The STEM education initiative “The Universe for All” is an international professional development program aiming to enhance science education through simple experiments and activities in modern physics and technology. In collaboration with leading institutions such as the Perimeter Institute for Theoretical Physics in Canada, the European Gravitational Observatory in Italy, a team of CERN researchers in Switzerland, and the Eugenides Foundation, as well as academic institutions in Greece, the program was piloted in Greece with science educators working in public primary and secondary schools. Quantitative and qualitative methods were employed to assess the program's effectiveness, focusing on the participant's needs and the impact on classroom teaching. Findings showed that hands-on teaching methods and direct interaction with researchers increased the educators' confidence and ability to engage students in STEM subjects. The collaboration fostered a shared learning environment. Suggestions were made for continuous scientific support and simplified educational tools. Overall, the educational program in question has the potential to enhance STEM education. The program's results indicate a strong need for continuous professional development in the modern sciences.

Massive Open Online Courses (MOOCs) have seen a rise in popularity, as they are considered as providing high-quality, diverse educational content to an equally heterogeneous student body from around the globe. However, high dropout rates have been recorded, thus raising concerns about their efficacy. This paper aims to pinpoint some of the factors behind non-completion among students in a hands-on physics MOOC in Greece. Triangulation was performed using a combination of specific research methods to collect both qualitative and quantitative statistical data. Personalized emails were sent to all MOOC students. According to the findings, key factors that influence completion rates include learner-specific characteristics, external life factors, as well as course design and structure. The results of this research may offer valuable insights for MOOC designers and educators if they are to control dropout rates and create more efficient learning experiences and student-centered MOOC environments.

The introduction of students to physics education from a young age is essential in stimulating scientific thinking and maximizing the effectiveness of STEM teaching at all levels. According to international research, the desire to pursue a profession in physics may begin in the primary school. Large research infrastructures worldwide are ideal educational environments for the development of training courses addressed to science teachers as part of their educational programs. The training lab presented in this paper was part of a CERN initiative titled “Playing with Protons," which was addressed to Greek primary school teachers who teach physics and information technology. The purpose of this lab was to integrate modern physics, cutting-edge scientific research and scientific methodology at the primary school educational level, through simple hands-on experiments on astrophysics and cosmology. Our paper focuses on the CERN astrophysics lab, which was tested in the K-6 school laboratory. The outcomes of both labs and the comprehension of fundamental physics laws by the participating teachers and students are analyzed.

This paper describes the technique and outcomes of a Massive Open Online Course lab on a series of electric experiments for primary school students, predominantly engaged physics teachers. This course will integrate simple electric and electronic experiments with fundamental physics concepts through simple hands-on experiments. The research concentrated on a teacher’s online physics lab that students in a classroom setting evaluated. The findings of both labs are assessed, and teachers’ and students’ comprehension of fundamental physics laws applied to simple electric circuits. By introducing students to experimental physics, the hands-on experiments encourage teachers to foster a research culture in their students. Our findings indicate a need for more emphasis on specific electrical and electromagnetic themes and research-based and research-validated educational materials.

This paper aims to illustrate the implementation of a lab on climate change, which is addressed to K-6 students. A part of the lab material was presented to Greek science teachers in the context of a Massive Open Online Course. The findings of both labs are assessed, both teachers’ and students’ comprehension of fundamental physics laws of heat transfer, thermal conductivity, and absorption of solar radiation. The hands-on activities encourage teachers to foster a culture of research in schools, by introducing students to experimental physics. The students who participated in the lab were able to comprehend the lab’s heat and climate change concepts, which helped them become more environmentally aware.

In this paper, we present school science teaching and learning activities using large research infrastructures as tools for primary teachers eager to engage their students in cutting-edge physics and engineering research. The activities were deployed from 2016 to 2019 in the framework of a professional development course addressed to primary school teachers, which took place at CERN. We focus on a laboratory of electromagnetism which Greek teachers tested with their students after participating in the course. The Large Hadron Collider and the particle detectors at CERN served as exciting engineering paradigms. The laboratory introduced participants to learning-by-doing methodologies for conducting simple experiments that aimed to foster student learning. The proposed laboratory is examined in terms of its impact on both teachers' and students' knowledge regarding experiments and the construction of engineering models as well as on their basic understanding of scientific and engineering research.

In October 2019, the first Greek Massive Open Online Course on science experiments for students took place online and lasted five weeks. Its content consisted of a substantial number of science experiments based on the school curriculum with simple, everyday materials. The audience addressed were not only students but also science teachers and people interested in science. A total of 7266 enrollments were recorded, the vast majority of participants being teachers of primary and secondary education. The data received during the course and the statistics that followed revealed notable findings on the need for epistemological development among teachers teaching science and engineering, the extent of teaching through experiments in Greek schools, the gender-biased inequalities in the communities of students and teachers, and the challenges that exist in the field. The course was repeated in March 2020 as soon as the pandemic spread in the country.

Abstract The performance of free‐space optics links strongly depends on scintillation effects caused by the atmospheric turbulence appearance. A widely adopted way to counterbalance the expected deterioration due to scintillation is to employ cooperative and multi‐hop arrangements. However, the use of multiple relays increases significantly the complexity of the mathematical models used to describe the overall performance of the system. Taking the latter into account, we approximate a generic multiple relay‐assisted free‐space optical configuration with a dual‐hop link in order to simplify the performance analysis. To this end, we provide new mathematical derivations for the evaluation of the outage probability and the average bit error rate by assuming typical turbulence models.

University students face several difficulties in comprehending electricity, as the relevant literature shows. It is well known into the scientific community that understanding electricity and circuits is fundamental to both science and technology. Thus, the design of new educational tools and their implementation are at the forefront of educational research today. Various methods have been proposed and implemented in order to overcome these difficulties. A very significant method is the Learning-by-doing (LBD). It is a modern, interesting and easily applied approach to students. In this paper we present some simple experiments on electronics we created, based on LBD, and how they helped undergraduate students improve their performance in electronics labs as well as their comprehension of scientific laws and natural phenomena.

The delivery of teaching and learning along with its approach is essential to 21st-century skills educational outcomes in the UAE. In today's society, it is crucial to identify specific competencies and skills to develop the learner and answer to the demand of what employers need for the future. The UAE Vision 2021's includes a directive for UAE Higher Education (HE) institutions to “listen closely to the needs of Emiratis and of their future employers” and to “balance their teaching to the demands of the workplace.” To respond to this call, engineering education and training institutes need to implement a pedagogical model that aims to challenge the ever-changing and complex challenges in the workplace. As UAE employers look for engineering graduates with skills in various areas such as critical thinking, effective communication, innovation, and problem-solving, the pedagogy models adopted by HE institutes seldom addresses these needs. How best to acquire and practice these skills is overlooked mainly as this has to do with the embedded approach of traditional information transmission model. This paper, considers the essential pedagogical approaches to contribute to the development and mastery of twenty-first-century competencies and skills and proposes a model to advance the quality and effectiveness of vocational learning atHEinstitutes across the UAE.

New and emerging technologies, combined with highly innovative approaches to learning, are transforming engineering classes and delivering a richer and more engaging learning experience for students and instructors worldwide. This paper investigates the impact of technology on the distance learning of the Emirati students. The aim of this paper is to determine how emerging technologies are providing a flexible format to teach engineering programs in remote areas of the UAE and to encourage new innovative approaches to teaching and learning. Four distance learning classrooms were installed at Madinat Zayed campus and another three at Ruwais campus of the Western Region Colleges (WRC). The Emirati engineering students from these colleges receive their education through live interaction using video conferencing equipment and shared interactive smart boards across the institutes' wide area network. Students in these classes did not engage in virtual classrooms rather, they participated in one extended connected class. While general feedback from the students and instructors clearly confirmed the benefits of using this technology to teach Emirati engineering students, four guiding principles are drawn and highlighted in this paper.

In this work, we present the research that we conducted in order to detect students' difficulties in understanding the basic concepts and phenomena of Electricity and Electronic Physics. The analysis not only confirms the findings of the existing literature, but also completes it with new ones. These results dictate us to create an educational approach that tackles the difficulties found.

Terrestrial free‐space optical (FSO) communication systems with subcarrier intensity modulation have experienced a particular research attention in the recent past. However, their performance strongly degrades in the presence of atmospheric turbulence, pointing errors, and phase noise impairments. In order to overcome these limitations, the authors consider a receiver diversity scheme of a typical subcarrier phase‐shift keying (PSK) system and investigate the performance by means of the average symbol error probability (ASEP). They assume a wide range of turbulence conditions, non‐zero boresight pointing errors, and phase noise strengths described through the gamma‐gamma, Beckmann, and Tikhonov distributions, respectively. Novel approximate ASEP expressions are derived for single‐input single‐output and single‐input multiple‐output (SIMO) configurations. Appropriate numerical results are depicted and validated by Monte Carlo simulations.

Wlth the United Arab Emirates' (UAE) strict 2013 call for Emiratisation, UAE Vision 2021, sees a higher education environment where students will “enrich their minds with the skills that their nation needs to fuel its knowledge economy”. In answer to this, Higher Colleges of Technology (HCT), a UAE public college system, mandated the practice of “Learning-by-doing”,(LBD), at the heart of its strategic plan for years 2012-2017. However, with the plan already a year into its implementation, no formal investigation has been done on how LBD is being implemented and the extent to which classes, syllabi, and curricula abide to it. Additionally, the researcher argues that if HCT is to act on its “commitment to aligning its academic programs with specific industry needs to meet market demands,” then the inclusion of 21st century skills into its curricula cannot be overlooked. This work intends to investigate the general question: “What constructively aligned learning-by-doing pedagogical model incorporating 21st century skills can be developed for teaching engineering subjects in Higher College of Technology, UAE?”. Taking a pragmatic stand, a mixed method convergent parallel design will be employed. To get a complete picture, inputs coming from its major stakeholders, will be investigated. Student survey, instructors and dean structured interviews, overt class observation and syllabi examination will be utilized for data triangulation. Ultimately, the paper aims to develop a collaborative LBD model tailor-fitted to the institution's engineering program and to UAE's culture.

ABSTRACT In this paper, a study on the end‐to‐end performance of multi‐hop non‐regenerative relaying networks over independent generalized‐gamma (GG) fading channels is presented. Using an upper bound for the end‐to‐end signal‐to‐noise ratio (SNR), novel closed‐form expressions for the probability density function, the moments, and the moments‐generating function of the end‐to‐end SNR are presented. Based on these derived formulas, lower bounds for the outage and the average bit error probability (ABEP) are derived in closed form. Special attention is given to the low‐ and high‐SNR regions having practical interest as well as to the Nakagami fading scenario. Moreover, the performance of the considered system when employing adaptive square‐quadrature amplitude modulation is further analyzed in terms of the average spectral efficiency, the bit error outage, and the ABEP. Computer simulation results verify the tightness and the accuracy of the proposed bounds. Copyright © 2011 John Wiley & Sons, Ltd.

The authors study the performance of a dual-hop plus a direct link multiple-input multiple-output (MIMO) wireless communication system using orthogonal space–time block codes. The system under consideration is based on the decode-and-forward relaying protocol and operates over spatially correlated Nakagami-m fading channels. The proposed analysis is generic enough to account for any MIMO correlation model either from measurements or having theoretical and analytical justification. Analytical expressions for the system end-to-end outage and average symbol error probability are obtained, while critical parameters of the MIMO channel are taken into consideration such as the angle of arrival, the antenna array configuration, the wavelength and non-isotropic scattering conditions. Various numerical and computer simulation results demonstrate the proposed mathematical analysis and the impact of the above parameters to the system performance.

In this paper, coherent detection for multilevel correlated signaling sets in additive white Gaussian noise is addressed. The contribution is twofold. Firstly, correlation structures that minimize the symbol error probability (SEP) of M-ary frequency-shift keying as well as of arbitrarily correlated signaling sets are investigated, while secondly, a general and analytical expression for the SEP is derived in the form of a single integral. The structure of the associated correlation matrix is generic and includes various known signaling sets as special cases. Specific correlation structures that minimize the SEP are also studied. Based on eigendecomposition or LU decomposition, generic methods for constructing a correlated signaling set for any correlation matrix under consideration are also provided.

Turbulence fading is one of the main impairments affecting the operation of free-space optical (FSO) communication systems. The authors study the performance of FSO communication systems, also known as wireless optical communication systems, over log-normal and gamma–gamma atmospheric turbulence-induced fading channels. These fading models describe the atmospheric turbulence because of its very good agreement with experimental measurement data. Closed-form expressions for the average (ergodic) capacity and the outage probability are derived for both statistical models. Another contribution of this work is a study of how the performance metrics are affected by the atmospheric conditions and other parameters such as the length of the link and the receiver's aperture diameter. The derived analytical expressions are verified by various numerical examples and can be used as an alternative to time-consuming Monte-Carlo simulations.

In this paper, coherent detection for multilevel correlated signaling sets in additive white Gaussian noise is addressed. From the decision rule, a general analytical expression for the symbol error probability (SEP) is derived, which is in the form of a single integral. Our new result is not only in agreement with a known equivalent expression, but it also has a much simpler analytical form. The structure of the correlation matrix under consideration of the signaling set is quite generic, including various known signaling sets as special cases. Hence the derived SEP expression is useful for analyzing the performance of various coherent modulation schemes such as multilevel phase-shift and frequency-shift keying. Specific correlation structures which minimize the SEP are also studied. Based on eigendecomposition or LU decomposition, generic methods for constructing a correlated signaling set for any correlation matrix under consideration are also provided.

In this letter, closed-form outage probability expressions are presented for an -relays dual-hop plus a direct link network, in which the decode-and-forward relaying protocol is employed. Our analysis significantly extends previous results on Rayleigh fading, considering a Nakagami- fading environment with either equal or distinct second hops fading parameters to average power ratios. Various numerical examples illustrate the proposed analysis.

In this paper, for an L-relays dual-hop plus a direct link wireless network, in which the decode-and-forward relaying protocol is employed, closed-form expressions for the end-end outage probability are presented. Our analysis considers a Nakagami-m fading environment with either equal or distinct second hops fading parameter to average power ratios. Various numerical examples illustrate the proposed analysis.

This paper presents a control-theoretic approach to the design of digital to analog converters and digital amplifiers leading to improved performance in audio and multimedia applications. The design involves oversampling and noise compression blocks as a pulse width modulation class-D amplifier, introduces an output-filter estimator block and applies a different modulation scheme. The theoretical model results in a family of digital circuits verified by software simulation and validated by a FPGA implementation with best performance 147 dB signal to noise ratio

It is known that during uniaxial compression of dielectric crystalline materials, acoustic and electromagnetic (EM) emission is detected. Such emissions are of particular interest, since they are related to the physical processes taking place during the preparation stage of an earthquake. In this letter, we report recent experimental results on the memory effects observed in the EM emission during successive cyclic mechanical loading-unloading of LiF crystal samples in a similar fashion, as it has been described by the so-called "Kaiser effect," i.e., the memory effect for the acoustic emission, and we discuss on a conceptual explanation.

We study the performance of L-branch equal-gain combining (EGC) and maximal-ratio combining (MRC) receivers operating over nonidentical Weibull-fading channels. Closed-form expressions are derived for the moments of the signal-to-noise ratio (SNR) at the output of the combiner and significant performance criteria, for both independent and correlative fading, such as average output SNR, amount of fading and spectral efficiency at the low power regime, are studied. We also evaluate the outage and the average symbol error probability (ASEP) for several coherent and noncoherent modulation schemes, using a closed-form expression for the moment-generating function (mgf) of the output SNR for MRC receivers and the Pade/spl acute/ approximation to the mgf for EGC receivers. The ASEP of dual-branch EGC and MRC receivers is also obtained in correlative fading. The proposed mathematical analysis is complimented by various numerical results, which point out the effects of fading severity and correlation on the overall system performance. Computer simulations are also performed to verify the validity and the accuracy of the proposed theoretical approach.

In mobile radio systems, antenna diversity is used to combat fading and reduce the impact of cochannel interference. In this paper, we analyze the performance of L-branch equal-gain combining receivers over correlated nonidentically distributed Nakagami-m fading channels, in the presence of multiple identical cochannel interferers and additive white Gaussian noise. The performance criterion considered is the average output signal-to-interference-plus-noise ratio, which is obtained in closed form for both independent and correlative fading. Due to the simple form of the derived expressions, they readily allow numerical evaluation for cases of practical interest.

The performance of dual-branch SC receivers over correlated Weibull fading channels is studied in this paper. Exact closed-form expressions are derived for the probability/cumulative density functions and the moments of the output signal-to-noise ratio (SNR). Important performance criteria, such as average output SNR, amount of fading (AoF), outage probability and average bit error probability (ABEP) for several modulation schemes, are studied and novel closed-form analytical expressions are derived. The proposed analysis is complemented by various performance evaluation results, including the effects of input SNRs unbalancing, fading severity and fading correlation on the overall system performance. Computer simulations results verify the validity and the accuracy of the proposed analysis.

Motivated by the suitability of the Weibull distribution to model multipath fading channels, the second order statistics and the spectral efficiency (SE) of L-branch SC receivers are studied. Deriving a novel closed-form expression for the probability density function (pdf) of the SC output SNR, the average level crossing rate (LCR), the average fade duration (AFD) and the Shannon's average SE, at the output of the SC, are derived in closed-forms. Our results are sufficiently general to handle arbitrary fading parameter and dissimilar branch powers.

The acoustic and electromagnetic emission detected during the uniaxial compression and before the catastrophic failure of dielectric crystalline materials is investigated in this letter. In particular, an appropriate experimental and measuring setup has been developed and used to simultaneously detect and monitor in both large and small scale the time series of acoustic and electromagnetic pulses emitted during deformation of a compressed LiF crystal sample, allowing a plausible mechanism of their origin to be suggested.

Ascertaining the importance of the dual selection combining (SC) receivers and the suitability of the Weibull model to describe mobile fading channels, we study the performance of a dual SC receiver over correlated Weibull fading channels with arbitrary parameters. Exact closed-form expressions are derived for the probability density function, the cumulative distribution function, and the moments of the output signal-to-noise ratio (SNR). Important performance criteria, such as average output SNR, amount of fading, outage probability, and average bit-error probability for several modulation schemes are studied. Furthermore, for these performance criteria, novel closed-form analytical expressions are derived. The proposed analysis is complemented by various performance evaluation results, including the effects of the input SNR's unbalancing, fading severity, and fading correlation on the overall system's performance. Computer simulation results have verified the validity and accuracy of the proposed analysis.

The spectral efficiency achieved by FDMA and DS-CDMA schemes during cellular operation in an additive white Gaussian noise (AWGN) and a Rayleigh fading environment is evaluated in terms of the assigned downlink and uplink channel capacity (in the Shannon sense). In particular, in Rayleigh fading, channel capacity is estimated in an average sense considering the inherent diversity potential that each scheme provides as a physical means for fading mitigation. However, in contrast to cellular FDMA, multiple-access and co-channel interference that are present in cellular DS-CDMA cause substantial spectral efficiency reduction. Hence, it is analytically shown that, under normalized conditions, FDMA spectral efficiency is always higher than that of DS-CDMA regardless the fact that DS-CDMA systems reduce the channel capacity degradation that is caused by signal fading.

An experimental point-to-point coverage prediction model based on field measurements taken in the region of Athens in the 900 MHz band is discussed. The developed model, incorporating a new method for effective height estimation in 3-dimensions, addresses the case of mobile radio propagation over urban and suburban areas with non-uniform terrain morphology in which negative effective height values are also present. The effectiveness of the proposed model is proved by comparing actual transmission loss values, for the specific area, to prediction values obtained by this model as well as by a number of known models.

Coverage prediction is essential for designing a mobile radio system operating in the 800/900 MHz band. A mobile radio field measurement and coverage prediction model evaluation procedure based on the utilization of a geographical information system (GIS) is described. Coordination of mean signal strength values with detailed point-to-point topographic characteristics through the GIS is used to obtain accurate and reliable information in the form of an integrated propagation and topographic database. The proposed procedure can be used to evaluate or even modify current coverage prediction models over composite urban areas.

We emphasise on the role of conformance testing in mobile data/voice communication systems by examining its formal methodology for its effectiveness and applicability in such systems. The importance of applying the right test method for each specific case is outlined and a tool for selecting a suitable test method is presented. As a result, the paper derives a set of basic requirements that should govern the design and development of mobile data/voice systems in order to allow the maximum degree of susceptibility to conformance testing.

A description of the conformance test system for the pan-European paging system ERMES is presented. This test system has been developed for checking the ERMES receivers for conformity to the relevant air interface and receiver operation standard specification according to the ISO 9646 standardized methodology for conformance testing services.>

The paper deals with the physical layer conformance testing of the Digital European Cordless Telecommunications (DECT) system. The abstract test suite, the test system and an automated test realization process are described in accordance with the OSI conformance testing methodology and framework (ISO/TEC 9646). The proposed test system has been adopted by the test laboratories which are going to provide a conformance test service on DECT equipment in Europe.>