Height Profile Measurements Research Articles

Distribution of Electron Density in Self-Assembled One-Dimensional Chains of Si Atoms.

Scanning tunneling microscopy measurements of height profiles, along the chains of Si atoms on the terrace edges of a perfectly ordered Si(553)-Au surface, reveal an STM bias-dependent mixed periodicity with periods of one, two and one and a half lattice constants. The simple linear chain model usually observed with STM cannot explain the unexpected fractional periodicity in the height profile. It was found that the edge Si chain stands for, in fact, a zigzag structure, which is composed of two neighboring rows of Si atoms and was detected in the STM experiments. Tight-binding calculations of the local density of states and charge occupancy along the chain explain the voltage-dependent modulations of the STM profiles and show that oscillation periods are determined mainly by the surface and STM tip Fermi energies.

Influence of dental prophylaxis procedures on the tooth veneer interface in resin-based composite and polymer-infiltrated ceramic veneer restorations: an in vitro study

ObjectivesThe aim of this study was to investigate the influence of dental prophylaxis cleaning procedures and artificial aging on veneers in human teeth. The external marginal and internal tooth veneer as well as the restoration surfaces were examined.Material and methodsThirty-two extracted premolars were restored with resin-based composite (RBC) and polymer-infiltrated ceramic network (PICN) veneers. Artificial aging by alternating thermocycling and subsequent prophylaxis procedure (glycine-based powder air polishing or ultrasonic scaling) was conducted for five consecutive cycles. The external marginal interface was examined by height profile measurements and the internal interface was investigated using micro X-ray computed tomography. In addition, the surface texture of the veneer surface was analyzed using confocal laser scanning microscopy.ResultsThe application of both prophylaxis procedures resulted in a deepening of the marginal interface (10 µm ± 8 µm) for materials. Furthermore, the internal interface of PICN restorations showed marginal gaps after both treatments and artificial aging (16 µm ± 3 µm). In contrast to the RBC specimens, a significant increase in surface roughness was identified for PICN veneers after ultrasonic scaling.ConclusionsThe marginal and internal interface regions in veneers fabricated from PICN and RBC were affected by prophylaxis procedures. Furthermore, it may result in increased veneer surface roughness, especially in PICN and after ultrasonic scaling, which might affect bioadhesion and longevity.Clinical relevanceAfter dental prophylaxis procedures, examination of the marginal and the internal interface as well as the veneer surface provides a precise insight into damage mechanisms and offers an assessment of longevity.

Wake Shape and Height Profile Measurements in a Concave Open Channel Flow regarding the Target in DONES

Wakes appearing downstream of disturbances on the surface of a water flow in a concave open channel were examined experimentally. The investigated channel geometry was similar to the liquid lithium target in DONES (Demonstration fusion power plant Oriented NEutron Source). The objective of the measurements was to analyze the effect of a disturbance on the downstream layer thickness. For measuring the height profiles in the channel, an optical measurement system based on laser triangulation was developed. It was shown that the wake of the undisturbed flow emerged from the nozzle corner, which was in accordance with analytical solutions. For sufficiently large disturbances at the nozzle edge, the height profiles located downstream showed symmetrical minima and maxima on both sides of the disturbance. The wake depth strongly depended on the diameter and penetration depth of the disturbance, as well as the circumferential position in the channel, which yields to a critical wake depth of one millimeter for the lithium target in DONES.

Laser line scanning of a shape of moving objects with various degree of transparency

Laser scanning methods for surface geometry reconstruction have become a common tool in many areas of application due to relative simplicity, high accuracy, and versatility. Nevertheless, scanning of glossy or translucent surfaces still poses a problem for these techniques. The present work aims at assessing the applicability of the laser line scanning method for evaluation of the height profile of a waste stream on a conveyor belt, taking into account that the waste stream may contain a large number of semi-transparent objects. In particular, preliminary results of height profile measurements with regard to the laser emission wavelength for polyethylene terephthalate (PET) bottles with various degrees of transparency, common in the municipal solid wastes, are reported in the paper.

Retrieval of temperature profiles using radio acoustic sounding system (RASS) with the equatorial atmosphere radar (EAR) in West Sumatra, Indonesia

The radio acoustic sounding system (RASS) with the equatorial atmosphere radar (EAR) at Koto Tabang, Indonesia was adapted to test the effects of the acoustic source location and acoustic frequency range on the continuous measurement of height profiles of temperature in the tropical troposphere. We installed the acoustic transmitting system by using six high-power horn speakers and four subwoofers. We developed a three-dimensional ray-tracing method of acoustic waves to predict the shape of acoustic wavefronts, accounting for the effects of the background winds on acoustic wave propagation. Then, we selected the appropriate antenna beam directions for EAR that satisfy the Bragg condition between the radar and acoustic wave propagation vectors. We carried out eight campaign observations in 2016, testing the performance of EAR–RASS. We found that the location and acoustic frequency range affected the RASS echoes. We also tested the compensation method of the background wind velocity with EAR to obtain the true sound speed. We intensively analyzed the RASS results from August 29 to September 3, 2016, when radiosondes were launched 12 times from the EAR site. We successfully retrieved the temperature profiles from RASS from 2 to 6–14 km with time and height resolutions of about 10 min and 150 m, respectively. Some temperature profiles were obtained up to about the tropopause at 17 km, although the observation period was short. During the RASS campaign, we detected a few interesting events regarding temperature variations as well as large perturbations in the three components of wind velocity.

Quantifying the grain boundary resistance against slip transfer by experimental combination of geometric and stress approach using stage-I-fatigue cracks

In recent studies, many groups have investigated the interaction of dislocations and grain boundaries by bi-crystals and micro-specimen experiments. Partially, these experiments were combined with supplementary simulations by discrete dislocation dynamics, but quantitative data for the grain boundary resistance against slip transfer is still missing. In this feasibility study with first results, we use stage-I-fatigue cracks as highly localised sources for dislocations with well-known Burgers vectors to study the interaction between dislocations in the plastic zone in front of the crack tip and selected grain boundaries. The stress concentration at the grain boundary is calculated with the dislocation-free zone model of fracture using the dislocation density distribution in the plastic zone from slip trace height profile measurements by atomic force microscopy. The grain boundary resistance values calculated from common geometric models are compared to the local stress distribution at the grain boundaries. Hence, it is possible to quantify the grain boundary resistance and to combine geometric and stress approach for grain boundary resistance against slip transfer to a self-contained concept. As a result, the prediction of the grain boundary resistance effect based on a critical stress concept is possible with knowledge of the geometric parameters of the grain boundary only, namely the orientations of both participating grains and the orientation of the grain boundary plane.

Joint radiosonde and doppler lidar measurements of wind in the atmospheric boundary layer

Results of joint measurements of height profiles of wind velocity and direction by the Stream Line pulse coherent Doppler lidar and RS92-SGP radiosonde in Tomsk from 23 to 27 of September, 2013, are presented. It has been established that wind profiles can be retrieved up to heights from 400 to 1100 m depending on the aerosol concentration in the atmospheric boundary layer from lidar data measured at an elevation angle of 45°. It is shown that the coefficient of correlation between lidar and radiosonde measurements of wind velocity and direction is equal to 0.97. The mathematical expectation and standard deviation of the difference between estimates for the wind velocity and direction from the radiosonde and lidar data amount to 0.1 and 0.7 m/s, respectively, for the velocity and 0.8° and 4°, respectively, for the wind direction.

Atomic Force Microscopy of Connexin40 Gap Junction Hemichannels Reveals Calcium-dependent Three-dimensional Molecular Topography and Open-Closed Conformations of Both the Extracellular and Cytoplasmic Faces

Atomic force microscopy was used to study the three-dimensional molecular topography and calcium-sensitive conformational changes of Connexin40 hemichannels (connexons) reconstituted in 1,2-dioeloyl-sn-glycero-3-phosphatidylcholine lipid bilayers. Two classes of objects were observed that differed in their protrusion heights above the bilayer (2.6 versus 4.2 nm). Comparison to reconstituted connexons containing Connexin40 truncated to eliminate most of its C-terminal cytoplasmic domain showed that the two height classes corresponded to the shorter extracellular and taller cytoplasmic aspects of the hemichannels and that the C-terminal tail of Connexin40 contributes ∼1.6 nm in thickness. Hemichannels imaged in solutions containing < 10 μm Ca(2+) showed 3.1-3.2 nm depressions (openings) in 30% of the cytoplasmic faces and 65% of the extracellular faces, and high-resolution three-dimensional topography of extracellular or cytoplasmic aspects of some connexons was observed. After addition of 3.6 mm Ca(2+), > 75% of the connexons in either orientation adopted closed conformations. In contrast, hemichannels imaged in the presence of 0.1 mm EDTA showed large (5.6- to 5.8-nm diameter) openings in nearly all hemichannels regardless of orientation, and detailed topography was visible in many connexons. Real-time imaging following the addition of 3.6 mm Ca(2+) showed transitions of both extracellular and cytoplasmic orientations from "open" into "closed" conformations within several minutes. These studies provide the first high-resolution topographic information regarding a connexin with a large cytoplasmic domain and suggest that the extramembranous portions of Connexin40 contribute to a channel entrance that is relaxed by chelation of residual divalent cations.

Random blisters on stickers: metrology through defects

Blisters are commonly observed when an adhesive sheet is carelessly deposited on a plate. Although such blisters are usually not desired for practical applications, we show through model experiments on angular blisters how material properties can be deduced from height profile measurements. In particular the typical curvature of the crests is found to be proportional to an elasto-capillary length that compares the bending stiffness of the sheet with the adhesion energy. In addition, the radius of the tip allows the estimation of the product of this length with the thickness of the sheet. The relevance of these results to realistic random configurations is finally confirmed.

A high speed and compact system for profile measurement of scroll compressors

Profile measurement of a scroll compressor is important for improving compression efficiency. This paper describes the height profile measurement of a scroll compressor in the manufacturing line using a prototype measurement system. A commercial CMM is also employed for comparison. The measurement repeatability of the height profile by the prototype measurement system is approximately ±1 µm, which satisfies the requirements from the manufacturing line. Through compensation of the tilt component, result of the prototype measurement system is in good agreement with that of the commercial CMM.

Self-assembly of rubrene on Cu(111)

We performed an ultra-high vacuum scanning tunneling microscopy (STM) investigation ofthe self-assembly of rubrene at room temperature on Cu(111), a metal surface withthreefold symmetry. Rubrene self-assembles into two different structures called row andtrimer. Both are different than the structures already observed on Cu(110) and Cu(100).Row and trimer structures have comparable molecular packing densities and are equallydistributed across the surface. In the row structure the molecules are oriented withtheir backbone along the same high symmetry directions of the surface: [], [] or []. The trimer structure is composed of units of three rubrene molecules, oriented along thehigh symmetry surface directions. These units are chiral, as revealed by height profilemeasurements by STM, and self-assemble in domains containing only one type ofenantiomer.

Effect of Flour Type and Baking Temperature on Cake Dynamic Height Profile Measurements During Baking

A dynamic height profile method using digital imaging of cakes at 2 min intervals during baking was used to analyze changes in volume during baking for cakes made with three different flour types (plain flour, heat-treated cake flour, and strong white flour) and baked at three different temperatures (175°C, 190°C, and 205°C). The cakes made from the different flours showed, with some exceptions, a similar trend in the shape and development of the top contour during baking. In the first 4–6 min of baking, there was relatively little expansion followed by a period of rapid expansion to the maximum volume and a period of contraction up to the end of baking. For the three flour types, volume peaked at 16–17 min for the medium and high baking temperatures and at 20 min for the low baking temperature. Cakes made from heat-treated cake flour and strong white flour baked at low and high temperatures produced cakes where the center of the cake was lower than the surrounding pins resulting in a final undesirable dimpled cake contour. A higher baking temperature caused the cake to rise more rapidly. Baking at high temperature produced cakes which shrank the most (P < 0.001) during cooling. Among all combinations of flour type and different temperature treatments, cake made from heat-treated cake flour baked at the middle temperature produced the best final cake in terms of a final dome-shape contour, an appreciable volume during baking, less volume shrinkage during baking, and maximum cross-sectional area of the half cake after 1 h cooling.

Triangulation methods for height profile measurements on instationary water surfaces

The precise measurement of water surface models or profiles plays an important role in experimental hydromechanics. Conventional gauge-based techniques often come with a large instrumental effort and a limited spatial resolution. The paper shows an e‰cient non-contact photogrammetric technique for the measurement of water-surface profiles, which is based on an extension of the well-known laser light sheet projection technique. While the original laser lightsheet triangulation technique is limited to surfaces with di¤use reflection properties, the developed technique is capable of measuring on reflecting instationary surfaces. This article presents the basic principle, potential and limitations of the method. Several evolution steps of the system with di¤erent applicability and di¤erent complexity are shown. A double projection plane system capable of simultaneously measuring water surface height and tilt profiles marks the ceiling of the development. Besides the geometrical models of different levels of complexity, system calibration procedures are described. The applicability of the techniques and their accuracy potential are shown in several practical tests.

Vehicle Classification Based on the Radar Measurement of Height Profiles

The problem of classifying road vehicles according to vehicle type is considered. The proposed solution is based on using vehicle height and length and height profiles obtained by a microwave (MW) radar sensor. We show that if the radar sensor satisfies certain requirements, then a precise feature vector can be extracted, and simple deterministic algorithms can be applied to determine the vehicle class. Field trials using a spread-spectrum MW radar sensor system operating on these principles have been carried out. They confirm that accurate classification of a large number of vehicle classes can be reached

Atomic force and scanning electron microscopy of atmospheric particles

Atomic force microscopy (AFM) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) have been used for both morphological and elemental mass analysis study of atmospheric particles. As part of the geometrical particle analysis, and in addition to the traditional height profile measurement of individual particles, AFM was used to measure the volume relative to the projection area for each particle separately, providing a particle shape model. The element identification was done by the EDS analysis, and the element mass content was calculated based on laboratory calibration with particles of known composition. The SEM-EDS mass measurements from two samples collected at 150 and 500 m above the surface of the Mediterranean Sea were found to be similar to mass calculations derived from the AFM volume measurements. The AFM results show that the volume of most of the aerosols that were identified as soluble marine sulfate and nitrate aerosol particles can be better estimated using cylindrical shapes than spherical or conical geometry.

Lumber surface profiling independent of bulk motion

A novel method is described to measure surface height profiles of lumber boards while they travel along a conveyor in a sawmill. Both surfaces of the board are identified independently, even on non-ideal conveyors where there are lateral motions relative to the sensors. Separate surface measurements are very useful for product quality control because each side of a piece of lumber is typically cut by a different tool. Therefore, such measurements open important new opportunities for machine fault diagnosis. The surface height profile measurement method uses multiple sequential sensors and a mathematical method based on linear inverse theory to separate surface profile information from lateral motions. The method was implemented using industrial-style laser sensors, and was effective both in the laboratory and in tests on the cant line of a large sawmill cutting dimension lumber.

Error analysis of Makyoh-topography surface height profile measurements

The errors of surface profile measurements using grid-illumination Makyoh topography is analysed using computer simulations. It is shown that two regions of imaging exists: at smooth surfaces and small screen-to-sample distances, the error is determined by the pixel reading error, while at less smooth surfaces and larger screen-to-sample distances, the errors of summation approximation dominates. The pixel reading error component can be decreased by increasing the screen-to-sample distance. It is demonstrated that the described evaluation algorithm gives maximum relative errors of roughly 1.5%.

Stratospheric CFCl3, CF2Cl2, and N2O height profile measurements at several latitudes

The mixing ratios of CFCl3, CF2Cl2, and N2O have been measured as a function of altitude from 6 to 37 km above sea level by using a balloon‐borne grab‐sampling system. The 24 flights were made during the period July 1976 to March 1979 from Wyoming, Panama, Brazil, and Antarctica. These data are reported here both numerically and graphically, the latter being examined for latitudinal and temporal trends. A mean tropopause height for each location and date was used as the reference for the height profiles. The resulting set of CF2Cl2 and N2O profiles show a discernible dependence on latitude; the lapse rate of these mixing ratios is greater for the mid‐latitudes when compared to the equatorial latitudes. The upper tropospheric portion of the CFCl3 and CF2Cl2 data show annual increases of 10.4±3.9 and 10.7±1.9%/yr, respectively, in the northern hemisphere for the middle of the measurement period (end of 1977). Furthermore, the limited number of southern hemispheric data for these constituents are about 8% lower than the northern hemispheric values but have a comparable annual increase. The corresponding N2O data show no interhemispheric differences and the possibility of only a slight increase (less than 2%/yr).

Contributions of acoustic echo sounding to atmospheric research and services

This paper reviews briefly the first few years of acoustic remote sensing that followed the introduction of the echosonde in 1966, and then surveys in more detail many aspects of recent developments in acoustic echo sounding. The early, qualitative, facsimile recordings have now been supplemented by attempts to make the echosonde data quantitative. This has involved careful comparison of data from calibrated sounders and instrumented meteorlogical towers. Evidence is presented supporting the claim that echosondes can supplement the facsimile records with height profiles of mean wind speed and direction, as well as profiles of the structure constant of velocity Cv and temperature CT. The former permits derivation of the height profiles of the turbulent energy dissipation rate ε and the latter the measurement of height profiles of the structure constant of optical refractive index Cn. Various realizations of Doppler echosondes are presented, together with an echosonde interferometer which may offer promise of measuring atmospheric temperature profiles. Some future directions for acoustic echo-sounding developments are summarized.

An investigation of the tropospheric fine scale properties using radio, radar and direct methods

The investigation comprises five different experimental methods applied simultaneously. 1. (a) Beam-swinging experiments using a 6000 Mc/s transmitter and two receivers distant 100 and 200 miles respectively from the transmitter. Field strength and Doppler spectrum is measured. 2. (b) Field strength and Doppler measurements on 1300 Mc/s. 3. (c) Back scatter measurements using a vertically-directed 10 cm radar located at the mid point of the forward scatter circuit. 4. (d) Airborne refractometer and temperature probings of the scatter volume. 5. (e) Measurement of height profile of temperature and humidity at the mid point of the radio path using a conventional radio-sonde. A special rapid-response radio-sonde measures temperature. Information about the atmospheric structure is obtained on the basis of the various techniques and the results are compared.