Optical Raytracing Analysis of a Scheffler Type Concentrator

The Scheffler type concentrator is a curved metal reflector particularly suitable for solar thermal systems with a receiver fixed to the ground. Its operating principle is to deform the reflector throughout the year to optimize its performance in collecting sunlight. This study analyses the optical performance of a Scheffler reflector during the year. A CAD software tool is utilized to reproduce the mechanical deformations of a real Scheffler concentrator and the shape of the light spot on the receiver is analyzed by means of raytracing simulations. The starting configuration is the equinoctial paraboloid, which produces a point-like spot on the two equinox days only. On all other days of the year, this paraboloid is deformed in a suitable way in order to keep the spot as small as possible, but, even so, it is no longer a point-like spot. In the present work the simulated light distributions on the receiver, generated by the paraboloids (deformed or original), are compared. The results confirm the working principle of the Scheffler type concentrator and allow correctly sizing the receiver.

OVERVIEW OF GAS ANALYZERS FOR METHANE

Разгерметизация газоиспользующего оборудования может привести к взрыву газовоздушной смеси или пожару. Для своевременного обнаружения утечки газа используются газоанализаторы. Настоящая статья содержит обзор газоанализаторов, отличающихся по конструктивному исполнению, функциональному назначению, по принципу действия чувствительных элементов (сенсоров). Отмечено, что для обнаружения утечек метана (в том числе природного газа) наиболее эффективными с точки зрения чувствительности и быстродействия являются датчики (сенсоры), основанные на принципах: термического катализа (ТКД), поглощения инфракрасного излучения (ИКД), изменения электропроводности (ППД). Depressurization of gas-using equipment can lead to an explosion of the gas-air mixture or to a fire. Gas analyzers are used for timely detection of gas leaks. This article contains an overview of gas analyzers that differ in their design, functionality and in the operating principle of detecting elements (sensors). It is noted that for detection of methane leaks (including natural gas) the most effective detectors (sensors) based on the principles of thermal catalysis, absorption of infrared radiation, changes in electrical conductivity are the most effective in terms of sensitivity and speed.

RUN-BOT: mobile robot for running exercises

This article describes the operating principle of a mobile robot for running exercises RUN-BOT, shows a visual model, demonstrates photos of a testing prototype, describes the algorithm of the robot’s work on a real work-area. The functional model of the robot’s operation and a brief justification for the choice of electronic components are also described.

Study on improving the resolution of an H-shaped piezoelectric ultrasonic actuator by stick-slip principle

Improving the performance of the motion stages driven by piezoelectric actuators is an enduring topic for expanding their applications. For the motion stage with a travel range of tens of millimeters, trade-offs are inevitable between getting high speed (hundreds of millimeters per second) and high resolution (tens of nanometers), due to the inherent limitations of the operating principles of the piezoelectric actuators. In order to improve the output resolution of an H-shaped piezoelectric ultrasonic actuator, sawtooth excitation voltages are used in this work rather than the conventional sinusoidal voltages in previous works. The configuration and operating principle of the actuator are discussed in detail. The actuator consists of two vertical and two horizontal longitudinal transducers. The ends of the vertical transducers act as the driving tips and drive the stage forward with the alternating slow extensions and rapid contraction, during which stick motions and slip motions of the stage are acquired. An analytic model is developed to estimate the horizontal and vertical output displacement of the driving tip. The maximum error between the predicted value of the analytical model and the experimental value is about 14%. A prototype of the motion stage is fabricated and experiments are carried out to evaluate its output characteristics. The experiment results confirm the operating principle and show that the resolution is upgraded to tens of nanometers. The prototype obtains a resolution of 19 nm, a maximum speed of 2.22 μm/s, and a maximum carrying load of 16.94 kg.

Synthesis of Optimal Information and Energy Schemes of Measuring and Converting Devices

The synthesis of information and energy schemes is posed as an extreme problem, the purpose of which is a weighted directed graph of the minimum length from the input value to the output value of the device. The nodes of the graph are the physical effects included in the given database, and the branches are the input and output values of the effects. Nodes and branches are mathematically defined by diagonal multidimensional matrices, whose elements are determined by the dimensions of the quantities in the selected system of physical coordinates with a given number of basic units of measurement. The weight or resource intensity of the graph elements is determined by the norm of the corresponding matrices. The resulting circuit is suitable for use in technical documentation to explain the operating principle of the device, as well as for patent protection.In the enhanced formulation of the extreme problem, restrictions are introduced on the numerical values of the input and output values of the effect and its dynamic properties in the form of the transfer function of the effect. In this case, the size of the transfer matrices of nodes and branches is expanded by one. As a result, the transfer matrix of the effect contains information not only about the dynamic properties of the effect, but also about the dimensions of the physical quantities at its input and output.In a detailed example, the case of searching for the operating principle of a measuring-converting device of a pressure sensor with an electric current output is considered. To simplify the geometric representation of graph vectors on a plane, the problem is considered for a two-dimensional system of physical quantities with basic units of length and time. The calculation of the resource capacity is carried out according to the scheme of dimensional simulation, in which the phase variables of the differential equation enter with their physical dimensions. According to the numerical value of the resource capacity, you can compare different versions of the implementation of the operating physical principle of the device.

In-Fiber Interferometric-Based Sensors: Overview and Recent Advances

In-fiber interferometric-based sensors are a rapidly growing field, as these sensors exhibit many desirable characteristics compared to their regular fiber-optic counterparts and are being implemented in many promising devices. These sensors have the capability to make extremely accurate measurements on a variety of physical or chemical quantities such as refractive index, temperature, pressure, curvature, concentration, etc. This article is a comprehensive overview of the different types of in-fiber interferometric sensors that presents and discusses recent developments in the field. Basic configurations, a brief approach of the operating principle and recent applications are introduced for each interferometric architecture, making it easy to compare them and select the most appropriate one for the application at hand.