Analysis of Platform Leveling Systems for Tracked Feller-Buncher Machines

The study was devoted to the analysis of feller buncher platform leveling systems. The widespread use of these systems in the design of modern feller-buncher machines makes the study relevant to assess operational efficiency. The analysis was conducted in five stages using analytical and stochastic mathematical modeling methods. In the first stage, the existing layouts of alignment systems were analyzed from the position of force on the hydraulic cylinder rods of the platform tilt drive. The three-cylinder layout scheme, where the force on the hydraulic cylinder rod was 50…60% less than that on the two-cylinder layout, appeared to be the most expedient. In the second stage, a mathematical model for determining changes in the position of the center of mass of the feller-buncher depending on the inclination angle of the platform was derived. In the third stage, a mathematical model was derived for determining the limiting angle of slope of the terrain when the feller buncher moved up the slope. For this purpose, two calculation schemes were considered when the machine moved up the slope without and with a tilted platform. Zero support reaction on the front roller was taken as the stability criterion. In the fourth stage, a mathematical model for determining the limiting angle of slope of the terrain during the roll of the feller-buncher machine was obtained. In the fifth stage, the efficiency of the application of leveling systems was evaluated. A graph of the dependence of changes in the terrain slope angle on the platform slope angle was plotted, and a regression dependence for an approximate estimate was obtained. A regression analysis was also carried out, and dependencies were obtained to determine the weight of a feller-buncher with a leveling system and the added pressure on the ground caused by the increase in the weight of the base machine. The analysis of platform leveling systems showed the effectiveness of their application in the designs of feller-buncher machines, as it allows the machines to work on slopes with an inclination of 50…60% more than without them.

Promoting Role of Amorphous Carbon and Carbon Nanotubes Growth Modes of Methane Decomposition in One-Pot Catalytic Approach

We report the simultaneous production of hydrogen fuel and carbon nanotubes (CNTs) via methane dehydrogenation catalyzed with Ni/SBA-15. Most Ni nanoparticles (NPs) with size between 10 and 30 nm were highly dispersed on SBA-15 and most of them had a strong interaction with the support. At temperatures ranging from 500 to 800 °C, methane could be decomposed to release hydrogen with 100% selectivity at conversion between 51 and 65%. There was no CO or CO2 detectable in the reaction fluent. In the initial stage of the reaction, amorphous carbon and dehydrogenated methane species adsorbed on the Ni NPs promoted the CH4 decomposition. The amorphous carbon atoms were then transformed into carbon nanotubes which chiefly consisted of a multiwall structure and grew towards different orientations via a tip-growth or a base-growth modes, controlled by the interaction strength between the Ni NPs and the SBA-15 support. Reaction temperature affected not only methane conversion, but also the diffusion of carbon atoms on/in the Ni NPs and their precipitation at the interfaces. At higher temperature, bamboo-like CNTs or onion-like metal-encapsulated carbons were formed, mainly due to the rate of carbon atom formation greater than that of carbon precipitation for CNTs construction. The CNTs formation mechanisms are discussed and their growth modes under different conditions are proposed.

A Novel Coaxial Balance Mechanism for Reciprocating Piston Engines

Vibration is an important issue faced by reciprocating piston engines, and is caused by reciprocating inertia forces of the piston set. To reduce the vibration without changing the main structure and size of the original engine, we proposed a novel coaxial balance mechanism design based on a compact unit body. By introducing a second-order balance mass, this mechanism can significantly increase the efficiency of vibration reduction. The proposed mechanism can effectively balance the first-order and second-order inertia forces with the potential of balancing high-order inertia forces. To accurately determine the second-order balance mass, a closed-form method was developed. Simulation results with a single-cylinder piston DK32 engine demonstrate the effectiveness and advantage of the proposed mechanism. At a crankshaft speed of 2350 r/min, compared with the first-order balance device, the average root mean square velocity of the test points on the engine’s cylinder was reduced by 97.31%, and the support reaction force was reduced by 96.54%.

Mechanics of Arboreal Locomotion in Swinhoe’s Striped Squirrels: A Potential Model for Early Euarchontoglires

Differences between arboreal and terrestrial supports likely pose less contrasting functional demands on the locomotor system at a small body size. For arboreal mammals of small body size, asymmetrical gaits have been demonstrated to be advantageous to increase dynamic stability. Many of the extant arboreal squirrel-related rodents display a small body size, claws on all digits, and limited prehensility, a combination that was proposed to have characterized the earliest Euarchontoglires. Thus, motion analysis of such a modern analog could shed light onto the early locomotor evolution of eurarchontoglirans. In this study, we investigated how Swinhoe’s striped squirrels (Tamiops swinhoei; Scuiromorpha) adjust their locomotion when faced with different orientations on broad supports and simulated small branches. We simultaneously recorded high-Hz videos (501 trials) and support reaction forces (451 trials) of squirrels running on two types of instrumented trackways installed at either a 45° incline (we recorded locomotion on inclines and declines) or with a horizontal orientation. The striped squirrels almost exclusively used asymmetrical gaits with a preference for full bounds. Locomotion on simulated branches did not differ substantially from locomotion on the flat trackway. We interpreted several of the quantified adjustments on declines and inclines (in comparison to horizontal supports) as mechanisms to increase stability (e.g., by minimizing toppling moments) and as adjustments to the differential loading of fore- and hind limbs on inclined supports. Our data, in addition to published comparative data and similarities to the locomotion of other small arboreal rodents, tree shrews, and primates as well as a likely small body size at the crown-group node of Euarchontoglires, render a preference for asymmetrical gaits in early members of the clade plausible. This contributes to our understanding of the ancestral lifestyle of this mammalian ‘superclade’.

Drug and non-drug treatments of vertigo

Patients with complaints of “dizziness” often make an odyssey of visits to physicians belonging to various specialties. The prevalence of vertigo in the population is 17–30%. In most cases, disorders of various areas of the vestibular analyzer form the pathogenetic basis of vertigo and unsteadiness, while the most common cause of these complaints is the pathology of the peripheral area of the vestibular system: benign paroxysmal positional vertigo, vestibular neuronitis, Meniere’s disease. The cerebral vessel disease caused by hypertensive cerebral microangiopathy and cerebral atherosclerosis can also manifest by vertigo and unsteadiness. They can be represented by acute cerebrovascular disorders in the vertebrobasilar arterial system, transient ischemic attacks, as well as manifestations of chronic cerebrovascular disease (chronic cerebral ischemia, discirculatory encephalopathy). Episodes of recurrent spontaneous vestibular vertigo can be caused by vestibular migraine, which is rarely diagnosed in our country. The variety of reasons for complaints of vertigo and unsteadiness defines many therapeutic approaches to the treatment of these diseases. In recent times, modern drug and non-drug approaches to the treatment have been developed for patients with various diseases manifested by vertigo and unsteadiness. The most effective treatment is a comprehensive therapeutic approach that combines non-drug therapy, including vestibular gymnastics, training on the stabilographic platform with biofeedback according to the support reaction, and drugs that help reduce the severity, duration, and frequency of vertigo attacks, as well as accelerate vestibular compensation. Many studies have shown the efficacy of drugs enhancing microcirculation used for the prophylactic treatment of various causes of vertigo and unsteadiness.

Neuroclusterization method of stabilometric data

Stabilometry is a modern method for assessing the functional state of a person by the ability to maintain a stable balance of an upright posture. Technically, the implementation of the stabilometry method consists in measuring, with the help of specialized devices, the values that make up the support reaction, with the subsequent determination, according to these measurements, of the coordinates of the center of body pressure on the support. The nature of the migrations of the center of pressure during the stabilometric study is a source of information about the features of the processes of postural regulation. At the same time, up to the present time, there is a problem of the correct interpretation of the results of stabilometry. The adequacy of the conclusions is largely determined by the human factor, i.e. qualification of a specialist analyzing stabilometry data. Thus, in our opinion, the task of objectifying the assessment of stabilometry results is urgent. The aim of this work is to study the possibility of applying the neurocluster method using self-organizing neural networks to objectify the analysis of stabilometry data. The authors proposed a technique for analyzing the structure of individual and group stabilometric data by clustering them using selforganizing Kohonen neural maps with Euclidean metrics. Neuroclusterization of stabilometric data allows in automatic mode (without human intervention) to identify the type of group of subjects corresponding to the norm or pathology, various types of pathologies, as well as individual biometric characteristics of the subjects. The subsequent analysis of the individual characteristics of the data of the subjects, grouped in this way, makes it possible to detect deviations indicating the presence of abnormalities or the formation of various pathological conditions, which can be useful for the early diagnosis of diseases.

Impact resistance analysis of grille dam based on fluid structure interaction

Aiming at the impact failure of debris flow grille dam, considering the interaction of boulder-debris flow slurry- grille dam based on SPH-FEM, this article analyzed the variation laws of velocity, impact force and support reaction before and after debris flow slurry and boulders passing through grille dam. The results show that: SPH-FEM coupling method can truly reappear the impact of debris flow on the grille dam; the velocity of debris flow slurry and boulder are reduced by nearly 60% after passing through the dam, and the effect is remarkable; debris flow slurry and boulder have secondary impact on the grille dam. In the first impact, the greater the radius of the boulder, the greater the impact force; in the second impact, the impact force has nothing to do with the radius of the boulder.

STRUCTURAL SOLUTION AND METHOD OF CALCULATION OF GLUED LAMINATED TIMBER BEAM AND COLUMN JOINTS

The current trend in the construction industry is the development of projects of multi-storey buildings with a hybrid structural system using mainly timber load-bearing elements. The joints of load-bearing elements are criti-cal points of the frame with glued timber structures in terms of ensuring the load-bearing capacity and servicea-bility of the entire system. Existing publications in this area are mainly aimed at theoretical and experimental as-sessment of the stress-strain state of joints, while information on the construction of components for multi-storey buildings and recommendations for their design is extremely insufficient. The article presents structural solutions of the joints of glued laminated timber columns and beams, namely, hinged, which takes and transmits to the col-umn the support reaction of the beam, and rigid, which in addition to the support reaction takes the bending mo-ment. The support reaction from the beam to the column is transferred through a bolted connection and a T-shaped welded metal element. The bending moment is taken by two angles, which are fixed to the beam and welded to a vertical plate. Criteria of conformity of the proposed joints to load-bearing capacity requirements are pro-posed. The load-bearing capacity of the joint under the action of the support shear force is determined by the shear strength of the bolts in the column; the embedment strength of the metal of the T-shaped plate in the hole and bearing capacity of the bolted connection in the timber element. The action of the support bending moment requires the strength of the angles fastening to the beam and wood in the area of the bolts installation. A detailed algorithm for calculating the proposed design solutions in accordance with the requirements of the design stand-ards has been developed. Keywords: joint, glued laminated timber, beam, column, bearing capacity.