A Clock Stabilization System for CHIME/FRB Outriggers

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has emerged as the prime telescope for detecting fast radio bursts (FRBs). CHIME/FRB Outriggers will be a dedicated very-long-baseline interferometry (VLBI) instrument consisting of outrigger telescopes at continental baselines working with CHIME and its specialized real-time transient-search backend (CHIME/FRB) to detect and localize FRBs with 50 mas precision. In this paper, we present a minimally invasive clock stabilization system that effectively transfers the CHIME digital backend reference clock from its original GPS-disciplined ovenized crystal oscillator to a passive hydrogen maser. This enables us to combine the long-term stability and absolute time tagging of the GPS clock with the short- and intermediate-term stability of the maser to reduce the clock timing errors between VLBI calibration observations. We validate the system with VLBI-style observations of Cygnus A over a 400 m baseline between CHIME and the CHIME Pathfinder, demonstrating agreement between sky-based and maser-based timing measurements at the 30 ps rms level on timescales ranging from one minute to up to nine days, and meeting the stability requirements for CHIME/FRB Outriggers. In addition, we present an alternate reference clock solution for outrigger stations that lack the infrastructure to support a passive hydrogen maser.

ANALYSIS THE REACTION OF LIGHTARMOR MACHINES ON THE ACTION OF POLYPULSES FORCES

In modern conditions, lightarmored vehicles with powerful weapon modules are widely used in the armies of different countries. These modules are equipped with small-caliber automatic cannons, which have a rate of fire of several hundred rounds per minute and a high level of recoil forces. Moreover, there are tendencies towards an increase in the rate of fire and the caliber of weapons (and, accordingly, recoil forces). Considering that weapon modules rely on the lightarmored vehicles skeleton, which has higher responsiveness characteristics than heavy combat vehicles in terms of weight, the problem of determining the reaction of the «weapon module - armored hull - suspension» system to the action of recoil forces in order to ensure on the one hand, the strength of armored hulls, and on the other hand, reducing the load on the guidance and stabilization system of weapons during firing.To study the response of elements of lightly armored vehicles to the action of recoil forces when firing a burst of combat modules, numerous models have been built with a small number of degrees of freedom. Using these models, the reaction of a dynamic system to the action of a number of impulses was investigated.These impulses caused by the action of recoil forces when firing shots from combat modules. Keywords: lightlyarmored vehicle; weapon module; small-bore automatic cannon; recoil force targeting and weapon stabilization system; dynamic system; numerical modeling; method of finite elements; natural vibration frequency

Development of a plasmid stabilization system in Vibrio natriegens for the high production of 1,3-propanediol and 3-hydroxypropionate

Vibrio natriegens is a promising industrial chassis with a super-fast growth rate and high substrate uptake rates. V. natriegens was previously engineered to produce 1,3-propanediol (1,3-PDO) from glycerol by overexpressing the corresponding genes in a plasmid. However, antibiotic selection pressure for plasmid stability was not satisfactory and plasmid loss resulted in reduced productivity of the bioprocess. In this study, we developed an antibiotic-free plasmid stabilization system for V. natriegens. The system was achieved by shifting the glpD gene, one of the essential genes for glycerol degradation, from the chromosome to plasmid. With this system, engineered V. natriegens can stably maintain a large expression plasmid during the whole fed-batch fermentation and accumulated 69.5 g/L 1,3-PDO in 24 h, which was 23% higher than that based on antibiotic selection system. This system was also applied to engineering V. natriegens for the production of 3-hydroxypropionate (3-HP), enabling the engineered strain to accumulate 64.5 g/L 3-HP in 24 h, which was 30% higher than that based on antibiotic system. Overall, the developed strategy could be useful for engineering V. natriegens as a platform for the production of value-added chemicals from glycerol. Graphic Abstract

DETERMINATION OF MODEL PARAMETERS OF ROCKET STABILIZATION SYSTEM IN FLIGHT

The dynamic characteristics of the system that includes the controlled object and the regulator largely depend on the choice of the control law, which is determined based on the nominal values of the parameters of the mathematical model of the stabilization process and its priority indicator. Due to the deviation of the missile parameters and, accordingly, the model from the nominal values, the designers set the safety factors based on the most unfavorable conditions, which negatively affects the overall performance, in particular, the relative weight of the payload. Therefore, there is a need to develop algorithms for adjustment that is identification model parameters during the flight using the signals of measuring devices and the capabilities of on-board computers. This will increase the efficiency of methods of choosing the control law based on such indicators as stabilization accuracy, stability margin and power requirements of the actuator. The aim of the article is to develop methods for refining the parameters of the rocket stabilization system in the yawing plane, which are based on the use of current data of measuring devices of the part of coordinates of the state vector, and verify the effectiveness of refinement in terms of the above indicators. A linear stationary model of a system for stabilizing the perturbed motion of a rocket taking into account the inertia of the actuator in the form of ordinary fifth-order differential equations is adopted. Two approaches are proposed to approximate the model parameters to their actual values. In the first in the model parameter space there is a minimum of the integral of the distance between the points of the trajectory according to the signals of the measuring devices and the trajectory obtained by modeling the perturbation compensation process. In the second, the actual values of the parameters are the result of solving a system of nonlinear equations, which includes data from measuring devices and the corresponding data obtained by simulation. On the example of space rocket parameters it is shown that the choice of the control law based on the actual coefficients of the model leads to a significant reduction of deviations from the set value of the system stability margin, stabilization error and power of the actuator.

Design of a new gas-dynamic stabilization system for a metal-cutting plasma torch

The analysis of the influence of various design solutions of the gas-dynamic stabilization system in plasma torches for cutting metals on the efficiency of equalizing the velocities of gas flows along the cross-section of the gas path is carried out. It is noted that the efficiency evaluation method developed by the authors should be based on the calculation of the uniformity of the gas flow velocity distribution over the cross-section of the gas-air path of the plasma torch. A vortex stabilization system using two swirlers is proposed. The effect of improving the reliability and quality of plasma cutting is shown. The results of the efficiency studies for the proposed system of gas-vortex stabilization in metal-cutting plasma torches are presented. The calculating results of equalization coefficients for the velocity distribution in different parts of the gas-dynamic stabilization system in the plasma torch are presented. Based on the results of the calculations, a constructive optimization of the gas-air path in the plasma torch was performed. The experimentally obtained advantages of the new upgraded plasma torch in terms of the gas-vortex stabilization efficiency are demonstrated. The effects of improved cutting quality and reduced nozzle wear in the new plasma torch are shown. This is due to the higher degree of the plasma arc stabilization in the new plasma torch, which leads to a decrease in its oscillations, and, consequently, to an increase in the efficiency of the cutting process.

Multiloop Multirate Continuous‐Discrete Drone Stabilization System: An Equivalent Single‐Rate Model

The article discusses the UAV lateral motion stabilization system, as a MIMO multiloop multirate continuous-discrete system, specified in the form of an input–output model in the domain of discrete Laplace transform or in the form of a structural diagram. Approaches to the construction of equivalent T and NT single-rate models for MIMO multiloop multirate continuous-discrete systems are considered. Here, T is the largest common divisor of the sampling periods of the system, N is a natural number that is the smallest common multiple of the numbers characterizing the sampling periods of the system. The resulting impulse representations of the outputs of equivalent models are in the form of rational functions. The basis for the construction of these models is a matrix of sampling densities—a structural invariant of sampling chains. An example of the construction of the indicated matrix and an equivalent single-rate model are given. Obtaining equivalent single-rate models for MIMO multiloop multirate systems allows us to extend the methods of research and synthesis of MIMO continuous and continuous-discrete systems to a common theoretical base—the theory of polynomials and rational functions, which are typical elements of the description of these classes of systems.

Method and stabilization system of position-sensitive spectrometer based on semiconductor strip detector

The paper proposes a method and its realization for stabilizing the characteristics of a multichannel position-sensitive spectrometer. The device uses a new design of the semiconductor strip detector, which allows a simultaneous injection of stable in time electric charges on all strips. This solution enables the electronics to track changes in the conversion characteristics of all electronic channels including detectors strips, and correct them during the spectrometer operation. In addition, the proposed detector design makes it possible to control the signal propagation along the strips, thus providing an on-line check of the integrity of strips metallization and the quality of their connection with the readout electronics.

Modeling and Simulation of Ship-Borne Weapon Stabilization System Based On Double Position Loop Control

In order to solve the problem of increasing system cost and low control accuracy by adding gyroscope or inertial navigation system, a dual position loop control ship-borne stabilization system is proposed in the paper. The mathematical model is established to analyze the influence of ship rolling factors on the space pointing of single position loop weapon system. On this basis, the control strategy of double position loop is proposed, and the simulation structure and control method of inner position loop and double position loop are described respectively. The simulation results show that the method can isolate the factors of ship rolling, realize the closed-loop stabilization control of weapon system in geodetic coordinate without adding system hardware cost, and have good control effect as well.

Synthesis of a mobile robot spatial stabilization system based on machine learning control by symbolic regression

The spatial stabilization system synthesis problem of the robot is considered. The historical overview of methods and approaches for solving the problem of control synthesis is given. It is shown that the control synthesis problem is the most important task in the field of control, for which there are no universal numerical methods for solving it. As one of the ways to solve this problem, it is proposed to use the method of machine learning based on the application of modern symbolic regression methods. This allows you to build universal algorithms for solving control synthesis problems. Several most promising symbolic regression methods are considered for application in control tasks. The formal statement of the control synthesis problem for its numerical solution is given. Examples of solving problems of synthesis of system of spatial stabilization of mobile robot by method of network operator and variation Cartesian genetic programming are given. The problem required finding one nonlinear feedback function to move the robot from thirty initial conditions to one terminal point. Mathematical records of the obtained control functions are given. Results of simulation of control systems obtained by symbolic regression methods are given.