Erosion Traces Research Articles

Preparation and corrosion resistance of β-Al2O3–MgAl2O4 multiphase materials for synthesising Li-ion battery cathode materials

The sagger, primarily composed of aluminum-silicon, serves as an essential vessel in the sintering process of ternary lithium battery anode materials (LiNixCoyMn1-x-yO2, LNCM). However, the acidic oxide SiO2 in the sagger material readily reacts with Li2O in the cathode material, forming substances such as LiAlO2 or LiAlSiO4, resulting in volume expansion, which makes the sagger spalled and damaged. In this study, β-Al2O3–MgAl2O4 multiphase materials with excellent alkali resistance were prepared using the high-temperature solid-state method. The effects of anhydrous sodium carbonate content and heat treatment temperature on the properties of the composites were investigated, and the thermal shock resistance of the specimens was evaluated by the water-rapid-cooling method, as well as the LNCM corrosion resistance of the specimens was evaluated by the static crucible method. The results showed that the overall performance of the specimens was the best at a anhydrous sodium carbonate content of 6 wt%, with a compressive strength of 57.50 MPa and a flexural strength of 42.49 MPa after firing at 1600 °C for 4 h. The strength retention of the specimens was 33.21 % after one thermal shock at a thermal shock temperature of 900 °C. The specimens showed excellent resistance to erosion as there were no obvious erosion traces on the surface of the specimens after undergoing five cycles of erosion.

Ichnology and Main Types of Trace Fossils

Ichnology studies the traces of activities left by modern and ancient animals. The advantage of trace fossils of biological activity and solid fossils is that the trace fossils are not modified by late diagenesis. They are the original deposits of organisms on the sedimentary environment and can directly reflect the living habits of animals and their living environment. According to the sedimentary substrate in which animals live, trace fossils can be divided into tracks, traceways, trails, crawling traces, resting traces, burrows on the soft ground, and erosion traces made by animals on the hard ground.

Sources, Transport, and accumulation of Mercury in the northwestern Mediterranean margin sediments during the Industrial Era and influence of turbiditic events

Sources and pathways of the Hg accumulated in the sediments of the Gulf of Lion (GoL) and its adjacent marine areas (Northwestern Mediterranean) have been explored using sediment grab samples, sediment cores, and sediment trap samples. The main source of Hg along this margin is the Rhône River, whose suspended sediments settle mainly in the prodelta area but also along the mid-shelf, then reaching the continental rise via wave resuspension and cascading of dense shelf waters. Seaward, these riverine particles are mixed with carbonated ooze conveyed to the bottom by the biological pump. The Hg is enriched in surface sediments of the GoL with decreasing concentrations westward and seaward from the Rhône prodelta to the continental rise. Dated cores from the Rhône prodelta give access to riverine sediments deposited over the last 400 years and show that the Hg concentration time trend resembles the evolution of coal consumption in France, peaking during in the 1960s. Similar trends were observed in sediment cores collected along the GoL slope and submarine canyons along with the preservation of traces of erosion and sediment instability events. Seaward, on the continental rise, the Hg concentration distribution suggests the deposition of fine planktonic-derived material and particles episodically advected from the shelf during deep cascading pulses. Anthropogenic Hg accumulated in GoL and continental rise sediments during the Industrialized Era is ∼ 150 Mg (tons), two-thirds of which are buried in the Rhône prodelta area. Significant correlations are found between Hg and organic matter in GoL sediments, but the relationships differ between areas and are disrupted by the inputs of anthropogenic Hg and by the Hg availability in the Rhône River watershed during the pre-industrial period. The HgT availability in waters appears to be the limiting factor to the Hg enrichment of the particulate organic matter. Monomethyl mercury (MMHg), which represents on average 0.3 % of the total Hg, was positively correlated to total Hg. Their distributions suggest in situ MMHg formation and a more effective net Hg methylation for surface sediment or particles collected in traps compared with particles buried in the sedimentary column.

Multi-hazard susceptibility model based on high spatial resolution data-a case study of Sali settlement (Dugi otok, Croatia).

The world has been facing an increase in various natural hazards. The coastal regions are recognized as one of the most vulnerable due to high population pressure and climate change intensity. Mediterranean countries have one of the most burnable ecosystems in the world, one of the most exposed to pluvial floods, and have the highest erosion rates within the EU. Therefore, the aim of this study was to develop the first multihazard susceptibility model in Croatia for the Sali settlement (island of Dugi otok). The creation of a multi-hazard susceptibility model (MHSM) combined the application of geospatial technology (GST) with a local perception survey. The methodology consisted of two main steps: (1) creating individual hazard susceptibility models (soil erosion, wildfires, pluvial floods), and (2) overall hazard susceptibility modeling. Multicriterial GIS analyses and the Analytical Hierarchy Process were used to create individual hazard models. Criteria used (32) to create models are derived from very-high-resolution (VHR) models. Two versions of MHSM are created: 1) all criteria with equal weighting coefficients and 2) weight coefficients determined based on public perception. According to MHSM 1, most of the research (58%) area is moderately susceptible to multiple hazards. Highly and very highly susceptible areas are 27% of the drainage basin and are mostly located near roads and houses. MHSM 2 reveals similar results to MHSM 1. The public perceives that the research area is the most susceptible to wildfires. The wildfire ignition risk is ranked as moderate (3.00) with a standard deviation of 1.16. Pluvial flood risk is ranked low (2.78), with a standard deviation of 1.15. The risk of soil is most inferior (2.24) with a standard deviation of 0.91. The the most significant difference between public perception and the GIS-MCDA model of hazard susceptibility is related to soil erosion. However, the accuracy of the soil erosion model was confirmed by ROC curves based on recent traces of soil erosion in the research area. The proposed methodological framework of multi-hazard susceptibility modeling can be applied, with minor modifications, to other Mediterranean countries.

In situ observation and understanding of the arc erosion behavior of electrical contact materials

Abstract Arc erosion studies are carried out on electrical contact materials in the switching current experiment. A test rig is developed to capture the 2-D image and the 3-D profile of eroded silver tin oxide electrical contact material in situ. Image processing algorithms are specially presented to accurately recognize the features of erosion region. The initial small patch of erosion traces gradually evolves into the deep crater with the increment of switching cycle enabling a study of the arc erosion behavior. 2-D image, 3-D profile, and micro surface morphologies of the eroded contacts are analyzed and then related to the extent of erosion. The results show that the evolution process of central erosion region could be divided into the enlargement in breadth of contact surface and the extension in depth of contact profile. The end result of arc erosion is the net loss of contact material, which would lead to the substantial reduction of contact force and potential electrical contact instability.

Reconstructing parameters of the Holocene paleofloods in alluvial lowland river valleys – An example from the Bug valley (East Poland)

One of the ways to improve the accuracy of hydrological forecasts is to extend the data strings with the parameters of the maximum flows in the river from the period preceding their instrumental recording. The reconstruction of such parameters is difficult in the case of alluvial river valleys, mainly due to the difficulties in determining the shape of the channel cross-section. The article proposes a method for reconstructing extreme Holocene paleo-flow in the case of large alluvial rivers in the European Plain. It is based on identifying specific features of the geological structure of the valley, as well as elements of its bottom morphology, which can act as high water marks (HWM). The research was carried out in the section of the Bug valley, a large lowland river flowing through Ukraine, Belarus, and Poland.In the valley reach under analysis, the cross-section of the high water channel is determined by: the surface of the resistant to erosion sub-alluvial bedrock protrusion built of glacial till, and traces of flood erosion on the Pleistocene terraces, including traces of dune washouts. The age of the paleo-flow was determined by means of the C14 dating of sediments filling the flood erosion troughs. Due to the limited number of tests, the reconstructed maximum flow values are subject to uncertainty. Yet, even quite uncertain the reconstructed paleofloods may result in a significant improvement in the estimates of high quantiles using the flood frequency analysis, or at least allow to prepare for the floods not recorded by the monitoring system. In consequence, increasing the number of measurement points, and thus improving the correctness of the determination of paleo channels cross-sections, may contribute to a significant reduction in the uncertainty of the obtained paleo-flow values.

Study on magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays

High-power DC relays are widely used in new energy power systems and DC distribution networks, and commonly use transverse magnetic fields to accelerate arc extinguishing. In this paper, the magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays are studied by experiments and simulations. The experiments are carried out to analyze the arc motion, contact erosion mass, and contact morphologies, and to verify the simulation model. Considering the energy transfer source term, the establishment of a more perfect magnetohydrodynamic arc model is accomplished, and an erosion model is further established. The results indicate that the magnetically blown arcing process has three stages while the arc shapes and motion characteristics are different, and the heat flux acting on the contact can be accurately obtained by the arc model. The greater external transverse magnetic field is more conducive to extinguishing the arc and reducing the arc erosion time. In contrast, the Archimedes force plays a very small positive role and the self-induced magnetic field of the arc has a negative effect. For contact erosion, the temperature distribution of the molten pool appears trailing effect. Moreover, the advanced mathematical model proposed for erosion mass has good accuracy. The calculation results of erosion rates show that Cr reduces erosion while the current increases erosion nonlinearly. Besides, the flow and deformation characteristics of the molten pool will lead to convex strip-shaped erosion traces and arcing position transfer, and the moving erosion will cause the lateral accretion effect. Furthermore, the analysis shows that the reason for edge droplet sputtering is the pressure difference caused by Plateau–Rayleigh instability, and optimization suggestions for reducing contact erosion are given.

Numerical Study of the Erosion Distribution of Sulfur-Containing Particulate Gas in 90-Degree Gathering Elbow

The phenomenon of pipeline erosion dominated by sulfur particles has become a key research target for sulfur-containing gas-gathering pipelines. Gas-solid two-phase flow of sulfur-containing gases is simulated with a coupled CFD-DPM model in this paper. The Realizable k-ε turbulence model was used to determine the changes in the complex flow field and the Euler-Lagrange method was used to describe the specific trajectory of sulfur particles in the complex flow field. The main erosion trace distribution and the effect of secondary flow effects at the elbow were analyzed and the erosion distribution pattern was investigated for different curvature ratios, particle sizes, and pipe diameters. The results show that the formation of erosion along the tip of the V-shaped erosion trace on the outlet sidewall of the elbow may be related to secondary flow effects. The increase of the curvature ratio RD reduces the erosion intensity of the maximum erosion area, but subsequent increase will result in new secondary erosion trace near the outlet of the elbow and reach the maximum when RD = 8. Variations in particle size will have a significant effect on the extent of the erosion distribution, causing the main erosion distribution of the elbow to vary between 48.2° and 84.2°, while variations in pipeline diameter will have a lesser effect. The Stokes number can also be reduced by controlling the variation in particle size and pipe diameter to alter the force profile on the particles and reduce the erosion effect.

Nano-and Microparticles of Carbon as a Tool for Determining the Uniformity of a Diffuse Discharge Exposure

At present, a diffuse discharge plasma of air and other gases at atmospheric pressure is widely used for the surface treatment of various materials. However, in many papers it is stated that erosion damages occur on flat anodes (targets) as a result of the discharge plasma action. The shape of these damages depends on the discharge mode. In this study, the exposure uniformity was investigated by using nano- and micro-sized carbon particles deposited on a flat copper anode (a carbon layer). The diffuse discharge was formed in a ‘point-plane’ gap with a non-uniform electric field strength distribution by applying voltage pulses with an amplitude of 18 kV. It has been established that at a gap width of 8–10 mm, an imprint of the discharge plasma on the carbon layer deposited on a copper anode has no traces of local erosion. In order for erosion to occur on the surface of the anode in the form of uniformly distributed microcraters, it is necessary to increase the current density at the anode, for example, by decreasing the gap width. When decreasing the gap width to 6 mm and less, spark channels occur. They damage both the carbon layer and the copper anode in its central part. It has been shown that there are three characteristic zones: a color-changing peripheral part of the carbon layer, a decarbonized central part of the anode, and an annular zone located between the central and peripheral parts and containing individual microcraters.

Dual-domain metal trace inpainting network for metal artifact reduction in baggage CT images

During the security check, the metal in the baggage engenders serious metal artifacts on the Computed Tomography (CT) image. To reduce the effect of metal artifacts on the judgment of prohibited items during such activity, a Deep Learning (DL) method combined with dual domain information in CT images is proposed in this work. As for the methodology of work, the metal areas are segmented, in the first phase, from the metal artifact CT image and they are then projected into the sinogram domain using the Forward Projection (FP) algorithm. As the trace of the metal-corresponding projection area in the sinogram domain is considered to be missing data, the linear interpolation method is adopted to correct the metal missing trace, and the Sino-Inpainting Network (SIN) is deployed to repair the metal erosion trace. By adopting the Filtered Back Projection (FBP) algorithm to reproduce the results of the sinogram restoration, the mutual information between the sinogram domain and the image domain is completed. In the second phase, the sinogram inconsistent artifacts are repaired using the Partial Refine Network (PRN) after the corrected image restoration. The PRN only depends on the effective pixels outside the metal damaged area to restore the trace area; thus, this technique can be more effective to refine the image details. Finally, the metal mask, obtained by threshold segmentation, is inserted into the repaired reconstructed image. Using both simulated data and real data, a comparison between the proposed method, the conventional method, and the DL method is performed. Quantitative results show that the Peak Signal-to-Noise Ratio (PSNR) and the Structural Similarity Index Measure (SSIM) in the reconstructed image of the baggage, obtained through the proposed network, are 31.0722 dB and 0.9718, respectively; thus, they are better than the other tested methods. Moreover, the results of the experiments demonstrate the effectiveness of the suggested method in recovering the lost data of the metal corrosion area in the sinogram and in suppressing the secondary artifacts in the reconstructed image.

Heterotrophic Bioleaching of Vanadium from Low-Grade Stone Coal by Aerobic Microbial Consortium.

Bioleaching is a viable method that assists in increasing the vanadium output in an economical and environmentally friendly manner. Most bioleaching is conducted by pure cultures under autotrophic conditions, which frequently require strong acidity and produce acid wastewater. However, little is known about heterotrophic bioleaching of vanadium by mixed culture. This study investigated the bioleaching of vanadium from low-grade stone coal by heterotrophic microbial consortium. According to the results, vanadium was efficiently extracted by the employed culture, with the vanadium recovery percentage in the biosystem being 7.24 times greater than that in the control group without inoculum. The average vanadium leaching concentration reached 680.7 μg/L in the first three cycles. The kinetic equation indicated that the main leaching process of vanadium was modulated by a diffusion process. Scanning electron microscopy revealed traces of bacterial erosion with fluffy structures on the surface of the treated stone coal. X-ray photoelectron spectroscopy confirmed the reduction of the vanadium content in the stone coal after leaching. Analysis of high-throughput 16S rRNA gene sequencing revealed that the metal-oxidizing bacteria, Acidovorax and Delftia, and the heterotrophic-metal-resistant Pseudomonas, were significantly enriched in the bioleaching system. Our findings advance the understanding of bioleaching by aerobic heterotrophic microbial consortium and offer a promising technique for vanadium extraction from low-grade stone coals.

NiB-CrC Coatings Prepared by Magnetron Sputtering Using Composite Ceramic NiCr-BC Target Produced by Detonation Spray Coating.

A metal–ceramic composite target for magnetron sputtering was fabricated for the first time by a robotic complex for the detonation spraying of coatings equipped with a multi-chamber detonation accelerator. A mixture of metal and ceramic NiCr/B4C powders was sprayed onto the copper base of the cylindrical composite target cathode. The study of the structure of a metal–ceramic composite coating target using scanning electron microscopy showed that the coating material is dense without visible pores; the elemental composition is evenly distributed in the material. The study of the cathode sputtering area after deposition in the DC mode showed that there are uniform traces of annular erosion on the target surface. The obtained cathode target with an NiCr-70B4C coating was used to deposit the NiB-Cr7C3 coating on flat specimens of 65G steel using equipment for magnetron sputtering UNICOAT 200. The coating was applied in the Direct Current mode. A dense NiB-Cr7C3 coating with a thickness of 2 μm was obtained. The NiB-Cr7C3 coating has a quasi-amorphous structure. The microstructures and concentration of oxygen and carbon impurities throughout the entire thickness of the coating were investigated by means of transmission electron microscopy. The results of the study show that the coatings have a nanocrystalline multi-phase structure. The microhardness of the NiB-Cr7C3 coating reached 10 GPa, and the adhesion fracture load exceeded 16 N. The results will open up new prospects for the further elaboration of technology for obtaining original composite cathodes for magnetron sputtering using detonation spraying of coatings.

Sedimentary conditions of the Abalak formation and Vogulkinskaya strata on the area of Kamennaya summit (Krasnoleninsky arch, Western Siberia)

As part of this work, various sedimentation environments were identified in the Middle-Late Jurassic (J2k–J3v1) on the territory of the Krasnoleninsky arch in Western Siberia. The heterogeneity of the seabed topography and the presence of islands formed by protrusions of the pre-Jurassic basement led to the formation of the Vogulka strata as a result of the removal of clastic material from the land. At the same time, far from the islands, in relatively calm shallow environments, clayey and glauconite-clayey sediments of the Abalak Formation accumulated. Gravelites and sandstones of the Vogulka strata were formed unevenly. The greatest thickness of these deposits is observed to the west of the central upland. The difference in the thickness of clastic strata on the western and eastern slopes could probably be caused by the specific horseshoe shape of the island and the absence of active currents on the western part of the slope, as well as its greater steepness. The upper member of the Vogulka strata, composed of detrital limestones, is extremely thin (no more than 1 m), and contains numerous unconformities. Probably, these traces of erosion can be indirect evidence of the influence of the Late Oxford regression on the structure of the section, which was previously noted in adjacent territories.

TURBIDITES IN THE MIDDLE PALEOCENE VARIEGATED FORMATIONS OF THE SKYBA NAPPE BETWEEN THE RIVERS OPIR AND SVICHA OF THE UKRAINIAN CARPATHIANS

The paper presents the results of the study of sections of the Middle Paleocene variegated the Yaremche horizon in the skybas of Parashka, Skolivska, Orivska Skiba tectonic nappe. The work is based on the results of geological observations between the rivers Opir and Svicha and laboratory studies. The Yaremche horizon is characterized by rhythmic-cyclic interlayering of greenish-gray siltpsammitic and siltpelitic turbidites and cherry-red hemipelagites and pelagites. The purpose of the paper is to study the features of horizon sections and to establish the features of paleogeodynamic and paleogeographic modes of their formation. Rhythmostratigraphic study of the Yaremche horizon, allows it to be included in the sequence of the first order, which contains sequences of higher, second and third orders. Terrigenous and carbonate turbidites take part in the construction of sections of the Yaremche horizon. For turbidite sequences, both terrigenous and carbonate composition, are characterized by elements of textures A. Bouma Tdce. However, there are terrigenous layers that have a disordered texture with intervals (bottom up) of dish (plate) structure, which contain fluide escape “pipes”, convoluted limination with gravitational intralayer deformations (in flat top). These layers have an unsorted, multi-grained, pudding structure. The lower contact is erosive, the upper – smooth with hidden traces of erosion. These layers are parallelized by the mechanism of formation with deposits of fluidized (and/or liquefied) flows that occur at the final stage of turbidity currents. The study of petrographic features of petrotypes of turbidite sequences makes it possible to isolate chlidolites (pattums, mixstolites), which belong to greywackes in terms of the material composition of the fragments. The content of cement in them is not less than 10–25 % and indicates the turbulent flow nature of the clay-sand mass from which the deposits were formed. Among the greywackes, a separate group is occupied by fragmentary carbonate rocks – calcarenite-calcillite turbidites (Parashka skyba, Oryava river). They were formed during the redeposition of shelf carbonate material and/or intra-oceanic uplift material to the deep-water sedimentary basin of the continental shelf, which at the time of their accumulation had depths above the CCD. The formation of the Yaremche horizon took place at the foot of the continental slope of the passive outskirts of Eurasia, on the border of the deep-water plain of the External Carpathian flysch paleobasin during the temporary stabilization of the tectonic regime. The continental foothills pulsatingly changed their bathymetric parameters, due to convergent events between Eurasia and the microcontinents of the Tethys Ocean. They controlled the periodic approach and formation of flysch nappe units of accretion prisms on the active continental margin. The scientific results of the study will contribute to a better understanding of the geological structure of the Skiba zone of the Ukrainian Carpathians. The practical results of the study will contribute to the study of geological bodies promising for hydrocarbons.

Study of Corrosion Resistance Properties of Heat Exchanger Metals in Two Different Geothermal Environments

Geothermal fluids harnessed for electricity production are generally corrosive because of their interaction with the underground. To ensure the longevity and sustainability of geothermal Organic Rankine Cycle (ORC) powerplants, the choice of heat exchanger material is essential. The performance of heat exchangers is affected by corrosion and scaling due to the geothermal fluids, causing regular cleaning, part replacement, and in the worst cases, extensive repair work. The properties of geothermal fluids vary between geothermal settings and even within geothermal sites. Differences in exposure conditions require different material selection considerations, where factors such as cost, and material efficiency are important to consider. This work studies in-situ geothermal exposure testing of four metals at two geothermal locations, in different geological settings. Four corrosion-resistant materials were exposed for one month at Reykjanes powerplant in Iceland and four months at Chaunoy oil field in France as material candidates for heat exchangers. The tested alloys were analysed for corrosion with macro- and microscopic techniques using optical and electron microscopes, which give an indication of the different frequencies of repairs and replacement. Inconel 625 showed no effects at Reykjanes and cracks at Chaunoy. The others (316L, 254SMO, and titanium grade 2) showed either corrosion or erosion traces at both sites.

Modifications of an electrolytic aluminum oxide film under the treatment with microdischarges during plasma electrolytic oxidation, a self-organized dielectric barrier discharge (DBD) and a DBD-like plasma jet

A key to the understanding of mechanisms during plasma electrolytic oxidation (PEO) is the interaction between microdischarges and an amorphous oxide film. The PEO microdischarges, which are randomly distributed on the surface of a treated lightweight metal substrate (Al, Ti, Mg), cause material extraction and support the formation of hard and dense crystalline oxide films. Characterization of these microdischarges is a complicated task under PEO conditions, because of the stochastically temporal and spatial behavior as well as the small dimension of the microdischarges. Microdischarges at atmospheric pressure conditions can leave similar erosion traces on metallic films (Al, Ti) as PEO microdischarges on oxide films, and possibly can support a better understanding of the plasma-solid-interactions as well as microdischarge characteristics during PEO. A porous aluminum oxide film is deposited on aluminum substrates by pre-anodizing at a voltage of 250 V and is treated afterwards with a relative short (duration of 1 min) PEO process at a voltage of about 500 V or filamentary dielectric barrier discharges, namely a self-organized Dielectric Barrier Discharge (DBD) and a DBD-like plasma jet operated both with a He/N2 (95%/5%) gas flow. The gas temperature at DBD plasma conditions, measured using the rotational distribution in the emission spectra of molecular nitrogen, is low and amounts to about 400 K. Erosion traces on the surface of the oxide film caused by PEO and plasma spots of both atmospheric pressure discharges are studied by scanning electron microscopy and energy dispersed x-ray spectroscopy. Form and dimensions of erosion traces and established modifications of the material composition generated by the treatment with these DBD microdischarges under atmospheric pressure conditions are similar to those ones generated by the PEO process. Hence, a similar mechanism of these processes is supposed. For stronger evidences of the assumed PEO mechanism additional experimental studies are needed.

Theoretical study of the arc motion in the hollow cathode of a dc thermal plasma torch

A 3D model of a hollow cathode of a thermal plasma torch was developed to study the motion of the electric arc in the upstream part as well as its influence on the characteristics of the thermal plasma generated at the entrance of the downstream part (anode). The translational motion along the axis and the rotational velocity of the cathodic arc root are studied. The results of the model are presented and compared with those of the literature and also with experimental results. Good agreements on the prediction of the axial arc position and of the rotational speed of the arc root are found with the literature. A correlation is also shown between the theoretical positions of the arc root and the experimental traces of erosion observed on the cathode.

On the presence and distribution of Borassus aethiopum during the Holocene: a rock art evidence from Ennedi (Northern Chad)

A recently discovered rock art site has revealed the presence of figures of fan palm (Borassus aethiopum), a species not recorded in the current flora of the Ennedi. Various evidences (style, superimpositions, themes represented, location in height, traces of erosion) make it possible to date them from the mid-Holocene and to attribute them to the earliest phases of the regional rock art. It is likely that the depictions of the fan palms were motivated by their importance for the population (food, medicine, construction). These data also make it possible to postulate that the northern limit of the distribution area of Borassus aethiopum in the Holocene was close to the Tropic of Cancer.

Thermal Effect on AMF Electrodes at Different Opening Speeds

The erosion and thermal states at current zero for the axial magnetic field (AMF) electrodes after high-current vacuum arcs (HCVAs) were studied at an average opening speed of 2 m/s. The results obtained are compared with similar results received earlier at an average opening speed of 1 m/s. The discharge was ignited in a demountable vacuum chamber by opening the contacts and was fed with the half-sine current pulse of 10 ms in duration. To determine the thermal state of the surface of the electrodes at zero current, a Phantom MIRO M310 high-speed video camera with a Carl Zeiss 100 mm F2 lens was used. In addition, the surface of the electrodes after the arc exposure was photographed by a Canon camera. The study showed that at the same current an increase of the opening speed leads to an increase in the thermal effect on the electrodes. Besides, the work revealed that at high opening speed (HOS) the process of appearances of erosion traces on the cathodes and, especially, on the anodes, is significantly different. The estimations made in the work showed that the difference in erosion traces on the anode is associated not only with an increase in the thermal effect but also with a change in the momentum transferred to the anode by cathode jets due to jets relaxation in the interaction with the secondary anode plasma in a long arc.

Environmental adaptation and hazard reduction strategies in relocation housing development by its occupants case: Indo-Tiongkok housing, Neuheun Aceh Besar

The construction of relocation housing is a form of housing assistance for victims of the 2004 tsunami, with various environmental designs. Indo-Tiongkok housing (Jacky Chan housing) is one of the relocation housing in the Neuheun area, designed with an approach adjusting the hilly topography. The disadvantage of building on contoured land is that it is susceptible to local erosion, which can damage buildings on the land (roads and buildings). This study reveals the phenomenon of environmental adaptation strategies by the community to reduce the risk of hazards in their home environment, and this is important to disclose to find out people’s attitudes and actions in maintaining the sustainability of their living space. The research method was in-depth interviews with the community to understand the understanding of environmental hazards and community strategies in reducing the risk of dangers that might occur. The information required relates to 2 things: 1) types of environmental hazards, risks, and patterns of threats; 2) attitudes and strategies of society to overcome these dangers. The results showed that the community understands the risk of hazards logically, by looking at signs of natural elements such as traces of erosion, and the impact on artificial elements (houses, soil, yard boundaries). The community strategy to reduce the risk of hazards is to combine various factors from engineering aspects (building materials and techniques), economic aspects, and suitability aspects of plant selection. Results showed that the strategy for adaptation patterns to the environment would appear in each occupant according to their problems and abilities so that the results of the appearance of the residential environment design would vary. This is so unique in the culture of living in each place, which will distinguish it from other places.