A variable band universal flux/charge modulator for VSI and CSImodulation

This paper presents an integrated approach for closed-loop control of the output voltage of a voltage-source inverter and the output current of a current-source inverter, using hysteresis with a rectangular bounding box in the synchronous d-q reference frame and a simple set of switching rules. The modulator is constrained to only select from the two nearest active space vectors to the target reference, and hence achieves a significantly improved harmonic performance compared to Sigma-Delta and other stationary frame hysteresis modulators. A further refinement then adjusts the dimensions of the bounding box to restrict the switching process to two active space vectors (and null vectors) only within a constant switching period. This achieves a harmonic performance similar to open-loop space-vector modulation. Discontinuous modulation can also be implemented using an alternative dimension-varying strategy and, since the modulator is a closed-loop system, it exhibits excellent robustness to parameter variations and other system disturbances. The practicability and performance of the modulator under various modulation conditions have been verified both in simulation and experimentally     

Reduced common-mode modulation strategies for cascaded multilevel inverters

This paper presents modulation strategies for cascaded multilevel inverters that substantially eliminate common-mode voltage on the output phases. The paper begins by developing generic multilevel inverter reference waveforms that use only "allowed" space vectors to achieve reduced common-mode voltage. A graphical technique is then proposed that allows various carrier disposition modulation strategies for a diode-clamped inverter to be converted to equivalent modulation of a cascaded inverter for any fundamental reference waveform. This graphical technique is confirmed for both alternative phase opposition disposition and phase disposition equivalent modulation of a cascaded inverter, and is then used to create reduced common-mode modulation strategies for cascaded inverters from their equivalent counterparts for diode-clamped inverters under both continuous and discontinuous switching conditions. The strategies have been confirmed by both simulation and experimental results obtained using a cascaded five-level inverter.     

The problem with Unicode

The author, in his 'Seven Great Blunders of the Computing World' column (Computer, July 2002, p.112, 110-111) claimed that Unicode was a blunder. The author reconsiders this and states that he stands by his claim, but states that this does not mean that he considers it to be a failure. He does however claim that a different approach would have worked much better for encoding text, documents, and writing systems.     

Design and fabrication of transdermal drug delivery patch with milliprojections using material extrusion 3D printing

This paper investigates the effect of various 3D printing parameters on a transdermal drug delivery system with milliprojections printed using poly(lactic acid) (PLA). The parameters studied involve printing temperature, layer thickness, extrusion width, infill width, and nozzle orifice diameter. Their effects on the final print quality were evaluated based on the surface finish and dimensional accuracy of the milliprojections. The change in the molecular weights of the polymers after extrusion and printing suggests thermal degradation. Further thermal analysis also showed that 3D printing decreases polymer crystallinity. The parameters studied showed varying effects on print quality with respect to PLA types and the dimensions involved. In general, it is sensible to process at temperature close to the melting point of a semicrystalline polymer or at the lowest temperature for which the polymer flows for an amorphous polymer. Although the layer thickness and extrusion width affect each dimension differently, it was found to be a reasonable approach to choose a thinner layer for a more accurate tip, and a thinner infill width for more accurate part diameters. Lastly, it was found that the smaller nozzle orifice and increased spacing between milliprojections produced better surface finish but had no significant effect on part accuracy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48777.     

Retention and stability of bioactive compounds in functional peach beverage using pasteurization,microwave and ultrasound technologies

Food Science and Biotechnology - The peach functional beverages pasteurized for 10 min at 90 °C, microwaved for 1.5 min at 850 W of power and sonicated for...     

Evaluation of Steelhead Passage Flows Using Hydraulic Modeling on an Unregulated Coastal California River

Passage and habitat connectivity flows for steelhead Oncorhynchus mykiss through depth sensitive natural, low gradient, critical riffle sites were investigated in the unregulated Big Sur River, California. The River2D two‐dimensional hydraulic habitat model, along with quantitative passage metrics and species‐specific and lifestage‐specific depth criteria, were used to evaluate and compare predicted fish passage flows with flows derived by a traditional empirical critical riffle fish passage method. Passage flows were also compared with historical unimpaired natural hydrology patterns to assess the frequency and duration of suitable passage flows under the naturally variable flow regimes characteristic of Central California coastal rivers. A strong relationship (r² = 0.93) was observed between flows predicted by hydraulic modeling and flows identified by the empirical critical riffle method. River2D provided validation that the flows derived using the traditional critical riffle methodology provided for contiguous passable pathways of suitable hydraulic (depth and velocity) conditions through complex cobble‐dominated riffle sites. Furthermore, steelhead passage flows were spatially and temporally consistent between lagoon and upstream riffles for adults, and were generally indicative of a river system in equilibrium with a naturally variable flow regime and associated intact ecological processes. An analysis of 25 years of continuous flow data indicated sufficient flows for upstream passage by young‐of‐year and juvenile steelhead were produced between 37% and 100% and between 1% and 95% of the time, respectively. September and October are the most challenging months for natural flows to meet young‐of‐year and juvenile passage and habitat connectivity flows. Careful consideration of seasonal and interannual flow variability dynamics, therefore, are critical components of an effective flow management strategy for the maintenance and protection of passage and habitat connectivity flows between lagoon and upriver habitats. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.     

Impacts of acid gases on mercury oxidation across SCR catalyst

A series of bench-scale experiments were completed to evaluate acid gases of HCl, SO₂, and SO₃ on mercury oxidation across a commercial selective catalytic reduction (SCR) catalyst. The SCR catalyst was placed in a simulated flue gas stream containing O₂, CO₂, H₂O, NO, NO₂, and NH₃, and N₂. HCl, SO₂, and SO₃ were added to the gas stream either separately or in combination to investigate their interactions with mercury over the SCR catalyst. The compositions of the simulated flue gas represent a medium-sulfur and low- to medium-chlorine coal that could represent either bituminous or subbituminous. The experimental data indicated that 5–50 ppm HCl in flue gas enhanced mercury oxidation within the SCR catalyst, possibly because of the reactive chlorine species formed through catalytic reactions. An addition of 5 ppm HCl in the simulated flue gas resulted in mercury oxidation of 45% across the SCR compared to only 4% mercury oxidation when 1 ppm HCl is in the flue gas. As HCl concentration increased to 50 ppm, 63% of Hg oxidation was reached. SO₂ and SO₃ showed a mitigating effect on mercury chlorination to some degree, depending on the concentrations of SO₂ and SO₃, by competing against HCl for SCR adsorption sites. High levels of acid gases of HCl (50 ppm), SO₂ (2000 ppm), and SO₃ (50 ppm) in the flue gas deteriorate mercury adsorption on the SCR catalyst.     

Investigations of plate-type windborne debris—Part II: Computed trajectories

In Part I, trajectories of plates, carried by strong winds, were studied experimentally by wind-tunnel and full-scale tests. The application is to windborne debris occurring in severe windstorms such as hurricanes. In this paper (Part II), a numerical model of square plate trajectories is described and compared with experimental data from Tachikawa, and that described in Part I. Generally, good to excellent agreement is found; lift forces induced by the Magnus effect were found to be significant in determining trajectories.     

Supportive psychotherapy. The search for positive meanings

BACKGROUND: The attempt to define psychotherapeutic skills appropriate for psychiatrists has aroused an interest in supportive psychotherapy, a previously undervalued and underdeveloped member of the psychotherapeutic family. This has been coupled with an increasing recognition of the importance of support within formal psychotherapies, especially when working with highly disturbed patients. METHOD: A review of supportive psychotherapy (ST) was performed, based on a Medline literature search. RESULTS: It is argued that, from the perspective of attachment theory, support is an integral part of al psychotherapies. ST is also a specific mode of treatment suitable for some patients suffering from psychotic illnesses and borderline personality disorder. ST is an eclectic treatment drawing on many theoretical approaches. A common theme based on a narrative co-constructionist perspective, the search for positive meaning, is identified. CONCLUSIONS: Supportive psychotherapy is an essential component of good psychiatric practice. Further research is needed to define its benefits and limitations.     

Fear-potentiated startle in posttraumatic stress disorder

Exaggerated startle is reputed to be one of the cardinal symptoms of posttraumatic stress disorder (PTSD); however, objective studies have given conflicting results as to whether or not startle is increased in PTSD. The present study investigated startle in PTSD during the threat of shock (fear-potentiated startle). The eyeblink component of the startle reflex was measured at various times preceding and following the anticipation of unpleasant electric shocks in 9 PTSD subjects and 10 age-matched, healthy controls. Startle amplitude was significantly greater during baseline and during shock anticipation in the PTSD subjects, compared to the controls. Habituation of the startle reflex was normal. Because other studies in the literature, as well as in our own laboratory, have failed to find exaggerated startle at baseline (i.e., absence of stress) in PTSD patients, it is unlikely that the present results reflect a chronic elevation of startle in this group. Instead, the higher levels of startle in the PTSD group probably resulted from a greater conditioned emotional response in this group, triggered by anticipation of electric shocks that generalized to the unfamiliar experimental context in which testing occurred. Hence, emotionally charged test procedures may be especially informative in distinguishing PTSD patients from other psychiatric diagnostic groups.