Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 50
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The paper presents analyses of current research projects connected with explosive material sensors. Sensors are described assigned to X and γ radiation, optical radiation sensors, as well as detectors applied in gas chromatography, electrochemical and chemical sensors. Furthermore, neutron techniques and magnetic resonance devices were analyzed. Special attention was drawn to optoelectronic sensors of explosive devices.

Go to article

Authors and Affiliations

Zbigniew Bielecki
Tadeusz Stacewicz
Jacek Janucki
Adam Kawalec
Janusz Mikołajczyk
Norbert Pałka
Mateusz Pasternak
Tadeusz Pustelny
Jacek Wojtas
Download PDF Download RIS Download Bibtex

Abstract

The impulse noise is agent harmful to health not only in the case of shots from firearms and the explosions of explosive materials. This kind of noise is also present in many workplaces in the industry. The paper presents the results of noise parameters measurements in workplaces where four different die forging hammers were used. The measured values of the C-weighted peak sound pressure level, the A-weighted maximum sound pressure level and A-weighted noise exposure level normalized to an 8 h working day (daily noise exposure level) exceeded the exposure limit values. For example, the highest measured value of the C-weighted peak sound pressure level was 148.9 dB. In this study possibility of the protection of hearing with the use of earplugs or earmuffs was assessed. The measurement method for the measurements of noise parameters under hearing protection devices using an acoustical test fixture instead of testing with the participation of subjects was used. The results of these measurements allows for assessment which of two tested earplugs and two tested earmuffs sufficiently protect hearing of workers in workplaces where forging hammers are used.

Go to article

Authors and Affiliations

Emil Kozłowski
Rafał Młyński
Jan Adamczyk
Download PDF Download RIS Download Bibtex

Abstract

In order to explore creativity in design, a computational model based on Case-Based Reasoning (CBR) (an approach to employing old experiences to solve new problems) and other soft computing techniques from machine learning, is proposed in this paper. The new model is able to address the four challenging issues: generation of a design prototype from incomplete requirements, judgment and improvement of system performance given a sparse initial case base library, extraction of critical features from a given feature space, adaptation of retrieved previous solutions to similar problems for deriving a solution to a given design task. The core principle within this model is that different knowledge from various level cases can be explicitly explored and integrated into a practical design process. In order to demonstrate the practical significance of our presented computational model, a case-based design system for EM devices, which is capable of deriving a new design prototype from a real-world device case base with high dimensionality, has been developed.

Go to article

Authors and Affiliations

Jun Ouyang
David Lowther
Download PDF Download RIS Download Bibtex

Abstract

In industrialized countries cardiovascular diseases are the major cause of death. The last clinical therapy option for some patients, suffering from terminal heart diseases, is donor heart transplantation. As the available number of donor organs is decreasing, many patients die while waiting for a transplant. For this reason Ventricular Assist Devices (VADs), which can mechanically support the human heart to achieve a sufficient perfusion of the body, are under development. For an implantable VAD, design constraints have to be deduced from the physiological conditions in the human body. In case of a VAD drive, these constraints are for example dimensions, electric losses, which might result in an overheating of blood, and a long durability. Therefore a hybrid permanent magnet hydrodynamic bearing is designed in this paper, which works passively and contactless. Based on Finite Element simulations of magnetic fields, various permanent magnet topologies are studied in terms of axial forces and stiffness.

Go to article

Authors and Affiliations

André Pohlmann
Kay Hameyer
Download PDF Download RIS Download Bibtex

Abstract

The ultrasonic flowmeter which is described in this paper, measures the transit of time of an ultrasonic pulse. This device consists of two ultrasonic transducers and a high resolution time interval measurement module. An ultrasonic transducer emits a characteristic wave packet (transmit mode). When the transducer is in receive mode, a characteristic wave packet is formed and it is connected to the time interval measurement module inputs. The time interval measurement module allows registration of transit time differences of a few pulses in the packet. In practice, during a single measuring cycle a few time-stamps are registered. Moreover, the measurement process is also synchronous and, by applying the statistics, the time interval measurement uncertainty improves even in a single measurement. In this article, besides a detailed discussion on the principle of operation of the ultrasonic flowmeter implemented in the FPGA structure, also the test results are presented and discussed

Go to article

Authors and Affiliations

Stanisław Grzelak
Marcin Kowalski
Jarosław Czoków
Marek Zieliński
Download PDF Download RIS Download Bibtex

Abstract

This paper proposes an advanced routing method in the purpose of increasing IoT routing device’s power-efficiency, which allows to centralize routing tables computing as well as to push loading, related to routing tables computation, towards the Cloud environment at all. We introduced a phased solution for the formulated task. Generally, next steps were performed: stated requirements for the system with Cloud routing, proposed possible solution, and developed the whole system’s structure. For a proper study of the efficiency, the experiment was conducted using the developed system’s prototype for real-life cases, each represents own cluster size (several topologies by each size), used sizes are: 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27 and 29. Expectable results for this research – decrease the time of cluster’s reaction on topology changes (delay, needed to renew routing tables), which improves system’s adaptivity.

Go to article

Authors and Affiliations

Valentyn Faychuk
Orest Lavriv
Bohdan Strykhalyuk
Olga Shpur
Ivan Demydov
Roman Bak
Download PDF Download RIS Download Bibtex

Abstract

Unlike traditional passive filters, modern active filters have the following multiple functions; harmonic filtering, damping, isolation and termination, reactive-power control for power factor correction and voltage regulation, load balancing, voltage-flicker reduction, and/or their combinations. Significant cost reductions in both power semiconductor devices and signal-processing devices have inspired manufactures to put active filters on the market. This paper deals with general pure active filters for power conditioning, and specific hybrid active filters for harmonic filtering of three-phase diode rectifiers, as well as traditional passive filters.

Go to article

Authors and Affiliations

H. Akagi
Download PDF Download RIS Download Bibtex

Abstract

The paper presents a prototype of a rehabilitation robot for lower extremities. It is created on the basis of cylindrical kinematic model, equipped with two rigid arms, special handles and fixtures. It has five active degrees of freedom and is designed to repeat the trajectories generated by physiotherapist during the learning phase. Presented prototype of rehabilitation robot has the ability to replay different types of trained exercises such as: hip and knee flexion/extension, leg abduction/adduction. The protection system (including overload detection) implemented in the robot ensures safe working with patients.

Go to article

Authors and Affiliations

Marcin Kaczmarski
Grzegorz Granosik
Download PDF Download RIS Download Bibtex

Abstract

The paper presents design and experimental verification of platform mechanism with cost-effective wire-based sensors for measuring of spatial displacement or pose of some moving object. This task, also known as spatial tracking, has a very wide application. The proposed mechanism, guided by the moving object, has a parallel structure with two platforms and at least six wire-based sensors for measuring distances between the platform points. Changes of the platform pose cause corresponding changes of the sensors' wire lengths. Forward position problem of an equivalent mechanism model with 6 degrees of freedom is described together with analyses of work space limitations and error propagation in a measurement system. A specific application is illustrated for tracking of a wheel knuckle of 5-link suspension mechanism used in passenger cars. The developed device has the following advantages: it can be installed in a wheel cavity; enables dynamic measurements on the road; is cost-effective. Performance of the latest prototype of the wire-based tracker was verified on the basis of measurements on a test rig, where two other measuring devices were used for comparison purposes.

Go to article

Authors and Affiliations

Marta Góra
Michał Maniowski
Download PDF Download RIS Download Bibtex

Abstract

The article contains a survey of methods of the mobile development with the FMX Application platform, which allows to build multi-platform solutions for the efficient Human-Computer Interaction. The test projects illustrate some important conclusions regarding the design and testing of mobile applications for iOS and Android operating systems. They demonstrate navigation controls designed in the skeumorphic and flat manner with some comparisons based on interviews with users in several age ranges. Test apps provide also touch gestures, sensor integration and connections to remote internet data sources. Some additional considerations about the localization and internationalization of the mobile applications built with the FMX platform were also presented. The proposed implementation of the software engineering methods for the mobile application development provides new insights, valuable for software developers dealing with the new FMX platform on iOS and Android.

Go to article

Authors and Affiliations

Zdzisław Sroczyński
Download PDF Download RIS Download Bibtex

Abstract

In this publication the effect of the operating temperature on the effective inductance of a controllable inductor is analysed. The main difference compared to a coil with a simple single core lies in the current-controlled inductance-value. This is achieved by a second core implemented perpendicular upon the load-toroid affecting the saturation within a limited shared volume. Corresponding to the presented analysis, the dependencies on the core temperatures are investigated by measurements.
Go to article

Authors and Affiliations

Guido Schierle
1
ORCID: ORCID
Michael Meissner
1
Klaus F. Hoffmann
1

  1. Helmut Schmidt University, Germany
Download PDF Download RIS Download Bibtex

Abstract

This paper presents a new interim check device for coordinate measuring machines (CMMs) built from an AISI 1020 carbon steel bar with the incorporation of calibrated spheres. This artifact’s construction was made to make the interim checks of machines of this type faster and cheaper. Three devices were designed based on the ISO 10360-2 standard, the good practice guide No. 42 (NPL), and prominent authors’ research on the subject. The three options are presented in detail, but only one was built due to budget, size, and adaptability restrictions. An exploratory study was conducted to verify the device’s usability in two CMMs and concluded that the differences between the measurements are not significant. However, one machine had absolute variation values and a total standard deviation higher than the other, generating a larger expanded uncertainty.
Go to article

Authors and Affiliations

Rodrigo Schons Arenhart
1
Morgana Pizzolato
1
Fernanda Hänsch Beuren
2
Adriano Mendonça Souza
3
Leandro Cantorski da Rosa
1

  1. Federal University of Santa Maria, Department of Production Engineering and Systems, Roraima Avenue, 1000, Santa Maria, Brazil
  2. State University of Santa Catarina, Department of Industrial Technology, Fernando Hastreiter Street, São Bento do Sul, Brazil
  3. Federal University of Santa Maria, Statistics Department, Roraima Avenue, 1000, Santa Maria, Brazil
Download PDF Download RIS Download Bibtex

Abstract

In this paper, the authors present a novel construction of an automatic balancing device applicable to balancing shafts working in a heavily polluted environment. The novelty of the presented system lies in the fact that its utilization requires no changes to be made in the already existing shafts. Also, the system is capable of working during the operation of the balanced shaft, so there is no need to stop it. The propulsion system is based on eddy current braking, therefore no wires need to be used in the device. During the development process of the system, three iterations of the device were created. Each iteration is presented, described, and discussed. The advantages and drawbacks of each version are pointed out and explained thoroughly. The correctness of the design was verified by the created devices that were assembled and fixed on shafts to prove the design assumptions.
Go to article

Bibliography

[1] J. Alsalaet. Dynamic Balancing and Shaft Alignment. College of Engineering – University of Basrah, Iraq, 2015.
[2] G.K. Grim, J.W. Haidler, and B.J. Mitchell. The Basics of Balancing. Balance Technology Inc., 2014.
[3] M. MacCamhaoil. Static and Dynamic Balancing of Rigid Rotors. Brüel & Kjær, 2016.
[4] R. Kelm, D. Pavelek, and W. Kelm. Rotor balancing tutorial. In: 45th Turbomachinery Symposium, pages 1–29, Huston, Texas, USA, Sept.12–15, 2016. doi: 10.21423/R1G59R.
[5] W.C. Foiles and P.E. Allaire. Single plane and multi-plane rotor balancing using only amplitude. In: 7th IFToMM International Conference on Rotor Dynamics, Vienna, Austria, Sept. 25–28, 2006.
[6] L. Li, S. Cao, J. Li, R. Nie, and L. Hou. Review of rotor balancing methods. Machines, 9(5):89, 2021. doi: 10.3390/machines9050089.
[7] Bendix Aviation Corp. Automatic Balancing of Rotating Bodies. Patent GB570170A, 1945.
[8] P. Żak. A survey of automatic balancing methods for shafts in motion. International Journal of Mechanical Engineering and Robotics Research, 9(4):559–564. doi: 10.18178/ijmerr.9.4.559-564.
[9] P. Loetzner, C.P. Hemingray, and C. Maas. Rotatable shaft balancing machine and method with automatic flexible shaft balancing equipment. Patent US20030024309A1, 2003.
[10] L. Capo and I. Goodbar. Device for the automatic static and dynamic balancing of rotating machinery. Patent GB679522A, 1952.
[11] G. Darrieus. Apparatus for automatic balancing of rotating bodies. Patent US2659243A, 1953.
[12] G. Darrieus. Device for automatic balancing of rotating machine parts. Patent US2778243A, 1957.
[13] J. Perdiart. System for automatically balancing a centrifuge in operation. Patent US4919646, 1990.
[14] O.A. Makarov, V.I. Nisenman, V.I. Pryadilov, and J.P. Tsimansky. Device for automatic balancing of grinding wheel. Patent US4905419, 1990.
[15] H. Wu, X. Pan, and H. Gao. Pneumatic liquid on-line automatic balancer of rotor. Patent US20140311281A1, 2014.
[16] P.C. Stein. Permanent automatic rotor balancer for shafts operating above critical speed. Patent US4117742A, 1978.
[17] W.R. Backer. Automatic balancing means. Patent GB957577A, 1962.
[18] K. Unno and K. Sugita. Automatic balancing apparatus for a rotating body. US3776065A, 1973.
[19] H. Kuwajima, H. Kita, H. Hashi, M. Miyamoto, Y. Ueno, T. Inagaki, and K. Matsuoka. Development of balanced-type high shock suspension for 0.85-in hard disk drive. IEEE Transactions on Magnetics, 42(2):255–260, 2006. doi: 10.1109/TMAG.2005.861736.
[20] Gao Jinji and Zhang Peng. Simulative study of automatic balancing of grinding wheel using a continuously-dripping liquid-injection balancing head. In: 2006 6th World Congress on Intelligent Control and Automation, pages 8002-8005, Dalian, China, 2006. doi: 10.1109/WCICA.2006.1713530.
[21] E. Lulay. Apparatus for balancing a rotary member. Patent US5676025A, 1997.
[22] M. Krygier, P. Żak, L. Podsędkowski, P. Wróblewski, and M. Podsędkowski. A novel autonomous balancing system for shafts in motion. 2022 20th International Conference on Mechatronics – Mechatronika (ME), pages 1-4, Pilsen, Czech Republic, 2022, doi: 10.1109/ME54704.2022.9983460.
[23] M. Krygier, P. Żak, and L. Podsedkowski. Numerical analysis of torques generated in a propulsion system using eddy currents phenomenon. 5th International Conference on Robotics Systems and Automation Engineering (RSAE) (RSAE 2023), April 20–22, 2023, online.
Go to article

Authors and Affiliations

Michał Krygier
ORCID: ORCID
Paweł Żak
1
ORCID: ORCID
Leszek Podsędkowski
1
ORCID: ORCID
Piotr Wróblewski
1
ORCID: ORCID
Maciej Podsędkowski
2
ORCID: ORCID

  1. Institute of Machine Tools and Production Engineering, Lodz University of Technology, Lodz, Poland
  2. Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
Download PDF Download RIS Download Bibtex

Abstract

This paper presents a detailed review on a present confused situation related to defining and measurement of the eyepiece diopter range of optical/electro-optical devices to be used for a direct observation by human observers. On the basis of this review three precise definitions of a direct view imagers eyepiece diopter are presented. One of these definitions is determined as optimal fit to describe the perception of human observers. Further on, design and measurement uncertainties of diopter meters are discussed and rules of accurate measurements are formulated. Finally, recommendations for the maximum acceptable errors of the diopter scale of eyepieces of classic types of direct view imagers are presented, as well.

Go to article

Authors and Affiliations

Krzysztof Chrzanowski
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

This study stacked a thin, dense BCuP-5 (Cu-Ag-P based filler metal) on a Cu-plate using the laser cladding (L.C) process to develop a method to manufacture Ag reducing multilayer clad electrical contact material with an Ag-M(O)/Ag/Cu/BCuP-5 structure. Then, the microstructure and macroscopic properties of the manufactured BCuP-5 coating layer were analyzed. The thickness of the manufactured coating layer was approximately 1.7 mm (maximum). Microstructural observation of the coating layer identified Cu, Ag and Cu-Ag-Cu3P ternary eutectic phases like those in the initial BcuP-5 powder. To evaluate the properties of the manufactured coating layer, hardness and adhesion strength tests were performed. The average hardness of the laser cladded coating layer was 183.2 Hv, which is 2.6 times greater than conventional brazed BcuP-5. The average pull-off strength measured using the stud pull test was 341.6 kg/cm2. Cross-sectional observation of the pulled-off material confirmed that the coating layer and substrate maintained a firm adhesion after pull-off. Thus, the actual adhesion strength of Cu/BcuP-5 was inferred to be greater than 341.6 kg/cm2. Based on the above findings, it was confirmed that it is possible to manufacture a sound Ag reducing multilayer clad electrical contact material using the laser cladding process.

Go to article

Authors and Affiliations

Kee-Ahn Lee
Joo Hyun Park
Yeun Ah Joo
Download PDF Download RIS Download Bibtex

Abstract

An ancient forging device in Spain has been studied, namely the forge with a waterwheel and air-blowing tube or hydraulic trompe, found near the village of Santa Eulalia de Oscos (province of Asturias, Spain). Three procedures using ad hoc methods were applied: 3D modelling, finite element analysis (FEA), and computational-fluid dynamics (CFD). The CFD results indicated the proper functioning of the trompe, which is a peculiar device based on the Venturi effect to take in air. The maximum air volume flow rate supplied to the forge by the trompe was shown to be 0.091 m3/s, and certain parameters of relevance in the trompe design presented optimal values, i.e. offering maximum air-flow supply. Furthermore, the distribution of stress over the motion-transmission system revealed that the stress was concentrated most intensely in the cogs of the transmission shaft (a kind of camshaft), registering values of up to 7.50 MPa, although this value remained below half of the maximum admissible work stress. Therefore, it was confirmed that the oak wood from which the motion system and the trompe were made functioned properly, as these systems never exceeded the maximum admissible working stress, demonstrating the effectiveness of the materials used in that period.

Go to article

Authors and Affiliations

J.I. Rojas-Sola
J.B. Bouza-Rodríguez
A. Comesaña-Campos
Download PDF Download RIS Download Bibtex

Abstract

T h e a i m: The aim of the study is to present the initial experience with continuous flow left ventricle assist device (CF-LVAD) in pediatric patients with BSA below 1.5 m2.

M a t e ri a l a n d M e t h o d s: Between 2016 and 2017, CF-LVAD (the Heartware System) have been implanted in three pediatric patients in the Department of Pediatric Cardiac Surgery, Jagiellonian University, Krakow, Poland. The indications for initiating CF-LVAD were end-stage congestive heart failure due to dilated cardiomyopathy in all children.

R e s u l t s: Implanted patients have had BSA of 1.09, 1.42, 1.2 m2, and 37, 34, 34 kg of body weight and the age 12, 11, 12 years, respectively. The time of support was 550 days in two patients and 127 in another one, and is ongoing. The main complication has been driveline infection.

C o n c l u s i o n: The outcomes from our single-center experience using the HeartWare CF-LVAD have been excellent with a low incidence of complication and no necessity to reoperation in our patients. Children could be successfully and safely discharged home.

Go to article

Authors and Affiliations

Vivek Rai
Julita Sacharczuk
Mirosława Dudyńska
Rafał Żurek
Magdalena Czerzynska
Aleksander Szypulski
Elżbieta Wójcik
Jerzy Pacholewicz
Janusz Skalski
Tomasz Mroczek
Download PDF Download RIS Download Bibtex

Abstract

The iron ore mine owned by the state concern of Luossavaara – Kiirunavaara AB-LKAB state concern has several mining skip shaft hoists for drawing iron ore. Despite using modern systems to secure the travel of these hoists in line with the Swedish regulations, units intended for the emergency breaking of vessels must be used in the so-called free travel paths in the tower and in the shaft sump. The paper discusses the main requirements that, in accordance with the Swedish regulations as regards the operational use of mining shaft hoists, must be met by devices of this type and a solution was proposed for a structure design of the braking unit for the mining shaft hoist installed in the B-1 shaft in the Kiruna mine. The frictional braking system in the form of moving bumping beams was decided to be used in the said hoist, developed in the Cable Transport Department in the University of Science and Technology in Krakow. The action of moving bumping beams consists in these beams, placed at the beginning of free travel paths, not only braking the rushing hoist vessels but also (with the integrated units for vessel capture) performing the function of grips. They secure the vessels against falling down into the shaft after the finished braking process. The advantage of such a solution is that the structural elements: the guiding shank of the tower, the head of the vessel and the bumping beams, transfer many times lower values of dynamic forces at the time of the strike of the vessel against the moving bumping beams when compared with dynamic forces arising at the time of the hit of the vessel against the fixed bumping beams. In the process of designing moving bumping beams, braking simulation is an important stage conducted with a computer program developed in KTL AGH. This program enables the modelling of load-bearing and balance ropes as flexible elements with elastic and suppressing properties. The results of these simulations, especially in the scope of the achieved braking deceleration of the vessels, the values of braking distances and forces in the load-bearing ropes are crucial in confirming the correctness of the assumed concept of the emergency braking system. The braking units in the form of moving bumping beams have been executed by the Polish company Coal-Bud Sp. z o.o. and are now being integrated in the tower and in the shaft sump of the B-1 shaft of the Kiruna mine in Sweden.

Go to article

Authors and Affiliations

Tomasz Rokita
Download PDF Download RIS Download Bibtex

Abstract

In this study, the noise sources to which a coal miner, who works at the Kurul panel of Kilimli Colliery, Zonguldak, was exposed were investigated. These sources were positioned at different points from the surface to the workface. Noise levels were measured according to the working periods of the coal miners around the machines. The results were evaluated under the Turkish Noise Regulation. The critical exposure times in which the coal miners could work without the use of personal protective equipment were examined according to the noise values to which they were exposed. In addition, the personal noise exposure values of the machine operators (boring machine, electro-hydraulic drill, and pick hammer) were determined during the development works. Two different types of noise measurements, with a microphone at the ear level and inside the ear protector, were conducted. The results obtained when the microphone of the personal dosimeter was at ear level, were found to be 15 dBA higher than those when the microphone was inside the ear protector. As a result, the selection methods of ear protectors were analyzed. Recommendations were given for those working on the risky tasks at the panel.
Go to article

Authors and Affiliations

Ilknur Erol
1
ORCID: ORCID
Okan Su
2
ORCID: ORCID

  1. Çukurova University, Dept. of Mining Engineering, Adana, Türkiye
  2. Zonguldak Bülent Ecevit University, Dept. of Mining and Mineral Extraction, Zonguldak, Türkiye
Download PDF Download RIS Download Bibtex

Abstract

The trend of reducing electricity consumption and environmental protection has contributed to the development of refrigeration technologies based on the thermal effect of adsorption. This article proposes a methodology for conducting numerical simulations of the adsorption and desorption processes. Experimental data available in the literature were used as guidelines for building and verifying the model, and the calculations were carried out using commercial computational fluid dynamics software. The simulation results determined the amount of water vapor absorbed by the adsorbent bed and the heat generated during the adsorption process. Throughout the adsorption process, the inlet water vapor velocity, temperature, and pressure in the adsorbent bed were monitored and recorded. The results obtained were consistent with the theory in the literature and will serve as the basis for further, independent experimental studies. The validated model allowed for the analysis of the effect of cooling water temperature on the sorption capacity of the material and the effect of heating water temperature on bed regeneration. The proposed approach can be useful in analyzing adsorption processes in refrigeration applications and designing heat and mass exchangers used in adsorption systems.
Go to article

Authors and Affiliations

Szymon Janusz
1 2
Maciej Szudarek
3
Leszek Rudniak
4
Marcin Borcuch
2

  1. Cracow University of Technology, Jana Pawla II 37, 31-864 Kraków, Poland
  2. M.A.S. Sp z o.o., Research and Development Department, Składowa 34, 27-200 Starachowice, Poland
  3. Warsaw University of Technology, Institute of Metrology and Biomedical Engineering, sw. Andrzeja Boboli 8, 02-525 Warszawa, Poland
  4. Warsaw University of Technology, Faculty of Chemical and Process Engineering, Warynskiego 1, 00-645 Warszawa, Poland
Download PDF Download RIS Download Bibtex

Abstract

Large venues and auditoriums are commonly associated with their astounding architecture. Their acoustic quality is an essential factor in its qualification as a great and functional, or a badly designed place. However, acoustics is often overlooked during the design stage of a building due to the complexity and high cost of the measurements involved. For this reason, it is important to explore more accessible ways to implement acoustics evaluations. The aim of this work is to compare typical experimental measuring methods and the use of mobile devices to assess the acoustic quality of a room. These measurements are contrasted with the software simulation of the same acoustical space. The results show that the mobile system can be used for professional measurements with low restrictions in the frequency range of interest of this study (90 Hz to 4000 Hz).

Go to article

Authors and Affiliations

David Ibarra-Zarate
Ana Laura Padilla-Ortiz
Download PDF Download RIS Download Bibtex

Abstract

In the early days, consumption of multimedia content related with audio signals was only possible in a stationary manner. The music player was located at home, with a necessary physical drive. An alternative way for an individual was to attend a live performance at a concert hall or host a private concert at home. To sum up, audio-visual effects were only reserved for a narrow group of recipients. Today, thanks to portable players, vision and sound is at last available for everyone. Finally, thanks to multimedia streaming platforms, every music piece or video, e.g. from one’s favourite artist or band, can be viewed anytime and everywhere. The background or status of an individual is no longer an issue. Each person who is connected to the global network can have access to the same resources. This paper is focused on the consumption of multimedia content using mobile devices. It describes a year to year user case study carried out between 2015 and 2019, and describes the development of current trends related with the expectations of modern users. The goal of this study is to aid policymakers, as well as providers, when it comes to designing and evaluating systems and services.

Go to article

Authors and Affiliations

Przemysław Falkowski-Gilski
Download PDF Download RIS Download Bibtex

Abstract

If we want to provide the efficient training intervention to increase the duration of using hearing protection devices (HPDs) by workers, we need a tool that can estimate the person’s hearing threshold taking into account noise exposure level, age, and work history, and compare them with audiometry to find out the percent reduction of workers hearing loss.

First, the workers noise exposure level was determined according to ISO 9612, then 4000 Hz audiometry was done to find age and work history. On basis of ISO 1999 the hearing threshold was estimated and if the hearing protection device was not used continuously and correctly, the hearing protection device’s actual performance was reduced adjusted with person’s audiometry. After training intervention, the estimate was done again and was compared with the adjusted audiometry.

According to ISO 1999 standard estimation results, the percent reduction of the workers hearing loss level was 6.48 dB in intervention group. This level remained unchanged in control group. The mean score of hearing threshold estimation (standard ISO 1999) was statistically more significant than mean score of hearing threshold (p-value ¡ 0.001). The results show not significant change in control group due to lack of changing of noise exposure level.

In regards to the results of hearing threshold estimation based on ISO 1999 and comparing with workers audiometry, it can be seen that BASNEF training intervention increases the duration of using the HPDs and it could be effective in reducing hearing threshold related to noise.

Go to article

Authors and Affiliations

Rohollah Fallah Madvari
Fereydoon Laal
Milad Abbasi
Mohammad Reza Monazzam
Alireza Fallah Madvari
Download PDF Download RIS Download Bibtex

Abstract

Due to the fixed rotor magnetic field, the main magnetic flux of conventional permanent magnet synchronous motors (PMSMs) cannot be flexibly adjusted. Recently, the axial-radial flux type permanent magnet synchronous machine (ARFTPMSM) based on the hybrid excitation concept is proposed, which provides a new method for the speed and magnetic field regulations for PMSMs. To analyze the mechanism of magnetic field variation inside the ARFTPMSM, in this paper, three – dimensional finite element models for electromagnetic field calculation of the ARFTPMSM are established. On this basis, the influence of the axial device on the motor is discussed, and the mechanism of flux regulation is explained. By the quantitative calculation of air-gap flux density and the noload back-electromotive force (EMF), the flux regulation capability of the ARFTPMSM is verified. In addition, the effect of the excitation magnetomotive force on the magnetic field harmonics is analyzed combined with the winding theory, and the influence of the axial magneto-motive force (MMF) on the torque fluctuation is obtained. The flux regulation performance of the motor and the validity of the numerical calculation analysis are verified by the experiments.
Go to article

Authors and Affiliations

Cunxiang Yang
1
Kun Wang
1
ORCID: ORCID
Ziyang Liu
1
Bin Xiong
2
Qiang Zhao
3

  1. Zhengzhou University of Light Industry, Zhengzhou, Henan, China
  2. Institute of Electrical Engineering of Chinese Academy of Sciences, Beijing, China
  3. Wolong Electric Nanyang Explosion Protection Group Co., LTD.China

This page uses 'cookies'. Learn more