Hasil untuk "Telecommunication"

M. Deubel, G. von Freymann, M. Wegener et al.

A. Pospischil, M. Humer, M. Furchi et al.

Optical interconnects are becoming attractive alternatives to electrical wiring in intra- and interchip communication links. Particularly, the integration with silicon complementary metal–oxide semiconductor (CMOS) technology has received considerable interest because of the ability of cost-effective integration of electronics and optics on a single chip1. Although silicon enables the realization of optical waveguides2 and passive components3, the integration of another, optically absorbing, material is required for photodetection. Traditionally, germanium4 or compound semiconductors5 are used for this purpose; however, their integration with silicon technology faces major challenges. Recently, graphene6 emerged as a viable alternative for optoelectronic applications7, including photodetection8. Here, we demonstrate an ultra-wideband CMOS-compatible photodetector based on graphene. We achieved a multigigahertz operation over all fibre-optic telecommunication bands beyond the wavelength range of strained germanium photodetectors9, the responsivity of which is limited by their bandgap. Our work complements the recent demonstration of a CMOS-integrated graphene electro-optical modulator10, and paves the way for carbon-based optical interconnects. A CMOS-compatible photodetector based on graphene with multi-gigahertz operation ranging from the O- to U-band of telecommunication bands is demonstrated, highlighting the promise of graphene as a new material for integrated photonics.

M. Sebastian, R. Ubic, H. Jantunen

M. Shalaev, Jingbo Sun, A. Tsukernik et al.

Metasurfaces are two-dimensional structures enabling complete control on light amplitude, phase, and polarization. Unlike plasmonic metasurfaces, silicon structures facilitate high transmission, low losses, and compatibility with existing semiconductor technologies. We experimentally demonstrate two examples of high-efficiency polarization-sensitive dielectric metasurfaces with 2π phase control in transmission mode (45% transmission efficiency for the vortex converter and 36% transmission efficiency for the beam steering device) at telecommunication wavelengths. Silicon metasurfaces are poised to enable a versatile platform for the realization of all-optical circuitry on a chip.

A. Houbi, Zharmenov A. Aldashevich, Yomen Atassi et al.

Abstract Recently, with the quick evolution of electronic technologies, and the development of telecommunication, high-performance microwave absorbing composites in which ferrite is one of their components have attracted a lot of attention. These composites should have high absorption intensity, a wide absorption bandwidth, a thin thickness, and finally light weightiness. These composites often exhibit efficiency to fulfill coveted magnetic and dielectric characteristics. This review provides a brief presentation of ferrites and among them are spinel ferrites and hexagonal ferrites. In addition to that, it discusses the classifications of ferrites according to magnetic properties, the synthesis methods to prepare nano ferrites, and control their properties. Also, it presents the main mechanism to absorb the microwaves (e.g. dielectric and magnetic losses) and finally discusses the microwave absorbing characteristics of ferrites and their composites in terms of matching frequency, reflection loss (RL) values, and absorption bandwidth.

J. Ajo-Franklin, S. Dou, N. Lindsey et al.

We present one of the first case studies demonstrating the use of distributed acoustic sensing deployed on regional unlit fiber-optic telecommunication infrastructure (dark fiber) for broadband seismic monitoring of both near-surface soil properties and earthquake seismology. We recorded 7 months of passive seismic data on a 27 km section of dark fiber stretching from West Sacramento, CA to Woodland, CA, densely sampled at 2 m spacing. This dataset was processed to extract surface wave velocity information using ambient noise interferometry techniques; the resulting VS profiles were used to map both shallow structural profiles and groundwater depth, thus demonstrating that basin-scale variations in hydrological state could be resolved using this technique. The same array was utilized for detection of regional and teleseismic earthquakes and evaluated for long period response using records from the M8.1 Chiapas, Mexico 2017, Sep 8th event. The combination of these two sets of observations conclusively demonstrates that regionally extensive fiber-optic networks can effectively be utilized for a host of geoscience observation tasks at a combination of scale and resolution previously inaccessible.

Tayyaba Akram, Shen Lei, Muhammad Jamal Haider et al.

Abstract This study attempts to find out the impact of organizational justice on the innovative work behavior of employees working in Chinese telecommunication sector, while analyzing the mediating role of knowledge sharing between the independent and dependent variables of this study. In order to test the study hypotheses, a data of 345 respondents working in Chinese telecommunication industry was collected. Confirmatory factor analysis suggested a good model fit, while structural equation model provided significant and positive effect of organizational justice on the employee innovative work behavior and knowledge sharing. Knowledge sharing mediated the relationship between organizational justice and employee innovative work behavior. Managerial and practical implications of the study are also provided.

M. Hassounah, Hafsa Raheel, Mohammed Alhefzi

Background The first case of COVID-19 in Saudi Arabia was confirmed on March 3, 2020. Saudi Arabia, like many other countries worldwide, implemented lockdown of most public and private services in response to the pandemic and established population movement restrictions nationwide. With the implementation of these strict mitigation regulations, technology and digital solutions have enabled the provision of essential services. Objective The aim of this paper is to highlight how Saudi Arabia has used digital technology during the COVID-19 pandemic in the domains of public health, health care services, education, telecommunication, commerce, and risk communication. Methods We documented the use of digital technology in Saudi Arabia during the pandemic using publicly available official announcements, press briefings and releases, news clips, published data, peer-reviewed literature, and professional discussions. Results Saudi Arabia’s government and private sectors combined developed and launched approximately 19 apps and platforms that serve public health functions and provide health care services. A detailed account of each is provided. Education processes continued using an established electronic learning infrastructure with a promising direction toward wider adoption in the future. Telecommunication companies exhibited smooth collaboration as well as innovative initiatives to support ongoing efforts. Risk communication activities using social media, websites, and SMS text messaging followed best practice guides. Conclusions The Saudi Vision 2030 framework, released in 2017, has paved the path for digital transformation. COVID-19 enabled the promotion and testing of this transition. In Saudi Arabia, the use of artificial intelligence in integrating different data sources during future outbreaks could be further explored. Also, decreasing the number of mobile apps and merging their functions could increase and facilitate their use.

Sana Sharif, Shahid Manzoor, Waleed Ejaz

Abstract The future sixth‐generation (6G) networks are envisioned to integrate satellites, aerial, ground, and sea networks to provide seamless connectivity. However, some challenges are associated with integrated networks, including optimal resource utilisation, energy efficiency, delay, higher data rates, heterogeneity, and on‐demand connectivity. This paper focuses on optimising energy efficiency, resource utilisation, and task priority‐based user association. To achieve this, a mathematical framework is formulated to maximise energy efficiency, resource utilisation, and user connectivity in integrated networks while satisfying constraints related to transmit power, data rate, and computation resources. The formulated problem is a binary linear programming problem, as the decision variable is binary and the constraints are linear. The authors solve this optimisation problem using three methods: the branch and bound algorithm (BBA), the interior point method (IPM), and the barrier simplex algorithm (BSA). The authors use the results obtained from BBA as a benchmark to evaluate the performance of IPM and BSA. Simulation results show that the performance of IPM and BSA is comparable to the BBA but with lower complexity.

Aleksandr Bystrov, Fatemeh Norouzian, Edward Hoare et al.

ABSTRACT This paper presents a comprehensive review of advancements in road surface classification technology utilising automotive microwave sensors, covering both active radar and passive radiometry, along with data analysis techniques. Accurate knowledge of road surface type and condition is crucial for improving driving safety, especially in the pursuit of fully autonomous driving. The paper begins with a comparative analysis of different sensing technologies, including microwave, optical, LIDAR and sonar sensors. It subsequently highlights the distinct advantages of microwave sensors, particularly in scenarios with low visibility, where other sensing methods are not sufficiently effective. The analysis of road surface classification methods using radar or radiometer data includes both technical aspects (signal parameters, sensor type, position and number of antennas, signal polarisation, etc.) and classification algorithms. These include analysing backscattered or emitted signal parameters based on specific criteria and making decisions based on this analysis or using statistical classification methods (e.g., k‐nearest neighbours, support vector machines, neural networks). The paper also discusses the current state of the field and explores future directions and potential advancements in surface classification technology.

Musa N. Hamza, Mohammad Tariqul Islam, Sunil Lavadiya et al.

This paper addresses the challenge of early-stage cancer diagnosis using microwave imaging (MWI) techniques by targeting circulating exosomes, recently identified as promising cancer biomarkers. We introduce an innovative nano-photonic perfect absorber (NPA) operating in the terahertz (THz) range, offering a significant improvement over existing MWI-based approaches in terms of simplicity, sensitivity, and specificity. Unlike previous THz absorbers, the proposed NPA achieves an exceptionally wide operating bandwidth from 100 GHz to 50 THz with an absorption efficiency exceeding 97.5%, while featuring an ultra-compact nanoscale footprint (100 × 100 nm², thickness 30 nm). The design integrates a silver (Ag) resonator and a nickel (Ni) ground plane on a silicon dioxide (SiO₂) substrate, with meticulously tuned geometries to create multiple resonance modes, enabling continuous broadband absorption. Full-wave electromagnetic simulations validate the structure’s performance, including electric and magnetic field distributions, surface currents, and scattering parameters. Comparative analysis with state-of-the-art absorbers demonstrates the superior bandwidth, absorption stability, and angular robustness of our device. Furthermore, we demonstrate the NPA’s unique ability to act as a label-free biosensor for exosome detection, where cancerous exosomes consistently induce stronger electric field responses than normal exosomes due to their distinct molecular compositions. These results confirm the proposed NPA as a novel, highly effective platform for non-invasive, early-stage cancer diagnostics via MWI.

WANG Zhongyong, ZHANG Hong, GONG Kexian et al.

Aiming at the problem of poor fault-tolerant performance in the reconstruction of the parity-check matrix of linear block codes, a parity-check matrix reconstruction algorithm based on fault-tolerant Gaussian elimination was proposed. Firstly, partial bits of codewords were randomly sampled multiple times to construct incomplete codewords. The reliability was calculated based on the mean and minimum of the absolute values of the bit log-likelihood ratios, so as to screen out high-reliability incomplete code groups. Secondly, for the partially incorrect states of the basis of the incomplete code groups, the fault-tolerant Gaussian elimination algorithm was used to solve the corresponding suspected parity-check vectors, and then the true parity-check vectors were determined and restored from them. Finally, according to whether the codeword bits could pass through the known parity-check vectors, the absolute values of the bit log-likelihood ratios were updated to further improve the bit reliability, bringing gains for the next random sampling of partial bits. The simulation results showed that, under the same identification conditions, the reconstruction rate of the proposed algorithm is higher than that of the existing algorithms. For the LDPC(648,324) code under the IEEE802.11n protocol, the existing algorithms fail when the bit error rate reaches 0.005 5, while the reconstruction rate of the proposed algorithm for the parity-check matrix still reaches over 98% when the bit error rate is 0.008.

Ming Long, Jun Yang, Mingjiu Lv et al.

Abstract A signal time‐frequency results inversion method is proposed for extracting micro‐motion features of rotor targets under low signal‐to‐noise ratios (SNRs). In the case of low SNRs, the echo's energy of rotor targets is mainly concentrated in the flash's echo component. Conventional micro‐motion feature extraction of rotor targets primarily utilises the sinusoidal modulation feature in time‐frequency results, whose energy is much lower than the flash. Under low SNRs, the sinusoidal modulation in the echo's time‐frequency results will be submerged in the noise, making feature extraction challenging. A deep learning network is used to inverse the time‐frequency results containing sinusoidal modulation based on the flash's features in the time‐frequency results. Based on the inversion time‐frequency results, the GS‐IRadon algorithm is used to extract micro‐motion features, which can significantly reduce the times of IRadon transformations and improve feature extraction speed and accuracy. Through simulation and analysis, a novel method using a deep learning network like UNet can effectively inverse time‐frequency results under low SNRs, providing a new technical approach for micro‐motion feature extraction. Time‐frequency results inversion is a novelty method used to achieve micro‐motion feature extraction of rotor targets.

O. O. Kostyria, A. A. Hryzo, O. M. Dodukh et al.

Використання у радіолокаційних системах сигналів із внутрішньо-імпульсною модуляцією дозволяє збільшити тривалість зондувальних імпульсів, а значить і випромінювану енергію при обмеженнях на пікову потужність. Стиснення сигналу в системі обробки забезпечує необхідне розрізнення за часом, але призводить до появи бічних пелюсток. Це в свою чергу обумовлює «розтягування» зони пасивних перешкод за дальністю та погіршує потенційні можливості з виявлення цілей. Тому зниження рівня бічних пелюсток обробленого сигналу є актуальним завданням радіолокації. Стосовно максимального рівня бічних пелюсток переваги мають сигнали з нелінійною частотною модуляцією, але моделі, що використовуються для їх математичного опису, потребують уточнення. Проведені авторами статті дослідження та отримані результати математичного моделювання пояснюють механізм виникнення стрибків частоти та фази в сигналах з нелінійною частотною модуляцією, що складаються з кількох лінійно-частотно модульованих фрагментів. Зазначені результати отримано для математичної моделі поточного часу, тобто, коли час кожного наступного фрагменту відраховується від кінця попереднього. У статті розглядаються математичні моделі дво- та трифрагментних сигналів, які використовують іншій підхід. Відмінність полягає, у тому, що початковий час кожного наступного лінійно-частотно модульованого фрагменту зсувається на початок відліку, тобто використовується зсунутий час. Перевагою цього підходу є відсутність стрибків частоти на стиках фрагментів, але стрибки фази в ці моменти часу все рівно спостерігаються. Таким чином існує потреба у розробці математичного апарату компенсації таких стрибків. Аналіз відомих публікацій, проведений у першому розділі статті, показує, що для математичних моделей зсунутого часу питання визначення величини стрибків фази на стиках фрагментів та механізми їх компенсації не розглядалися. З цього витікає завдання дослідження, яке сформульовано у другому розділі роботи. Математичні викладки щодо визначення величини фазових стрибків, які виникають в зазначених математичних моделях, а також результати перевірки удосконаленого математичного апарату наведено у третьому розділі роботи. Подальші дослідження планується спрямувати на особливості використання розроблених математичних моделей при вирішенні прикладних завдань у радіолокаційних системах.

Miłosz Wawrzyniec Romaniuk, Joanna Łukasiewicz-Wieleba

The article presents the results of the questionnaire research carried out after the first and repeated after the second semester of crisis distance education, conducted at the Academy of Special Education. Academic lecturers participating in the study indicate a significant decrease in the level of commitment, activity, the regularity of work and the quality of performing tasks presented by students. Lecturers benefit from training and technical support organized by the university. They feel an acute inability to contact students personally, but appreciate the time savings and no need to travel to work. The respondents point to the problem of controlling student integrity during remote examinations. Growing experience in remote education results in higher IT competences and conviction to this type of teaching.

Xi Chen, Shuai Qian, Fei Yu et al.

In this paper, we propose a method to design the pseudorandom number generator (PRNG) using three kinds of four-wing memristive hyperchaotic systems (FWMHSs) with different dimensions as multientropy sources. The principle of this method is to obtain pseudorandom numbers with good randomness by coupling XOR operation on the three kinds of FWMHSs with different dimensions. In order to prove its potential application in secure communication, the security of PRNG based on this scheme is analyzed from the perspective of cryptography. In addition, PRNG has passed the NIST 800.22 and ENT test, which shows that PRNG has good statistical characteristics. Finally, an image encryption algorithm based on PRNG is adopted. In the encryption algorithm, the optimized Arnold matrix scrambling method and the diffusion processing based on XOR are used to obtain the final encrypted image. Through the evaluation of encryption performance, it is concluded that there is no direct relationship between the pristine image and encrypted image. The results show that the proposed image encryption scheme has good statistical output characteristics and security performance in line with cryptography.

Shaoliang PENG, Liang BAI, Li WANG et al.

With the rapid development of internet of things technology,in order to better develop modern medicine,avoid the “isolated” crisis of information,and meet the requirements of timeliness and computing performance of massive data generated by edge devices,it is a new trend of the times to combine edge computing with smart healthcare treatment.However,edge computing has a certain degree of openness,and it is prone to potential safety hazards.Therefore,people pay more and more attention to the security and privacy protection of edge computing system for smart healthcare treatment.The edge computing system and its architecture for smart healthcare were introduced,and the security risks encountered by smart healthcare in edge computing was explained,and some scholars’ solutions to the security risks were introduced.Finally,a security framework,and specific solutions for security and privacy protection under the framework were put forward,which providing some help for the trusted research of smart healthcare edge computing.

Yinghui LIU, Nan LIU, Yixin CAI et al.

With the national economic transition and rapid development of technology,enterprises need digital transition.How to accelerate transition through IT architecture upgrading has become a new research topic for enterprises.The definition,function and common types of middle platforms were stated.The strategy and architecture of different enterprises’ middle platforms which differ in service chain length were also compared and analyzed.The concept of planning middle platform was proposed on the basis of decoupling production from operation.Considering the current situation of operators,some suggestions were put forward on how to design the middle platform and which type to choose.

Gholamreza Khalili, Kianoush Zahrakar, Abdurrahim Kasaee Esfahani

Background: Different studies have shown that solution-focused brief therapy and rational-emotional-behavioral therapy have been effective on improving work indices, but the question is that “are trainings based on solution-focused brief therapy and rational-emotive-behavioral therapy effective on meaning of work and, if so, which one is more effective?” Aims: The present research was conducted by the aim of comparing the effectiveness of training based on solution-focused brief therapy and rational-emotive-behavioral therapy on meaning of work among employees of oil Company. Method: The present research was conducted by semi-experimental method in which a pretest-posttest-follow up with control group design was used. The research population included all the headquarters’ staff of the oil pipeline and telecommunication company of the North region of Sari, Iran, in 2017 who were 230 individuals. The sample included 45 individuals who were selected by available sampling method and were assigned into two experiment groups and one control group through random assignment method. The research tool was Work as Meaning of Steger, Dik and Duffy (2012). The first experiment group received training based on solution-focused brief therapy (Abbas Pour, 2014), and the second experiment group received training based on rational-emotional-behavioral therapy (Jahanyan Najaf Abadi, 2010) in eight 2-hour sessions. For analyzing the data, variance analysis with repeated measures and Bonferroni post hoc test were used. Results: Results indicated that, in the end of the therapy and after one-month follow-up, both training interventions were effective on improving meaning of work and its components (positive meaning, meaning-making through work, and higher motivations) in experiment groups. Moreover, there was significant difference between the effective of training based on solution-focused brief therapy and training based on rational- emotive -behavioral therapy, and the latter was more effective on improving meaning of work and its components (p< 0/01). Conclusions: Training based on rational- emotive -behavioral therapy is an appropriate and effective interventional option for improving meaning of work among staff.