Force Imbalance Research Articles

Historical background and consequences of the kanal Istanbul construction

The security and stability of the Black Sea Region is vital for the interests of Russia. The current status of the Black Sea Straits, which is regulated by the 1936 Montreux Convention, generally ensures this security. A destabilizing factor for the region may become Turkey’s desire to strengthen control over the Straits and the construction of an alternative channel, which will be under Turkish jurisdiction and which will not be subject to the Montreux Convention. The construction of the Kanal Istanbul in the context of global instability and the existence of serious contradictions between Western countries and Russia can lead to an imbalance of forces in the Black Sea region. In this regard, this article provides a brief historical overview of how Russia has defended its vital interests in this region over the centuries, as well as how the control over the passage from the Black Sea to the Mediterranean by the different actors was influencing the balance of power in the region. In addition, for a better understanding of the military, political, economic, and ecological consequences of the construction of the Kanal Istanbul the article analyzes the current situation around this project using a matrix of interests. Consequently, by studying the historical and modern processes taking place in the Black Sea region, and also considering the importance of this region for the security and economic well-being of Russia, the author came to the conclusion that the future status of the Kanal Istanbul should be included in the Russian-Turkish agenda.

АНАЛІЗ ФАКТОРІВ ВПЛИВУ НА КОНКУРЕНТОСПРОМОЖНІСТЬ МІКРО-, МАЛИХ ТА СЕРЕДНІХ ПІДПРИЄМСТВ УКРАЇНИ НА СВІТОВОМУ РИНКУ

The article considers a number of factors that affect the competitiveness of micro, small and medium-sized enterprises of Ukraine on the world market. The great role of MSMEs in the economy and development of the country is shown. The need to ensure a high level of competitiveness of MSMEs at the international level was emphasized. The following factors influencing competitiveness are listed, such as: the introduction of innovations, opportunities to attract capital, the availability of qualified workers and managers, joining business associations, the presence of demand for MSME goods/services, the presence of partners abroad, the country's image, state support policy, the presence of a brand, the ability to ensure the necessary volumes of production, compliance with international standards, as well as social responsibility of business. Their influence on the competitiveness of MSMEs in the world market is analyzed. A study of each influencing factor in modern conditions was made. It is considered that the introduction of innovations by MSMEs is much faster than by large enterprises, the interest of small enterprises in carrying out innovative activities is aimed at non-technological improvements both in the field of service provision and in the industry. During the war, MSMEs lack qualified personnel due to the labor force imbalance in Ukraine. Emphasis was placed on the need to include MSMEs in business associations for successful work in the conditions of global market competition. It is shown that the positive image of our country on the international market, which is being formed now, has an impact on competitiveness and ensures a good attitude towards the products of Ukrainian manufacturers. Ensuring the necessary production volumes is currently possible only under the conditions of reformatting of logistics, mutual assistance, and state support. Means of finding partners abroad by Ukrainian MSMEs, possible sources of financing are listed. The importance of social responsibility of MSMEs, the need for branding their products was noted. compliance with international standards.

Biotherapic T. cruzi 17DH when continuously used clinically improves mice infected with T. cruzi.

Introduction: In Trypanosoma cruzi infection, the pathogenesis is the result of a rupture in the host - parasite relationship [1]. This rupture is related to the imbalance of the vital force of the host, expressed through signs and symptoms, defined by Hahnemann (1995)[2] as being the source of the disease. There is no research in the literature about the clinical evolution of mice experimentally infected with T. cruzi and treated in different ways using biotherapic. Therefore, this is an area to be studied in the future.
 
 Aim: To evaluate the effect of different ways of treatment using biotherapic T. cruzi 17 DH on clinical evolution of mice experimentally infected with T. cruzi.
 
 Materials and methods: A blind randomized controlled trial was performed, using 30 swiss male mice, aged 28 days, divided into groups according to the treatment: CONTROL - animals treated with 7% water-alcohol solution diluted in water given ad libitum in an amber bottle; GAVAGE – animals treated with medication highly diluted T. cruzi 17 DH from 4th to 9th day of infection by gavage; WATER -animals treated with highly diluted T. cruzi 17 DH in water ad libitum offered in an amber bottle until the end of the study period. The groups were infected with the Y strain of T. cruzi, intraperitoneal, 1400 blood trypomastigotes. The medicine was handled according to the Brazilian Homeopathic Pharmacopoeia [3] with microbiological test according to RDC n° 67 and in vivo biological risk. Parasitemic curve was determined by daily counting of the parasites [4]. Were measured temperature, weight, intake of water and feed, the ruffle fur and survival of mice. Statistical analysis was performed using the tests Fisher Exact and Log-Rank, with a significance of 5%. The experiment was approved under the protocol n° 030/2008 - Ethics in Animal Experimentation of the Universidade Estadual de Maringá.
 
 Results: The mice under different treatment ways using biotherapic T. cruzi 17DH showed differences in the clinical evolution. The treatment using biotherapic diluted in water initially shows hypothermia, with subsequent recovery of normal temperature (p=0.05) (Fig1). The weight curve shows a better evolution in mice treated with water compared to control groups (p=0.055) and the groups treated by gavage (p=0.0064). Feed and water intake did not differ among the groups. While the mice that were treated with biotherapic diluted in water showed a slight level of ruffled fur, the mice in control groups and the ones treated by gavage showed a more intense level of ruffled fur (p=0.00001). The difference in the evolution of mortality among the groups was significant (p=0.034), while in the group treated with biotherapic diluted with water, the mortality rate started later, reaching the maximum of 90%. This group showed a better clinical result, expressed by the smaller extent of ruffled fur, a better evolution of the temperature curve and higher gain of weight. This is an important result because the Y strain of T. cruzi has a mortality rate of 100% in mice, showing once again the good performance of biotherapic in this model of infection. 
 
 Conclusion: The use of biotherapic T. cruzi 17DH for a long period causes clinical improvement of the infected mice with Trypanosoma cruzi. The clinical use of these results in human beings should consider the allometric medicine dosage which takes into account the metabolic rate of each organism.

Dimeric colloidal inclusion in a chiral active bath: Effective interactions and chirality-induced torque.

Colloidal inclusions suspended in a bath of smaller particles experience an effective bath-mediated attraction at small intersurface separations, which is known as the depletion interaction. In an active bath of nonchiral self-propelled particles, the effective force changes from attraction to repulsion, an effect that is suppressed when the active bath particles are chiral. Using Brownian dynamics simulations, we study the effects of channel confinement and bath chirality on the effective forces and torques that are mediated between two inclusions that may be fixed within the channel or may be allowed to rotate freely as a rigid dimer around its center of mass. We show that the confinement has a strong effect on the effective interactions, depending on the orientation of the dimer relative to the channel walls. The active particle chirality leads to a force imbalance and, hence, a net torque on the inclusion dimer, which we investigate as a function of the bath chirality strength and the channel height.

Balancing high-speed rotors at low speed using optimized parametric excitation and tuned nonlinear feedback

The paper presents an improved slow-speed mass balancing procedure capable of reducing high-speed related imbalance. Parametric excitation is used to project the small imbalance forces onto a chosen mode of vibration, corresponding to a high critical rotation speed. The method employs two kinds of parametric excitation leading to combination and principal parametric resonances. The former projects the imbalance forces onto a selected vibration mode, and the latter significantly amplifies the dynamic response due to imbalance. In addition to the parametric excitations, specially tuned nonlinear feedback forces are applied to limit the response to desired vibration levels and achieve a pseudo-linear behavior. In situ proper tuning of the nonlinear terms, and parametric excitations, enables to increase both amplification and sensitivity to the imbalance forces without having to compromise between the two. The latter includes digital, nonlinear feedback that enhances the sensitivity to imbalance forces, while limiting the level of vibration. This method allows to identify the projection of the imbalance on any desired mode, and therefore to cancel them by adding or removing mass. An experimental realization of the method validates the theory with good accuracy.

Associations between facet tropism and vertebral rotation in patients with degenerative lumbar disease

BackgroundVertebral rotation and facet tropism are very common in various lumbar degenerative diseases. Facet tropism means the presence of asymmetric angles on both sides of the facet joints. Studies have shown that facet tropism contributes to lumbar degenerative disease, and also inevitably leads to the asymmetry of movement and the imbalance of force, which may be possible to rotate the vertebral body. The aim of this study was to explore the correlation between lumbar vertebral rotation and facet tropism in patients with lumbar degenerative diseases.MethodsA total of 198 patients with lumbar degenerative diseases from 2018 to 2019 were enrolled. Five hundred and seventy vertebral rotation angles and 1140 facet angles were measured. The vertebral bodies are divided into non-rotation group (Group A) and rotation group (Group B) with the vertebral rotation angle of 3° as the boundary. The information including gender, age, BMI (body mass index), bone mineral density, history of smoking, drinking, hypertension, diabetes, diagnosis, segment distribution, and degree of facet degeneration were also counted. Using inter-class correlation coefficients (ICC) to test the reliability of measurement results. Univariate and multivariate logistic regression analysis were used to analyze the relationship between vertebral rotation and facet tropism.ResultsThe consistency of the ICC within the groups of the observers is above 0.8, with good agreement. The results of univariate analysis showed that facet tropism was significantly different between group A and group B (OR (odds ratio) = 3.30, 95% CI = 2.03–5.35, P < 0.0001). Other significant factors were included as adjustment variables into the multivariate regression model. Three models were analyzed separately (Model 1: non-adjusted. Model 2: adjust for age; facet degeneration; Model 3: adjust for age; disease distribution; segment distribution; facet degeneration). The results showed that after adjusting the confounders, the correlation between facet tropism and vertebral rotation did not change (Model 1: OR = 3.30, 95% CI = 2.03–5.35, P < 0.0001; Model 2: adjusted OR = 2.87, 95% CI = 1.66–4.97, P = 0.0002, Model 3: adjusted OR = 2.84, 95% CI = 1.56–5.17, P = 0.0006).ConclusionCurrent research demonstrates that there is an association between vertebral rotation and facet tropism, suggesting that vertebral rotation may also have a certain degree of correlation with lumbar degenerative diseases.

Synchrony of sarcomeric movement regulates left ventricular pump function in the in vivo beating mouse heart.

Sarcomeric contraction in cardiomyocytes serves as the basis for the heart's pump functions. It has generally been considered that in cardiac muscle as well as in skeletal muscle, sarcomeres equally contribute to myofibrillar dynamics in myocytes at varying loads by producing similar levels of active and passive force. In the present study, we expressed α-actinin-AcGFP in Z-disks to analyze dynamic behaviors of sequentially connected individual sarcomeres along a myofibril in a left ventricular (LV) myocyte of the in vivo beating mouse heart. To quantify the magnitude of the contribution of individual sarcomeres to myofibrillar dynamics, we introduced the novel parameter "contribution index" (CI) to measure the synchrony in movements between a sarcomere and a myofibril (from -1 [complete asynchrony] to 1 [complete synchrony]). First, CI varied markedly between sarcomeres, with an average value of ∼0.3 during normal systole. Second, when the movements between adjacent sarcomeres were asynchronous (CI < 0), a sarcomere and the ones next to the adjacent sarcomeres and farther away moved in synchrony (CI > 0) along a myofibril. Third, when difference in LV pressure in diastole and systole (ΔLVP) was lowered to <10 mm Hg, diastolic sarcomere length increased. Under depressed conditions, the movements between adjacent sarcomeres were in marked asynchrony (CI, -0.3 to -0.4), and, as a result, average CI was linearly decreased in association with a decrease in ΔLVP. These findings suggest that in the left ventricle of the in vivo beating mouse heart, (1) sarcomeres heterogeneously contribute to myofibrillar dynamics due to an imbalance of active and passive force between neighboring sarcomeres, (2) the force imbalance is pronounced under depressed conditions coupled with a marked increase in passive force and the ensuing tug-of-war between sarcomeres, and (3) sarcomere synchrony via the distal intersarcomere interaction regulates the heart's pump function in coordination with myofibrillar contractility.

The Cross‐Shore Component in the Vertical Structure of Wave‐Induced Currents and Resulting Offshore Transport

AbstractA comprehensive field survey was conducted, and a numerical model based on the Princeton Ocean Model was established to investigate the vertical structure of current induced by surface waves and identify its effect on sand loss from a beach. Previous studies have examined wave‐induced longshore transport, whereas this study focused on cross‐shore transport caused by waves. The introduction of vertically dependent radiation stress revealed that wave‐induced vertical gyres existed with onshore and offshore flows in the upper and lower layers, respectively, besides the well‐known wave‐induced longshore flow. It was found that the vertical gyres were caused by the onshore wave force (a gradient of radiation stress) in the upper layer and the offshore wave force usually existed in the lower layer, as well as the horizontal imbalance of local wave force. The locations of wave‐induced vertical gyres were found to correspond to the location of sediment erosion, and thus the lower part of the vertical gyres drove the offshore transport of eroded sediment. Moreover, the vertical gyres were located in areas with a highly variable topographic gradient (e.g., at a bar), and their driven offshore currents (undertow/return flow) extended far beyond the surf zone. The topographic slope had a profound effect on the vertical structure. Numerical experiments showed that an extended breakwater from the eastern headland of the bay could prevent sediment from being eroded. Furthermore, the shear front at the rim of a horizontal gyre could retain suspended sediment in the center of the gyre.

Cross‐valley vortices in the Inn valley, Austria: Structure, evolution and governing force imbalances

AbstractExchange of momentum and scalars in the mountain boundary layer is achieved through an interaction of meso‐to‐microscale motions, occurring to varying extents depending on the combined effect of thermally driven as well as dynamically driven forcings. One such motion, known as a secondary circulation, results from a horizontal force imbalance across a curved valley segment, wherein the centrifugal force towards the outside of the valley bend can create a pressure gradient force in the opposite direction. The lack of adequate measurement strategies capable of sampling such motions in curved mountain valleys explains the near‐absence of any observational evidence of secondary circulations there. The goal of the CROSSINN (Cross‐valley flow in the Inn valley investigated by dual‐Doppler lidar measurements) campaign, conducted in a curved segment of the Inn valley, Austria, was to determine the character of the cross‐valley flow by means of a coplanar retrieval applied to a multi‐Doppler wind lidar configuration. A signature of a secondary circulation, hereafter referred to as a cross‐valley vortex, stood out particularly during intense daytime upvalley flow episodes. Vortices were detected on 23 upvalley wind days, with a declining frequency of occurrence from August to October. Nearly all identified vortices were marked by a low‐level upvalley jet, a clockwise wind direction turning with height, and a cessation of upvalley flow at the local ridgeline level. The routinely sampled coplanar‐retrieved cross‐valley wind field enabled the quantification of more advanced parameters based on vorticity, revealing a faster spin rate of the vortex around its streamwise axis given a stronger upvalley flow, and a period of revolution on the order of several tens of minutes. A detailed inspection of the lateral momentum budget and associated uncertainties confirmed the importance of the relationship between the centrifugal and the pressure gradient force for the cross‐valley vortex occurrence in a curved valley.

Usefulness of inclined circular cylinders for designing ultra-wide bandwidth piezoelectric energy harvesters: Experiments and computational investigations

This study proposes to change the inclination angle (α) of a circular cylinder with respect to oncoming flow in order to broaden the effective wind speed bandwidth of the piezoelectric energy harvester. Comprehensive wind tunnel experiments are conducted to investigate the energy harvesting characteristics of the system under different inclination angles. The experimental results demonstrate that compared to the conventional vortex-induced vibration piezoelectric energy harvester (VIVPEH), an appropriate inclined cylinder can broaden the effective wind speed range for the VIVPEH. It is experimentally shown that the inclined cylinder at α = 60° can reduce the threshold wind speed and broaden the effective wind speed bandwidth by more than 229%. In addition, inclined circular cylinders at α = 25°, 30°, 35°, 40°, and 45° can produce torsional vibration and high voltage output under high wind speed. Through frequency analysis and computational fluid dynamics (CFD) simulations, the influence mechanism and causes of torsional vibration are explored in detail. The results show that the axial flow will prevent the free shear layer from falling off and cause the force imbalance at the top and bottom of the inclined cylinder, resulting in a torsional vibration and a series of other phenomena. The appearance of the torsional vibration rapidly reduces the frequency of the conventional transverse vortex-induced vibration (VIV). The superposition of the transverse bending vibration and the torsional vibration within a certain wind speed range results in a high voltage output.

Analytical and numerical calculation of the detachment of particle structures from fibers

Not much research has been done on the detachment of deposit structures from fibers in gas flow. This study presents two approaches to determine the fluid velocities uc required for detachment. The first is an analytical model based on the imbalance of drag and adhesive forces. With the help of available models in literature two curves for uc as a function of deposit diameter were calculated. The two curves represent the different conditions present in a deposited structure, consisting of a mixture of reactive and inert matter, before and after reaction. It approximates the structure by one sphere, that consists of two identical half spheres, of which one detaches due to drag. The second approach is a CFD model, in which the deposited particle structure is represented through an immersed boundary method (IBM). It calculates adhesive forces based on the van der Waals force between two half-spaces, while drag is directly evaluated from flow properties at the structure’s surface. To be comparable with the analytical approach, it also approximates the deposit with two half spheres. The models are capable of describing detachment velocity behavior as a function of deposit structure size and porosity as reported in literature.Copyright © 2021 American Association for Aerosol Research

Modeling of Cutting Rock: From PDC Cutter to PDC Bit—Modeling of PDC Bit

Summary In this paper, we integrated our polycrystalline diamond compact (PDC) cutter model (Chen et al. 2021) into a PDC bit model that can predict the weight on bit (WOB), torque on bit (TOB), and imbalanced side force on a bit under given drilling conditions. We first proposed a method to determine the actual cutting plane and depth of cut of each cutter on a PDC bit. Once the two parameters for each cutter are determined, the cutter model can then be applied to calculate the cutting force of each cutter. The final bit force and moment (i.e., WOB, TOB, and imbalanced side force) are calculated as the resultant force and moment of cutting forces of all cutters. The PDC bit model in this paper considers all bit design parameters, including bit matrix geometry, blade profile, cutter layout, and the inclination of each cutter. Furthermore, the bit model also considers some bottomhole assembly (BHA) parameters (e.g., bit tilt angle, location of first fulcrum point, and tool face/steering plane angle), which allows the bit model to simulate a bit under different drilling modes. The bit model is also validated by published test data and field applications. Finally, case studies are conducted, and the influence of bottomhole stresses, BHA parameters, and drilling modes on bit force and moment are discussed. A field application of the bit model is also provided. The bit model can be directly used for PDC bit design and simulation. In fact, this paper presents a general way to integrate a cutter model into a PDC bit model. Readers are also encouraged to apply this method to integrate their own cutter model into a PDC bit model.

Importance of condition monitoring in mechanical domain

This paper discusses the importance of condition Monitoring in the mechanical domain. Over the last few decades, researchers have been particularly interested in mechanical condition tracking. Automatic machinery is susceptible to malfunction and progressive degradation from its initial state in harsh environments. For this, a suitable parameter that shows real-time internal conditions and mechanical device fault incidence must be selected; as a result, continuous system monitoring is a more critical part of early detection of failure that can trigger system shutdown, reducing system downtime and saving money. Force imbalances, gearing system failures, bearing failures, shaft loading conditions, and incorrect machine selection for a particular job may all cause faults in mechanical systems. System parameters such as efficiency, vibrations, noise, temperature, strain, wear on movables, and lubrication monitoring are needed to detect the fault. Several early sensors are being used in this case to monitor the status of device parameters in real time. Signal processing methods are used to convert the sensors' signal to an electrical signal, which is then processed and analyzed. The device's smooth operation necessitates parameter sensing and monitoring in-process. The use and benefits of sensors and transducers, as well as advanced signal processing, each have their own set of benefits and drawbacks. The basics of various condition monitoring techniques, approaches to condition monitoring, Condition Monitoring Types, and other related topics will be covered in this article. The aim of this paper was to expand condition monitoring to a variety of mechanical domains, including bearing defect detection, rotary machine vibration monitoring, cutting tool monitoring, machine tool monitoring, electricity, vehicles, gear defect detection, and bearing defect detection, to name a few.

Eliminating spurious currents in phase-field-theory-based lattice Boltzmann equation for two-phase flows

Spurious currents are frequently observed near an interface in the equilibrium multiphase flow system by lattice Boltzmann equation (LBE). These unphysical phenomena are the result of force imbalance of LBE at a discrete level. In this paper, we develop a well-balanced Cahn–Hilliard equation-based LBE for incompressible two-phase flows. The effects of small initial perturbation of order parameter or dynamic pressure and nonisotropic discretization of gradient in force term on eliminating the spurious currents are investigated systematically. Numerical simulations including flat interface and stationary droplet problems are carried out to show the capability of present LBE for eliminating the spurious currents and its accuracy. The results predicted by the present LBE are compared with those by mixed isotropic discretizations scheme (MIDS) frequently used in the LBE community. Numerical results show that the initial perturbation of order parameter or dynamic pressure and nonisotropic discretization of gradient term has no significant effect on eliminating the spurious currents by present LBE, while the MIDS is sensitive to them.

Abordagem fisioterapêutica no tratamento da síndrome do estresse tibial medial –canelite em corredores de rua

As an exponential increase in road corridors, there is also an increase in injuries, within them, to Medial Tibial Stress Syndrome (SETM), which is described as a lesion in the external layer of the tibia, causing the posteromedial region to have a size of approximately ≥ 5cm. The objective of this study is to identify the factors of the cliff, how it has been carried out or the diagnosis and physiotherapeutic treatment for the SETM. Methodology: it is about a literature review, using a qualitative research method, of a descriptive nature. A bibliographic survey was carried out in PubMed, Google Scholar and SciELO data banks. Result: Due to the exact cause of SETM is unknown, being more oily than it is a multifatorial condition, identified cliff factors: o increased BMI; navicular left above 10mm; increase in plantar flexion ADM; inappropriate treinamento plane; Previous injuries no 2/3 distal to the leg and imbalance of muscular forces. Its diagnosis was made through a clinical evaluation, containing a historical examination, followed by a physical examination. Despite the clinical evaluation being certified, image exams may be necessary in some specific cases. Conclusion: Despite the great incidence of SETM, it was not identified during the literature review of this study, a standard protocol considered effective, therefore its treatment is concentrated on the clinical presentation of the patient, being generalized interventions, lacking further scientific evidence of good quality. to verify the effectiveness of a specific physiotherapeutic intervention, not specific treatment of SETM.

Turbocharger rotor vibration reduction methodology with an active control scheme

The turbocharger rotors are often supported on the dual film floating ring bearings that are meant for high-speed applications. The damping ability of these bearings is relatively high. However, due to highly nonlinear bearing forces, often system instability occurs. The present work focuses on the dynamic analysis and active vibration control studies of a practical turbocharger rotor system with the use electromagnetic actuator (EMA) system. Initially, the system is analyzed using the finite element approach. The inner and outer film forces are considered along with rotor imbalance forces. The dynamic responses at the critical operating speeds are obtained numerically. To minimize the vibration amplitudes, a tiny EMA system is installed at one of the nodes along the shaft. The effect of the EMA parameters such as the number of turns of winding coil around a pole ( N c) and pole-face area ( A a) on the response of the system is studied. Further, an open-loop control configuration is practically studied by using a vibration shaker at the bearing node under different operating speeds, and the percentage reduction in critical vibration amplitudes is recorded. The EMA system is effectively controlling the high-speed rotor system vibrations. The EMA parameters N c and A a are influencing the system vibration response. Further, an experimental result has given considerable vibration reduction with the present approach.

Janus sand filter with excellent demulsification ability in separation of surfactant-stabilized oil/water emulsions: An experimental and molecular dynamics simulation study

Developing efficient separation materials for surfactant-stabilized oil/water emulsions is of great importance while significantly challenging. In this work, a sand filter with Janus channels was prepared by simply mixing superhydrophilic and superhydrophobic quartz sand in a mass ratio of 1:1. Due to the imbalanced force of droplets in those Janus channels, better separation performance under gravity was achieved for both surfactant-stabilized oil-in-water and water-in-oil emulsions than the superhydrophilic or superhydrophobic sand filter alone. It also received high flux (1080.13 L m−2 h−1 for dichloroethane-in-water emulsion and 1378.07 L m−2 h−1 for water-in-dichloroethane emulsion) and high separation efficiency (99.80% for dichloroethane-in-water emulsion and 99.98% for water-in-dichloroethane emulsion). Molecular dynamics based computational work and experimental studies revealed that the Janus channels of mixed sand layer exhibited greater interaction energy with emulsion droplets for more efficient adsorption, resulting in better demulsification capability and separation performance. The as-prepared Janus sand filters retained excellent separation performance after 50 cycles of the stability test. Together with the needs on only cheap and easily accessible raw materials and its environmentally friendly preparation method, this Janus sand filtration process exhibits its great potential for the separation of surfactant-stabilized oil/water emulsions.

Learning Fairly With Class-Imbalanced Data for Interference Coordination

Deep neural networks (DNNs) have been widely applied for classification tasks in wireless communications such as link scheduling, user association and base station (BS) muting. When training a DNN using datasets with highly-skewed class distribution where most data belong to a few majority classes, learning performance for minority classes will degrade since the imbalanced data forces the training process to be biased towards the majority classes. In many wireless problems, multiple decisions for classification are made jointly, say deciding which BSs in a network should be muted to avoid interference. In this paper, we employ DNN to learn an optimal predictive interference coordination policy, and strive to avoid biased learning in such a multi-label multi-class classification problem. The major contribution is proposing a training method to encourage fairness among classes by minimizing the maximal cost of decisions among classes, which is converted into a problem to optimize the weighting factors on the training cost of each class. We provide a gradient descent algorithm to optimize the weighting factors and the model parameters of the DNN by alternative updates. Simulation results show that the training method can improve the learning performance for the minority class and can achieve higher network utility than existing training methods.

Simulations and experiments of phase separation in binary dusty plasmas.

Molecular dynamics simulations of binary dusty plasmas have been performed and their behavior with respect to the phase separation process has been analyzed. The simulated system was inspired by experimental research on phase separation in dusty plasmas under microgravity on parabolic flights. Despite vortex formation in the experiment and in the simulations the phase separation could be identified. From the simulations it is found that even the smallest charge disparities lead to phase separation. The separation is due to the force imbalance on the two species and the separation becomes weaker with increasing mean particle size. In comparison, experiments on the phase separation have been performed and analyzed in view of the separation dynamics. It is found that the experimental results are reproduced by the simulation regarding the dependency on the size disparity of the two particle species.

АНИЗОТРОПИЯ РАДИАЛЬНОЙ ЖЕСТКОСТИ РАСТОЧКИ КОРПУСА ПОД ОПОРЫ ШПИНДЕЛЯ ТОКАРНОГО СТАНКА

In the paper there are considered problems connected with the radial stiffness anisotropy of body borings for lathe spindle bearings. Factors having an influence upon stability of its operation characteristics of a machine-tool during idling are considered. &#x0D; The analysis of force factors having an influence upon bearings of a spindle unit during lathe idling is carried out. The work purpose is to determine a quantitative and qualitative situation in the changes of boring forms for spindle bearings under the impact of loads mentioned. As an object of investigations there is chosen the lathe “Vector” manufactured at the Middle-Volga machine-tool plant. A finite element modeling is carried out for deformation investigations in the body boring of the spindle unit under the impact of forces caused by weight and imbalance of the rotating spindle. There is shown a geometrical model of a spindle carrier body, the peculiarities of a finite element model formation and a procedure for the fulfillment of a numerical experiment are described, and approaches of boundary conditions setting are also considered. As a result of a finite element there are obtained values of finite element unit displacements lying on the surface of the body boring of the spindle carrier under the impact of the mentioned power factors. The results found are presented for illustration in the form of solid and flat graphical dependences. The analysis of numerical experiment results has confirmed the presence of the stiffness anisotropy in spindle unit bearings. The phenomenon of stiffness anisotropy in bearings was already under consideration in investigations carried out earlier. But the results of the numerical experiments carried out by us have shown that along with other factors the imbalance forces together with design peculiarities of body parts have an influence upon the constancy of elastic characteristics of bearings. &#x0D; The matter obtained can be used during development of measures for design changes in a spindle unit body with the purpose of stiffness anisotropy decrease in the borings for bearing.