Good Surface Conditions Research Articles

Magnetic Prospection in the Eastern Lower City of Artashat-Artaxata in the Ararat Plain of Armenia

In March of 2021, the Berlin-based company cmp continued geophysical prospection works at the ancient city of Artashat-Artaxata (Ararat Province, Armenia). The city was founded by Artashes-Artaxias I in the early 2nd century BC and served as his capital. First magnetic measurements were conducted by the Eastern Atlas company in September 2018. In 2021, during the 5-day survey a total surface of approximately 19.5 ha was investigated by use of the LEA MAX magnetic gradiometer array. This system was configured with seven fluxgate gradiometer probes, similar to the system used in the first survey of 2018. The investigated areas of the Eastern Lower City of Artaxata, located to the south of the investigated field of 2018, had good surface conditions with a moderate amount of sources causing disturbance. However, the general level of the magnetic gradient values measured was significantly lower compared to the 2018 data. Despite the lower magnetic field intensity, a continuation of linear structures towards the south was observed. These lines, most likely reflecting streets and pathways, criss-cross the central part of the Eastern Lower City in a NW–SE and NE–SW direction and exhibit partly positive, partly negative magnetic anomalies. Attached to them, some isolated spots with building remains were identified. The negative linear anomalies point to remains of limestone foundations, as detected in the northern part of the Lower City. The low magnetic intensity and fragmentation of the observed structures are most likely due to severe destruction of the ancient layers by 20th-century earthworks for agricultural purposes. Moreover, the southern part of the surveyed area was affected by major changes caused by modern quarries at Hills XI and XII. In general, the results of the two magnetic prospection campaigns greatly aid our understanding of the archaeological situation in the area of the Eastern Lower City of Artaxata, justifying further investigations that will surely contribute to greater contextualization of the identified archaeological structures. The full data sets are also published in open access on Zenodo.

Sample-dependent excitation behavior of the structured green luminescence band in ZnO

The photoluminescence spectra excited by different wavelength light from ZnO samples with and without SiOx passivation demonstrated that the excitation behavior of structured green luminescence (GL-S) band is determined by the surface conditions or the morphological forms. The lowest energy of photons able to excite the GL-S band varied from 3.380 eV down to a value far below the zero phonon line of GL-S band, depending on the defect density in the region near to the sample surface. The imperfections like cracks, scratches, and voids etc. were found decisive for the effectiveness of SiOx passivation on the GL-S band, which is removable only for the samples with good surface conditions. In addition, the phonon energy in GL-S band was determined to be ~3 meV lower than that of longitudinal optical phonons and thus was associated with the surface optical mode. The evidence of a link between the GL-S band and the optical emissions on sample surface revealed that there is no necessity to connect the GL-S band with any specific defects in the inside of samples. This optical emission mechanism is not only helpful to settle the relevant issues of visible luminescence in the research of ZnO, but also important to the study of other phenomena related to photoexcitation.

Study of the Surface Integrity and High Cycle Fatigue Performance of AISI 4340 Steel after Composite Surface Modification

In the field of materials science, the fabrication of a material with severe surface plastic deformation and a good surface state is an issue encountered in the development of counterbalanced gradient materials. For this paper, AISI 4340 steel was first processed with abrasive water jet peening (AWJP) and then with ultrasonic surface rolling (USRE) to obtain a good surface state while maintaining large plastic deformation. The AISI 4340 steel composite surface was therefore modified, and the surface integrity and cycle fatigue performance were analyzed. The results show that the plastic deformation layer of the modified composite surface of the 4340 steel was 310 µm from the surface of the sample, the grain size 40 µm from the surface layer was refined to 70 nm, and the maximum surface roughness Ra is 0.06. The fatigue limit of the modified composite surfaces obtained by the tensile fatigue test was 595.7 MPa, which was 85.7 MPa higher than the 510 MPa fatigue limit of the unmodified matrix, indicating that the method of composite surface modification can produce a deep deformation layer while maintaining good surface conditions. The results show that work hardening caused by a composite surface treatment is the most important factor for improving the fatigue performance of materials.

Predicting crash-relevant violations at stop sign–controlled intersections for the development of an intersection driver assistance system

ABSTRACTObjective: Intersection crashes resulted in over 5,000 fatalities in the United States in 2014. Intersection Advanced Driver Assistance Systems (I-ADAS) are active safety systems that seek to help drivers safely traverse intersections. I-ADAS uses onboard sensors to detect oncoming vehicles and, in the event of an imminent crash, can either alert the driver or take autonomous evasive action. The objective of this study was to develop and evaluate a predictive model for detecting whether a stop sign violation was imminent.Methods: Passenger vehicle intersection approaches were extracted from a data set of typical driver behavior (100-Car Naturalistic Driving Study) and violations (event data recorders downloaded from real-world crashes) and were assigned weighting factors based on real-world frequency. A k-fold cross-validation procedure was then used to develop and evaluate 3 hypothetical stop sign warning algorithms (i.e., early, intermediate, and delayed) for detecting an impending violation during the intersection approach. Violation detection models were developed using logistic regression models that evaluate likelihood of a violation at various locations along the intersection approach. Two potential indicators of driver intent to stop—that is, required deceleration parameter (RDP) and brake application—were used to develop the predictive models. The earliest violation detection opportunity was then evaluated for each detection algorithm in order to (1) evaluate the violation detection accuracy and (2) compare braking demand versus maximum braking capabilities.Results: A total of 38 violating and 658 nonviolating approaches were used in the analysis. All 3 algorithms were able to detect a violation at some point during the intersection approach. The early detection algorithm, as designed, was able to detect violations earlier than all other algorithms during the intersection approach but gave false alarms for 22.3% of approaches. In contrast, the delayed detection algorithm sacrificed some time for detecting violations but was able to substantially reduce false alarms to only 3.3% of all nonviolating approaches. Given good surface conditions (maximum braking capabilities = 0.8 g) and maximum effort, most drivers (55.3–71.1%) would be able to stop the vehicle regardless of the detection algorithm. However, given poor surface conditions (maximum braking capabilities = 0.4 g), few drivers (10.5–26.3%) would be able to stop the vehicle. Automatic emergency braking (AEB) would allow for early braking prior to driver reaction. If equipped with an AEB system, the results suggest that, even for the poor surface conditions scenario, over one half (55.3–65.8%) of the vehicles could have been stopped.Conclusions: This study demonstrates the potential of I-ADAS to incorporate a stop sign violation detection algorithm. Repeating the analysis on a larger, more extensive data set will allow for the development of a more comprehensive algorithm to further validate the findings.

Development of a lightweight BMC material using fly ash

Many mechanical and electrical devices are produced by the bulk molding compound (BMC) process, as it has many advantages, such as its fast producing speed and good surface conditions. To increase the strength, many kinds of agents, such as glass or carbon fiber, are added. In this paper, a new composition of BMC is developed using fly ash as a filler agent so that products using the developed BMC are very light and inexpensive. In addition, since fly ash is obtained by collecting exhaust gas, it is quite eco-friendly. For the developed material, the mechanical properties are obtained by a simple tensile test, and the appropriate FEM analysis option parameters are selected by comparing them with the experimental results. Therefore, the parameters can be used in designing products using the developed BMC material.

Improving Pervious Concrete Pavements for Achieving More Sustainable Urban Roads

Pervious concrete is a novel pavement material characterized by a porous structure that allows the water to percolate through it with consequent numerous environmental benefits. However, high-drainability characteristics do not generally correspond to high strength and good surface conditions when submitted to vehicular traffic, hence, to date, the applications of pervious concrete are limited to particular urban areas. In addition, mix design and rigorous construction standards have not yet been defined. The present laboratory study aimed to compare the properties of several pervious concrete mixtures submitted to different compaction energies. The main objectives were, on one hand, to define the effects of compaction energy on the design requirements of strength and drainability, on the other, to compare the reinforcing effect of different admixtures on the material properties. Different percentages of sand and several reinforcing fibres with various physical and chemical properties were added to the mixes, changing water to cement ratio while fixing the aggregate size distribution and the paste content. Laboratory tests, such as indirect tensile strength, elastic modulus, and Cantabro resistance, were conducted to measure the mechanical behaviour of the material; while, porosity, bulk density and drainability capacity were evaluated to define volumetric and functional characteristics. The result of this investigation provided useful information about the effectiveness of laboratory compaction to achieve the optimal strength-drainability balance, adequate for the different urban uses. Moreover, this study identified the suitable admixtures, with the appropriate proportioning, that could enhance the mechanical properties of the material leading to a wiser use in medium-high traffic roads.

Enhancement of the photo conversion efficiencies in Cu(In,Ga)(Se,S)2 solar cells fabricated by two-step sulfurization process

Cu(In,Ga)(Se,S)2 (CIGSS) absorber layers were fabricated by using a modified two-stage sputter and a sequential selenization/sulfurization method, and the sulfurization process is changed from one-step to two-step. The two-step sulfurization was controlled with two different H2S gas concentrations during the sulfurization treatment. This two-step process yielded remarkable improvements in the efficiency (+0.7%), open circuit voltage (+14 mV), short circuit current (+0.23 mA/cm2), and fill factor (+0.21%) of a CIGSS device with 30 × 30 cm2 in size, owing to the good passivation at the grain boundary surface, uniform material composition among the grain boundaries, and modified depth profile of Ga and S. The deterioration of the P/N junction quality was prevented by the optimized S content in the CIGSS absorber layer. The effects of the passivation quality at the grain boundary surface, the material uniformity, the compositional depth profiles, the microstructure, and the electrical characteristics were examined by Kelvin probe force microscopy, X-ray diffraction, secondary ion mass spectrometry, scanning electron microscopy, and current-voltage curves, respectively. The two-step sulfurization process is experimentally found to be useful for obtaining good surface conditions and, enhancing the efficiency, for the mass production of large CIGSS modules.

Modelling of time-dependent behavior of the basal sliding surface of the Åknes rockslide area in western Norway

abstract Numerical modelling based on the finite difference code FLAC3D and the Burger–Creep Viscoplastic material model has been used for analysing time-dependent behavior of the unstable rock slope at Aknes in western Norway. The rockslide has an estimated volume of 43 million m3, with a basal sliding surface located 105–115 m below the surface. Displacement measurements by GPS and reflector points, which since 2004 have revealed average annual displacements in the order of 26 mm/year in the central part of the sliding area, have been used to calibrate the model. The modelling shows that a set of parameters believed to represent the conditions of the slope at present time (3% intact rock in the sliding plane and surface conditions representing “good surface conditions” in the GSI system) results in displacements which stabilise within a 100 year period. However, as the shear strength parameters are reduced according to 1% intact rock in the sliding layer and surface conditions representing “fair surface conditions” in the GSI system, increased displacement and indications of failure at the toe of the slope are evident within the same time span.

Synthesis of thin and compact mesoporous MCM-48 membrane on vacuum-coated α-Al 2O 3 tube

A thin and compact mesoporous MCM-48 membrane had been successfully synthesized on vacuum-coated α-Al 2O 3 support with pore size of 1 μm. The pretreated supports and the membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and single gas permeation test. The pretreated supports were gas permeable for N 2 and the as-synthesis membrane was gas tight, indicating that the defects left in the vacuum step disappeared in the multi-hydrothermal synthesis process. The XRD pattern of the membrane was represented to the typical cubic I a 3 ¯ d space group. And the SEM images showed that the membrane was continuous and 4-μm thick. Additionally, the separation factor of the calcined membrane for H 2/N 2 was up to 3.33 and the Knudsen contribution to the total flux for N 2 permeation was 97.8%. All the results indicated that the good surface conditions of the large-pore supports improved by the vacuum coating method were favorable for the formation of a compact MCM-48 membrane on it.

Engineering Design, Installation, and Conditioning of Ferritic Steel Plates/Wall for AMTEX in JFT-2M

The JFT-2M tokamak has been modified three times during the Advanced Material Tokamak EXperiment (AMTEX) program to investigate the compatibility of the low-activation ferritic steel F82H with tokamak plasmas as structural material for future reactors. The ferritic steel plates/wall were installed inside and/or outside of the vacuum vessel to reduce the ripple of the toroidal magnetic field step by step through three modifications. This paper focuses on engineering aspects of these modifications: electromagnetic analysis to find a suitable way to attach these plates, installation procedure to keep small tolerances, and a three-dimensional magnetic field measurement device used to obtain information of the actual shape of the vacuum vessel used as a standard installation surface. To maintain good surface conditions of the ferritic steel plates/wall that rust easily, careful treatment was executed before the installation. To reduce oxygen impurities further, a boronization system with trimethyl boron, which is safe and easy to operate, was developed.

RESIDUAL STRESS CHARACTERISATION OF GRIT BlASTED STEEL SURFACES

With most surface engineering procedures it is necessary to create good initial surface conditions. In the case of thermal spraying processes it is recommended that a rough surface is created to enhance adhesion of the coating, especially when the coating contains ceramics. For optimum mechanical properties, in particular fatigue behaviour, the surface must remain in a compressive stress state. When high velocity oxyfuel spraying is used a compressive residual stress condition is strongly advised in view of the pressure and velocity with which the powder particles reach the substrate. The method of surface preparation employed can strongly affect the resultant compressive stresses. The effects of grit blasting conditions on the resultant residual stress state have been studied. Compressive residual stress in the surface layer increases with grit blasting time. Time, gun-specimen distance, and impingement angle have also been evaluated and show complementary behaviour.

Optimising process for making pasta from maize in admixture with durum wheat

AbstractProcessing conditions for making pasta from blends of maize (Zea mays L) flour and durum wheat (Triticum durum Desf) semolina (ratio 66:33 w) were studied. The maize mill stream characteristics determined the quality of the maize pasta; flours with low lipid content and very fine granulometry produced pasta with good colour characteristics and high cooking quality (with especially good surface conditions). The use of white maize varieties was preferred; they produced pasta which, after heat treatment, had colour indices close to those of durum wheat pasta. Extrusion conditions affected the colour characteristics and cooking quality of the pasta. The cooking qualities of macaroni products were better than those of spaghetti. In all cases, heat treatment (90°C for 2 h) improved the cooking quality of the pasta: it reduced cooking losses but did not alter the surface condition and viscoelasticity index.

ピロリン酸溶液からの金めっきにおける添加剤の効果

The behavior of thiourea and potassium tetracyanonickel (II) as additives has been studied with a view to obtaining a good surface of gold electrodeposit from a gold pyrophosphate solution. Gold exists in pyrophosphate solution as a gold cyanic complex salt without combining with pyrophosphate. The current-potential curve at gold electrodeposition is not affected by additives. Addition of either thiourea or potassium tetracyanonickel (II) resulted in good surface conditions of gold electrodeposits. Analysis of both surfaces showed no impurities and it considered that it was the difference in the strength of crystal orientation that produced good surface conditions. The co-electrodeposited potassium, however had a deleterious effect or the surface condition of gold electrodeposit.

Nation's water picture mixed

The nation's water picture for April showed mixed trends: More than half of the index gaging stations reported normal streamflow conditions during the month, while the spring snowmelt boosted streamflow in the Northeast and Northwest to well above normal levels. Parts of the Southeast, however, from West Virginia south to the Carolinas, reported well‐below normal streamflow conditions, according to a month‐end check on water resources conditions by the U.S. Geological Survey, Department of the Interior.After nearly 2 years of drought conditions the three major reservoirs supplying New York City reached full storage capacity and were spilling during April. Combined contents of the three reservoirs on May 1, 1982, was 272 billion gallons, 101% of their full usable capacity. The full reservoirs and the generally good surface and groundwater conditions throughout the Delaware River basin allowed the Delaware River Basin Commission to lift its drought emergency warning on April 27.

Visible Radiation Characteristics of Incandescent Oxides

Energy radiated in the visible part of the spectrum of various oxides and their mixtures when heated to red brightness temperatures between 1400\ifmmode^\circ\else\textdegree\fi{} and 2000\ifmmode^\circ\else\textdegree\fi{}K by means of cathode-ray bombardment, and gas-air and oxy-gas flames was measured by an optical pyrometric method. The oxides investigated were urania, ceria, lanthana, neodymia, erbia, yttria, zirconia, thoria, alumina, beryllia, magnesia, and mixtures of thoria with one percent ceria (the Welsbach mantle mixture), one percent and less of urania, one percent neodymia, and one percent manganese oxide. These were either pressed or fused to insure good surface conditions. In general, linear relations were found between the logarithm of the red-blue intensity ratio and the reciprocal of the brightness temperature, and between the logarithm of the candles emitted per unit surface area and the logarithm of the brightness temperature. Different modes of heating gave different radiation curves for the same oxide. Tables are given of the candles per square centimeter and the relative blue brightness for red brightness temperatures of 1400, 1500, 1600, 1700, 1800, 1900, and 2000\ifmmode^\circ\else\textdegree\fi{}K.

Visible radiation characteristics of incandescent oxides

Energy radiated in the visible part of the spectrum of various oxides and their mixtures when heated to red brightness temperatures between 1400\ifmmode^\circ\else\textdegree\fi{} and 2000\ifmmode^\circ\else\textdegree\fi{}K by means of cathode-ray bombardment, and gas-air and oxy-gas flames was measured by an optical pyrometric method. The oxides investigated were urania, ceria, lanthana, neodymia, erbia, yttria, zirconia, thoria, alumina, beryllia, magnesia, and mixtures of thoria with one percent ceria (the Welsbach mantle mixture), one percent and less of urania, one percent neodymia, and one percent manganese oxide. These were either pressed or fused to insure good surface conditions. In general, linear relations were found between the logarithm of the red-blue intensity ratio and the reciprocal of the brightness temperature, and between the logarithm of the candles emitted per unit surface area and the logarithm of the brightness temperature. Different modes of heating gave different radiation curves for the same oxide. Tables are given of the candles per square centimeter and the relative blue brightness for red brightness temperatures of 1400, 1500, 1600, 1700, 1800, 1900, and 2000\ifmmode^\circ\else\textdegree\fi{}K.