Dynamics rammers with two pairs of shock generators

The results of a numerical-analytic study for the dynamics of a vibro-impact mechanism with a crank vibration generator are presented in this paper. We show bifurcation diagrams and stability regions that let us find basic patterns in the reorganization of motion modes when the mechanism’s parameters change

Deformations of the Retaining Structures Upon Deep Excavations in Moscow

Foundation trenches for the buildings having underground floors and vehicular traffic tunnels are excavated in Moscow in congested urban housing environment. A retaining structure is a “slurry wall” made of cast-in-place reinforced concrete), and “soil-mixed-wall”. Retaining structures of trenches are fastened with the help of anchors, metal tie-beams, struts or floor structures. During the monitoring performed at major Moscow construction sites with deep trenches the (NIIOSP) named after Gersevanov created a database on retaining structures deformations

Heat treatment forming a dissipative metal base in wear-resistant chromium-alloyed cast iron

The maximum abrasive wear resistance is provided by a metal base from metastable retained austenite and martensite. Such a microstructure of 260Kh16M2 and 250Kh25MFT chromium cast irons with different types of Cr 7 C 3 and Cr 23 C 6 , carbides is created by high-temperature quenching with heating to temperatures of 1125-1170 °C and cooling in oil or air. Austenite is transformed to disperse martensite on the working surface as a result of the impact of abrasive particles during operation. Together with carbides, it provides a high hardening level and a high working capacity of the secondary microstructure of the cast irons. © 2018 Author(s)

Features of the exogenic development of Passalurus ambiguus (Nematoda, Oxyuroidae) at different temperature regimes

Passalurosis is a prevalent disease among helminthiases of domestic rabbits. This invasion is caused by the nematode Passalurus ambiguus (Nematoda, Oxyuroidae), which is cosmopolitan and localized in the cecum and colon of rabbits. Passalurosis is highly contagious and capable of unlimited spread, due to the biological characteristics of its pathogen, such as the conditions that ensure maximum preservation of parasites at exogenous stages of their development. Experimental research in the laboratory established the timing of development of P. ambiguus eggs isolated from the gonads of female helminths, depending on temperature regimes and features of their growth and development. According to the morphological features of Passalurus eggs, four stages were distinguished in their exogenous development: zygote, cleavage and formation of blastomeres, formation of larvae and motile larvae. Depending on the cultivation temperature, the duration of embryogenesis ranged from 4 to 9 days, and egg viability ranged from 59.3% to 72.7%. The most favourable temperature regime for the development of P. ambiguus eggs was the temperature of 35 °C, at which 72.7% of eggs with motile larvae were formed within 4 days. At this temperature, the zygote stage lasted for 1 day of cultivation, the stage of cleaving and formation of blastomeres occurred on days 1–2, the stage of larval formation on days 1–3, and the stage of formation of motile larva on days 3–4. At lower temperatures, the term of development of Passalurus eggs increased, and the number of viable eggs decreased. At temperatures of 30 °С and 25 °С, the development of Passalurus eggs took place during 5 and 7 days, respectively, and the viability was 66.7% and 62.7%. At these temperatures, the zygote stage lasted 1–2 and 1–3 days, the stage of cleaving and formation of blastomeres occurred on days 1–3 and 1–4, the stage of larval formation lasted from days 2–4 and 2–6, and the stage of formation of motile larvae took place on days 3–5 and 4–7, respectively. The least favourable temperature for the development of P. ambiguus eggs was the temperature of 20 °С, at which the formation of motile larvae occurred in 9 days, and their viability was only 59.3%. At this temperature, the zygote stage lasted 1–4 days, the stage of cleaving and blastomere formation occurred on days 2–6, and the larval formation stage on days 3–8, and the motile larval stage happened on days 5–9. The growth and development of P. ambiguus eggs was accompanied by significant changes in morphometric parameters, such as the increase in egg width and thinning of egg shell at the egg shell plug. The obtained data will allow preventive measures to be effectively implemented on rabbit farms that are susceptible to pinworms, taking into account the terms of exogenous development of pathogens in different seasons

The experimental cascade curves of EAS at E sub 0 10(17) eV obtained by the method of detection of Cherenkov pulse shape

The individual cascade curves of EAS with E sub 0 10 to the 17th power eV/I to 3/ were studied by detection of EAS Cherenkov light pulses. The scintillators located at the center of the Yakutsk EAS array within a 500-m radius circle were used to select the showers and to determine the main EAS parameters. The individual cascade curves N(t) were obtained using the EAS Cherenkov light pulses satisfying the following requirements: (1) the signal-to-noise ratio fm/delta sub n 15, (2) the EAS axis-detector distance tau sub 350 m, (3) the zenith angle theta 30 deg, (4) the probability for EAS to be detected by scintillators W 0.8. Condition (1) arises from the desire to reduce the amplitude distortion of Cherenkov pulses due to noise and determines the range of EAS sizes, N(t). The resolution times of the Cherenkov pulse shape detectors are tau sub 0 approx. 23 ns which results in distortion of a pulse during the process of the detection. The distortion of pulses due to the finiteness of tau sub 0 value was estimated. It is shown that the rise time of pulse becomes greater as tau sub 0.5/tau sub 0 ratio decreases

The dynamics of eccentric vibration mechanism (Part 1)

This paper presents a mathematical model of a new multi-striker eccentric shock-vibration mechanism (ESVM) with a crank-sliding bar vibration exciter (CSVE) and an arbitrary number of pistons. Analytical solutions for the parameters of the model are obtained to determine the regions of existence of stable periodic motions. Under the assumption of an absolutely inelastic collision of the piston, we derive equations that single out a bifurcational unattainable boundary in the parameter space, which has a countable number of arbitrarily complex stable periodic motions in its neighborhood. We present results of numerical simulations, which illustrate the existence of periodic and stochastic motions. The methods proposed in this paper for investigating the dynamical characteristics of the new crank-type conrod mechanisms allow practitioners to indicate regions in the parameter space, which allow tuning these mechanisms into the most efficient periodic mode of operation, and to effectively analyze the main changes in their operational regimes when the system parameters are changed

Influence of orthopedic pathology on progression of children myopia

The problem of studying myopia as multifactorial disease remains relevant due to the increase and morbidity of the disease, particularly in childhood. One of the factors of progressing myopia among children - orthopedic pathology which progresses simultaneously with myopia - is discussed in the article. The aim of the work was to reveal dependance between orthopedic pathology and progression of myopia. A retrospective analysis of the restuls of prophylactic examination of children of decreed ages in 2007-2012 years was realized. The analysis of the results of medical examinations showed that myopia and accomodation spasm come to 80 % of cases in the structure of revealed ophthalmic pathology. It was revealed that orthopedic pathology accompanies and often provides development and progression of myopia. The increase of morbidity with refraction disorder is registered during 5years. Direct dependance between orthopedic pathology and progression of myopia was revealed

A study of Instagram as a platform for patients preventive healthcare programs

The article discusses results of social network Instagram review as a platform for conducting social projects for patients on the prevention of diseasesВ статье рассматриваются результаты исследования социальной сети Instagram как площадки для проведения социальных проектов для пациентов о профилактике и лечении заболевани