A battery-less switch for use in 802.15.4 / ZigBee applications

Wireless switches to control light systems are important parts of wireless networks in building automation. For success, it is important to avoid frequent battery replacement, or even better to eliminate them. Although this is possible in some proprietary systems today, at the expense of some features, it is still a challenge for networks such as ZigBee. The main difficulties lie in the power available and the requirements for communication. In this paper, we present the design of a battery-less wireless switch that can be integrated in 802.15.4 / ZigBee systems. We use a standard energy harvesting module for generating power when the switch is activated. The important and required power management aspects implemented in hardware and software are discussed, in the light of the network specifications. After showing the challenges needed to overcome the use of a battery-less switch in wireless systems such as 802.15.4, we present our solutions and the results of some tests

Political Accountability and Determinants of Governance under Principal-Agent Theory

This study examines the theory that quality of governance is largely dependent upon political accountability, and that the effect of political accountability on governance varies based on three main determinants: level of democracy, level of information available to the public, and diversification of the economy (Adserà et al. 2003). With quality of governance, represented by the World Bank’s World Governance Indicators (WGI), as the dependent variable, this study considers how these three independent variables, and several control variables, affect governance quality. Incorporating data from 2010 – 2015 for 143 countries in both cross-sectional OLS and fixed effects panel regression analysis, this study finds that level of democracy has a direct relationship with voice and accountability and regularity quality, and an inverse relationship with governance effectiveness and rule of law. Information available to the public has a direct relationship with governance effectiveness, while diversification of the economy has a direct relationship with governance effectiveness and regularity quality, and an inverse relationship with rule of law and control of corruption. This research also demonstrates that several other factors affect governance quality. Level of economic development, openness to trade, level of education, size of population, freedom of the press, cell phone penetration rate, and state fragility all play a role in determining at least some aspects of governance quality. While these variables are all shown to have a significant relationship with governance, they are still only part of the equation. Future research should endeavor to enhance the current findings and strive to identify the other factors that may contribute to governance quality

RF Spatial Combining and Field Control in Dielectric Media

Recent developments in higher static magnetic field MRIs have allowed for increased sensitivity and improved imaging compared to current clinical MRIs due to the inherent low SNR of nuclear magnetic resonance. Ultra-high field MRI promises to improve medical imaging technology with higher SNR, increased parallel imaging performance, and higher spectral dispersion. With the decrease in wavelength inside of the imaging volume, standing waves develop and decrease the high homogeneity required for accurate diagnosis of medical problems. Additionally, at higher operating frequencies the bore becomes a loaded waveguide which supports propagating modes. This thesis focuses on the development of circularly polarized patch probes for traveling wave MRI at small bore 16.4 T, wide-bore 7T and 10.5T systems with boundary modification structures to improve field coupling and homogeneity. The attenuation of the wave in the unloaded portion of the waveguide becomes an issue with available RF systems as the excitation is placed away from the imaging volume. Additionally, boundary modifying structures are developed to improve coupling and SNR inside of the imaging volume. These boundary modifying structures placed around the imaging volume can be relatively simple and provide an increase in field homogeneity. To improve the relatively poor received spatial coverage of the single patch probe, an additional array is developed with interdigitated capacitor probes at 10.5 T. Multiple excitations can be combined with various relative magnitude and phase excitations, known as B1 shimming. These two techniques can be combined to drastically increase the field coverage inside of an imaging volume. The techniques proposed for cavity excitations in MRIs can be translated to microwave heating systems that convert waste to carbon-rich fuel. Recent military interest in the development of waste-to-fuel techniques have used pyrolysis and incineration, however, these approaches are relatively large due to the necessary supporting infrastructure to operate them

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Micromechanical characterization of spider silk particles

Spider silk fibers are well known for their mechanical properties, and they are therefore in the focus of materials scientists. Additionally, silks display biocompatibility making them interesting materials for applications in medicine or cosmetics. Due to the low abundance of natural spider silk proteins because of the spider's cannibalism, the recombinant spider silk protein eADF4 has been established for material science applications. Once processed into micron-sized particles by controlled salting-out, these particles can be used as drug delivery vehicles. For any application of the silk particles it is important to know their mechanical characteristics for processing and storage reasons. Here, we examine the swelling behavior and mechanics of these particles. Upon hydration, a drastic drop in elastic modulus occurs by orders of magnitude, from 0.8 GPa in the dry state to 2.99 MPa in the wet state. Importantly, the elastic modulus of recombinant silk particles can be tuned by varying the molecular weight of the used proteins, as well as chemical crosslinking thereof

Performance of CMS hadron calorimeter timing and synchronization using test beam, cosmic ray, and LHC beam data

This paper discusses the design and performance of the time measurement technique and of the synchronization systems of the CMS hadron calorimeter. Time measurement performance results are presented from test beam data taken in the years 2004 and 2006. For hadronic showers of energy greater than 100 GeV, the timing resolution is measured to be about 1.2 ns. Time synchronization and out-of-time background rejection results are presented from the Cosmic Run At Four Tesla and LHC beam runs taken in the Autumn of 2008. The inter-channel synchronization is measured to be within ±2 ns