Column Inclination Angle Research Articles

UV-photodegradation of R6G dye in three-phase fluidized bed reactor: Modeling and optimization using adaptive neuro-fuzzy inference system and artificial neural network

The development of an efficient photoreactor is still the most challenging task in the photocatalytic process. The main challenges include the determination of the optimal hydrodynamic conditions required for the efficient photodegradation of biorecalcitrant pollutants. In this study, a TiO2-ZnO/BAC composite catalyst was applied to investigate the hydrodynamic characteristics of a three-phase fluidized bed reactor in the UV-photodegradation of rhodamine 6G dye. Artificial neural network (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) were used for modeling and optimization of the photodegradation process. From the preliminary study, 70° column inclination angle and 0.028 ms−1 superficial gas velocity, showed good axial solid distribution and average gas holdup. Subsequently, 0.019 ms−1 gas flow rate at 70° column inclination angle was found to be the optimum condition for the removal of rhodamine 6G (97.0 %). Moreover, solid distribution was found to be a dominant limiting factor in the photodegradation process as compared to gas holdup. Meanwhile, sensitivity analysis showed that all the input parameters (lamp position, inclination angle, and superficial gas velocity) were above 10%, confirming a strong influence on the process. The ANN-trainlm and ANFIS-hybrid with R-values of 0.9911 and 0.9546, respectively confirmed that the predicted model fits well with the experimental data. Furthermore, the inclination angle of 70° can be important in solar photoreactors to attain a relatively efficient tilt angle when using solar energy.

Reliability estimation of a Tibetan heritage timber structure with inclination in its Que-Ti joints

The reliability of a Tibetan timber frame in a heritage building in Lasha, China is studied. The frame is featured with stochastic Que-Ti joints with inclination. A new method integrating the relative entropy-based probabilistic sensitivity analysis and the Probabilistic Density Evolution Method with absorbing boundary condition is developed for this study. The contributions of stochastic parameters to the probabilistic bearing capacity of the joint can be clearly defined from the differences between the probability density functions of the bearing capacity with different parameter perturbation. Results are obtained via sensitivity analysis with engineering considerations of the heritage frame structure with a large number of uncertain parameters. The Que-Ti inclination angle, column inclination angle, the parallel-to-grain shear modulus and perpendicular-to-grain elastic modulus, which have greater influence on the performances of the heritage frame structure are identified with acceptable computation requirements. A reduced-dimensioned model of the structure with selected variables is then verified and used for the reliability estimation. The structural reliability is noted efficiently implemented with the random variables of the frame system reduced from 13 to 4. The frames in this heritage building with stochastic inclined Que-Ti joints are relatively safe comparing to the recommended reliability limit in the design code.

Microstructure Dependence of Effective Thermal Conductivity of EB-PVD TBCs.

Microstructure dependence of effective thermal conductivity of the coating was investigated to optimize the thermal insulation of columnar structure electron beam physical vapor deposition (EB-PVD coating), considering constraints by mechanical stress. First, a three-dimensional finite element model of multiple columnar structure was established to involve thermal contact resistance across the interfaces between the adjacent columnar structures. Then, the mathematical formula of each structural parameter was derived to demonstrate the numerical outcome and predict the effective thermal conductivity. After that, the heat conduction characteristics of the columnar structured coating was analyzed to reveal the dependence of the effective thermal conductivity of the thermal barrier coatings (TBCs) on its microstructure characteristics, including the column diameter, the thickness of coating, the ratio of the height of fine column to coarse column and the inclination angle of columns. Finally, the influence of each microstructural parameter on the mechanical stress of the TBCs was studied by a mathematic model, and the optimization of the inclination angle was proposed, considering the thermal insulation and mechanical stress of the coating.

Proposal of a Novel Semi-Submersible Floating Wind Turbine Platform Composed of Inclined Columns and Multi-Segmented Mooring Lines

The semi-submersible floating offshore wind turbine has been studied in detail due to its good stability. However, the occurrence of typhoons are very frequent in China’s offshore area, putting forward a higher requirement for the stability of the floating wind turbine system. By changing the connection mode of the mooring line as well as the structural form of the platform based on the original OC4 model, two groups of models were examined by an in-house developed code named as the Analysis Tool of Floating Wind Turbine (AFWT). The influence of the arrangement of the mooring lines and the inclination angle of the upper columns on the motion response were clarified. It was found that the surge motion of the platform would be obviously decreased by decreasing the length of the upper segments of the mooring lines, while the heave motion of the platform would be significantly decreased as increasing the inclined angle of the columns. Therefore, a new model integrating the optimized multi-segmented mooring lines and the optimized inclined columns was proposed. The examinations showed that compared with the response motions of the original OC4 semi-submersible model, the proposed model could reduce both the surge and heave motions of the platform effectively.

Deformation Monitoring for Chinese Traditional Timber Buildings Using Fiber Bragg Grating Sensors.

The Fiber Bragg Grating (FBG) sensing technique is suitable for a wide variety of measurements, including temperature, pressure, acceleration, liquid level, etc., and has been applied to many bridges and buildings in the past two decades. The fact that the FBG technique can only monitor and measure strain data for most cases when it is used for deformation measurements impedes application of the FBG sensing technique in civil infrastructures. This paper proposes FBG sensing-based deformation monitoring methods that are applicable to monitoring beam deflection, column inclination angle and mortise-tenon joint dislocation for Chinese traditional timber structures. On the basis of improved conjugated beam theory and geometrical trigonometric function relationship, the relationships between the FBG sensing strain values and the deflection of beam, inclination angle of column, as well as the amount of dislocation of mortise-tenon joint are deducted for Chinese traditional buildings. A series of experiments were conducted to verify the applicability and effectiveness of the proposed deformation monitoring methods. The results show that a good agreement is obtained between the values given by the methods proposed in this paper and other methods. This implies that the proposed deformation monitoring methods are applicable and effective in the health monitoring of Chinese traditional timber structures.

Three‐dimensional simulations of gas‐liquid cocurrent downflow in vertical, inclined, and oscillating packed beds

The hydrodynamic behavior of gas‐liquid downflow in vertical, inclined, and oscillating packed beds related to offshore floating applications was analyzed by means of three‐dimensional unsteady‐state two‐fluid simulations. Angular oscillations of the column between two angled symmetrical positions and between vertical and inclined position were considered while bed non‐uniformity was described using radial porosity distributions. For vertical and slightly inclined columns, two‐phase flow was concentrated in the core area of the bed. However, the two‐phase flow was predicted to deviate significantly from axial symmetry at higher inclinations with prominent liquid accumulation in the bottommost reactor cross‐sectional area. Oscillating packed beds unveiled complex reverse secondary flows radially and circumferentially resulting in oscillatory patterns of liquid holdup and pressure drop whose amplitude and propagation frequency were affected by column inclination angle and travel time between vertical and angled positions. © 2015 American Institute of Chemical Engineers AIChE J, 62: 916–927, 2016

Substrate-tilt angle effect on structural and optical properties of sputtered ZnO film

A new one-step method utilizing a special holder for a direct current magnetron sputtering system has enabled simultaneous deposition of ZnO films with different substrate tilt angles on quartz and silicon substrates. Observation from scanning electron microscopy shows that a typical columnar structure is obtained and the column inclination angle varies from 0° to 34°. From X-ray diffraction analysis, the strains in the ZnO films decrease with increasing substrate tilt angle, which is confirmed by the variation of the longitude optical phonon vibration in the Raman spectra. The band-gap energies decrease from 3.19eV to 3.07eV mainly due to the changes of strain relaxation induced by the defect variations in the films. Photoluminescence spectra revealed that the generation, type and concentration of the complex defects are influenced by the substrate tilt angle.

The Relationship Between Cervical Column Curvature and Sagittal Position of the Jaws: Using a New Method for Evaluating Curvature

For determining the cervical column curvature, the curve fitting method is the most precise method, but using this method in clinic seems to be difficult if not possible. In this study, we used a modification of cervical column inclination angle that has been already mentioned The aim of this study was to evaluate the posture and curvature of the cervical column introducing a modified constructed angle in order to evaluate the cervical column curvature in a relax position in relation to the jaws sagittal position. The lateral cephalometries of patients with no anomaly were taken in the natural head position. The mean age of the patients was 13.49 years including 56 female and 44 male. Steiner and Wits analysis was used to evaluate the sagittal position of the jaws. Modified constructed CVT/HOR and OPT/HOR angles were used to evaluate the cervical column posture and curvature. Patients were classified into three groups according to the angle's classification. The results showed a significant positive correlation between modified constructed angles and sagittal jaw relationships (P < 0.05). Besides, in class II patients, there was a significant correlation between OPT/HOR and parameters ANB and Wits (P < 0.05 and P < 0.01, respectively). Age could not affect the curvature and posture of the cervical column. According to the result of this study using modified constructed angles may be a simple method for evaluation of the relation between cervical column curvature and sagittal position of the jaws. There is significant correlation between cervical column posture angles and parameters ANB and Wits in Cl. II patients.

A MODEL FOR POST-EARTHQUAKE FIRE SPREAD CONSIDERING STRUCTURAL DAMAGE OF BUILDINGS CAUSED BY SEISMIC MOTION AND ITS PROGRESSION DUE TO HEATING OF FIRE

A physics-based model for post-earthquake fire spread was developed by modifying the prototype model previously proposed by the authors. In the new model, seismic motion and heating of fire are both considered as the causes of damage upon building members. The damage results in the change of fire behavior for individual building and criteria for building-to-building ignition. Indices representing the structural damage of a building are as follow: inclination angle of columns; falling ratio of exterior claddings; and deficit ratio of partitioning walls. Charring of wooden column gradually reduces its bearing capacity along with the decrease in its area of cross section. This may yield buckling of the column as well as collapse of the entire building. As to the falling of exterior claddings and burn-through of partitioning walls, the rates of degradation are assumed to be proportional to the cumulative heat flux received by the building members. The falling of exterior claddings increases the probability of ignition due to external heating, and the burn-through of partitioning walls allows transfer of heat and mass between neighboring rooms. For the verification of the new model, simulation of fire spread which followed 1995 Kobe Earthquake was conducted. Behavior of fire spread obtained by the numerical simulation was compared with the survey data at which reasonable agreement was obtained.

The dynamics and structure of a liquid–solid fluidized bed in inclined pipes

Abstract The dynamics and structure of a fluidized bed in inclined columns are investigated experimentally. Experiments were conducted in two glass columns of L / D = 95 and 150, and diameters of 2.58 and 2.78 cm, which can be positioned in the whole range of inclination angles, from horizontal to vertical. The fluidizing agent is water and the grain material is particles of different densities and characteristic diameters. Measurements of the pressure loss, flow rate of the fluidizing agent and fluidized bed position and height are carried out. Particle flow patterns were visualized using a digital camera. The expansion process of the fluidized bed depends strongly on the inclination angle. Consequently the critical velocity for the bed escape varies with the column inclination angle and exhibits a maximum at about 45°. The column length was found to have a minor effect on the phenomena involved.

The effect of TBC morphology and aging on the erosion rate of EB-PVD TBCs

Since thermal barrier coatings (TBCs) have been used in gas turbines most of the research conducted on them has involved the bond coat and the growth of the thermally grown oxide (TGO) as failure of the bond coat and the TGO were considered to be the primary causes of failure. Erosion of TBCs has been considered as a secondary problem and as such received less attention. Most of the initial work on the erosion of TBCs covered the effects of velocity and impact angle on the erosion rates of both plasma sprayed (PS) and electron beam physical vapour deposited (EB-PVD) TBCs and compared the differences between the two deposition systems. It must be noted that most of the tests were conducted on coatings in the as received condition. This paper aims at expanding the understanding of the erosion of EB-PVD TBCs by examining the effects of TBC morphology, column diameter, column inclination angle and the effects of aging and sintering on the erosion rates of EB-PVD TBCs. The paper also looks at how erosion rate changes as the coating is eroded through to the bond coat. The paper also looks at the mechanisms of foreign object damage of EB-PVD TBCs under a range of different impact conditions. The different damage mechanisms have been identified and related to the size and impact velocity of the impacting particles. The effect of temperature on the plasticity and hence the mechanisms are also discussed, while mapping is used to set the boundary limits for the different types of damage mechanisms that have been identified. It was found that at temperatures above 800 °C the coatings can accommodate a large degree of plastic deformation, while at room temperature there is a greater degree of cracking, for similar types of FOD impact. The 800 °C is not necessarily a limit, but the temperature at which the coatings were tested, and the limiting temperature could in fact be significantly lower. It was found that, all else being equal, erosion rate decreases with a decrease in the column diameter, while aging results in an increase in the erosion rate, dependent on the aging temperature and time. A decrease in the inclination angle of the columns with respect to the substrate increases the erosion rate, when the inclination angle is less than 60° the erosion rate increases catastrophically. These effects are all discussed and explained in terms of erosion mechanisms and mechanical properties in the paper.

The effect of TBC morphology on the erosion rate of EB PVD TBCs

Since thermal barrier coatings (TBCs) have been used in gas turbines most of the research conducted on them has involved the bond coat and the growth of the thermally grown oxide (TGO) as failure of the bond coat and the TGO were considered to be the primary causes of failure. Erosion of TBCs has been considered as a secondary problem and as such received less attention. Most of the initial work on the erosion of TBCs covered the effects of velocity and impact angle on the erosion rates of both plasma sprayed (PS) and electron beam physical vapour deposited (EB PVD) TBCs and compared the differences between the two deposition systems. Most of the tests were conducted on coatings in the as-received condition. This paper aims at expanding the understanding of the erosion of EB PVD TBCs by examining the effects of TBC morphology, column diameter, column inclination angle and the effects of aging and sintering on the erosion rates of EB PVD TBCs. Monte Carlo modelling and mapping of EB PVD TBCs is also briefly discussed along with the associated mechanisms. It was found that, all else being equal, erosion rate decreases with a decrease in the column diameter, while aging results in an increase in the erosion rate, dependent on the aging temperature and time. A decrease in the inclination angle of the columns with respect to the substrate increases the erosion rate, when the inclination angle is less than 60° the erosion rate increases catastrophically. These effects are all discussed and explained in terms of erosion mechanisms and mechanical properties in the paper.

Determination of the refractive indices of highly biaxial anisotropic coatings using guided modes

Precise determination of the main refractive indices of biaxial anisotropic coatings is essential for the calculation of their optical performance. Earlier measurements based on wave guiding methods have proved to yield excellent results with obliquely deposited and hence anisotropic layers, deposited under an angle of or less. But with higher deposition angles, new problems arise due to the less defined microstructure and the increasing influence of the accuracy of the column inclination angle on the resulting indices. In a theoretical study, these effects are shown to limit the precision of the method. Experimental results at on coatings, deposited at angles of , , and , are given. All three main refractive indices were found to decrease with an increasing deposition angle, while anisotropy increases almost linearly.

Effect of liquid depth, column inclination and baffle plates on gas holdup in bubble columns.

The effects of liquid depth, inclination angle of the column from vertically and baffle plates on gas holdup in bubble columns were determined, using three bubble columns. When liquid depth Hl was less than the critical liquid depth Hlc, gas holdup eg decreased with increasing Hl, but when Hl was larger than Hlc, eg was nearly constant. eg decreased with increasing column inclination angle, and the effect on eg was correlated. eg was independent of the cross-sectional shape of the column. Baffle plates set in bubble columns increased eg, and the effects of the area and number of baffle plates on eg were correlated.