Modeling and analysis of power processing systems: Feasibility investigation and formulation of a methodology

A review is given of future power processing systems planned for the next 20 years, and the state-of-the-art of power processing design modeling and analysis techniques used to optimize power processing systems. A methodology of modeling and analysis of power processing equipment and systems has been formulated to fulfill future tradeoff studies and optimization requirements. Computer techniques were applied to simulate power processor performance and to optimize the design of power processing equipment. A program plan to systematically develop and apply the tools for power processing systems modeling and analysis is presented so that meaningful results can be obtained each year to aid the power processing system engineer and power processing equipment circuit designers in their conceptual and detail design and analysis tasks

Differential amplifier with regulator achieves high stability, low drift

When d-c signals are to be amplified, the usual approach is to use a direct-coupled circuit. The difficulty of maintaining sufficiently low drift in a direct-coupled configuration led to the development of chopper and chopper-stabilized circuits, where a mechanical chopper reduces drift to low values. Unfortunately, other shortcomings arise, and in most applications the direct-coupled d-c amplifier would be preferable if the drift could be reduced to an acceptable value. The advantages over the chopper or the chopper-stabilized types include rapid recovery from overload, freedom from hash, simplicity and small size due to absence of transformers and capacitors

Physical prognostic factors predicting outcome following anterior cruciate ligament reconstruction: Protocol for a systematic review

Introduction Injuries of the anterior cruciate ligament (ACL) are a common musculoskeletal complication and can cause significant reduction in patient function and quality of life. Many undergo ACL reconstruction, with high-quality rehabilitation key to successful outcome. Knowledge of physical prognostic factors, such as quadriceps strength, is crucial to inform rehabilitation and has important implications for outcome following ACL reconstruction. However, these factors predicting outcome are poorly defined. Therefore, the aim of this systematic review is to establish physical prognostic factors predictive of outcome in adults following ACL reconstruction. Outcome will be subdivided into two groups of outcome measures, patient-reported and performance-based. Physical prognostic factors of interest will reflect a range of domains and may be modifiable/non-modifiable. Results will help decide most appropriate management and assist in planning and tailoring preoperative and postoperative rehabilitation. Methods and analysis This systematic review protocol is reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. MEDLINE, CINAHL and EMBASE databases, key journals and grey literature will be searched from inception to July 2019. Prospective cohort studies including participants aged ≥16 years who have undergone ACL reconstruction will be included, with articles focusing on multi-ligament reconstructions and ACL repair surgery, or not published in English excluded. Two independent reviewers will conduct searches, assess study eligibility, extract data, assess risk of bias (Quality in Prognostic Studies tool) and quantify overall quality of evidence (modified Grading of Recommendations, Assessment, Development and Evaluation guidelines). If possible, a meta-analysis will be conducted, otherwise a narrative synthesis will ensue focusing on prognostic factors, risk of bias of included studies and strength of association with outcomes. Ethics and dissemination Findings will be published in a peer-reviewed journal, presented at conferences and locally to physiotherapy departments. Ethical approval is not required for this systematic review. PROSPERO registration number CRD42019127732

The Venerable Converter: A New Approach to Power Processing

A regulating dc-to-dc converter is described which utilizes a new circuit configuration to achieve several desirable features including higher efficiency, a single circuit for regulation and conversion, minimized output filter requirements, and simplified control system applications. The dc operating characteristics are derived and the efficiency of the new converter is shown to compare favorably with the conventional boost regulator. An ac model is derived and a comparison is made between analytical and experimental results

Loss of inhibin alpha uncouples oocyte-granulosa cell dynamics and disrupts postnatal folliculogenesis

AbstractTargeted disruption of the inhibin α gene (Inha–/–) in mice results in an ovarian phenotype of granulosa cell tumors that renders the animals infertile. Little is known about the reproductive defects prior to tumor development. Here, we report novel data on early follicle dynamics in Inha–/– mice, which demonstrate that inhibin α has important consequences upon follicle development. Morphological changes in both germ and somatic cells were evident in postnatal day 12 ovaries, with Inha−/− mice exhibiting numerous multilayered follicles that were far more advanced than those observed in age-matched controls. These changes were accompanied by alterations in follicle dynamics such that Inha−/− ovaries had fewer follicles in the resting pool and more committed in the growth phase. Absence of inhibin α resulted in advanced follicular maturation as marked by premature loss of anti-Müllerian hormone (AMH) in secondary follicles. Additionally, gene expression analysis revealed changes in factors known to be vital for oocyte and follicle development. Together, these data provide key evidence to suggest that regulation of the inhibin/activin system is essential for early folliculogenesis in the prepubertal mouse ovary

Optimum Noise Performance of Transistor Input Circuits / Transistor AC and DC Amplifiers with High Input Impedance

Some results are presented for optimum noise performance of transistor input stages when fed from resistive or reactive sources. Standard theory has shown that a common-emitter transistor fed from a resistive source presents a minimum noise figure F_m when the source resistance has a certain value R_gm in the order of lkΩ. In this paper, expressions are developed for minimum noise figure and optimum source resistance in the presence of base bias resistors, emitter degeneration resistance, and various kinds of feedback. Results are in terms of F_m and R_gm only, and do not contain other functions of the transistor internal noise sources. It is shown that the minimum noise figure is never less than F_m, but the optimum source resistance can be either greater or less than R_gm. In the case of reactive sources, noise figure is meaningless and the quantity of interest is signal-to-noise ratio over the passband. It is shown that for an inductive source, such as a magnetic tape head, there is a maximum signal-to-noise ratio obtainable with an optimum source inductance, and that a Figure of Merit can be assigned to the source which is independent of its inductance. Experimental results presented for both resistive and inductive sources show good agreement with the theoretical predictions

Single-particle measurements of bouncing particles and in situ collection efficiency from an airborne aerosol mass spectrometer (AMS) with light-scattering detection

A light-scattering module was coupled to an airborne, compact time-of-flight aerosol mass spectrometer (LS-AMS) to investigate collection efficiency (CE) while obtaining nonrefractory aerosol chemical composition measurements during the Southeast Nexus (SENEX) campaign. In this instrument, particles scatter light from an internal laser beam and trigger saving individual particle mass spectra. Nearly all of the single-particle data with mass spectra that were triggered by scattered light signals were from particles larger than ĝ1/4 280ĝ€nm in vacuum aerodynamic diameter. Over 33ĝ€000 particles are characterized as either prompt (27ĝ€%), delayed (15ĝ€%), or null (58ĝ€%), according to the time and intensity of their total mass spectral signals. The particle mass from single-particle spectra is proportional to that derived from the light-scattering diameter (dva-LS) but not to that from the particle time-of-flight (PToF) diameter (dva-MS) from the time of the maximum mass spectral signal. The total mass spectral signal from delayed particles was about 80ĝ€% of that from prompt ones for the same dva-LS. Both field and laboratory data indicate that the relative intensities of various ions in the prompt spectra show more fragmentation compared to the delayed spectra. The particles with a delayed mass spectral signal likely bounced off the vaporizer and vaporized later on another surface within the confines of the ionization source. Because delayed particles are detected by the mass spectrometer later than expected from their dva-LS size, they can affect the interpretation of particle size (PToF) mass distributions, especially at larger sizes. The CE, measured by the average number or mass fractions of particles optically detected that had measurable mass spectra, varied significantly (0.2-0.9) in different air masses. The measured CE agreed well with a previous parameterization when CE > 0.5 for acidic particles but was sometimes lower than the minimum parameterized CE of 0.5