A Single-Chip Ultra-Wideband Based Wireless Sensor Network Node

This dissertation presents the design of a next-generation wireless sensor network node. The node incorporates many new and innovative technologies such as an ultra-wideband radio which allows very low-energy communication, a low-power radiation detection front end, and an efficient implementation of dynamic voltage scaling which improves the energy efficiency of the integrated processor. The complete design is integrated on a single chip for maximum power savings and minimal size. The ultra-wideband transceiver includes many novel techniques to produce a receiver with low power consumption and fast and accurate packet acquisition and reception. These include the use of a standard symmetric inductor in a non-standard way as a T-coil load which extends the bandwidth of RF amplifiers, and a novel baseband architecture which relies on parallel analog processing to achieve both low power and fast and accurate signal acquisition and tracking. Other features include a very low power interface to radiation detection detectors which uses an architecture in which the ADC only samples when an event occurs. This decreases the power over a conventional continuous-sampling scheme. A low-power charge sensitive amplifier is designed for the front end while the peak detection is done in the analog domain before an ADC converts the peak value to digital. An efficient implementation of dynamic voltage scaling allows for unmatched computational power consumption combined with good sleep mode power. This is achieved through the integration of two buck converters which have high efficiency even at light loads. The complete design was integrated on a single chip using a 0.18 micron CMOS process with a total die area of 3x4.5 mm. The fabricated chip was tested and the measured results show that the chip does indeed achieve low power consumption. The measured results validate the approaches chosen, and field tests show the system is useful when interfaced to a variety of sensors for detecting various types of radiation

A Directional Gamma Ray Detector Using a Single Chip Computational Sensor

This paper presents the design and test results of a computational radiation sensor system based on a single chip solution that can determine the direction of gamma rays emitted from a radiation source. The overall system is formed by merging a sensor section with a compact and low power computational radiation sensor section. The sensor section houses three NaI gamma ray detectors arranged in a spatial configuration that allows for direction finding. The computational sensor is based on a single chip solution developed by authors that houses multiple low power sensor front ends, event driven analog-to-digital converters, and a dedicated microcontroller on the same die. The presented system is capable of gathering the pulse height spectra from the gamma isotope data received from the three separate NaI detectors. Further processing of the data is possible by executing software algorithms using the computation resources available on chip. To that end, a compact fixed-point program was developed to perform on-chip real-time gamma ray collection and direction estimation. The single chip solution was fabricated in a 0.18 μm CMOS technology with field tests demonstrating the validity of the approaches taken. The total computational sensor system power consumption is less than 20 μW, excluding the detector power consumption. The gamma isotope direction finding program executes in less than 1 ms with 5◦ accuracy

A Single Chip Computational Sensor System for Neutron Detection Applications

This paper presents the design and test results of a standalone computational radiation sensor system based on a single chip solution. A low-power sensor front end with a charge sensitive amplifier and an event driven analog-to-digital converter is integrated on the same chip as a dedicated microcontroller to process and bin the data from the neutron detector diode heterojunction according to pulse height. This combination effectively implements a single chip multichannel analyzer with the capability to do further processing of the data in software. The design was fabricated in a 0.18 CMOS technology with field tests demonstrating the validity of the approaches taken. The total system power consumption is 24 W

Sea Level Variability and Change

Land surface albedo represents the fraction of solar radiation scattered backward by land surfaces. In the presence of vegetation, surface albedo results from complex nonlinear radiation transfer processes determining the amount of radiation that is scattered by the vegetation and its background, transmitted through the vegetation layer, or absorbed by the vegetation layer and its background. Anomalies in mid- and high latitude regions of the Northern Hemisphere result mainly from interannual variations in snow cover extent and duration in winter and spring. The large negative anomalies over the United States reflect the lack of snowfall and snowpack over the Rockies, the Midwest, and much of the eastern half of the country.JRC.H.7-Climate Risk Managemen

State of the Climate in 2012

For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Nevertheless, other large-scale climate patterns and extreme weather events impacted various regions during the year. A negative phase of the Arctic Oscillation from mid-January to early February contributed to frigid conditions in parts of northern Africa, eastern Europe, and western Asia. A lack of rain during the 2012 wet season led to the worst drought in at least the past three decades for northeastern Brazil. Central North America also experienced one of its most severe droughts on record. The Caribbean observed a very wet dry season and it was the Sahel's wettest rainy season in 50 years. Overall, the 2012 average temperature across global land and ocean surfaces ranked among the 10 warmest years on record. The global land surface temperature alone was also among the 10 warmest on record. In the upper atmosphere, the average stratospheric temperature was record or near-record cold, depending on the dataset. After a 30-year warming trend from 1970 to 1999 for global sea surface temperatures, the period 2000-12 had little further trend. This may be linked to the prevalence of La Ni a-like conditions during the 21st century. Heat content in the upper 700 m of the ocean remained near record high levels in 2012. Net increases from 2011 to 2012 were observed at 700-m to 2000-m depth and even in the abyssal ocean below. Following sharp decreases in to the effects of La Ni a, sea levels rebounded to reach records highs in 2012. The increased hydrological cycle seen in recent years continued, with more evaporation in drier locations and more precipitation in rainy areas. In a pattern that has held since 2004, salty areas of the ocean surfaces and subsurfaces were anomalously salty on average, while fresher areas were anomalously fresh. Global tropical cyclone activity during 2012 was near average, with a total of 84 storms compared with the 1981-2010 average of 89. Similar to 2010 and 2011, the North Atlantic was the only hurricane basin that experienced above-normal activity. In this basin, Sandy brought devastation to Cuba and parts of the eastern North American seaboard. All other basins experienced either near-or below-normal tropical cyclone activity. Only three tropical cyclones reached Category 5 intensity-all in Bopha became the only storm in the historical record to produce winds greater than 130 kt south of 7 N. It was also the costliest storm to affect the Philippines and killed more than 1000 residents. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June both reached new record lows. June snow cover extent is now declining at a faster rate (-17.6% per decade) than September sea ice extent (-13.0% per decade). Permafrost temperatures reached record high values in northernmost Alaska. A new melt extent record occurred on 11-12 July on the Greenland ice sheet; 97% of the ice sheet showed some form of melt, four times greater than the average melt for this time of year. The climate in Antarctica was relatively stable overall. The largest maximum sea ice extent since records begain in 1978 was observed in September 2012. In the stratosphere, warm air led to the second smallest ozone hole in the past two decades. Even so, the springtime ozone layer above Antarctica likely will not return to its early 1980s state until about 2060. Following a slight decline associated with the global 2 emissions from fossil fuel combustion and cement production reached a record 9.5 +/- 0.5 Pg C in 2011 and a new record of 9.7 +/- 0.5 Pg C is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, to 392.6 ppm. In spring 2012, 2 concentration exceeded 400 ppm at 7 of the 13 Arctic observation sites. Globally, other greenhouse gases including methane and nitrous oxide also continued to rise in concentration and the combined effect now represents a 32% increase in radiative forcing over a 1990 baseline. Concentrations of most ozone depleting substances continued to fall