Fully automatic welding of thick-walled pressure vessels by the narrow gap subarc process

The demands for welding of thick-walled pressure vessels are very stringent. The cost of repairing a weld defect deep down in a weld joint could be very high. As submerged arc welding is considered to be a reliable process for both the welding of pressure vessels and other demanding applications, ESAB chose this process when developing their narrow gap welding technique. This two-pass narrow gap process is described together with the welding and control equipment. The welding results using two types of agglomerated fluxes are presented.     

Design and evaluation of an active electromechanical wheel suspension system

This paper presents an electromechanical wheel suspension, where the upper arm of the suspension has been provided with an electric levelling and a damper actuator, both are allowed to work in a fully active mode. A control structure for the proposed suspension is described. The complex design task involving the control of the electric damper and its machine parameters is tackled by genetic optimisation. During this process, these parameters are optimised to keep the power dissipation of the electric damper as low as possible, while maintaining acceptable comfort and road-holding capabilities. The results of the evaluations carried out demonstrate that the proposed suspension can easily adopt its control parameters to obtain a better compromise of performance than that offered by passive suspensions. If the vehicle is to maintain acceptable performance during severe driving conditions, the damper has to be unrealistically large. However, if the electric damper is combined with a hydraulic damper, the size of the electric damper is significantly reduced. In addition, the design of the electric damper with the suggested control structure, including how it regenerates energy, is discussed.     

Managing Project Transformation in a Complex Context

Complex projects are often undertaken in uncertain situations in which project participants who adopt a rational‐oriented strategy tend to face difficulties in adapting and adjusting to changes that occur during the project. In this context a process‐oriented strategy, although difficult to manage, can be a better way to handle project transformation. Collective learning then becomes crucial. This article describes some lessons learned when a project manager and team applied a process‐oriented strategy in a complex project. Data has been collected through interactive research and evaluation with different methods including surveys, observations and interviews. The analysis shows that it is possible to organize for learning and to manage transformation in a complex context. Important factors for success are a process‐oriented strategy, a creative climate, formative evaluation and systematic reflections. A major issue that is discussed in the article is the transfer of outcomes from the project to the participating organizations.     

Preparation of Titanium Nitride/Alumina Laminate Composites

A preparation route for TiN/Al₂O₃ laminate composites has been described. A water-based process using Al₂O₃ and TiN slurries with solids contents of 40 and 35 vol%, respectively, was used to make TiN and Al₂O₃ tapes. The removal of the binder was monitored by weight-loss measurements in a thermogravimetry unit. Bodies composed of Al₂O₃ and TiN tapes were densified at temperatures of 1400° and 1500°C using the Spark Plasma Sintering^® (SPS) technique. Densities of >98% of the theoretical densities were approached. Crack-free and almost fully densified TiN/Al₂O₃ compacts were prepared by heating the burned-out green bodies to the final sintering temperature (1500°C) at a rate of 100°C/min, and with a holding time of 5–10 min, under a pressure of 75 MPa. The microstructures of the obtained compacts were studied using scanning electron microscopy. Grain sizes in the sintered Al₂O₃ and TiN compacts were similar to those of the precursor powders. Hardness and indentation fracture toughness were measured at room temperature, and the monolithic compacts as well as the laminate composites exhibited anisotropic mechanical behavior; i.e., the cracks propagated much more easily in a direction parallel to the laminas than perpendicular to them.     

Note: The intermodulation lockin analyzer

Nonlinear systems can be probed by driving them with two or more pure tones while measuring the intermodulation products of the drive tones in the response. We describe a digital lockin analyzer which is designed explicitly for this purpose. The analyzer is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback, and stability in operation. The use of the analyzer is demonstrated for intermodulation atomic force microscopy. A generalization of the intermodulation spectral technique to arbitrary drive waveforms is discussed.     

The In-Situ Technique for Measuring Input Impedance and Connection Effects of RFID Tag Antenna

In this paper, an indirect noninvasive method for measuring input impedance and the variations in the assembly of the interconnect and packaging between antenna and the integrated circuit (IC) effects of passive radio frequency identification (RFID) transponder (tags) antennas is presented. The analysis of different RFID tags is presented together with the experimental data.     

Ecological effects of river regulation on mammals and birds: A review

Although most of the world's river systems are regulated, the effects of river regulation on mammals and birds are little known. In fact, speculations are more common than empirical data. A review of this topic is presented, emphasizing northern rivers where most impacts have been described. Effects are related to the major causes of change. It is concluded that the two most disastrous effects of river regulation on mammals and birds are the permanent inundation of vast areas of land, and the disruption of the seasonal flood regime along the river. The design of future investigations to improve our knowledge is considered.     

Simplified Large‐Area Manufacturing of Organic Electrochemical Transistors Combining Printing and a Self‐Aligning Laser Ablation Step

A hybrid manufacturing approach for organic electrochemical transistors (OECTs) on flexible substrates is reported. The technology is based on conventional and digital printing (screen and inkjet printing), laser processing, and post‐press technologies. A careful selection of the conductive, dielectric, and semiconductor materials with respect to their optical properties enables a self‐aligning pattern formation which results in a significant reduction of the usual registration problems during manufacturing. For the prototype OECTs, based on this technology, on/off ratios up to 600 and switching times of 100 milliseconds at gate voltages in the range of 1 V were obtained.     

Pattern Noise in the Frequency ΔΣ Modulator

In this paper, we show that the first-order frequency delta–sigma modulator is equivalent to a traditional delta–sigma modulator with respect to pattern noise. We further propose two techniques for reducing the effect of pattern noise. The first technique is based on time-domain dithering which is implemented by adding white phase noise to the FM signal. The second technique is based on locating the narrow dynamic range that may be in this kind of modulators, in a pattern noise valley. This technique can utilize pattern noise to make the modulator provide significantly higher digital resolution than the white quantization noise model predicts. Finally, the theory is verified by measurements.