Results of a pilot experiment on monitoring the condition of buildings and structures using unmanned aerial vehicles

The purpose of the experimental study presented in the paper is to generate new knowledge about the possibility of using unmanned aerial vehicles to survey buildings and structures for subsequent extraction of information about their condition in hard-to-reach or remote places. As objects for the pilot experiment, the following were selected: a residential building in an urban environment that has been destroyed during operation; an object of unfinished construction; a roadway on the carriageway. An unmanned aerial vehicle of the model: DJI Mavic Air was used to survey the objects. The results of the study of objects are recorded in the form of photo and video streams for each object. Comparison of the results of the inspection of objects by experts and unmanned aerial vehicles showed the possibility and necessity of using new means to collect information about the condition of buildings and structures. The primary processing of the obtained images revealed their features: the effect of illumination on the color characteristics of the object of study; the presence of a textural component that complicates the process of separating the defect from the background; the presence of objects in the image that are not related to the elements of surface destruction; the change in the initial size of the object over time. The detected features of the images allow the use of standard algorithms and processing and require the synthesis of unique trajectories of their application.

Formulation of Environmentally Safe Graffiti Remover Containing Esterified Plant Oils and Sugar Surfactant

The removal of graffiti or over-painting requires special attention in order to not induce the surface destruction but to also address all of the important eco-compatibility concerns. Because of the necessity to avoid the use of volatile and toxic petroleum-based solvents that are common in cleaning formulations, much attention has recently been paid to the design of a variety of sustainable formulations that are based on biodegradable raw materials. In the present contribution we propose a new approach to graffiti cleaning formulations that are composed of newly synthesized green solvents such as esterified plant oils, i.e., rapeseed oil (RO), sunflower oil (SO), or used cooking oil (UCO), ethyl lactate (EL), and alkylpolyglucosides (APGs) as surfactants. Oil PEG-8 ester solvents were synthesized through the direct esterification/transesterification of these oils using monobutyltin(IV) tris(2-ethylhexanoate) and titanium(IV) butoxide catalysts under mild process conditions. The most efficient formulations, determined by optimization through the response surface methodology (RSM) was more effective in comparison to the reference solvents such as the so-called Nitro solvent (denoting a mixture of toluene and acetone) and petroleum ether. Additionally, the optimal product was found to be effective in removing graffiti from glass, metal, or sandstone surfaces under open-field conditions in the city of Wrocław. The performed studies could be an invaluable tool for developing future green formulations for graffiti removal.

Cylindrical Caved Space Stability Analysis for Extension Prediction of Mining-Induced Surface Subsidence

Subsequent extension of surface subsidence after vertical caving leads to large-scale surface destruction, as well as associated geological hazards. The extension prediction for cylindrical caved space, which appears circular surface subsidence, is still an intractable issue, due to the absence of robust models. To fill such a research gap, this paper provides an analytical model for the depth and orientation where the shear failure of isotropic rocks around the caved space is firstly observed. The anisotropy of surrounding rocks is further involved to enable this model to analyze the slip failure along discontinuities in anisotropic stress state. The prediction for the extension of the surface subsidence in Xiaowanggou iron mine is conducted, and the comparison between the prediction and the observation in satellite images demonstrates the validity of the proposed model. Even though this model cannot provide a definite boundary after extension, the prediction for the orientation surface subsidence extends to contribute to mitigating the effect of geological hazards. Another contribution of this work is to provide guidance to mitigate the impact of surface subsidence on safety and environment, such as filling the interspace between large-sized caved rocks by dumping small-sized waste rocks or backfilling the caved space with waste rocks.

Testing the Wear Mechanisms of the Components of Machines Used in Fossil Energy Resource Extraction

The paper presents the results of tests of wear of hardened wear-resistant steels in the presence of quartz, coal and coal-mineral abrasives of a differentiated ratios of each component and in the case without abrasives. The tests were carried out on a ring-on-ring test stand. Volume loss was the parameter used to characterize the wear level. Based on the Scanning Electron Microscopy (SEM) observations, different mechanisms of surface destruction depending on the type of abrasive were found. For the quartz abrasive, it was shown that the quartz grains cause micro-cutting, but surface cracks also appear that further transform into shallow holes. In the case of mixtures of quartz with coal, the surface was micro-scratched by quartz grains, but some of these grains were hammered into the surface, what was favoured by the presence of coal fractions. In the case of coal abrasive, traces of single cutting were observed, as well as unremoved scratches formed at the sample grinding stage. Based on the wear observation, two models of steel surface wear in the presence of coal and coal-mineral abrasives were determined.

Application of CT Image Based on Three-Dimensional Image Segmentation Algorithm in Diagnosis of Osteoarthritis

Objective: To investigate the application of multi-slice spiral CT in degenerative changes of lumbar facet joints using the LOG algorithm. Methods: The CT findings of 100 cases of degenerative vertebral facet joint disease were reviewed and analyzed in this paper. Results: The main CT manifestations of facet disease are osteophyte formation, articular hyperplasia and hypertrophy, osteosclerosis, narrowing of joint space, articular surface destruction, joint capsule calcification, joint gas accumulation, joint subluxation, and lateral recesses and vertebrae. Signs such as narrow mesopores. Conclusion: The multi-slice spiral CT (MSCT) and multi-planar reconstruction (MPR) techniques are analyzed by the LOG operator algorithm. It is found that the two techniques can fully display the anatomical structure and pathological changes of the vertebral facet joints, and are useful for the diagnosis of facet joint disease. Provide enough imaging evidence.

DAMAGING AND DESTRUCTION OF REDUCTION TRAINS OF MI-8 HELICPTER AND ITS MODIFICATIONS

The results of quantitative factographic study of the Mi-8 helicopter (its modifications) reduction trains with different types of gear coupling, the destruction of which occurred while in flight due to the presence of preliminary material damage at the stage of production of the gear wheels and during their operational employment are presented in a generalized form. Contact teeth destruction as the main cause of failures of high-speed gear wheels in well-lubricated enclosed gears are considered. The causes of the wearing and sticking of the teeth along their lateral surfaces as well as scoring and destruction depending on the origin of the cracks are revealed. The main causes of damaging and destruction of helicopter reduction trains, locations and origination of fatigue cracks spots are identified. Different types of contact and fatigue destructions due to various reasons are considered. Dynamic loading of gear wheels disks as a result of their rotation damages the material of the wheels in the area of multi-cycle fatigue due to the repeatability of flight load cycles. Lamination or deep contact destruction of the material, which sometimes take place in gears with surface hardened (cemented, tempered, nitrided, etc.) teeth, are much more dangerous than surface destruction of the material since sufficiently large fractions of the hardened material layer are split away from the teeth that can quickly break down an entire gear train. The main causes of contact teeth destruction are load concentration along the length and profile of the teeth, the presence of residual tensile stresses on the working surfaces of the teeth, adverse operational damage to the tooth profiles and negative effect of lubricating fluid on the teeth. For a repaired gear train the cause of the uneven load distribution along the length of the teeth may be the poor assembly of the gear wheels and other transmission parts which leads to unsatisfactory contact of the gear teeth in the assembled unit. The revealed peculiarities of the destruction process indicate regular crack proliferation from flight to flight. According to the operation conditions of the gear weel, its regular extensive loading refers only to the full cycle of starting and stopping the reducer train or unloading the helicopter in flight, which in this case corresponds to the cycle of helicopter operation in one flight. Therefore, the number of detected fatigue lines corresponds to the number of helicopter flights. To increase the smoothness of gear train running which affects positioning accuracy, reduce wear during running-in, decrease noise, eliminate early jamming, and ultimately, to increase the resource, it is necessary to eliminate the edge interaction of the teeth, which causes their excessive wear.

Relationship between Pain Behavior and Changes in KCNA2 Expression in the Dorsal Root Ganglia of Rats with Osteoarthritis

Objective. To investigate the relationship between pain behavior and potassium voltage-gated channel subfamily A member 2 (KCNA2) expression in dorsal root ganglia (DRGs) of rats with osteoarthritis (OA). Methods. Male Sprague-Dawley rats were randomly divided into three groups: blank control group (group C), normal saline group (group S), and group OA. Paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured one day before injection and one, two, four, and six weeks after injection. At one, two, four, and six weeks after injection, pathological knee joint changes and activated transcription factor-3 (ATF-3) and KCNA2 expressions in DRGs were analyzed. Results. Compared with preinjection, PWMT and PWTL at two, four, and six weeks after injection were significantly decreased in the group OA (P<0.05 or 0.01). Compared with group C, PWMT and PWTL at two, four, and six weeks after injection were significantly decreased in the group OA (P<0.05 or 0.01). In the group OA, slight local articular cartilage surface destruction was found at week one. The cartilage surface destruction gradually developed, and the exacerbation of cartilage matrix reduction and bone hyperplasia were increasingly aggravated and eventually evolved into advanced OA in the second to sixth weeks. Compared with group C, ATF-3 expression was significantly increased, and KCNA2 expression was significantly decreased in the group OA at two, four, and six weeks after injection (P<0.05 or 0.01). Compared to baseline, ATF-3 expression was significantly increased, and KCNA2 expression was significantly decreased in the group OA (P<0.05 or 0.01). Conclusion. Pain behavior in OA rats was associated with decreased KCNA2 expression in DRGs.

DAMAGING AND DESTRUCTION OF REDUCTION TRAINS OF MI-8 HELICPTER AND ITS MODIFICATIONS

The results of quantitative factographic study of the Mi-8 helicopter (its modifications) reduction trains with different types of gear coupling, the destruction of which occurred while in flight due to the presence of preliminary material damage at the stage of production of the gear wheels and during their operational employment are presented in a generalized form. Contact teeth destruction as the main cause of failures of high-speed gear wheels in well-lubricated enclosed gears are considered. The causes of the wearing and sticking of the teeth along their lateral surfaces as well as scoring and destruction depending on the origin of the cracks are revealed. The main causes of damaging and destruction of helicopter reduction trains, locations and origination of fatigue cracks spots are identified. Different types of contact and fatigue destructions due to various reasons are considered. Dynamic loading of gear wheels disks as a result of their rotation damages the material of the wheels in the area of multi-cycle fatigue due to the repeatability of flight load cycles. Lamination or deep contact destruction of the material, which sometimes take place in gears with surface hardened (cemented, tempered, nitrided, etc.) teeth, are much more dangerous than surface destruction of the material since sufficiently large fractions of the hardened material layer are split away from the teeth that can quickly break down an entire gear train. The main causes of contact teeth destruction are load concentration along the length and profile of the teeth, the presence of residual tensile stresses on the working surfaces of the teeth, adverse operational damage to the tooth profiles and negative effect of lubricating fluid on the teeth. For a repaired gear train the cause of the uneven load distribution along the length of the teeth may be the poor assembly of the gear wheels and other transmission parts which leads to unsatisfactory contact of the gear teeth in the assembled unit. The revealed peculiarities of the destruction process indicate regular crack proliferation from flight to flight. According to the operation conditions of the gear wheel, its regular extensive loading refers only to the full cycle of starting and stopping the reducer train or unloading the helicopter in flight, which in this case corresponds to the cycle of helicopter operation in one flight. Therefore, the number of detected fatigue lines corresponds to the number of helicopter flights. To increase the smoothness of gear train running which affects positioning accuracy, reduce wear during running-in, decrease noise, eliminate early jamming, and ultimately, to increase the resource, it is necessary to eliminate the edge interaction of the teeth, which causes their excessive wear.