Phenomenology of GeV-scale Heavy Neutral Leptons

We review and revise phenomenology of the GeV-scale heavy neutral leptons (HNLs). We extend the previous analyses by including more channels of HNLs production and decay and provide with more refined treatment, including QCD corrections for the HNLs of masses $\mathcal{O}(1)$ GeV. We summarize the relevance of individual production and decay channels for different masses, resolving a few discrepancies in the literature. Our final results are directly suitable for sensitivity studies of particle physics experiments (ranging from proton beam-dump to the LHC) aiming at searches for heavy neutral leptons.Comment: journal versio

Compliance error compensation in robotic-based milling

The paper deals with the problem of compliance errors compensation in robotic-based milling. Contrary to previous works that assume that the forces/torques generated by the manufacturing process are constant, the interaction between the milling tool and the workpiece is modeled in details. It takes into account the tool geometry, the number of teeth, the feed rate, the spindle rotation speed and the properties of the material to be processed. Due to high level of the disturbing forces/torques, the developed compensation technique is based on the non-linear stiffness model that allows us to modify the target trajectory taking into account nonlinearities and to avoid the chattering effect. Illustrative example is presented that deals with robotic-based milling of aluminum alloy

Compensation of Tool Deflection in Robotic-Based Milling

International audienceThe paper presents the compliance errors compensation technique for industrial robots, which are used in milling manufacturing cells. under external loading, which is based on the non-linear stiffness model. In contrast to previous works, it takes into account the interaction between the milling tool and the workpiece that depends on the end-effector position, process parameters and cutting conditions (spindle rotation, feed rate, geometry of the tool, etc.). Within the developed technique, the compensation errors caused by external loading is based on the non-linear stiffness model and reduces to a proper adjusting of a target trajectory that is modified in the off-line mode. The advantages and practical significance of the proposed technique are illustrated by an example that deals with milling with Kuka robot

Elasto-Dynamic Model of Robotic Milling Process Considering Interaction between Tool and Workpiece

International audienceIn this paper, a reduced elasto-dynamic model of the robotic based milling process is presented. In contrast to previous works, it takes into account the interaction between the milling tool and the workpiece that depends on the end-effector position, process parameters and cutting conditions (spindle rotation, feed rate, geometry of the tool, etc.). To reduce the dimension of the problem, the robot dynamics is described as an equivalent mass-spring-damper system with six dimensions. This approach, based on the Rayleigh-Ritz approximation, aims at decreasing computational cost and at avoiding inaccuracy due to ill-conditioning in the full size model. To achieve a realistic modeling of the milling process, the machining efforts due to the interaction between robot, tool and working material are introduced into the robot model and calculated at each time instant. Using this global model that integrates the robot dynamics and the milling process particularities, it is possible to obtain the movement of the robot end-effector and corresponding quality of the final product (profile, macro geometry, etc.). In addition, this model allows selecting the best process parameters and avoiding the vibratory behavior of this machining system which can dramatically affect the milling quality. The developed model is applied to the behavior analysis of KUKA KR270 robot used for milling applications. This allows finding acceptable range for robot motion profile parameters

Influence du talonnage sur la stabilité du système usinant

Le phénomène du talonnage est un problème important dans les opérations d’usinage. Il se produit lorsque la face en dépouille de l’outil entre en contact avec la surface usinée. Un modèle de prédiction de l’effet de talonnage a été proposé. L’objectif de cet article est de faire une analyse de la stabilité du système usinant. En effet les lobes de stabilité se décalent dans la zone des hautes fréquences sous l’influence de talonnage ou ce phénomène modifie l’amortissement du système. Les résultats obtenus permettent d’optimiser les paramètres de coupe associés à une opération d’usinage

Extending service life of rails in the case of a rail head defect

Tračnice su tijekom svoje uporabe izložene procesima trošenja, korozije i kontaktnog zamora uslijed savijanja. Kao posljedica tih procesa, na tračnicama dolazi do raznih oštećenja i neispravnosti. Nastavak uporabljivosti tračnica ovisi o veličini, položaju i smjeru oštećenja. U ovom su radu izračunane maksimalno dopuštene vrijednosti veličine pukotine metodom konačnih elemenata. Smjer ravnine pukotine analiziran je u odnosu na ravninu kontaktne površine kotač-tračnica. Utemeljena je ovisnost faktora veličine naprezanja o površini pukotine. To omogućuje daljnju upotrebu oštećenih tračnica i siguran nastavak rada na željezničkim prugama sa slabijom aktivnošću.Rails are subjected to the processes of wear, corrosion and contact and bending fatigue during their lifecycle. As a result of these processes, various types of damage and defects are formed in rails. The residual life of rails depends on the size, position, and orientation of defects. Maximum permissible crack-size values are calculated in this paper using the finite element method. The crack plane orientation relative to the contact surface plane is analysed. The dependence of the stress intensity factor on the crack area is established. This allows continued use of defective rails and safe operation on low-activity railways

Technique for calculating technological parameters of non-Newtonian liquids injection into oil well during workover

Technique for automated calculation of technological parameters for non-Newtonian liquids injection into a well during workover is presented. At the first stage the algorithm processes initial flow or viscosity curve in order to determine rheological parameters and coefficients included in equations of rheological models of non-Newtonian fluids. At the second stage, based on data from the previous stage, the program calculates well design and pump operation modes, permissible values of liquid flow rate and viscosity, to prevent possible hydraulic fracturing. Based on the results of calculations and dependencies, a decision is made on the necessity of changing the technological parameters of non-Newtonian liquid injection and/or its composition (components content, chemical base) in order to prevent the violation of the technological operation, such as unintentional formation of fractures due to hydraulic fracturing. Fracturing can lead to catastrophic absorptions and, consequently, to increased consumption of technological liquids pumped into the well during workover. Furthermore, there is an increased risk of uncontrolled gas breakthrough through highly conductive channels

Probabilistic-statistical models of the dynamics of climatic changes in the Altai Mountains

A probabilistic-statistical parameterization of time series characterizing geological and climatic processes allows determining some regularities by an autocorrelation analysis of signals which differ in nature. The use of the autocorrelation method for analyzing data related to solar and tectonic activity and characterizing the level of stratospheric ozone (total ozone content), hydrothermal regimes (De Martonne aridity index), and wood structure (maximum density of annual rings) allows us to find regularities in time series of various natural processes. Data on the maximum density of Siberian larch trees growing in the Altai Mountains made it possible to calculate the past changes in total ozone content and the aridity index in the Altai Mountains from 1900 to 2014 based on some similarities in the series and a separation of a dendrochronological signal into its main components

Wrongfulness of the act and current issues of legal regulation

It is important that in determining the delictual capacity of an individual, his guilt and the nature of mental attitude to the deed, which can be expressed in the form of intent and negligence, should be taken into account. This requires the establishment of three signs, including awareness by a person of unlawfulness of committed actions, anticipation by a person of the onset in socially harmful (socially dangerous) consequences and a person's attitude to the consequences that have occurred. It should be taken into account that during the reform of the criminal law, close attention should be focused on the presence of a person's motivation for unlawful behavior and the factors that determine it. Among such factors it is proposed to include biological features of personality, including sex, age, state of physical and mental health, state of nervous system, reaction to external stimuli, the presence of pathological deviations, character traits, temperament, level of emotional perception, intellectual and mental abilities

Electrochemical push-pull probe: from scanning electrochemical microscopy (SECM) to multimodal altering of cell microenvironment

To understand biological processes at the cellular level, a general approach is to alter the cells’ environment and to study their chemical responses. Herein, we present the implementation of an electrochemical push-pull probe, which combines a microfluidic system with a microelectrode, as a tool for locally altering the microenvironment of few adherent living cells by working in two different perturbation modes, namely electrochemical (i.e. electrochemical generation of a chemical effector compound) and microfluidic (i.e. infusion of a chemical effector compound from the pushing microchannel, while aspirating it through the pulling channel thereby focusing the flow between the channels). The effect of several parameters such as flow rate, working distance and probe inclination angle on the affected area of adherently growing cells was investigated both theoretically and experimentally. As a proof of concept, localized fluorescent labeling and pH changes were purposely introduced to validate the probe as a tool for studying adherent cancer cells through the control over the chemical composition of the extracellular space with high spatiotemporal resolution. A very good agreement between experimental and simulated results showed for instance, that the electrochemical perturbation mode enables to affect precisely only few living cells localized in a high-density cell culture