Average Tilt Angle Research Articles

Electric Field Effect on Condensed-Phase Molecular Systems. VI. Field-Driven Orientation of Hydrogen Chloride in an Argon Matrix.

The orientation state of hydrogen chloride (HCl) molecules in a solid argon matrix was reversibly controlled by applying an external electric field of up to 4 × 108 V·m-1 using the ice film capacitor method. The rovibrational transitions of the field-oriented HCl were measured by reflection absorption infrared spectroscopy with p-polarized light. Upon application of the external field, free rotation of HCl inside the matrix gradually changed to perturbed rotation and then to a pendular state harmonically bound in the Stark potential well. Further increase in the field strength increased the degree of dipole alignment along the field direction, approaching an asymptotically perfect orientation of the molecules with an average tilt angle of <30° at a field strength above 1 × 108 V·m-1.

A Proposed Design for Illumination and Cameras Surveillance System for Optimum Supervision at a Perimeter Area of Nuclear Facility

An important component of a comprehensive security plan is lighting. Security Protective Lighting has three functional objectives: To illuminate a person, object, place or condition of security to permit observation and identification, to be a physical deterrent through the glare effect of direct light on the human eye and to be a psychological deterrent creating in an intruder's mind the awareness that he or she will be discovered and observed during any unauthorized entry attempt. The most obvious reason for protective lighting is to make certain any person, object, place or condition will be sufficiently illuminated to provide effective security in a given region. Where perimeter lighting is required, the lighting units for a perimeter fence should be located a sufficient distance within the protected area and above the fence so that the light pattern on the ground will include an area both inside and outside the fence. Perimeter lighting should be continuous and on both sides of the perimeter fence and should be sufficient to support CCTV and other surveillance equipment where required. The cone of illumination from lighting units should be directed downward and outward from the structure or area being protected. The lighting should be arranged so as to create minimal shadows and minimal glare in the eyes of security guards. In this study a proposed design for security lighting and cameras surveillance system for optimum supervision at a perimeter area of a hypothetical nuclear facility will be presented. The illumination poles, lamps type, towers space distance, average and minimum Lighting Levels and Tilt Angle, required for camera surveillance system will be computed and determined. The work provides the requirements of cameras surveillance system at nuclear reactors isolation zone. Width of images sensitive area, lens focal length, lens format and angel of view will be determined by calculation method. The work determines cameras type, distributions, camera’s parameters and formulas according to the physical protection design process. Cameras angles of view, Lens Format, Lens focal length, F-Number and angle of view will be calculated. The optimum designing results for the security lighting (35 poles with 250 watt high pressure sodium and 34 m poles span with minimum lighting level equal 7 lux. The optimum CCTV design resulting in 15 cameras with length format 0.25 inch, length focal length 50 mm, F-stop number 1.8, angle of view 5.26 degree. In the future work; designers should consider the natural properties of reflectance, light absorption capacity, mobility and an object's inherent sensitivity to light to be sufficient to support CCTV system.

Noise Reduction on the Tilt Sensor for the Humanoid Robot Balancing System Using Complementary Filter

The aim of the research is to present the design of a system which is capable for noise reduction on the reading of the tilt sensor data used in a balancing system on humanoid robots. Humanoid robot is a robot that has body construction like a human. Humanoid robots can make a movement by walking with both legs. In order to walk properly, humanoid robot needs to have a proper balancing system. The humanoid robot balancing system consists of tilt sensors, either an accelerometer or a gyroscope sensor, main processing unit and actuator in the form of servo motors on each robot’s joint. The tilt sensor is used to detect tilt angle of the robot body. When sensor gives information about the robot is in a position of tilt angle that will cause the robot to fall, the main processor will send commands to the actuators to do the balancing action so the robot will go to a balancing position. Unfortunately, the tilt angle reading value obtained from tilt sensor, still contain noise. That noise makes the reading of the tilt angle of the robot body to be inaccurate. Therefore, a filtering method is required to reduce the noise. In this research, complementary filter is used to overcome this problem. From the test result, the complementary filter is able to reduce noise on the tilt sensor data value reading. The optimum filtering result was obtained with the use of filter coefficient of 0.96 and sampling time of 50ms, where the average tilt angle error value is 0.775° on the x-axis and 0.691° on the y-axis. In another test, the robot is able to perform a balancing action based on the output of the complementary filter. So the robot was always able to maintain its position on balanced condition.

Topography and area of weared flank surface of radial nose PcBN cutter when turning hardened steel

The dependencies of PcBN Kiborit cutters wear described allows to propose the method of real relief worn flank surface area of cutter calculation when the total main and additional cutting edges length, flank wear height and average tilt angle of micron relief wear groove walls measured are determined. Based on the studies carried out, it has been established that the presence of a furrow-like profile on the back surface of the tool increases the actual contact area with the treated material by 30 % in comparison with the area of the nominal wear contour.

Electric Field Effect on Condensed-Phase Molecular Systems. IV. Conformational Change of 1,2-Dichloroethane in a Frozen Molecular Solid

In this work, we studied the effect of an externally applied electric field on the conformation and orientation of 1,2-dichloroethane (DCE) in a frozen molecular solid. An electric field in the order of 108 V m–1 was applied across the sample by means of interfacial charging of Cs+ ions. Reflection absorption infrared spectroscopy (RAIRS) was used to monitor the gauche/trans conversion and reorientation of the DCE molecules due to an electrostatic interaction with the field. trans-DCE molecules were converted to gauche conformers via internal C–C rotation with the conversion efficiency of 24% at the field strength of 1.5 × 108 V m–1 and temperature 75 K. gauche-DCE molecules were reoriented along the field at an average tilt angle of 36° under the same conditions. These field-induced molecular changes were prohibited at 8 K and visible above 50 K. Therefore, both electrostatic and thermal energies are required to induce molecular transformations in the metastable solid by overcoming the activation barrier...

Localization and Orientation of Xanthophylls in a Lipid Bilayer

Xanthophylls (polar carotenoids) play diverse biological roles, among which are modulation of the physical properties of lipid membranes and protection of biomembranes against oxidative damage. Molecular mechanisms underlying these functions are intimately related to the localization and orientation of xanthophyll molecules in lipid membranes. In the present work, we address the problem of localization and orientation of two xanthophylls present in the photosynthetic apparatus of plants and in the retina of the human eye, zeaxanthin and lutein, in a single lipid bilayer membrane formed with dimyristoylphosphatidylcholine. By using fluorescence microscopic analysis and Raman imaging of giant unilamellar vesicles, as well as molecular dynamics simulations, we show that lutein and zeaxanthin adopt a very similar transmembrane orientation within a lipid membrane. In experimental and computational approach, the average tilt angle of xanthophylls relative to the membrane normal is independently found to be ~40 deg, and results from hydrophobic mismatch between the membrane thickness and the distance between the terminal hydroxyl groups of the xanthophylls. Consequences of such a localization and orientation for biological activity of xanthophylls are discussed.

Influence of stack effect on flame shapes of gas burner fires

To study the influence of stack effect on air flow and flame shapes of gas burner fires, a set of experiments was conducted in a 1/3th scale building model. One 0.15m square porous gas burner with propane as fuel was used with 6 different HRRs (heat release rates) of 13.54, 27.08, 40.63, 54.17, 67.71 and 81.25kW. The window at different floors was opened respectively for different HRRs. Results show that the upper average smoke temperatures in the fire room are higher than that in the atria for the smaller HRR. With the increase of HRR, the upper average smoke temperatures in the fire room are lower than that in the atria. The heat pressure induced by smoke in the stairwell increases with the HRR and the height of opened window. The relationships between the non-dimensional air flow velocity, HRR and height from fire source to the centerline of opened window are put forward based on the experimental results. The non-dimensional mean flame length is also proportional to the 2/5 power of non-dimensional HRR, but shows smaller than the Heskestad’s equation. For the propane porous gas burner, whose HRR is independent of the heat feedback to the burner surface, the average flame tilt angle increases with HRR, but the increment becomes relatively small for the larger HRR.

Insight into Water Structure at the Surfactant Surfaces and in Microemulsion Confinement.

Interactions with surfactant molecules can significantly alter the structure of interfacial water. We present a comparative study of water-surfactant interactions using two different spectroscopic approaches: water at planar surfactant monolayers by sum frequency generation (SFG) spectroscopy and interfacial water confined in reverse micelles formed by the same surfactants using IR absorption spectroscopy. We report spectral features in the OH-stretching region (3200-3700 cm-1) that are observed in both IR and SFG spectra, albeit with different relative amplitudes, for ionic surfactant sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) and nonionic surfactant polyoxyethylene(4)lauryl ether (Brij L-4) reverse micelles in hexane and the corresponding monolayers at the air/water interface. A prominent feature in the SFG spectra of the OH stretch at 3560 cm-1 is attributed to water molecules that have a weak donor hydrogen bond to the surfactant headgroup. The same feature is observed in the IR spectra of reverse micelles after deconvoluting the interfacial versus bulk spectral contributions. We performed an orientational analysis of these water molecules utilizing the polarization-dependent SFG spectra, which shows an average tilt angle of the OH stretch of surfactant-bound water molecules of ∼155° with respect to the surface normal.

Reconstruction of the Filament Properties, Based on Centenarian Daily Observations of the Sun in Hα Line

AbstractPreliminary results of distinguishing solar filaments on daily observation data at the Hα spectral line of the Kodaikanal Solar Observatory (1912-2002) are presented.To distinguish the boundaries of solar filaments, methods have been developed, based on automatic procedures for distinguishing low-contrast objects on the solar disk as well as on editing the boundaries of selected structures in semi-automatic mode. An analysis of solar filaments’ characteristics has been performed. We are considered variation of the average tilt-angle and the radius of curvature of the filaments in 15-23 cycles of activity.

Gramicidin A ion channel formation in model phospholipid bilayers tethered to gold (111) electrode surfaces

Electrochemical and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) techniques were employed to study the ion channel properties of gramicidin A (gA) in tethered bilayer lipid membranes (tBLMs) with varying concentrations of gA added to the outer leaflet of the bilayer. The electrochemical impedance spectroscopy (EIS) results demonstrate that gA forms conductive ion channels in tBLM systems even at concentrations as low as 0.5 mol%. The impedance of the membrane depended on the gA concentration where a minimum was observed at 10 mol%. When the amount of gA in the bilayer is increased to a concentration above 10%, the ion channels appear to arrange into a non-conducting state. PM-IRRAS spectra suggest that the gA molecules adopt a tilt angle of ∼29±4° in the conductive ion channel state. In the non-conducting state, the average tilt angle of the gA molecules is ∼52±3°, which implies that gA peptides assume a random orientation in the tBLM.

Mechanical effects of traction on lumbar intervertebral discs: A magnetic resonance imaging study

BackgroundAlthough traction has long been used for treating patients with low back pain (LBP), its effects are still inconclusive mainly because of limited high-quality evidence. ObjectiveTo provide evidence of the mechanism of traction on lumbar intervertebral discs. DesignA quantitative approach with a repeated measurement protocol. MethodNine participants (mean age = 22.1 ± 0.8 years) without any LBP history were recruited. Magnetic Resonance Images of the lumbar spine of each participant were recorded before and after 30 min of horizontal lying and directly after 30 min of horizontal traction of 42% body weight. The average, anterior, central, and posterior disc height and tilt angle of each lumbar disc and lumbar lordosis were measured. ResultsA significant increase in the average disc height for all lumbar discs, a significant reduction of lumbar lordosis and changes in tilt angle were observed after the application of 30 min of resting followed by 30 min of traction. A significant increase in the average disc height was observed only in lower lumbar discs after 30 min of traction. The increase in the posterior disc height was more apparent than that in the anterior disc height. ConclusionsHorizontal traction was evidently effective in increasing the disc height of lower lumbar levels, particularly in the posterior regions of the discs. Further evidence of the effects of traction of different modes, magnitudes, and durations on the change in disc height is required for proper control of traction applied to specific disc levels.

Molecular Alignment and Electronic Structure of N,N'-Dibutyl-3,4,9,10-perylene-tetracarboxylic-diimide Molecules on MoS2 Surfaces.

The molecular orientation of organic semiconductors on a solid surface could be an indispensable factor to determine the electrical performance of organic-based devices. Despite its fundamental prominence, a clear description of the emergent two-dimensional layered material-organic interface is not fully understood yet. In this study, we reveal the molecular alignment and electronic structure of thermally deposited N,N'-dibutyl-3,4,9,10-perylene-dicarboximide (PTCDI-C4) molecules on natural molybdenum disulfide (MoS2) using near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The average tilt angle determination reveals that the anisotropy in the π* symmetry transition of the carbon K-edge (284-288 eV range) is present at the sub-monolayer regime. Supported by ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), and resonant photoemission spectroscopy (RPES) measurements, we find that our spectroscopic measurements indicate a weak charge transfer established at the PTCDI-C4/MoS2 interface. Sterical hindrance due to the C4 alkyl chain caused tilting of the molecular plane at the initial thin film deposition. Our result shows a tunable interfacial alignment of organic molecules on transition metal dichalcogenide surfaces effectively enhancing the electronic properties of hybrid organic-inorganic heterostructure devices.

Absorption Spectroelectrochemistry on Mixed Perylenediimide‐Based Self‐Assembled Monolayers: Non‐Linear Dependence of Absorbance versus Surface Coverage

AbstractThe study of mixed self‐assembled monolayers of perylenediimide and hexanethiol by cyclic voltammetry and absorption spectroelectrochemistry shows a non‐linearity of absorbance maxima as a function of the surface coverage. This surprising result could be supported by an increase in the average tilt angle at low coverage, suggesting that the dilution of redox species through an alkanethiol would induce a change of the orientation of immobilized chromophores and, therefore, a modification of the optical properties of the monolayer.

Spectral assignment and orientational analysis in a vibrational sum frequency generation study of DPPC monolayers at the air/water interface.

The interfacial behavior of the benchmark zwitterionic phospholipid molecule dipalmitoylphosphatidylcholine (DPPC) has been extensively investigated by surface-selective vibrational sum frequency generation spectroscopy (VSFG). However, there is still a lack of agreement between various orientational measurements of phospholipid monolayers at the air/water interface, mainly because of the difficulty in assigning congested VSFG features. In this study, polarization-dependent VSFG measurements reveal a frequency shift between the in-plane and out-of-plane antisymmetric stretching modes of the terminal methyl groups in the DPPC alkyl tails, favoring the model of Cs local symmetry rather than the previously assumed C3v symmetry. Further VSFG experiments of isotopically labeled DPPC successfully capture the vibrational signatures of the glycerol backbone. With the newly derived VSFG polarization selection rules for Cs symmetry and the refreshed spectral assignments, the average tilt angles of the alkyl tail groups, choline headgroup, and glycerol backbone of DPPC molecules can all be determined, showing the powerful capability of VSFG spectroscopy in revealing the structural details at interfaces. The VSFG polarization dependence rules and the orientational analysis procedures developed for Cs symmetry in this work are applicable to other bulky molecules in which the methyl group cannot freely rotate, and they therefore have general applications in future VSFG studies.

Orientational Analysis of Interfacial Molecular Groups of a 2-Methoxyethyl Methacrylate Monomer Using Femtosecond Sum Frequency Generation Spectroscopy

This study employs femtosecond sum frequency generation (FS-SFG) spectroscopy to identify the functional groups at the air–liquid interface of the 2-methoxyethyl methacrylate (MEMA) monomer. Based on the collected spectra, the methoxy group (−OCH3), the methylene (−CH2) group from the ethyl side chain of MEMA, the α-methyl group (α-CH3), and the alkene-methylene (═CH2) groups are present at the interface. Tilt angle was determined by calculating the intensity ratio values from the fitting results, and then the ratios are compared to the simulated SFG curves. The results derived from the conventional polarization combination (SSP, PPP, and PSS) approach show average tilt angles of 60° for −OCH3 symmetric stretch vibration dipoles. Using the polarization mapping method, the tilt angle for the symmetric stretch of the −OCH3 group was 48° with an intensity ratio (SSP/PPP) of 17. The orientation distribution of the functional groups was also obtained from the amplitude ratios using the two methods. In conclusi...

A novel model to estimate the cleaning frequency for dirty solar photovoltaic (PV) modules in desert environment

Accumulated dust on solar photovoltaic (PV) modules can significantly decrease their energy output in desert environment. Therefore, cleaning the deposited dust on the PV module surface is crucial in engineering applications to maintain the high power output of solar power plants, especially in desert areas. Nevertheless, it is difficult to predict the reasonable cleaning frequency for PV modules by traditional methods. In this paper, a novel model to simply estimate the cleaning frequency was developed for dirty PV modules in desert areas based on the dust deposition velocity and the relationship between deposited dust density and PV module power performance. The studied parameters are the installation tilt angles, the dust concentration in the ambient air and the representative average particle diameter. Based on this model, module cleaning frequency for desert regions is approximately 20days when the power output reduction and particle concentration equal to 5% and 100μg/m3, respectively. In addition, the effects of accumulation density, average particle diameter, tilt angles and wind velocity on the cleaning frequency are discussed and analyzed respectively.

Sunspot positions, areas, and group tilt angles for 1611−1631 from observations by Christoph Scheiner

Digital images of the observations printed in the books "Rosa Ursina sive solis" and "Prodromus pro sole mobili" by Christoph Scheiner as well as the drawings from Scheiner's letters to Marcus Welser are analysed in order to obtain information on positions and sizes of sunspots that appeared before the Maunder minimum. In most cases, the given orientation of the ecliptic is used to set up the heliographic coordinate system for the drawings. Positions and sizes are measured manually on the screen. Very early drawings have no indication of their orientation. A rotational matching using common spots of adjacent days is used in some cases, while in other cases, the assumption of images being aligned with a zenith-horizon coordinate system appeared to be the most probable. In total, 8167 sunspots were measured. A distribution of sunspot latitudes versus time (butterfly diagram) is obtained for Scheiner's observations. The observations of 1611 are very inaccurate, the drawings of 1612 have at least an indication of their orientation, while the remaining part of the spot positions from 1618-1631 have good to very good accuracy. We also computed 697 tilt angles of apparently bipolar sunspot groups observed in the period 1618-1631. We find that the average tilt angle of nearly 4 degrees is not significantly different from 20th-century values.

Optical study of orientational dynamics of nematic discotic liquid crystals under magnetic field

The present study determined ordinary and extraordinary refractive indices of lyotropic nematic discotic mesophase under magnetic field and the effective refractive index of the mesophase were measured based on time, according to which an attempt was made to calculate average tilt angles of the mesophase directors oriented by the field. Therefore, dynamics of orientation of the mesophase under magnetic field were defined graphically. Moreover, changes in textures of the mesophase in the field were studied using polarizing microscopy.

Clinical and Radiologic Outcomes of Partial Lateral Patellar Facetectomy in Total Knee Arthroplasty.

Recently, some authors have performed partial lateral patellar facetectomy in total knee arthroplasty (TKA) and reported good results. However, research on partial lateral patellar facetectomy in TKA is still lacking. The aim of this study was to evaluate the clinical and radiologic results of partial lateral patellar facetectomies in patellar non-resurfacing and resurfacing TKAs. Total 251 TKAs (patellar non-resurfacing: 131; resurfacing: 120) that were followed up for at least 24 months to evaluate the clinical and radiologic results of partial lateral patellar facetectomies in patellar non-resurfacing and resurfacing TKAs were retrospectively reviewed. The radiologic evaluations involved assessments of the patellar tilt angle and the lateral patellar displacement, and the clinical evaluations involved assessments of the Knee Society knee score, Knee Society function score, Feller patellar score, and Kujala score. In patellar non-resurfacing TKA, the average postoperative patellar tilt angle and lateral patellar displacement of the group that did not undergo facetectomy were 7.0 ± 4.8 degrees and 2.4 ± 3.6 mm, respectively, and the average postoperative patellar tilt angle and lateral patellar displacement of the group that did undergo facetectomy were 4.0 ± 3.8 degrees and 0.7 ± 2.5 mm, respectively. Significant differences were observed in the postoperative patellar tilt angle and lateral patellar displacement (p < 0.001 and p = 0.004, respectively). In patellar resurfacing TKA, while the patellar tilt angle showed a significant difference between the group that underwent facetectomy (6.7 ± 3.1 degrees) and the group that did not (8.3 ± 4.4 degrees) (p = 0.023), it exhibited no difference in the lateral patellar displacement between the two groups. In both patellar non-resurfacing TKA and resurfacing TKA, the postoperative clinical results did not show any difference between no-facetectomy group and facetectomy group. Partial lateral patellar facetectomies in patellar non-resurfacing and resurfacing TKAs improved the patellar tilt angles and patellar lateral displacements but were not related to improvements in the clinical outcomes in the minimum 2-year follow-up.

Features of the diagnostics of metamorphic InAlAs/InGaAs/InAlAs nanoheterostructures by high-resolution X-ray diffraction in the ω-scanning mode

This study is devoted to the search for new possibilities of characterizing crystal-structure features using high-resolution X-ray diffraction. The emphasis is on the scanning mode across the diffraction vector (ω-scanning), since researchers usually pay little attention to this mode, and its capabilities have not yet been completely revealed. For the [011] and [01\(\bar 1\)] directions, the ω-peak half-width and the average tilt angle of the sample surface profile are compared. The diagnostic capabilities of X-ray scattering mapping are also studied. The objects of study are semiconductor nanoheterostructures with an InAlAs/InGaAs/InAlAs quantum well and an InxAl1–xAs metamorphic buffer grown by molecular-beam epitaxy on InP and GaAs substrates. Such nanoheterostructures are used to fabricate microwave transistors and monolithic integrated circuits. The objects under study are more completely characterized using the Hall effect, atomic-force microscopy, and low-temperature photoluminescence spectroscopy at 79 K.