Adaptive beamforming using frequency invariant uniform concentric circular arrays

This paper proposes new adaptive beamforming algorithms for a class of uniform concentric circular arrays (UCCAs) having near-frequency invariant characteristics. The basic principle of the UCCA frequency invariant beamformer (FIB) is to transform the received signals to the phase mode representation and remove the frequency dependence of individual phase modes through the use of a digital beamforming or compensation network. As a result, the far field pattern of the array is electronic steerable and is approximately invariant over a wider range of frequencies than the uniform circular arrays (UCAs). The beampattern is governed by a small set of variable beamformer weights. Based on the minimum variance distortionless response (MVDR) and generalized sidelobe canceller (GSC) methods, new recursive adaptive beamforming algorithms for UCCA-FIB are proposed. In addition, robust versions of these adaptive beamforming algorithms for mitigating direction-of-arrival (DOA) and sensor position errors are developed. Simulation results show that the proposed adaptive UCCA-FIBs converge much faster and reach a considerable lower steady-state error than conventional broadband UCCA beamformers without using the compensation network. Since fewer variable multipliers are required in the proposed algorithms, it also leads to lower arithmetic complexity and faster tracking performance than conventional methods. © 2007 IEEE.published_or_final_versio

A semi-definite programming (SDP) method for designing IIR sharp cut-off digital filters using frequency-response masking

IEEE International Symposium on Circuits and Systems Proceedings, Vancouver, Canada, 23-26 May 2004This paper studies the design of frequency response masking (FRM) filters with infinite duration impulse response (IIR) model and masking sub-filters. They are useful in realizing sharp cutoff digital filters with low passband delays. The designs of the model and masking filters are carried out by means of semidefinite programming (SDP) and model order reduction. Design results show that low complexity FRM filters with low passband delay can be obtained.published_or_final_versio

Adaptive beamforming using uniform concentric circular arrays with frequency invariant characteristics

This paper proposes a new method for adaptive beamforming using uniform concentric circular array (UCCA) that has nearly frequency invariant (FI) characteristics. The basic principle of FI UCCA is to transform the received signals to the phase mode and compensate for the frequency dependency of the individual phase mode through the use of a digital beamforming network. The far field pattern of the array is then determined by a set of weights and it is approximately invariant over a wide range of frequencies. Therefore, the minimum variance beamforming (MVB) approach can be used to adapt the small set of weights, as if it is a narrowband array, Design examples and simulation are given to demonstrate the usefulness of the proposed FI UCCA in broadband DOA estimation and beamforming. © 2005 IEEE.published_or_final_versio

A mini review on renewable sources for biofuel

Rapid growth in both global energy demand and carbon dioxide emissions associated with the use of fossil fuels has driven the search for alternative sources which are renewable and have a lower environmental impact. This paper reviews the availability and bioenergy potentials of the current biomass feedstocks. These include (i) food crops such as sugarcane, corn and vegetable oils, classified as the first generation feedstocks, and (ii) lignocellulosic biomass derived from agricultural and forestry residues and municipal waste, as second generation feedstocks. The environmental and socioeconomic limitations of the first generation feedstocks have placed greater emphasis on the lignocellulosic biomass, of which the conversion technologies still faces major constraints to full commercial deployment. Key technical challenges and opportunities of the lignocellulosic biomass-to-bioenergy production are discussed in comparison with the first generation technologies. The potential of the emerging third generation biofuel from algal biomass is also reviewed. © 2014 Elsevier Ltd

Recurrent acute heart failure caused by sliding hiatus hernia

The case is reported of a 75 year old woman who presented with recurrent nocturnal episodes of acute pulmonary oedema. The cause was uncertain as she had normal cardiothoracic ratio on chest radiography and normal left ventricular systolic and diastolic function by transthoracic echocardiogram. Another transthoracic echocardiogram was repeated when she was recumbent for an hour and had a full stomach. It showed a striking finding of severe left atrial compression by an external structure. Computed tomography of the thorax showed an intrathoracic mass behind the left atrium causing external compression of the left atrium suggestive of a sliding hiatus hernia. Cardiac catheterisation confirmed the diagnosis by showing a pronounced rise of pulmonary capillary wedge pressure in the recumbent position compared with the sitting up position.published_or_final_versio

Resident's strategy survey on a new end use of recycled water in Australia

The concept of using recycled water for washing machine was introduced as a new end use. As there is a noticeable lack social research in understanding the general public perceptions of this application, the resident's strategy survey was carried out at some selective suburbs in Sydney with demographically based significant differences of general, gender, age, education, and property style and ownership. The survey indicates that the majority in the community considers the use of recycled water for washing machine is indispensable in view of continuing drought and the associated water shortages. Given safety assurance and demonstration, recycled water for washing machine has a considerable proportion within the responses. The general level of knowledge in community clearly understand that recycled water is more environmentally friendly option, whereas from cleanness and public health point of view, higher quality water is required to be reused in washing machine. Moreover, the residents reckon to have a small unit for pre-treatment (point of use) before recycled water entering washing machines might assure the quality and safety. The survey also shows the major concerns for a resident to use recycled water for washing machine are public health, water cleanness and washing machine durability. © 2009 Desalination Publications

Optimization of culture conditions for gamma-aminobutyric acid production by newly identified Pediococcus pentosaceus MN12 isolated from 'mam nem', a fermented fish sauce

This study was aimed to identify and optimize the culture conditions for gamma-aminobutyric acid (GABA) production by a lactic acid bacterium strain isolated from mam nem, a fermented fish sauce. Among the six isolates obtained from mam nem, the MN12 had the most potent GABA-producing capability. The strain was then identified to be Pedioccocus pentosaceus by employing MALDI-TOF-MS and phenylalanyl-tRNA synthase sequencing methods. The initial cell density of 5.10(6) CFU/mL, monosodium glutamate concentration of 60 mM, initial pH of 7, temperature of 45 degrees C and cultivation time of 72 h were found to be the optimal culture conditions for highest production of GABA, reaching 27.9 +/- 0.42 mM, by this strain. The cultivation conditions for GABA production by P. pentosaceus MN12 have been successfully optimized, providing a foundation for the development of fermented foods enriched with GABA

テレビ帯における周波数共用技術の進展

(R,R)-Dimethyl tartrate acetonide 7 in THF/HMPA undergoes deprotonation with LDA and reaction at −78 °C during 12–72 h with a range of alkyl halides, including non-activated substrates, to give single diastereomers (at the acetonide) of monoalkylated tartrates 17, 24, 33a–f, 38a,b, 41 of R,R-configuration, i.e., a stereoretentive process (13–78% yields). Separable trans-dialkylated tartrates 34a–f can be co-produced in small amounts (9–14%) under these conditions, and likely arise from the achiral dienolate 36 of tartrate 7. Enolate oxidation and acetonide removal from γ-silyloxyalkyl iodide-derived alkylated tartrates 17 and 24 give ketones 21 and 26 and then Bamford–Stevens-derived diazoesters 23 and 27, respectively. Only triethylsilyl-protected diazoester 27 proved viable to deliver a diazoketone 28. The latter underwent stereoselective carbonyl ylide formation–cycloaddition with methyl glyoxylate and acid-catalysed rearrangement of the resulting cycloadduct 29, to give the 3,4,5-tricarboxylate-2,8-dioxabicyclo[3.2.1]octane core 31 of squalestatins/zaragozic acids. Furthermore, monoalkylated tartrates 33a,d,f, and 38a on reaction with NaOMe in MeOH at reflux favour (≈75:25) the cis-diester epimers epi-33a,d,f and epi-38a (54–67% isolated yields), possessing the R,S-configuration found in several monoalkylated tartaric acid motif-containing natural products

Estimating Long-Term Survival of Critically Ill Patients: The PREDICT Model

BACKGROUND: Long-term survival outcome of critically ill patients is important in assessing effectiveness of new treatments and making treatment decisions. We developed a prognostic model for estimation of long-term survival of critically ill patients. METHODOLOGY AND PRINCIPAL FINDINGS: This was a retrospective linked data cohort study involving 11,930 critically ill patients who survived more than 5 days in a university teaching hospital in Western Australia. Older age, male gender, co-morbidities, severe acute illness as measured by Acute Physiology and Chronic Health Evaluation II predicted mortality, and more days of vasopressor or inotropic support, mechanical ventilation, and hemofiltration within the first 5 days of intensive care unit admission were associated with a worse long-term survival up to 15 years after the onset of critical illness. Among these seven pre-selected predictors, age (explained 50% of the variability of the model, hazard ratio [HR] between 80 and 60 years old = 1.95) and co-morbidity (explained 27% of the variability, HR between Charlson co-morbidity index 5 and 0 = 2.15) were the most important determinants. A nomogram based on the pre-selected predictors is provided to allow estimation of the median survival time and also the 1-year, 3-year, 5-year, 10-year, and 15-year survival probabilities for a patient. The discrimination (adjusted c-index = 0.757, 95% confidence interval 0.745-0.769) and calibration of this prognostic model were acceptable. SIGNIFICANCE: Age, gender, co-morbidities, severity of acute illness, and the intensity and duration of intensive care therapy can be used to estimate long-term survival of critically ill patients. Age and co-morbidity are the most important determinants of long-term prognosis of critically ill patients