Due to unique advantages of Jet Electrochemical Machining (Jet‐ECM) such as the absence of mechanical and thermal effects, there is an increasing demand for the implementation of the technology in industrial sectors. However, meeting the stringent quality requirements of the current technological level is a challenge in Jet‐ECM especially for complicated microstructures. Hence, the implementation of an adequate metrology system is necessary to minimise deviations and to enhance the process towards zero‐defect‐manufacturing. The metrology system should be capable of measuring the workpiece before machining in order to enable the machine to adjust the process parameters and to reach the desired micro‐structure. Post‐machining measurements to compare the machined part with the desired shape should be possible as well. This will enhance the machine to make corrections on the workpiece before delivery to the next section in a process chain. However, in order to reach the desired microstructures, the characteristics of workpiece like material properties and previously machined structures on the size and shape of the machined microstructure should be taken into consideration. This is done through the implementation of results of the fingerprint study into the process control. In this study the effects of previously machined single grooves which intersect the secondly machined groove on the size, shape and surface roughness are investigated. The previously machined groove was generated by milling or Jet‐ECM. Since at the intersections the gap size changes and this lead to changes in current and current density, it is expected to observe changes in size and surface roughness. This investigation will show how grooves change at the intersections and whether the mentioned changes are significant. Besides, some suggestions will be provided in order to minimise the effects in Jet‐ECM of intersecting single grooves.

In all common hydrostatic pumps, compressibility affects the commutation phases of the displacing chambers, as they switch their connection from/to the inlet to/from the outlet port, leading to pressure peaks, localized cavitation, additional port flow fluctuations and volumetric efficiency reduction. In common pumps, these effects are reduced by proper grooves that realizes gradual port area variation in proximity of these transition regions. This paper presents a method to automatically find the optimal designs of these grooves, taking as reference the case of external gear pumps. The proposed procedure does not assume a specific geometric morphology for the grooves, and it determines the best feasible designs through a multi-objective optimization procedure. A commercial gear pump is used to experimentally demonstrate the potentials of the proposed method, for a particular case aimed at reducing delivery flow oscillations.

Det finns otaliga metoder att komponera musik på, och resultatet blir alltid annorlunda. Den föredragna metoden för många är gemensam komposition och andra tycker det finns mer kontroll och bekvämhet i att komponera ensam. Så är frågan vilka verktyg fungerar bäst för den ene kompositör. Det kan vara ett instrument, ett program eller en metod för att skapa musiken, och det val av verktyg som väljas har också en påverkan på kompositionsprocessen och de idéer som följer efter. Som kompositören gradvis börjar att utvecklar en bestämt stilar for att komponera, utvecklar kompositören också musiske mönster som blir ett kännemärke för kompositörens ljud. De mönstren kan omedvetet återanvändas till en senare komposition tillfälle och kan bli en barriär för att skapa ny musik. Om det är ett problem eller inte måste kompositören själv bestämma.   Uppgiften med detta examensarbete är att utforska 4 olika metoder för komposition med el-bas som verktyg och se om det är möjligt att undvika de vanliga kompositions rutiner och skapa musik som känns original och färsk. / <p>Vi gjorde en Live Session i Danmark i en studentlägenhet pga COVID-19 - Allt är spelat in med en iPad. </p>

G-quadruplex structures are found in important regions of the eukaryotic genome, such as telomeres and regulatory sequences of genes, and are likely to play important roles in regulation of biological events. The significant structural differences with duplex DNA make quadruplex DNA a very attractive target for anticancer drug design. The purpose of this study is to explore conformational space in a series of heterocyclic cations to discover novel structural motifs that can selectively bind and stabilize specific G-quadruplex arrangements. A variety of biophysical techniques such as thermal melting experiments, biosensor surface plasmon resonance, circular dichroism, fluorescence displacement assay and mass spectrometry were employed to evaluate the affinity of the compounds and their recognition properties. The screening of the molecules allowed the identification of not only selective G-quadruplex ligands but also potential quadruplex groove binders. These results can be useful for the development of new efficient telomerase inhibitors which are endowed with pharmacological activity.

Terahertz waveguides are the focus of considerable research interest due to their potential for sensing, imaging and communications applications. Two of the most promising designs are the metal wire waveguide and the parallel-plate waveguide. The metal wire waveguide exhibits excellent low loss and low dispersion characteristics. However, the radiation is only weakly coupled to the wire and the beam extends a great distance from the waveguide, which can lead to high bending loss. In my research I show that this large beam extent also gives a high degree of flexibility in the geometry required to couple radiation into the waveguide or between waveguide sections. I also show that the traditional formalism of bending loss is incomplete, and that there is an optimum radius of curvature to reduce loss. The relationship between the beam extent and the radius of the wire presents the possibility of a tapered waveguide to confine the radiation as it propagates. I here present experimental data and simulations results to verify this subwavelength confinement at the tip of a tapered metal wire waveguide, which is of great interest for near-field imaging applications. The parallel-plate waveguide is another design frequently employed due to its low loss and low dispersion characteristics. Resonant structures may also be easily incorporated into the waveguide for sensing and filtering applications. One such structure is a single rectangular groove, which serves as a notch filter with a very narrow linewidth when the transverse-electric (TE) mode of the waveguide is excited, though its physical origin is poorly understood. In this work I present a detailed experimental and theoretical study of the rectangular resonant cavity in a TE-mode parallel-plate waveguide, particularly with respect to its potential as a microfluidic refractive index sensor. This study is extended to include the possibility of two grooves, in both coupled and non-coupled geometries, and their efficacy as multichannel or high-resolution single-channel microfluidic sensors.

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Puslaidininkinių prietaisų pramušimo įtampos valdymas formuojant griovelį periferiniame perimetre yra viena iš labiausiai paplitusių technologinių operacijų, gaminant galios diodus bei tiristorius Si pagrindu. Aukštavolčių didelės galios puslaidininkinių prietaisų, kurie dirba kelių tūkstančių amperų diapazone, o uždarymo įtampa iki kelių tūkstančių voltų, didelė problema elektrinio lauko pasiskirstymas ties kristalo briauna, kur p-n sandūra išeina į paviršių ir kur vyksta griūtinis krūvininkų skaičiaus didėjimas. Darbo stabilumui užtikrinti būtina pasyvuoti paviršių kristalo periferijoje, ant profiliuoto krašto. Šiame darbe išanalizuota galingų puslaidininkinių struktūrų konstrukcija, pagrindinės charakteristikos, parametrų tarpusavio ryšis, taip pat technologinis procesas ir jo ypatumai. Išanalizuotos technologinio gamybos maršruto silpniausios pozicijos. Nustatyta izoliacinių griovelių ėsdinimo charakteristikų priklausomybė nuo ėsdiklio sudėties, nuo ėsdinimo įrenginio struktūros ir nuo ėsdiklio temperatūros kitimo. Sukurta stiklo pasyvacijos difuzinės krosnies monitoringo sistema, kuri skirta aukštų temperaturų ir dujų srautų matavimui proceso metu. Rekombinacijų charakteristikų kitimo pagalba, matuojant be kontakte MW-PCT technika, įvertinama izoliacinių griovelių pasyvacijos kokybė. Technologiniame gamybos maršrute, po izoliacinio griovelio ėsdinimo operacijos, prieš stiklo pasyvaciją sudarinėjamas porėtojo silicio sluoksnis, taip pat siūloma įvesti homogeniškumo... [toliau žr. visą tekstą] / Thin dielectric passivation layer is one of the basic construction elements in semiconductor device technology. There are few materials, from which the layers may be manufactured. They are oxides mainly, with Si02 as the most popular of them, although, the phosphor- and boron-silicon glasses are used as passivation layers, too. In choosing a passivant of power thyristors and diodes, there are two important considerations in addition to the usual requirement for providing uniform high breakdown voltage via substrate. One consideration is the thermal stability of the passivant to subsequent high-temperature processes. The other consideration is the bias-temperature stability of the passivation layers affecting the operation life expectancy of a device. In the technology of thyristors and diodes on silicon substrates the bias-breakdown voltage is not uniform over substrate due to non-homogeneity of passivated surface of the p-n junction. In this work, passivation of moat surface by means of electrochemical etching, formation of hydrogen-rich porous silicon layers and glass in-melting steps has been investigated. Passivation quality was controlled by the measurements of surface recombination characteristics after each technological step using a non-invasive technique, which employed microwave probed photoconductivity transients (MW-PCT). It has been shown that electrochemical etching - glass melting steps involved in passivation technological procedures resulted in a decrease of... [to full text]

This thesis is devoted on passenger car tyres. Theoretical part covers description of production, construction and tyre parameters. Practical part is comprised experimental measurement of influence of tread grooves depth on achievable vehicle deceleration. First, it is focused on preparation conditions of measurement, with subsequent processing and evaluation of the data obtained.

The purpose of this diploma thesis is to describe the influence of artificially produced surface grooves on transition from full EHL regime to mixed lubrication in point contact using optical interferometry. This article focuses on influences of grooves orientation, length in contact area, elastic properties of contact surfaces and different types of oil defined by pressure-viscosity coefficient. Empirical prediction model of groove influence on film thickness was established based on experimental data. The groove influence was incorporated into lubrication parameter. This modified definition was compared to classic one. It showed that avoiding groove influence in classic definition lead to significant underestimation. Influence of groove on friction coefficient is also studied.

Due to unique advantages of Jet Electrochemical Machining (Jet‐ECM) such as the absence of mechanical and thermal effects, there is an increasing demand for the implementation of the technology in industrial sectors. However, meeting the stringent quality requirements of the current technological level is a challenge in Jet‐ECM especially for complicated microstructures. Hence, the implementation of an adequate metrology system is necessary to minimise deviations and to enhance the process towards zero‐defect‐manufacturing. The metrology system should be capable of measuring the workpiece before machining in order to enable the machine to adjust the process parameters and to reach the desired micro‐structure. Post‐machining measurements to compare the machined part with the desired shape should be possible as well. This will enhance the machine to make corrections on the workpiece before delivery to the next section in a process chain. However, in order to reach the desired microstructures, the characteristics of workpiece like material properties and previously machined structures on the size and shape of the machined microstructure should be taken into consideration. This is done through the implementation of results of the fingerprint study into the process control. In this study the effects of previously machined single grooves which intersect the secondly machined groove on the size, shape and surface roughness are investigated. The previously machined groove was generated by milling or Jet‐ECM. Since at the intersections the gap size changes and this lead to changes in current and current density, it is expected to observe changes in size and surface roughness. This investigation will show how grooves change at the intersections and whether the mentioned changes are significant. Besides, some suggestions will be provided in order to minimise the effects in Jet‐ECM of intersecting single grooves.