AC Voltage Regulation of a Bidirectional High-Frequency Link Converter Using a Deadbeat Controller

This paper presents a digital controller for ac voltage regulation of a bidirectional high-frequency link (BHFL) inverter using deadbeat control. The proposed controller consists of inner current loop, outer voltage loop and a feed-forward controller, which imposes a gain scheduling effect according to the reference signal to compensate the steady-state error of the system. The main property of the proposed controller is that the current- and the voltage-loop controllers have the same structure, and use the same sampling period. This simplifies the design and implementation processes. To improve the overall performance of the system, additional disturbance decoupling networks are employed. This takes into account the model discretization effect. Therefore, accurate disturbance decoupling can be achieved, and the system robustness towards load variations is increased. To avoid transformer saturation due to low frequency voltage envelopes, an equalized pulse width modulation (PWM) technique has been introduced. The proposed controller has been realized using the DS1104 digital signal processor (DSP) from dSPACE. Its performances have been tested on a one kVA prototype inverter. Experimental results showed that the proposed controller has very fast dynamic and good steady-state responses even under highly nonlinear load

The association between incident vertebral deformities, health-related quality of life and functional impairment: a 10.7-year cohort study

We aimed to describe longitudinal changes in health-related quality of life (HRQoL) measures associated with incident vertebral deformities (VDs) over 10.7 years. Incident VDs are associated with clinically significant functional impairment in men, and reduction in overall HRQoL in older women. Increasing severity and number of incident VDs are associated with clinically meaningful functional impairment in men, but not women

Elevated CO2 priming as a sustainable approach to increasing rice tiller number and yield potential

Tillering and yield are linked in rice, with significant efforts being invested to understand the genetic basis of this phenomenon. However, in addition to genetic factors, tillering is also influenced by the environment. Exploiting experiments in which seedlings were first grown in elevated CO2 (eCO2) before transfer and further growth under ambient CO2 (aCO2) levels, we found that even moderate exposure times to eCO2 were sufficient to induce tillering in seedlings, which was maintained in plants grown to maturity plants in controlled environment chambers. We then explored whether brief exposure to eCO2 (eCO2 priming) could be implemented to regulate tiller number and yield in the field. We designed a cost-effective growth system, using yeast to increase the CO2 level for the first 24 days of growth, and grew these seedlings to maturity in semi-field conditions in Malaysia. The increased growth caused by eCO2 priming translated into larger mature plants with increased tillering, panicle number, and improved grain filling and 1000 grain weight. In order to make the process more appealing to conventional rice farmers, we then developed a system in which fungal mycelium was used to generate the eCO2 via respiration of sugars derived by growing the fungus on lignocellulosic waste. Not only does this provide a sustainable source of CO2, it also has the added financial benefit to farmers of generating economically valuable oyster mushrooms as an end-product of mycelium growth. Our experiments show that the system is capable of generating sufficient CO2 to induce increased tillering in rice seedlings, leading eventually to 18% more tillers and panicles in mature paddy-grown crop. We discuss the potential of eCO2 priming as a rapidly implementable, broadly applicable and sustainable system to increase tillering, and thus yield potential in rice

An analysis of inter-professional collaboration in osteoporosis screening at a primary care level using the D'Amour model

Objectives This study describes the perspective of patients, nurses, pharmacists, doctors and policy makers to identify the level of collaboration and the areas for improvement to achieve inter-professional collaboration between doctors, nurses, pharmacists and policy makers in a primary care clinic. Methods Patients (n = 20), Nurses (n = 10), pharmacists (n = 11), doctors (n = 10) and policy makers (n = 5) from a primary care were individually interviewed using a semi-structured topic guide. Purposive sampling was used. Interviews were transcribed verbatim and analysed using thematic analysis informed by constant comparison. Results Patients, doctors, nurses, pharmacists and policy makers were eager for pharmacists to be more proactive in creating health awareness and conducting osteoporosis screening at the primary care clinic via inter-professional collaboration. These findings were further examined using the D'Amour's structural model of collaboration which encompasses four main themes: shared goals and visions, internalization, formalization and governance. This model supports our data which highlights a lack of understanding of the pharmacists' role among the doctors, nurses, policy makers and pharmacists themselves. There is also a lack of governance and formalization, that fosters consensus, leadership, protocol and information exchange. Nonetheless, the stakeholders trust that pharmacists have sufficient knowledge to contribute to the screening of osteoporosis. Our primary care clinic can be described as developing towards an inter-professional collaboration in managing osteoporosis but is still in its early stages. Conclusions Inter-professional collaboration in osteoporosis management at the primary care level is beginning to be practised. Efforts extending to awareness and acceptance towards the pharmacists' role will be crucial for a successful change

Supporting patients to get the best from their osteoporosis treatment: a rapid realist review of what works, for whom, and in what circumstance

Systematic reviews that examine effectiveness of interventions to improve medicines optimisation do not explain how or why they work. This realist review identified that interventions which effectively optimise medicines use in osteoporosis include opportunities to address patients' perceptions of illness and treatment and/or support primary care clinician decision making. INTRODUCTION: In people with osteoporosis, adherence to medicines is poorer than other diseases and patients report follow-up is lacking, and multiple unmet information needs. We conducted a rapid realist review to understand what contextual conditions and mechanisms enable interventions to support osteoporosis medication optimisation. METHODS: A primary search identified observational or interventional studies which aimed to improve medicines adherence or optimisation; a supplementary second search identified research of any design to gain additional insights on emerging findings. Extracted data was interrogated for patterns of context-mechanism-outcome configurations, further discussed in team meetings, informed by background literature and the Practicalities and Perception Approach as an underpinning conceptual framework. RESULTS: We identified 5 contextual timepoints for the person with osteoporosis (identifying a problem; starting medicine; continuing medicine) and the practitioner and healthcare system (making a diagnosis and giving a treatment recommendation; reviewing medicine). Interventions which support patient-informed decision making appear to influence long-term commitment to treatment. Supporting patients' practical ability to adhere (e.g. by lowering treatment burden and issuing reminders) only appears to be helpful, when combined with other approaches to address patient beliefs and concerns. However, few studies explicitly addressed patients' perceptions of illness and treatment. Supporting primary care clinician decision making and integration of primary and secondary care services also appears to be important, in improving rates of treatment initiation and adherence. CONCLUSIONS: We identified a need for further research to identify a sustainable, integrated, patient-centred, and cost- and clinically effective model of long-term care for people with osteoporosis

High-Frequency Transformer-Link Inverter with Regenerative Snubber

This work proposes a bidirectional high-frequency link High-frequency link inverters are now commonly used in inverter using center-tapped high-frequency transformer. The uninterruptible power supply and renewable energy source topology also incorporates a regenerative snubber to clamp the systems. In these applications, the types of loads connected to high voltage spikes due to the leakage inductance of the the inverter are rather uncertain. Nonlinear loads such as transformer. The closed-loop control method used is Deadbeat rectifier in computer systems could cause intense distortion in control, which provides fast response and low harmonic the output current and voltage waveform. It is desirable that the distortion, even under nonlinear loads. A lkVA prototype inverter be able to maintain a sinusoidal output voltage inverter is built and the workability of the system is waveform over all loading conditions. This can only be experimentally verified

Spike Suppression in a Bidirectional High-Frequency Transformer-Link Inverter Using a Regenerative Snubber

This paper presents a spike suppression method for Bidirectional High-Frequency Link (BHFL) inverter using a regenerative snubber. Unlike the RCD snubber, this regenerative snubber dampens the voltage spike by charging its snubber capacitor during switch transition. The energy is then pumped back into the main power circuit. A 1kVA prototype inverter is constructed and the workability of the regenerative snubber is tested on the inverter. The results show that the voltage spike is significantly reduced. The efficiency of the inverter is also increased by about 5%

A bidirectional inverter with high frequency isolated transformer

There is a growing interest to develop renewable energy, particularly the solar energy to meet the growing energy demand. In this paper, a bidirectional photovoltaic (PV) inverter using high frequency (HF) transformer is proposed. The HF transformer provides electrical isolation between the DC supply and AC output. Besides, by using minimum power switches at the active rectifier on the secondary side of HF transformer, the system has low switching losses. Therefore, the proposed inverter has advantages of reliable, lightweight, low cost and increased efficiency. A prototype inverter is implemented using a low cost microcontroller and laboratory experiments are carried out to verify the system viability

A near-infrared, continuous wavelength, in-lens spectroscopic photon emission microscope system

10.1109/IPFA.2007.4378092Proceedings of the International Symposium on the Physical and Failure Analysis of Integrated Circuits, IPFA240-24

Determination of intrinsic spectra from frontside & backside photon emission spectroscopy

Annual Proceedings - Reliability Physics (Symposium)620-621ARLP