scholarly journals Channel Occupancy Measurements in 868 MHz ISM Band in Residential Areas

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7805
Author(s):  
Sebastian Kozłowski ◽  
Krzysztof Kurek
Keyword(s):  
Software Defined Radio ◽  
Rapid Development ◽  
Idle Time ◽  
Residential Areas ◽  
Medium Access ◽  
Frequency Channel ◽  
Ism Band ◽  
Set Up ◽  
Over Time ◽  
Channel Occupancy

The rapid development of Internet of Things (IoT) has led to more and more devices using ISM frequency bands. Because they are not time synchronized, medium access collisions are unavoidable. The probability of such a collision is usually reasonably low; however, it increases with the number of transmitters competing for the same frequency channel. For this reason, ISM bands’ occupancy is regularly monitored by researchers. This paper presents the results of the measurement campaign during which a selected part of the 868 MHz ISM frequency band was monitored for the presence of transmissions in six locations in various residential areas in Warsaw, Poland. For the purpose of the campaign, a dedicated measurement set-up comprising a software-defined radio (SDR) module was assembled. The measurements results showed that the channel occupancy is in most cases lower than 1% with a maximum observed value of 2%. The paper presents selected characteristics of the detected signals. Additionally, distribution over time of the detected signals was used together with the Monte Carlo simulations to analyze how long idle time blocks are available for new transmitters that could be deployed in the band under testing.

A tuneable rat-race coupler for full duplex communications

2021 ◽  
pp. 1-7
Author(s):  
G. T. Watkins
Keyword(s):  
Interference Cancellation ◽  
Phase Shifter ◽  
Dipole Antenna ◽  
Full Duplex ◽  
Frequency Channel ◽  
Ism Band ◽  
Single Antenna ◽  
Variable Attenuator ◽  
Degree Of Isolation ◽  
Better Than

Abstract Full duplex (FD) could potentially double wireless communications capacity by allowing simultaneous transmission and reception on the same frequency channel. A single antenna architecture is proposed here based on a modified rat-race coupler to couple the transmit and receive paths to the antenna while providing a degree of isolation. To allow the self-interference cancellation (SiC) to be maximized, the rat-race coupler was made tuneable. This compensated for both the limited isolation of the rat race and self-interference caused by antenna mismatch. Tuneable operation was achieved by removing the fourth port of the rat race and inserting a variable attenuator and variable phase shifter into the loop. In simulation with a 50 Ω load on the antenna port, better than −65 dB narrowband SiC was achieved over the whole 2.45 GHz industrial, scientific and medical (ISM) band. Inserting the S-parameters of a commercially available sleeve dipole antenna into the simulation, better than −57 dB narrowband SiC could be tuned over the whole band. Practically, better than −58 dB narrowband tuneable SiC was achieved with a practical antenna. When excited with a 20 MHz Wi-Fi signal, −42 dB average SiC could be achieved with the antenna.

Historical background and evolution of Soil Mechanics

2021 ◽  
Vol 18 ◽  
pp. 96-113
Author(s):  
Philotheos Lokkas ◽  
Ioannis Chouliaras ◽  
Theodoros Chrisanidis ◽  
Dimitrios Christodoulou ◽  
Emmanouil Papadimitriou ◽  
...  
Keyword(s):  
Building Material ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Rapid Development ◽  
Building Construction ◽  
Historical Background ◽  
Education Of Students ◽  
Scientific Fields ◽  
Important Branch ◽  
Over Time

The behavior of soil either as a building material or as a load receiver is particularly important and presents a paramount significance in both infrastructure and building construction. Geotechnical engineering has shown a rapid development over the last fifty years and holds a prominent position in all scientific fields of engineers. This paper mainly aims at the historical background along with the progress made on Soil Engineering as an important branch of Surveyors, Civil and Mining Engineers, where, through an important citation of technical works and constructions over time, may be considered as a significant tool for teaching and education of students

Grafinscripties

Lampas ◽  
2021 ◽  
Vol 54 (1) ◽  
pp. 39-65
Author(s):  
Onno van Nijf
Keyword(s):  
Late Antiquity ◽  
Archaic Period ◽  
Social Strategies ◽  
Public And Private ◽  
Content Type ◽  
Frequent Type ◽  
The Social ◽  
Funerary Inscriptions ◽  
Set Up ◽  
Over Time

Abstract This article offers a brief introduction to the most frequent type of inscription: funerary inscriptions or epitaphs. The article offers a chronological overview from the Archaic period to late Antiquity, with an emphasis on Athens. It opens with a brief discussion of the archaeological and ritual contexts in which funerary inscriptions were set up, followed by a discussion of archaic epigrams and the social strategies that lay behind them. This is followed by a discussion of public and private graves that shows how epigraphic habits changed over time. The article continues with a discussion of funerary epigraphic habits outside Athens and closes with a few examples of Christian epitaphs.

Research on Multimedia Sports Humanistic Information Systems

2014 ◽  
Vol 926-930 ◽  
pp. 2706-2709
Author(s):  
Ming Wen Hu
Keyword(s):  
Information System ◽  
Information Systems ◽  
Program Implementation ◽  
Social Life ◽  
Technology Development ◽  
Rapid Development ◽  
Development Environment ◽  
Sports Culture ◽  
The Core ◽  
Set Up

With the rapid development of social productive forces and increasingly higher level of social life, the sports humanity as the core spirit of sports culture in informational times, which is the sum of the psychological aspects of sports culture from the cultural spirit. Its essence is the pursuit of truth, good and beautiful as the core values and ideals, people's healthy development as the ultimate goal. This paper discusses basic mode ,the basic framework of the multimedia sports humanistic information system, the processing technology, development environment ,tools and methods . Through the analysis program implementation elements and design ideas of multimedia sports humanistic information system, in order to set up multimedia sports humanistic information systems, we proposes a viable framework and models with a theoretical basis and practical value.

scholarly journals Minimizing Hiring Cost of the Machine Under No Idle Constraints in N*2 Flow Shop Scheduling with Transportation and Set Up Time.

2019 ◽  
Vol 9 (2) ◽  
pp. 5227-5229
Keyword(s):  
Flow Shop ◽  
Setup Time ◽  
Idle Time ◽  
Flow Shop Scheduling ◽  
Start Time ◽  
Transportation Time ◽  
Shop Scheduling ◽  
Set Up

The present paper deals with a problem of n*2 flow shop scheduling where setup time of the machines are separated from their dispensation time and transportation time for moving from first machine to second machine is also given. Our aim is to get the most favorable jobs sequence which can make machines idle time equal to zero so that rental cost can be minimized. In order to ensure no idle constraint, we have developed an algorithm in which we have delayed the start time of machine B, so that machine B works continuously without any idle time. A simple mathematical example is also given to clear the concept.

scholarly journals UPAYA MENGURANGI CHANGE OVER TIME PADA PROSES PENJAHITAN DI SEWING LINE A20 PT. DF

Texere ◽  
2021 ◽  
Vol 17 (2) ◽  
Author(s):  
Tina Martina ◽  
Nur Rofiqoh Utami ◽  
Pratiwi Wulansari
Keyword(s):  
Lean Manufacturing ◽  
Change Over Time ◽  
Set Up ◽  
Over Time

Pada industri pakaian jadi pelayanan dan kepuasan buyer menjadi hal penting dalam menghadapi persaingan agar dapat terus tumbuh dan berkembang. Order produksi setiap tahun terdiri dari berbagai macam style yang akan berganti setelah selesai diproduksi. Perusahaan akan melakukan penetapan waktu yang harus dicapai dalam menyelesaikan satu order, sehingga dapat berpengaruh pada efisiensi waktu proses dikarenakan seringnya aktivitas change over. Change over merupakan pergantian aktivitas produksi disuatu lini produksi dari satu produk ke produk lainnya. Metoda yang akan digunakan untuk mengurangi change over time (COT) pada lini produksi yaitu menggunakan Quick Change Over (QCO). Tujuan mengurangi COT untuk mengefisiensikan waktu proses produksi walaupun tidak untuk menambah kapasitas produksi. Waktu yang dibutuhkan selama set up mesin dalam QCO menjadi faktor yang paling lama sehingga beberapa proses set up harus disederhanakan sesuai dengan prinsip lean manufacturing. Upaya mengurangi COT pada proses penjahitan yaitu dengan penerapan pemeliharaan mesin yang terjadwal, menempatkan operator sesuai dengan skill matrix dan mempersiapkan aksesoris ketika diperlukan bagian produksi. Hasil setelah penerapan metoda QCO untuk style yang repeat order menunjukan bahwa COT line A20 mengalami penurunan, walaupun belum memenuhi standar target yang ditetapkan oleh perusahaan. Penurunan COT ini akan berdampak pada peningkatan produktivitas dan efisiensi di line A20.

scholarly journals On Rapid Development of Reactive Wireless Sensor Systems

2019 ◽  
Vol 1 (1) ◽  
pp. 574-582
Author(s):  
Paweł Gburzyński ◽  
Elżbieta Kopciuszewska
Keyword(s):  
Operating System ◽  
Software Development ◽  
Programming Language ◽  
Independent Living ◽  
Rapid Development ◽  
Wireless Sensor ◽  
Sensors And Actuators ◽  
Execution Platform ◽  
Small Footprint ◽  
Set Up

AbstractWe present a software platform for designing and testing wireless networks of sensors and actuators (WSNs). The platform consists of three components: an operating system for small-footprint microcontrollers (dubbed PicOS), a software development kit (SDK) amounting to a C-based, event-oriented (reactive) programming language, and a virtual execution platform (VUE2) capable of emulating complete deployment environments for WSNs and thus facilitating their rapid development.1 Its most recent incarnation introduced in the present paper is a component of the WSN lab being currently set up at Vistula in collaboration with Olsonet Communications Corporation.2 We highlight the platform’s most interesting features within the context of a production WSN installed at independent-living facilities.

The Mechanism of Language Death: A Reflection of Malay Language in Tanjung Balai

2021 ◽  
Vol 1 (1) ◽  
pp. 23-32
Author(s):  
Muhammad Natsir ◽  
Fauziah Khairani Lubis
Keyword(s):  
Qualitative Research ◽  
Qualitative Methods ◽  
Qualitative Method ◽  
Rapid Development ◽  
National Language ◽  
Common Elements ◽  
Language Death ◽  
The Future ◽  
The Common ◽  
Over Time

This study deals with the phenomenon while language can be lost slowly if it can't be defended. This happens along with the rapid development of the era towards modernization which is feared that in the future, the Tanjung Balai Malay language, which is owned and proudly has been threatened with extinction over time, but what needs to be realized is that it does not mean to displace the position of Indonesian which has been agreed as the national language. This research took place in Tanjung Balai when in Tanjung Balai Malay language is used as the habitual language.  This study was conducted using descriptive with qualitative method purposed to find out the words as dysfunction verb in Tanjung Balai Language. Qualitative research was related to assisting in describing the common elements of the various forms of qualitative methods. Thirty dysfunctional Malay verbs were collected and analyzed as the data findings.

Spray-on Ceramic Insulation up to 450°C and Encapsulating existing corrosion without sandblast

2013 ◽  
Author(s):  
Joseph E. Pritchett
Keyword(s):  
Heat Load ◽  
Time Frame ◽  
Trial And Error ◽  
System Research ◽  
Coated Film ◽  
Resin Solution ◽  
Set Up ◽  
Ceramic Compounds ◽  
Hot Surface ◽  
Over Time

Ceramic compounds have been around for many years, but the research to find which compounds, what size, crystalline structure and density would perform to block “heat load” is the keys the selecting the correct compounds to use. “Blocking heat load from radiation or resisting the absorption and loading of heat when used over a hot surface” is determined by the aspects stated above. None of this could be determined from the ceramic catalogs of listed compounds stating referenced characteristics. To determine how a compound would react in a paint/coating form could only be realized by trial and error when the compound is mixed in a resin solution with other compounds to see the result. This process has taken 23 years and over 3600 compounds to find 12 compounds that will continue to work when wet and mixed with other materials. As to the corrosion encapsulation without the need for sandblasting, this was studied after finding that most all corrosion protection specifications require sandblast, primers and top coats which over time did not perform as theory had projected. Part of the reason is due to the time frame after the blast is performed before the paints are applied. By the time the paints are applied a flash rust or bloom has set up and the surface is now out of specification and the result is a failure of the system. Research was applied on how a corrosion coating could be made to first penetrate deep into the pores of metal or rust, then swell and encapsulate the pores and/or surface rust before it sets up to 6780 psi surface tensile strength. In this way, the surface rust is used as the profile needed to anchor the coating and add to the strength of the coated film.

From ‘Sustainability’ to ‘Competitive Industry’

2015 ◽  
Author(s):  
Gillian Doyle
Keyword(s):  
Film Industry ◽  
Competitive Industry ◽  
Key Players ◽  
Set Up ◽  
The Moment ◽  
Over Time ◽  
The Way

Although from the moment the Film Council was set up, it was clear that the intention was to found an organisation focused on bringing ‘sustainability’ to the British film industry, the Council gradually retreated from this term in favour of a wider set of priorities and the way in which it articulated its mission also gradually shifted. Drawing on a wealth of original interviews with senior politicians, film executives, independent producers, industry experts and leading filmmakers, this chapter examines the key players, forces and assumptions which drove the Film Council’s agenda, how the weighting of priorities shifted over time and why the Council’s sense of mission changed over its lifetime.

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