A device for wireless measurement and display of indoor air quality

Zrak v notranjem okolju je v večini primerov onesnažen mnogo bolj kot zunanji zrak. Zato smo se z ekipo odločili ustvariti preprosto napravo, ki spreminja barve glede na kvaliteto zraka v notranjem okolju. Naprava, ki smo jo izdelali, vsebuje različne senzorje in barvno LED-diodo za prikazovanje stanja kvalitete zraka po barvni lestvici: od modre za čist zrak pa vse do vijolične za onesnažen zrak. Poleg tega je naprava opremljena z brezžično povezavo s pametnim telefonom preko tehnologije Bluetooth Low Energy. Napravo smo širši javnosti predstavili na tekmovanju iTime Startup, Slovenskem forumu inovacij in naši spletni strani. Prve primerke naprave smo želeli prodati na platformi za množično financiranje Kickstarter. V začetnem delu diplomskega dela je opisana celotna problematika kvalitete zraka. V nadaljevanju so predstavljeni nekateri senzorji za merjenje kvalitete zraka v notranjih prostorih in njihovo delovanje. Osrednji del prikazuje potek razvoja naprave od prvih prototipov do izdelka na tiskanem vezju. Na koncu je predstavljena implementacija komunikacije med pametnim telefonom in opisano napravo.Indoor air is much more polluted than the air outside. That is why our team decided to create a simple device that changes color relative to the indoor air quality. The device that we created contains a variety of sensors and color LED for indicating the status of the air quality ranging from blue for clean air to violet for polluted air. In addition, the device is also provided with a wireless connection to a smartphone via the Bluetooth Low Energy technology. The device was presented to the general public at iTime Startup competition, Slovenian innovation forum and on our website. We wanted to sell the first pieces of the device on the Kickstarter crowdfunding platform. The initial part of the thesis deals with the problem of the air quality. After that, some sensors for measuring the quality of indoor air and a way of their functioning are presented. The main part describes the development process of the device from the first prototypes to the product made on printed circuit board. At the end the implementation of comunication between smartphone and the described device is presented

DESIGN AND IMPLEMENTATION OF PORTABLE TRACKING DEVICE

Spletno sledenje je danes eden izmed najbolj uporabljanih sistemov za varovanje lastnine in osebno varovanje. Za diplomsko delo sem si izbral razvoj in izdelavo prenosne naprave za sledenje. Naprava pobere GPS podatke o lokaciji in jih preko GSM omrežja pošilja na strežnik, kjer se podatki shranjujejo. Gibanje naprave in s tem predmeta ali osebe, ki jo nosi, lahko spremljamo preko spletne aplikacije. Cilj je bil izdelati priročno prenosno sledilno napravo v velikosti bančne kartice. Njena debelina naj ne bi presegala 10 mm. Pred načrtovanjem vezja je bilo treba poiskati potrebne elemente vezja, izbrati ustrezno postavitev in izrisati ohišje. Idejo o napravi je pregledal zunanji oblikovalec, ki je pripravil risbe končnega izdelka. Pri načrtovanju vezja je bila uporabljena programska oprema Altium Designer. Prototipna tiskana vezja so dvo- in štirislojna, izdelana v zunanjem podjetju, opremila – spajkala pa so se ročno. Sledil je preizkus delovanja naprave. S 3D tiskalnikom smo naredili tudi nekaj ohišij. Naprava je samostojna enota, ki jo napaja vgrajena baterija. Ta se polni preko standardnega USB polnilnika. Določene režime delovanja izbiramo preko vgrajene tipke, za indikacijo pa poskrbijo led diode. Zahtevnejše nastavitve je možno programirati preko SMS sporočil, preko strežnika ali preko serijske povezave.Nowadays online tracking is one of the most used systems for property and personal protection. For the thesis I chose the development and manufacturing of portable tracking device. The device collects the GPS location data and sends them over the GSM network to the data server. Tracking of a person or an object is enabled through a web interface. The main goal was to create a convenient portable tracking device, size of a bank card with maximum thickness 10 mm. Before designing the circuit, it was necessary to find the necessary elements of the circuit, select an appropriate layout and design the housing. Concept sketches of the device were send to a designer, who designed the final product. I designed multi-layer circuits using Altium Designer software and they were manufactured by an external partner. Assembling and soldering of the equipment were manual, followed by operation test of the device. For final usability test we also 3D printed a few housings. The device is a standalone unit and it is powered by built-in battery that is charged by standard micro USB charger. Some operation modes are switched by the embedded keysstatus is indicated by LED diodes. Advanced settings are programmed through SMS messages, web server or by a serial connection

Non-destructive low-temperature contacts to MoS2\textrm{MoS}_2 nanoribbon and nanotube quantum dots

Molybdenum disulfide nanoribbons and nanotubes are near-one dimensional semiconductors with strong spin-orbit interaction, a nanomaterial highly promising for quantum electronic applications. Here, we demonstrate that a bismuth semimetal layer between the contact metal and this nanomaterial strongly improves the properties of the contacts. Two-point resistances on the order of $100\textrm{k}\Omega$ are observed at room temperature. At cryogenic temperature, Coulomb blockade is visible. The resulting stability diagrams indicate a marked absence of trap states at the contacts and the corresponding disorder, compared to previous devices using low-work function metals as contacts. Single level quantum transport is observed at temperatures below 100mK.Comment: 7 pages, 5 figure

Supplementary materials for "Understanding University Student Priorities for Mental Health and Well-being Support: A Mixed-Methods Exploration using the Person-Based Approach"

These supplementary materials comprise some of the study materials used in a mixed-methods exploration of student engagement with and priorities for well-being and mental health support at university. They include the content of an online survey instrument (part 1, quantitative), the focus group discussion schedule (part 2, qualitative), and anonymised data from the survey and focus groups. Research took place in the summer of 2020; the participants were students of the University of Bath at that time.Full details of the methodology may be found in the associated paper. The survey instrument and focus group schedule are included in the dataset.The data archived here has been anonymised in line with the nature of informed consent obtained from participants.Transcripts and descriptively analysed survey data are in MS Word (docx) format. Anonymised and pre-processed survey data are in MS Excel (xlsx) format. The qualitative analysis was conducted in NVivo.The online survey was open between 25th June and 5th August 2020. The three focus groups took place in July 2020

Superconducting tantalum disulfide nanotapes; growth, structure and stoichiometry

Superconducting tantalum disulfide nanowires have been synthesised by surface-assisted chemical vapour transport (SACVT) methods and their crystal structure, morphology and stoichiometry studied by powder X-ray diffraction (PXD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and nanodiffraction. The evolution of morphology, stoichiometry and structure of materials grown by SACVT methods in the Ta-S system with reaction temperature was investigated systematically. High-aspect-ratio, superconducting disulfide nanowires are produced at intermediate reaction temperatures (650 degrees C). The superconducting wires are single crystalline, adopt the 2H polytypic structure (hexagonal space group P6(3)/mmc: a = 3.32(2) angstrom, c = 12.159(2) angstrom; c/a = 3.66) and grow in the <2<(1)over bar>(1) over bar0> direction. The nanowires are of rectangular cross-section forming nanotapes composed of bundles of much smaller fibres that grow cooperatively. At lower reaction temperatures nanowires close to a composition of TaS3 are produced whereas elevated temperatures yield platelets of 1T TaS2

Coulomb Blockade Spectroscopy of a MoS2 Nanotube

Low-temperature transport spectroscopy measurements on a quantum dot lithographically defined in a multiwall MoS2 nanotube are demonstrated. At T = 300 mK, clear Coulomb blockade is observed, with charging energies in the range of 1 meV. In single-electron tunneling, discrete conductance resonances are visible at finite bias. Additionally, a magnetic field perpendicular to the nanotube axis reveals clear indications of quantum state transitions, with effective g factors consistent with published theoretical predictions

Twisted Nanotubes of Transition Metal Dichalcogenides with Split Optical Modes for Tunable Radiated Light Resonators

Synthesized micro- and nanotubes composed of transition metal dichalcogenides (TMDCs) such as MoS$_2$ are promising for many applications in nanophotonics, because they combine the abilities to emit strong exciton luminescence and to act as whispering gallery microcavities even at room temperature. In addition to tubes in the form of hollow cylinders, there is an insufficiently-studied class of twisted tubes, the flattened cross section of which rotates along the tube axis. As shown by theoretical analysis, in such nanotubes the interaction of electromagnetic waves excited at opposite sides of the cross section can cause splitting of the whispering gallery modes. By studying micro-photoluminescence spectra measured along individual MoS$_2$ tubes, it has been established that the splitting value, which controls the energies of the split modes, depends exponentially on the aspect ratio of the cross section, which varies in "breathing" tubes, while the relative intensity of the modes in a pair is determined by the angle of rotation of the cross section. These results open up the possibility of creating multifunctional tubular TMDC nanodevices that provide resonant amplification of self-emitting light at adjustable frequencies

Active removal of waste dye pollutants using Ta[sub]3N[sub]5/W[sub]18O[sub]49 nanocomposite fibres

A scalable solvothermal technique is reported for the synthesis of a photocatalytic composite material consisting of orthorhombic Ta3N5 nanoparticles and WOx≤3 nanowires. Through X-ray diffraction and X-ray photoelectron spectroscopy, the as-grown tungsten(VI) sub-oxide was identified as monoclinic W18O49. The composite material catalysed the degradation of Rhodamine B at over double the rate of the Ta3N5 nanoparticles alone under illumination by white light, and continued to exhibit superior catalytic properties following recycling of the catalysts. Moreover, strong molecular adsorption of the dye to the W18O49 component of the composite resulted in near-complete decolourisation of the solution prior to light exposure. The radical species involved within the photocatalytic mechanisms were also explored through use of scavenger reagents. Our research demonstrates the exciting potential of this novel photocatalyst for the degradation of organic contaminants, and to the authors’ knowledge the material has not been investigated previously. In addition, the simplicity of the synthesis process indicates that the material is a viable candidate for the scale-up and removal of dye pollutants on a wider scale