Harmonics and transient overvoltages due to capacitor switching

This work presents a study of the steady-state and transient effects of power factor correction capacitors on the utility and on the customer. In the presence of harmonic-producing loads, capacitors used for power factor correction can cause parallel or series resonance problems which tend to increase the total harmonic distortion (THD) of the voltage and current waveforms. The cases studied in this work considers the addition of a power factor correction capacitor, in the presence of downstream harmonic loads and at the harmonic load site. In both cases the resonance created by the addition of the capacitor caused the harmonic distortion of the voltage and current waveforms to increase. Another problem is transient overvoltages created by switching the capacitor. A case study is reported where the operation of a semiconductor controlled motor drive is effected by transient overvoltages     

Computing MOSCED parameters of nonelectrolyte solids with electronic structure methods in SMD and SM8 continuum solvents

An efficient method to predict modified separation of cohesive energy density model (MOSCED) parameters for nonelectrolyte solids using electronic structure calculations in SMD and SM8 continuum solvents is proposed and applied to acetanilide, acetaminophen, and phenacetin. The resulting parameters are ultimately used to predict the equilibrium solubility in a range of solvents over a range of temperatures. By combining MOSCED with SMD and SM8, we are able to leverage the strengths of both methods while eliminating shortcomings that would prevent their use alone for solvent selection in design processes involving nonelectrolyte solid solutes. Comparing to 77 non‐aqueous experimental solubilities of acetaminophen over the range 10–30°C, the proposed method has an average absolute error of 0.03 and 0.04 mol fracs for SMD and SM8 regressed parameters, respectively. Aqueous solubilities of acetaminophen over this temperature range are predicted with an average error of 0.030 and 0.0023 mol fracs, respectively. © 2016 American Institute of Chemical Engineers AIChE J, 63: 781–791, 2017     

GRETA: utilizing new concepts in γ-ray detection

We present a new concept for γ-ray detector arrays. An example, called GRETA (Gamma-Ray Energy Tracking Array), consists of highly segmented HPGe detectors covering 4π solid angle. The new feature is the ability to track the scattering sequence of incident γ-rays and in every event, this potentially allows one to measure with high resolution the energy deposited, the location (incident angle) and the time of each γ-ray that hits the array. GRETA will be of order of 1000 times more powerful than the best present arrays, such as Gammasphere or Euroball, and will provide access to new physics.     

Performance analysis of multi-homed transport protocols with network failure tolerance

The performance of multi-homed transport protocols tolerant of network failure is studied. It evaluates the performance of different retransmission policies combined with path failure detection thresholds, infinite or finite receive buffers for various path bandwidths, delays and loss rate conditions through stream control transmission protocol simulation. The results show that retransmission policies perform differently with different path failure detection threshold configurations. It identifies that retransmission of all data on an alternate path with the path failure detection threshold set to zero performs the best in symmetric path conditions but its performance degrades acutely in asymmetric path conditions even when the alternate path delay is shorter than the primary path delay. It illustrates that retransmission of all data on the same path with the path failure detection threshold set to one or zero gives the most stable performance in all path configurations.     

School children's use of computers and teachers' education in computer ergonomics

A national survey to investigate the education of teachers in computer-related ergonomics was carried out by postal questionnaire. The use of computers by primary school children (age 4-12 years) was also investigated. Data were collected from a random sample of 25% (n = 830) of primary schools in the Republic of Ireland. Questionnaires (n = 1863) were returned from 416 schools giving a response rate of 50.1%. Almost all schools (99.7%) had computers for children's use. The computers were most often (69.8%) used in the classroom. The majority (56.3%) of children worked in pairs. Most teachers (89.6%) had received computer training, but few (17.6%) had received ergonomics information during the training. Respondents were not satisfied with their current knowledge of ergonomics. Over 90% stated that they would like to receive further information by printed format or during a training course, rather than by computer (web or CD-ROM).     

Comparing transmission potential networks based on social network surveys,close contacts and environmental overlap in rural Madagascar

Social and spatial network analysis is an important approach for investigating infectious disease transmission, especially for pathogens transmitted directly between individuals or via environmental reservoirs. Given the diversity of ways to construct networks, however, it remains unclear how well networks constructed from different data types effectively capture transmission potential. We used empirical networks from a population in rural Madagascar to compare social network survey and spatial data-based networks of the same individuals. Close contact and environmental pathogen transmission pathways were modelled with the spatial data. We found that naming social partners during the surveys predicted higher close-contact rates and the proportion of environmental overlap on the spatial data-based networks. The spatial networks captured many strong and weak connections that were missed using social network surveys alone. Across networks, we found weak correlations among centrality measures (a proxy for superspreading potential). We conclude that social network surveys provide important scaffolding for understanding disease transmission pathways but miss contact-specific heterogeneities revealed by spatial data. Our analyses also highlight that the superspreading potential of individuals may vary across transmission modes. We provide detailed methods to construct networks for close-contact transmission pathogens when not all individuals simultaneously wear GPS trackers.