Surveys of natural radiation exposure in UK dwellings with passive and active measurement techniques

A representative sample of over 2,000 UK dwellings was monitored for a year using thermoluminescent and etchable plastic dosemeters to measure gamma-ray dose rates and radon concentrations. The survey was carried out by post. Each householder completed a questionnaire on the type of dwelling and its characteristics. These data will be used in the assessment of the factors affecting indoor exposure. The mean gamma-ray dose rates were 0.062 and 0.057 μGy h^?1 in air and the mean radon concentrations were 25 and 18 Bq m^?3 for living areas and bedrooms respectively. Other results of the preliminary data analysis are given.More detailed surveys were conducted in areas where the local geology indicated that elevated exposures to natural radiation might occur. Over 800 dwellings were visited and measurements made of several parameters. The mean gamma-ray dose rates varied from 0.05 to 0.10 μGy h^?1 in air. The mean radon concentrations varied from 14 Bq m^?3 to 520 Bq m^?3. Other findings related to equilibrium factors and regional differences are discussed.     

<Emphasis Type="Italic">H</Emphasis><Subscript>2</Subscript>-optimization of time-delayed sampled-data systems on the basis of the parametric transfer matrix method

A solution to the H ₂-optimization problem for multi-input-multi-output sampled-data system with delay is presented on the basis of the parametric transfer matrix concept. A procedure is developed for design of the optimal controller by means of factorization and separation of real rational matrices. Some qualitative properties of the H ₂-optimal system are established, which are useful for applications. In particular, it is proved that there is a set of fixing poles of continuous-time elements of the system, and performance of the optimal system is limited because of them. A constructive algorithm is given for determination of the set of fixing poles.     

Airborne Particulate Matter and Human Health: A Review

Results of recent research show that particulate matter (PM) composition and size vary widely with both space and time. Despite the variability in PM characteristics, which are believed to influence human health risks, the observed relative health risk estimates per unit PM mass falls within a narrow range of values. Furthermore, no single chemical species appears to dominate health effects; rather the effects appear to be due to a combination of species. Non-PM factors such as socioeconomic status and lifestyle are also believed to affect the health risk, although accounting for these confounding factors is challenging. Airborne PM is also responsible for a number of effects aside from human health, such as alterations in visibility and climate. Because the PM problem is associated with a range of societal issues such as energy production and economic development, making progress on reducing the effects of PM will require integrated strategies that bring together scientists and decision makers from different disciplines to consider tradeoffs holistically.     

Performance of BICM-OFDM systems in UWB interference

In this paper, we develop an analytical framework for performance analysis of generic bit-interleaved coded modulation orthogonal frequency-division multiplexing (BICMOFDM) systems impaired by ultra-wideband (UWB) interference. For practical relevance we consider multi-band OFDM (MB-OFDM), direct-sequence UWB (DS-UWB), and impulseradio UWB (IR-UWB) interference formats following recent IEEE/ECMA standards or standard proposals. Besides the exact analysis we calculate the bit error rate (BER) for the case when the UWB interference is modeled as additional Gaussian noise. Our results show that in general the BER of the BICM-OFDM system strongly depends on the UWB format and the OFDM sub-carrier spacing. While the Gaussian approximation is very accurate for DS-UWB, it may severely overor underestimate the true BER for MB-OFDM and IR-UWB interference. Our analysis is applicable to e.g. IEEE 802.11 wireless local area networks (WLANs), IEEE 802.16 wireless access systems (WiMAX), and 4th generation mobile communication systems. Furthermore, since the ECMA MB-OFDM standard is also based on the BICM-OFDM concept, our analysis can also be used to evaluate the impact of other UWB signals on ECMA MB-OFDM UWB systems.     

Microvia filling by copper electroplating using diazine black as a leveler

An organic additive, Diazine Black (DB), was employed as a leveler for microvia filling using copper electroplating. DB is a derivative of Janus Green B (JGB), which is a common leveler used for copper fill of submicron or micron circuit metallization in electronic products. This study determined the optimal DB concentration for achieving the best filling performance. The electrochemical behavior of DB and its interaction with other additives, such as a suppressor and an accelerator were characterized using galvanostatic measurements. These electrochemical analyses helped explaining the filling mechanism of the plating formula containing the DB. Various surface morphologies and the crystalline orientation of the plated copper films caused by different DB concentrations were characterized by a scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The corresponding chemical activity of the surface atoms of the plated copper films caused by different DB concentrations was characterized using a test of etching rate.     

Complete orders from incomplete data: Interactive ordering and tailored testing.

Ordered sets, whether of stimuli or Ss, are characterized by certain regular properties in the relations between pairs of their members. An incomplete matrix of pair-wise preference judgments may thus be completed. The necessary condition is that the relations between adjacent members in the order be known. If the S is interacting with a computer, the computer can choose the pairs to be presented so as to minimize the number of judgments necessary to define the final order. Mental test data have a formal resemblance to incomplete order relations, so that the principles presented here may also be applicable to computer-interactive testing. Computer-interactive systems must take account of the unreliability of human responses and the limited capacity of computers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Equalization for DS-UWB Systems—Part I: BPSK Modulation

Ultra-wideband wireless transmission has attracted considerable attention both in academia and industry. For high-rate and short-range transmission, direct sequence based ultra-wideband (DS-UWB) systems are a strong contender for consumer market applications. Due to the large transmission bandwidth, the UWB channel is characterized by a long root-mean-square delay spread and the RAKE receiver cannot always overcome the resulting intersymbol interference. We therefore study equalization for DS-UWB systems. This paper is comprised of two parts. In this first part, we consider DS-UWB with binary phase-shift keying (BPSK) modulation, which is the mandatory transmission mode for DS-UWB systems promoted by the UWB Forum industry alliance. We derive matched filter bounds for optimum equalization taking into account practical constraints like receiver filtering, sampling, and the number of RAKE fingers when RAKE preprocessing is applied at the receiver. Our results show that chip-rate sampling is sufficient for close-to-optimum performance. For analysis of suboptimum equalization strategies we further study the distribution of the zeros of the channel transfer function including RAKE combining. Our findings suggest that linear equalization is well suited for the lower data rate modes of DS-UWB systems, whereas nonlinear equalization is preferable for high-data rate modes. Moreover, we devise equalization schemes with widely linear processing, which improve performance while not increasing equalizer complexity. Simulation and numerical results confirm the significance of our analysis and equalizer designs and show that low-complexity (widely) linear and nonlinear equalizers perform close to the pertinent matched filter bound limit.