Jan Vcelak

• Team Leader at Czech Technical University in Prague

Mass timber construction systems, incorporating engineered wood products as structural elements, are gaining acceptance as a sustainable alternative to multi-story concrete or steel-frame structures. The relative novelty of these systems brings uncertainties on whether these buildings perform long-term as expected. Consequently, several structural...

Condition of road bridges in central as well as eastern Europe is not excellent. Lack of funding for maintenance requires precise identification of road bridge in need of investment. Integration of permanent monitoring sensors during construction of new bridge is a tool for integrated diagnostics. While the integrated Fiber Bragg Grating (FBG) sens...

Social workers require a better understanding of the impact of pandemic measures on the level of physical activity of their clients to better target client activation. In this retrospective tracker-based study (two years of measurement), we examined changes in the physical activity of the elderly population (204 participants with an average age of...

Long-term structural health monitoring (SHM) plays an important role in the safety of public transport infrastructure such as bridges or tunnels and warns in the event of any emerging problem. This article describes development and testing of system based on fiber Bragg grating (FBG) sensors that can detect changes in strain and temperature. The fi...

Historic buildings are often classified as highly energy-intensive buildings with low energy efficiency. Thanks to their overall percentage share in the European real estate market, it is important to focus on these dwellings with an innovative approach and functional, sensitive aesthetic solutions, thus significantly reducing their energy intensit...

There are not many energy plus building projects in Czech Republic. Project described in this paper aims even higher because the goal is to renovate older building to energy plus standard and not build it from the scratch. This article describes concept of energy active building which will be renovated in Litoměřice. Older military building from 19...

The paper focuses on the design, implementation and measurement of parameters of an air handling unit (AHU) with the Peltier cells. This is a small local modular AHU for fresh air flows of 50 to 200 m ³ /hr. The unit is designed for ventilation of residential and administrative buildings. Computer simulations were utilized designing the unit (inclu...

Recently, there has been an increased interest in structural health monitoring (SHM) of building and transport structures. Standard strain gauges placed on a beam surface are mostly used to monitor the mechanical stresses of timber or concrete structures. However, these sensors are susceptible to mechanical damage, electromagnetic interference or n...

This article focuses on simulation accuracy of photovoltaic (PV) systems designed for local energy usage in households. The results of simulations can be misleading when the input data is estimated not correctly or the input data has a low time resolution. Load profile is difficult to estimate due to the changes in user behaviour and possible high...

The current era is favorable for the expansion of renewable energy sources and their integration into the energy economy of buildings for residential or commercial use. According to the long-term statistics, buildings consume about 40 % of all energy produced. At the same time, the buildings together with the industry provide a huge potential for t...

The paper deals with the issue of the irradiation prediction. It describes the current state of forecasting services and their use with regard to photovoltaic systems. It presents the basic methods for evaluation of the irradiation prediction accuracy. It also presents the results of these methods for five forecasting data sources during the whole...

In recent years, a lot of attention has been directed towards the fabricating of smart structures with embedded optical sensors providing in-situ, non-destructive and real time or on-demand information of the construction structural health.

In this paper, the fiber Bragg gratings are investigated in the context of sensing of deformation inside a sample of a glued laminated timber. For this purpose, a fiber with acrylate recoated Bragg grating is placed and glued between the timber laminates. Since there are still some open questions leading now, one of the goals is to specify, if the se...

The paper deals with the experimental analysis focused on the determination of strain in wooden building structures using optical fibers with FBG sensors. Firstly, optical fibers were used to measure displacements of layers and surface strain of the lower surface of the ceiling panels made from mechanically jointed cross laminated timber (CLT). The...

Alloy composition (Co94Fe6)72.75Si12.25B13.25Cr1.75 was designed to develop nearly zero-magnetostrictive materials in the form of ribbons and wires to obtain suitable magnetic properties for use as giant magneto-impedance (GMI) and low-noise fluxgate sensor core. During the development of magnetic sensing core using amorphous wires of diameter 80 μ...

Soft magnetic materials rich on iron or cobalt have found vast range of usability for sensors such as fluxgates [1] and also, the recently re-invented, magneto-impedance sensors [2]. Giant magneto-impedance (GMI) has experienced huge increase of interest since the late 80's. Although the fluxgate sensor is commercially available, the easy manufactu...

METGLAS 2714AZ material has been stress annealed without any applied magnetic field to obtain suitable magnetic properties for use as low-noise fluxgate sensor core. During the development of magnetic cores, we observed an unusual change of the anisotropy direction on Co-based amorphous alloy of METGLAS 2714 AZ. The anisotropy direction moves from...

Navigation, position tracking, search for unexploded ammunition, and geophysical prospection of magnetic or conducting ore are key applications where very small magnetic field signatures and field increments should be detected in the presence of the Earth’s magnetic field, typically 50,000 nT. The industry calls for a new generation of portable vec...

Our novel position sensor is based on the combination of the eddy-current and permeability effects. The primary field is excited by a coil, but instead of induction coil, the sensing part uses anisotropic magnetoresistor (AMR) which also measures DC magnetic field. As the AMR is being flipped by the excitation frequency, the sensor is self-demodula...

Undersurface localization systems are accuracy demanding application. Localization methods used for common position estimation in open space or in building cannot be used since they are usually based on RF signal transmission or satellite navigation. Magnetic localization methods are usually the only usable solution. Horizontal directional drilling...

Measuring an arrow's ballistic performance such as arrow velocity on impact, total time of flight and arrow shaft oscillation is challenging because of the dynamic nature of arrow flight. This challenge becomes increasingly difficult as the distance of the shot increases. It is also of great interest to bowhunters to understand the ballistic perfor...

This paper presents a new long-range full 3-D magnetic tracking system for horizontal directional drilling, and describes its performance. The system is able to determine the full 3-D mutual position of the receiver with respect to the transmitter. The system presented here belongs to the category of hybrid trackers using an active magnetic ranger,...

Paper presents long range magnetic position estimation system which evaluates mutual position between transmitter and receiver in applications where other methods are not available. System is designed for deep subsurface localization between transmitter and receiver. The localization is based on excitation of the coils in transmitter with the known...

A novel miniaturised system for measurement of the in-flight characteristics of an arrow is introduced in this paper. The system allows the user to measure in-flight parameters such as the arrow's speed, kinetic energy and momentum, arrow drag and vibrations of the arrow shaft. The system consists of electronics, namely a three axis accelerometer,...

The automotive industry developments in the electrification of power train systems (i.e. HEVs and EVs), chassis systems (i.e. X-by wire systems) and auxiliaries (e.g. HVAC) have created a rapidly growing demand of advanced high temperature robust and reliable power electronics systems. This will require further efforts both in nanoelectronics semic...

Triaxial fluxgate sensors working in parallel mode with electroplated Permalloy (Ni80Fe20) cores were manufactured utilizing a low-cost printed circuit board technology and subsequently characterized. Sensor versions with various core shapes are compared and they are all shown to be capable of measuring low intensity magnetic field in three axes. I...

Analysis of various errors of orientation and motion sensors and their influence on resulting compass attitude information are investigated and quantified in this paper. A triple-axis acceleration sensor and a triple-axis magnetic sensor are considered to form a compass module giving full orientation information (attitude). 3D-compass module with P...

A novel fluxgate sensor with a single ferromagnetic core capable of measurement in three principal axes is presented. The sensor manufacturing process and internal coil structure is explained and its excitation is modelled using FEM. The sensor was implemented utilizing multilayer printed circuit board copper routes and electroplated through holes...

The performance of a simple compass with dual-axis magnetic sensor will be addressed in this paper. The digital compass with three miniature fluxgate sensors and tri axial accelerometer tilt sensors will be introduced in this paper. The paper is focused on the hardware construction, used sensors and methods of imperfections compensation and calibra...

Location of UXO (unexploded ordnance) using its DC magnetic signature requires precise gradiometers: resonant scalar and vectorial fluxgate sensors are used. The needed resolution is 1 nT in 50 000 nT Earth's field. Scalar gradiometers are very stable, but in some positions the scalar gradient is very small and the target may be overlooked. The dis...

The new compact digital compass with PCB fluxgate sensors and accelerometers will be introduced in this contribution. Competitive low-cost, low-accuracy compasses are dedicated for measurement in horizontal plane only. The main advantage of developed compass is that it is able to determine azimuth in every position. The compass module consists of a...

We compare the performance of eddy-current metal detectors for finding small bombs and other items of unexploded ordnance (UXO) with the potencial of DC gradiometers of scalar and resonant type. Extensive database of results was collected during laboratory measurements and field trials performed by JRC. There are two main obstacles for bomb detecti...

The description of simple and fast calibration procedures used for double-probe triaxial fluxgate gradiometer is provided in this paper. The calibration procedure consists of three basic steps. In the first step both probes are calibrated independently in order to reach constant total field reading in every position. Both probes are numerically ali...

The cross-axis effect error of typical AMR sensor can reach ±1100nT in the Earth's field, which in the worst case may result in ±2.4° error in azimuth reading of triaxial anisotropic magnetoresistive (AMR) compass. In systems, which cannot use flipping or feedback, the cross-axis error can be numerically corrected, if we know the sensitivity and fi...

The article deals with fully digital compass based on AMR sensors and accelerometers. The developed device gives information about actual azimuth, roll and pitch. The article is especially focused on errors caused by sensors misalignment, cross-axis effect and temperature offset drifts of the sensors. The influences of these errors on the calculate...

The advantages and disadvantages of using several types of magnetic sensors to design vector magnetometer will be discussed in this paper. Three developed versions of vector magnetometers with AMRs (anisotropic magnetoresistors), ring-core fluxgate (Aschenbrenner-Goubau type) and PCB fluxgate sensors will be presented as well as the calibration tec...

The article deals with fully digital navigation system based on AMR sensors and accelerometers. It provides information about actual azimuth, roll and pitch. The developed navigation system as well as the methods of error calibration and then compensation is described. The article is especially focused on calibration of errors caused by sensors dev...

The paper gives an overview of the multiple-input multiple-output (MIMO) systems and discusses their benefi ts enabling an increase in the system capacity and an increase of system reliability. The former is attained by signal multiplexing and the later by space encoding. The basic algorithms required for a proper operation of the MIMO systems, i.e...

This paper presents principles of optical position measurement methods based on opto- electronic gate. The developed opto-electronic gate extends the resolution by using a CCD line sensor instead of a simple photo detector. The use of the CCD line sensor increases the range and precision of measurement. Three optical measurement methods will be int...

The advent of MEMS inertial sensors has reduced the size, cost and power requirements of 6 Degrees-of-Freedom inertial measurement systems to a level where their use can be considered for wearable wireless monitoring devices. Many applications for such Wearable Wireless Inertial Measurement Units exist in the area of sports and sports science. Such...