Real-time 3D thermal modeling of a magnetically levitated planar actuator

A transient thermal model used to monitor the temperature distribution in real-time in a long-stroke moving-magnet planar actuator is presented. The temperature distribution in the stator coils of the planar actuator depends on the trajectory of the levitated magnet plate as the set of active coils changes with the position of the translator. Using the presented real-time model, the transient thermal behavior can be investigated. Using this thermal model, the commutation algorithm of the planar actuator is adjusted to actively limit the temperature of the coils, and better spread the temperature over the stator coils.     

The deformation of the moving magnet plate of a commutated magnetically levitated planar actuator

This paper presents a method to calculate the deformation of the magnet plate of a commutated magnetically levitated planar actuator using a linked electromagnetic–mechanical model. The force and torque distribution on the moving magnet array is obtained from an electromagnetic model based on the surface charge method and the Lorentz force and torque integral. The mechanical model is a state-space model derived from FEM. This mechanical model uses the force and torque distribution to determine the deformation of the magnet plate during movement due to the commutated coil set.     

Power saving through state retention in IGZO‐TFT AMOLED displays for wearable applications

We present a qHD (960 × 540 with three sub‐pixels) top‐emitting active‐matrix organic light‐emitting diode display with a 340‐ppi resolution using a self‐aligned IGZO thin‐film transistor backplane on polyimide foil with a humidity barrier. The back plane process flow is based on a seven‐layer photolithography process with a CD = 4 μm. We implement a 2T1C pixel engine and use a commercial source driver IC made for low‐temperature polycrystalline silicon. By using an IGZO thin‐film transistor and leveraging the extremely low off current, we can switch off the power to the source and gate driver while maintaining the image unchanged for several minutes. We demonstrate that, depending on the image content, low‐refresh operation yields reduction in power consumption of up to 50% compared with normal (continuous) operation. We show that with the further increase in resolution, the power saving through state retention will be even more significant.     

Mobile satellite reception with a virtual satellite dish based on a reconfigurable multi-processor architecture

Traditionally, mechanically steered dishes or analog phased array beamforming systems have been used for radio frequency receivers, where strong directivity and high performance were much more important than low-cost requirements. Real-time controlled digital phased array beamforming could not be realized due to the high computational requirements and the implementation costs. Today, digital hardware has become powerful enough to perform the massive number of operations required for real-time digital beamforming. With the continuously decreasing price per transistor, high performance signal processing has become available by using multi-processor architectures. More and more applications are using beamforming to improve the spatial utilization of communication channels, resulting in many dedicated digital architectures for specific applications. By using a reconfigurable architecture, a single hardware platform can be used for different applications with different processing needs.In this article, we show how a reconfigurable multi-processor system-on-chip based architecture can be used for phased array processing, including an advanced tracking mechanism to continuously receive signals with a mobile satellite receiver. An adaptive beamformer for DVB-S satellite reception is presented that uses an Extended Constant Modulus Algorithm to track satellites. The receiver consists of 8 antennas and is mapped on three reconfigurable Montium TP processors. With a scenario based on a phased array antenna mounted on the roof of a car, we show that the adaptive steering algorithm is robust in dynamic scenarios and correctly demodulates the received signal.     

UniTi: Unified Composition and Time for Multi-domain Model-based Design

To apply model-based design to embedded systems that interface with the physical world, including simulation and verification, current tools fall short. They must provide mathematical (model) definitions that stay close to the specification of the system. They must allow multiple domains, such as the continuous-time, discrete-time and dataflow domain, in a single model including well-defined interaction. They must support model transformations for refining a model during development. And most importantly, they must accurately include and simulate different notions of time in the model. UniTi is a model-based design flow and modelling and simulation environment that delivers on all these aspects. It is based on components that are signal transformations, and therefore mathematical functions. However, in each domain the representation of a signal differs. As components have the same structure in each domain, we can use unified composition operators to represent multiple domains in a single model. Furthermore, this composition provides a unified perspective on time in the domains, even though we differentiate between different notions of time. Time becomes a local property of the model, allowing us to represent and simulate time transformations such as time delays exactly without losing efficiency. Finally, model transformations are defined for such components, which are used for refining and developing the model and which are guided by the design steps in the design flow. We will formally define the domains, composition operators and transformations of UniTi and verify the approach with a case study on a phased array beamforming system.     

One laminated bamboo-frame house per hectare per year

This paper presents an outline of a quantitative analysis that demonstrates the global potential of bamboo as a “modern” construction material. The underlying goal is to contribute to a real shift in resource management by focussing on renewable resources in general and on the high brow, modern use of bamboo as an alternative for construction products such as concrete, brick and (hard)wood in particular. The analysis illustrates how laminated bamboo-frame building could be a direct alternative for wood-frame building, bamboo having a great advantage in yearly yield per forest area compared to wood. Current and potential bamboo resources in Colombia are posed against required material volumes for constructing a model house, resulting in a practical and realistic view on bamboo’s global potential on lowering the environmental impact of the built environment.     

New energy retrofit concept: ‘renovation trains’ for mass housing

A large operation is required to make Europe's existing housing stock more energy efficient, in terms of both demand reduction as well as the installation of local renewable energy technologies. The combination of overall (national) energy targets and the European Union's Energy Performance of Buildings Directive (EPBD) targets suggests the scale of this task involves the retrofitting of millions of houses. An example of a large-scale, rapid process is presented where a series of houses have been retrofitted using a standardized process. A pilot project exploring this strategy has been completed in Kerkrade, the Netherlands. Several innovations were introduced, tested and refined for the renovation of 150 houses: a serial retrofit process, a renovation time of ten days per house with the houses inhabited during the process, and responsibility for energy performance assigned to the construction team. The construction process is a ‘renovation train’ moving from one house to the next. The experiences are now being used and developed for a follow-up project: a new concept can be used to scale up the process from 100 to 10 000 renovations a year.     

Spurious-Free Dynamic Range of a Uniform Quantizer

Quantization plays an important role in many systems where analog-to-digital conversion and/or digital-to-analog conversion take place. If the quantization error is correlated with the input signal, then the spectrum of the quantization error will contain spurious peaks. Although analytical formulas describing this effect exist, numerical evaluation can take much effort. This brief provides approximations for the spurious-free dynamic range (SFDR) of a uniform quantizer with a single sinusoidal input, with and without additive Gaussian noise. It is shown that the SFDR increases by approximately 8 dB/bit, in case there is no noise. Generalizing this result to multitone inputs results in an additional 2 dB/bit per additional tone. Additive Gaussian noise decorrelates the sinusoid(s) and the quantization error, which results in a dramatic increase in SFDR.