Conventional Nanoindentation in Self-Assembled Monolayers Deposited on Gold and Silver Substrates

Peer reviewe

Reconstruction of the Haiba reservoir into a natural swimming pool

Magistritöö Vesiehituse ja veekaitse õppekavalUuritavaks objektiks oli looduslike basseinide konstruktsiooniline lahendus ning neis kasutatavad veepuhastusmeetodid. Töö eesmärgiks oli leida tehniline lahendus loodusliku ujula rajamiseks Haiba veehoidlasse, eelkõige veehoidla ääres asuva lastekodu lastele kasutamiseks. Magistritöö eesmärgi saavutamiseks uuriti erialakirjandust ning kehtivaid regulatsioone, mille põhjal koostati töö teoreetiline osa. Haiba veehoidlas teostati veehoidla settemahu mõõdistamine. Looduslikud basseinid on Eestis uudne lahendus. Looduslikes basseinides toimub veepuhastus bioloogiliste, füüsikaliste ja füüsikalis-keemiliste protsesside abil. Looduslikes basseinides ei ole vee desinfitseerimisel kasutusel kloori ega muid keemilisi vahendeid, mis on ka peamine erinevus traditsioonilistest basseinidest. Haiba veehoidlasse rajata ujula veepuhastamiseks planeeritud taimefilter ning tehismärgala. Taimefilter kombineerituna tehismärgalaga peaks hoidma lämmastiku ja fosfori sisalduse basseinivees alla 30 mg/l NO3 ja 0,01 mg/l P ning tagama vastavuse basseiniveele seatud mikrobioloogilistele näitajatele.The object of the study was the design of natural pools and the water treatment methods used in them. The study aimed to find a technical solution for constructing a natural swimming pool in the Haiba reservoir, particularly for the children of the children's home near the reservoir. The literature and existing regulations were studied to aim for the thesis, based on which the theoretical part of the thesis was written. In addition, a measurement of the sediment volume of the Haiba reservoir was measured. Natural swimming pools are a novel solution in Estonia. In natural pools, water purification is completed by biological, physical, and physicochemical processes. Natural pools do not use chlorine or other chemicals to disinfect the water, which is the main difference from traditional pools. A Hydrobotanocal System and Technical Wetland will be installed in the Haiba reservoir to purify the swimming pool water. The Hydrobotanocal System combined with the Technical Wetland should keep the nitrogen and phosphorus concentrations in the pool water below 30 mg/l NO3 and 0.01 mg/l P and ensure compliance with the microbiological parameters set for the pool water

Conventional Nanoindentation in Self-Assembled Monolayers Deposited on Gold and Silver Substrates

Self-assembled monolayers (SAMs) are promising materials for micromechanical applications. However, characterization of mechanical properties of monolayers is challenging for standard nanoindentation, and new efficient analysis techniques are needed. Hereby, a conventional nanoindentation method has been combined in a unique way with efficient data analysis based on consumed energy calculation and load-displacement data. The procedure has been applied on SAMs of 4,4 -biphenyldithiol (BPDT) on Au, 1-tetradecanethiol (TDT), and 1-hexadecanethiol (HDT) on Au and Ag substrates being the first study where SAMs of the same thiols on different substrates are analyzed by nanoindentation providing a new insight into the substrate effects. Unlike TDT and HDT SAMs, which are found to strongly enhance the homogeneity and stiffness of the underlying substrate, the BPDT covered Au substrate appears softer in mechanical response. In the case of TDT and HDT SAMs on Ag the structures are softer showing also faster relaxation than the corresponding structures on Au substrate. The proposed procedure enables a fast and efficient way of assessing the complex behaviour of SAM modified substrates. As a consequence, the results are relevant to practical issues dependent on layer activity and toughness

Laser Additively Manufactured Magnetic Core Design and Process for Electrical Machine Applications

Additive manufacturing (AM) is considered the enabling technology for topology optimized components, with its unparalleled, almost free-form design freedom. Over the past decade, AM of electromagnetic materials has evolved into a promising new area of research. Considerable efforts have also been invested by the electrical machine (EM) research community to develop and integrate novel additive components. Several challenges remain, however, in printing soft magnetic flux guides—most prominently, reducing the induced eddy currents to achieve competitive AM core efficiency. This paper demonstrates the workflow of laser additive manufacturing magnetic cores with superior magnetic properties to soft magnetic composites (at 50 Hz excitation): describing the workflow, parameter tuning for both printing and annealing, and shape optimization. Process optimization yielded the optimal energy density of 77 J/mm3 and annealing temperature of 1200 °C, applied to prepare the samples with the highest relative density (99.86%), lowest surface roughness Rz (0.041 mm), minimal hysteresis losses (0.8 W/kg at 1.0 T, 50 Hz), and ultimate yield strength of 420 MPa. For Eddy current suppression, the sample (5 × 5 × 60 mm toroid) with bi-directional grading reached specific core losses as low as 1.8 W/kg (W10,50). Based on the findings, the advantages and disadvantages of AM graded cores are discussed in detail

Laser Additively Manufactured Magnetic Core Design and Process for Electrical Machine Applications

Additive manufacturing (AM) is considered the enabling technology for topology optimized components, with its unparalleled, almost free-form design freedom. Over the past decade, AM of electromagnetic materials has evolved into a promising new area of research. Considerable efforts have also been invested by the electrical machine (EM) research community to develop and integrate novel additive components. Several challenges remain, however, in printing soft magnetic flux guides—most prominently, reducing the induced eddy currents to achieve competitive AM core efficiency. This paper demonstrates the workflow of laser additive manufacturing magnetic cores with superior magnetic properties to soft magnetic composites (at 50 Hz excitation): describing the workflow, parameter tuning for both printing and annealing, and shape optimization. Process optimization yielded the optimal energy density of 77 J/mm3 and annealing temperature of 1200 °C, applied to prepare the samples with the highest relative density (99.86%), lowest surface roughness Rz (0.041 mm), minimal hysteresis losses (0.8 W/kg at 1.0 T, 50 Hz), and ultimate yield strength of 420 MPa. For Eddy current suppression, the sample (5 × 5 × 60 mm toroid) with bi-directional grading reached specific core losses as low as 1.8 W/kg (W10,50). Based on the findings, the advantages and disadvantages of AM graded cores are discussed in detail