track

Márcio Galindo Kiuchi 대한신장학회 2018 Kidney Research and Clinical Practice Vol.37 No.4

Hypertension is a common cause as well as one of the main consequences of chronic kidney disease (CKD). In 2000, it was projected that more than 25% of the world’s adult population had hypertension, two-thirds of them in developing countries. It is predicted that this amount will rise by ~60% to 1.56 billion in 2025 [1], becoming one of the most critical public health problems in the world. Hypertension control is poor in the presence of CKD, as show in the “Kidney Early Evaluation Program (KEEP),” in which only 13.2% of participants achieved good blood pressure control [2].

Composition operators on uniform algebras and the pseudohyperbolic metric

P. Galindo,T. W. Gamelin,M. Lindstr\ 대한수학회 2004 대한수학회지 Vol.41 No.1

Let A be a uniform algebra, and let φ be a self-map of the spectrum MA of A that induces a composition operator Cφ on A. It is shown that the image of MA under some iterate φn of φ is hyperbolically bounded if and only if φ has a finite number of attracting cycles to which the iterates of φ converge. On the other hand, the image of the spectrum of A under φ is not hyperbolically bounded if and only if there is a subspace of A∗∗ “almost” isometric to ∞ on which C∗∗ φ is “almost” an isometry. A corollary of these characterizations is that if Cφ is weakly compact, and if the spectrum of A is connected, then φ has a unique fixed point, to which the iterates of φ converge. The corresponding theorem for compact composition operators was proved in 1980 by H. Kamowitz [17].

EGR TRANSIENT OPERATIONS IN HIGHLY DYNAMIC DRIVING CYCLES

Jose Galindo,Hector Climent,Benjamin Pla,Chaitanya Patil 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.4

EGR is one of the proven and well tested strategies within the specific operating range of the engine. Necessity of an implementation of this exhaust gas recirculation all over the engine operating range is emerging. Therefore, a systematic study has been carried out to identify the specific and frequent transient operations on newly developed dynamic cycles like WLTC and RDE. To perform detailed observations, these transients are imitated individually on the diesel engine test bench. High frequency gas analyzers are used to track the instantaneous CO2 and NOx concentration respectively at the intake and exhaust lines of the engine. A parametric study has been carried out using different valve movement profiles of the LPEGR and HPEGR during severe engine load change operations. An analysis is presented suggesting the best suited valve control during these harsh transients which can be helpful for transient calibration of a turbocharged diesel engine. The effect of length of Long route LPEGR line is also acknowledged. This study reveals the dynamic behavior of a diesel engine during transient operation with exhaust gas recirculation. It outlines the trade-off between performance and NOx emission and opacity for the initial phase of the transient before acquiring the steady state situation.

Atrial fibrillation and chronic kidney disease: A bad combination

( Marcio Galindo Kiuchi ) 대한신장학회 2018 Kidney Research and Clinical Practice Vol.37 No.2

The effects of different physical activities on atrial fibrillation in patients with hypertension and chronic kidney disease

( Márcio Galindo Kiuchi ),( Shaojie Chen ),( Neil Alexander Hoye ) 대한신장학회 2017 Kidney Research and Clinical Practice Vol.36 No.3

Background: Atrial fibrillation (AF) is highly common, and is most frequently observed in individuals with hypertension and structural cardiac disease. Sympathetic hyperactivity plays a fundamental role in the progression, maintenance and aggravation of arrhythmia. Endurance exercise training clearly lowers sympathetic activity in sympathoexcitatory disease states, and is well-tolerated by patients with chronic kidney disease (CKD). Methods: We assessed 50 CKD patients with hypertension. Each patient provided a complete medical history and underwent a physical examination. We used an implantable cardiac monitor over a 3-year follow-up period to evaluate the effects of high-intensity interval training (HIIT) and moderate exercise (ModEx) physical activity protocols on AF occurrence, and determined the effectiveness of these protocols in improving renal function. Subjects were followed up every 6 months after the beginning of the intervention. Results: During the 3-year follow-up, AF onset was higher in CKD patients who engaged in HIIT (72%) than in those who engaged in ModEx (24%) (hazard ratio, 3.847; 95% confidence interval, 1.694-8.740, P = 0.0013 by log-rank test). Both groups exhibited significant intra-group changes in the mean systolic 24-hour ambulatory blood pressure measurements (ABPM) between baseline and 12, 24, and 36 months. There were also significant differences in the mean systolic 24-hour ABPM between the groups at the same time points. Conclusion: In CKD patients with hypertension, improvements in AF onset, renal function and some echocardiographic parameters were more evident in subjects who engaged in ModEx than in those who engaged in HIIT during 3 years of follow-up.

Hydrolysis catalyst effect on the textural and structural properties of sol-gel mixed oxides TiO₂-CeO₂

Félix Galindo-Hernández,Gloria del Ángel,Carlos Guzmán,Ricardo Gómez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

Sol-gel TiO2-CeO2 semiconductors were synthesized at pH 3 and 9 using titanium alkoxide as the initial reactant; and either nitric acid or ammonium hydroxide as hydrolysis agents. The gels annealed at 473, 673 and 873 K were characterized by nitrogen adsorption,X-ray diffraction and Raman spectroscopy. The surface fractal dimension, crystallite size, titanium deficiency and electron density were calculated by the Frenkel-Halsey-Hill method, Rietveld refinement, and Fourier electron density map, respectively. Mesoporous materials showing high specific surface areas (250-99m2/g for pH 3 and 267-88 m2/g for pH 9) were obtained in both preparations. Anatase and anatase-cerianite crystalline phases were observed by X-ray diffraction in the samples prepared at pH 3 and pH 9 respectively. Nanocrystalline structures (from 7.1 to 43.6 nm) and an important titanium deficiency, depending on the synthesis conditions are reported. The Fourier electron density maps showed that for the semiconductors prepared at pH 3 the electron density was contracted in comparison with the samples synthesized at pH 9 where enlarged electron density maps were observed. A good agreement between the electron density maps and the surface fractal dimensions was obtained. Sol-gel TiO2-CeO2 semiconductors were synthesized at pH 3 and 9 using titanium alkoxide as the initial reactant; and either nitric acid or ammonium hydroxide as hydrolysis agents. The gels annealed at 473, 673 and 873 K were characterized by nitrogen adsorption,X-ray diffraction and Raman spectroscopy. The surface fractal dimension, crystallite size, titanium deficiency and electron density were calculated by the Frenkel-Halsey-Hill method, Rietveld refinement, and Fourier electron density map, respectively. Mesoporous materials showing high specific surface areas (250-99m2/g for pH 3 and 267-88 m2/g for pH 9) were obtained in both preparations. Anatase and anatase-cerianite crystalline phases were observed by X-ray diffraction in the samples prepared at pH 3 and pH 9 respectively. Nanocrystalline structures (from 7.1 to 43.6 nm) and an important titanium deficiency, depending on the synthesis conditions are reported. The Fourier electron density maps showed that for the semiconductors prepared at pH 3 the electron density was contracted in comparison with the samples synthesized at pH 9 where enlarged electron density maps were observed. A good agreement between the electron density maps and the surface fractal dimensions was obtained.

Fabrication process of a microstructures based on hydrogenated amorphous SiGe films for applications in MEMS devices

M. Galindo-Mentle,F. López-Huerta,R. Palomino-Merino,C. Zúñiga-Islas,W. Calleja-Arriaga,A. L. Herrera-May 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.4

We present a fabrication process of microstructures using both boron-doped hydrogenated amorphous silicon and hydrogenated amorphoussilicon-germanium (a-SiB:H and a-Si0.5Ge0.5B:H) films for applications in devices based on microelectromechanical systems(MEMS). These microstructures are fabricated through plasma enhanced chemical vapor deposition (PECVD) with a low temperature of300°C at 110 kHz and a pressure of 0.6 Torr. The proposed microstructures have three different geometries (Diamond, cantilever andbridge) considering a single structural layer of 1 μm thickness and are fabricated using surface micromachining. The fabricated a-Si0.5Ge0.5B:H microstructures do not present sticking problems and have good mechanical stability, which can allow their use in MEMSdevices. Our fabrication process with hydrogenated amorphous SiGe films is simple. This process decreases the residual stress of themicrostructures and allows the metal deposition on the microstructures surfaces.