There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

2 1 The innovative transport systems and the CityMobil project 10 1.1 The research questions 10 2 The state of art in the field of automatic transport systems 12 2.1 Case studies and demand studies for innovative transport systems 12 3 The design and implementation of surveys 14 3.1 Definition of experimental design 14 3.2 Questionnaire design and delivery 16 3.3 First analyses on the collected sample 18 4 Calibration of Logit Multionomial demand models 21 4.1 Methodology 21 4.2 Calibration of the “full” model. 22 4.3 Calibration of the “final” model 24 4.4 The demand analysis through the final Multinomial Logit model 25 5 The analysis of interaction between the demand and socioeconomic attributes 31 5.1 Methodology 31 5.2 Application of Mixed Logit models to the demand 31 5.3 Analysis of the interactions between demand and socioeconomic attributes through Mixed Logit models 32 5.4 Mixed Logit model and interaction between age and the demand for the CTS 38 5.5 Demand analysis with Mixed Logit model 39 6 Final analyses and conclusions 45 6.1 Comparison between the results of the analyses 45 6.2 Conclusions 48 6.3 Answers to the research questions and future developments 52

The European commission

Additive manufacturing of metallic components – Process, structure and properties

Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.

The metallurgy and processing science of metal additive manufacturing

The tool steel X220CrVMo 13-4 (DIN 1.2380) containing (mass%) 2.2C, 13Cr, 4V, 1Mo and the binary alloy Fe–2.03 mass% C were studied using transmission electron microscopy, Mossbauer spectroscopy, X-ray diffraction and internal friction with the aim of shedding light on processes occurring during deep cryogenic treatment. It is shown that the carbon atoms are essentially immobile at temperatures below −50 °C, whereas carbon clustering in the virgin martensite occurs during heating above this temperature. An increase in the density of dislocations, the capture of immobile carbon atoms by moving dislocations, the strain-induced partial dissolution of the carbide phase, and the abnormally low tetragonality of the virgin martensite are found and interpreted in terms of plastic deformation that occurs during martensitic transformation at low temperatures where the virgin martensite is sufficiently ductile.

Low-temperature martensitic transformation and deep cryogenic treatment of a tool steel

The special properties of nickel–titanium shape memory alloys are currently used in micro-engineering and medical technology. In order to integrate NiTi components into existing parts and modules, they often need to be joined to other materials. For this reason, the present contribution deals with the laser welding of thin pseudoelastic NiTi wires (100 μm) with an Nd:YAG laser. Based on extensive parameter studies, faultless joints were produced. This study deals with the structural changes occurring in the fusion and heat-affected zones, the performance of the joints in static tensile tests and their functional fatigue. It can be shown that NiTi/NiTi joints reach about 75% of the ultimate tensile strength of pure NiTi wires. For welding NiTi to steel, no interlayer was used. The dissimilar NiTi/steel joints provide a bonding strength in the fusion and heat-affected zones higher than the plateau stress level. NiTi/steel joints of thin wires, as a new aspect, enable the possibility to benefit from the pseudoelastic properties of the NiTi component.

Laser welding of NiTi wires

Low-temperature martensitic transformation in tool steels in relation to their deep cryogenic treatment

Part A Fundamentals of ferrous materials A.1 Constitution A.1.1 Pure Iron A.1.2 Iron-carbon A.1.3 Iron alloys A.2 Microstructure A.2.1 Near-equilibrium structures A.2.2 Non-equilibrium structures A.2.3 Morphology of cementite and graphite A.3 Heat treatment A.3.1 Annealing treatments A.3.2 Hardening and related treatments A.3.3 Surface treatments A.3.4 Side effects A.4 Properties A.4.1 Mechanical properties A.4.2 Tribological properties A.4.3 Chemical properties A.4.4 Special physical properties Part B Ferrous materials and their application B.1 Materials for general use B.1.1 Carbon steels B.1.2 Cast irons B.2 High strength materials B.2.1 Weldable rolled steels B.2.2 Forged steels with integrated heat treatment B.2.3 Heat treated constructional steels B.2.4 Heat treated cast irons B.3 Materials for surface treatment B.3.1 Materials for surface hardening B.3.2 Nitriding steels B.3.3 Case-hardening steels B.4 Tools for processing minerals B.4.1 Material concept B.4.2 Tools made of hot-worked steels B.4.3 Cast tools B.4.4 Coated tools B.5 Tools for processing metals and polymers B.5.1 Cold-work tool steels B.5.2 Steels for polymer processing B.5.3 Hot-work tool steels B.5.4 Tools for metal cutting B.6 Chemically resistant materials B.6.1 General comments B.6.2 Stainless steels B.6.3 Heat-resistant steels B.6.4 Cast irons B.7 Creep resistant steels B.7.1 Properties B.7.2 Key applications B.8 Functional materials B.8.1 Soft magnetic materials B.8.2 Hard magnetic materials B.8.3 Non-magnetic materials B.8.4 Materials of special thermal expansion B.8.5 Shape memory alloys B.8.6 Materials for electrical heating Appendix C.1 Designation of steels and cast-iron along European Standards EN C.2 Short history of iron C.3 References to figures and tables

Ferrous Materials: Steel and Cast Iron

Electro discharge machining (EDM) is a common fabrication process for miniaturized components in medical technology and micro engineering today. As EDM induces material changes in the near surface zone, the surface integrity becomes ever more important, the smaller the components are. In order to characterize the influence of EDM on the near surface zone, basic metallurgical investigations on pseudo-elastic NiTi shape memory alloys (SMAs) were carried out. Material removal in EDM depends on the electric discharge processes between the tool and the workpiece electrode in a dielectric fluid. Material is removed by melting and vaporization in single sparks. This results in craters with varying size and depth depending on the discharge energy. The microstructure of this melting zone is characterized by hollows, cracks and precipitation. Cracks open at the surface in consequence of randomly and locally overlapping thermal shocks. The cracks grow vertically into the material, starting at the surface. In the melting zone, significant precipitations were detected and subsequently identified by EDX as titanium carbides. The material removal rate, which is an important process factor in manufacturing, approximately increases in linear proportion with the discharge energy, and achieves commercially interesting values by using an electrode made of copper and tungsten. The results of the microstructure analysis require the removal of the near surface zone to ensure the properties of the components. This is possible via a smooth EDM-process, followed by electrolytic polishing.

Werner Theisen

Papers

Low-temperature martensitic transformation and deep cryogenic treatment of a tool steel

Laser welding of NiTi wires

Low-temperature martensitic transformation in tool steels in relation to their deep cryogenic treatment

Ferrous Materials: Steel and Cast Iron

Electro discharge machining of nickel–titanium shape memory alloys