Sensitivity analysis of the scattering parameters of microwave filters using the adjoint network method

A novel approach is presented to calculate the sensitivities of the scattering parameters of microwave filters obtained with the full‐wave mode‐matching (MM) technique. Using only the MM simulation of the original network, the sensitivities of the scattering parameters with respect to all designable parameters are obtained. The adjoint network method (ANM) is applied to the generalized scattering matrices of the different filter components. This guarantees good accuracy of the calculated sensitivities. The implementation details are discussed for N‐resonator ridge waveguide filters. Excellent agreement is obtained between the sensitivities calculated using ANM and those obtained using the expensive central differences. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Autonomous mental development: soaring beyond tradition

This article provides a brief overview of the history of autonomous mental development as a discipline     

Self-powered wireless temperature sensors exploit RFID technology

Emerging RFID technology lets us embed sensors into a very small chip, creating a wireless sensing device. So, we set out to develop such a single-chip versatile temperature sensor. We also wanted to be able to transfer our design to an implantable temperature sensor for an animal healthcare application with minimal structural modification. We discuss the implementation of temperature sensor. The fully integrated complementary metal-oxide semiconductor (CMOS) batteryless device measures temperature and performs calibration to compensate for the sensor's inherent imperfections. An RF link using passive RFID's backscattering technique wirelessly transmits the data to a reading device while extracting power from the same "airwave," letting the device operate anywhere and last almost forever. The entire microchip, including the temperature sensor, consumes less than a few microamperes over a half a second, so the scanning device can capture data from longer read distances.     

The microscopy cell (MicCell), a versatile modular flowthrough system for cell biology, biomaterial research, and nanotechnology

We describe a novel microfluidic perfusion system for high-resolution microscopes. Its modular design allows pre-coating of the coverslip surface with reagents, biomolecules, or cells. A poly(dimethylsiloxane) (PDMS) layer is cast in a special molding station, using masters made by photolithography and dry etching of silicon or by photoresist patterning on glass or silicon. This channel system can be reused while the coverslip is exchanged between experiments. As normal fluidic connectors are used, the link to external, computer-programmable syringe pumps is standardized and various fluidic channel networks can be used in the same setup. The system can house hydrogel microvalves and microelectrodes close to the imaging area to control the influx of reaction partners. We present a range of applications, including single-molecule analysis by fluorescence correlation spectroscopy (FCS), manipulation of single molecules for nanostructuring by hydrodynamic flow fields or the action of motor proteins, generation of concentration gradients, trapping and stretching of live cells using optical fibers precisely mounted in the PDMS layer, and the integration of microelectrodes for actuation and sensing.     

The Einstein relation in nanostructured materials: simplified theory and suggestion for experimental determination

An attempt is made to study the Einstein relation for the diffusivity–mobility ratio (DMR) in quantum wells (QWs) and quantum well wires (QWWs) of tetragonal compounds on the basis of a newly formulated electron energy spectrum taking into account the combined influences of the anisotropies in effective electron mass, the spin–orbit splitting, and the presence of crystal field splitting, respectively. The results for quantum-confined III–V compounds form a special case of our generalized analysis. The DMR has also been studied for QWs and QWWs of II–VI and IV–VI materials. Taking QWs and QWWs of CdGeAs₂, InAs, CdS and PbSe as examples, it was found that the DMR increases with increasing carrier statistics and decreasing film thickness respectively in various oscillatory manners emphasizing the influence of dimensional quantizations and the energy band constants in different cases. An experimental method of determining the DMR in nanostructures with arbitrary dispersion laws has also been suggested and the present simplified analysis is in agreement with the suggested relationship. The well-known results for nanostructures with parabolic energy bands have also been obtained as special cases from this generalized analysis under certain limiting conditions.     

Modeling of anaerobic treatment of wastewater in ponds.

A mathematical model to simulate the performance of anaerobic ponds was developed incorporating both settling of particulate components and the biological anaerobic digestion process. The biological activity includes solubilization of particulate organic matter; methanogenesis and the sulphate reduction process. The model considers that an anaerobic pond comprises a series of equal size columns. Each column has three compartments viz. liquid layer, active sediment layer and inert sediment layer. The existence of organic matter and sulphate removal mechanisms both in the bulk as well as sediment layer of the ponds and the exchange of the soluble components between the layers has been included in the model. The model was transferred to a computer program using VisSim Basic software. The model was verified by comparing simulated results with full-scale as well as with laboratory-scale anaerobic pond performance data. A good agreement between the simulated and the observed pond performance was achieved.     

Accurate Low Order Model for Hydraulic Turbine-Penstock

A method for obtaining accurate reduced order models for hydro-turbines with long penstocks is presented. The inadequacy of the customary first order model is demonstrated. It is also shown that an appropriately chosen second order model provides the necessary accuracy while preserving model simplicity which is essential for ease in controller design, in assessing stability margins, and in power system simulation.     

Existential theory: Guidelines for practice in child therapy.

One reason for the limited attention to existential psychology in child treatment is the assumption that children are restricted in the amount of freedom and responsibility they can assume. However, current research on child development reveals that children actively influence their social and physical environment and hence begin from birth the process of self-determination. This article presents guidelines for implementing existential psychology with children derived from theoretical tenets and case study findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)