Simple Guidelines Research Articles

Distal Radioulnar oint Prosthesis.

The distal radioulnar joint (DRUJ) prostheses have been available for many years and despite their superior outcomes compared to conventional DRUJ reconstructions in both short and long-term follow-ups, they have not become as popular as common hip and knee prostheses. In the current review article, at the first step, we discussed the applied anatomy and biomechanics of the DRUJ, and secondly, we classified DRUJ prostheses according to available literature, and reviewed different types of prostheses with their outcomes. Finally we proposed simple guidelines to help the surgeon to choose the appropriate DRUJ prosthesis.

What does the Shinyei PPD42NS Low-Cost Dust Sensor Really Measure?

Deteriorating air quality is of great concern around the world. Recently, citizen scientists, researchers, and many others have used low-cost devices such as the Shinyei PPD42NS dust sensor to measure particulate matter pollution in both developed and under-developed countries. However, few articles exist specifically on the features and performance of these sensors. Some have shown mixed results in terms of precision, accuracy, and repeatability, especially for portable applications. Frequently, users assemble the electronics and the sensors applying simple guidelines, using electric schematics, and coding extraneous algorithms to get questionable data. There is a need to better understand how it works exactly, its limitations and the effect of the program used to interpret the outputs of this sensor. This article provides a short electronic analysis of the Shinyei PPD42NS dust sensor and shows that the internal sensor electronic design (filters and detection stage) as well as the used data processing algorithm, limit its precision and accuracy by generating nonlinearities and biases. These issues avoid some applications like moving ones and imply that the algorithm used to process the sensor signals must be clearly presented in future articles.

Using Positive Language for Impact on individuals’ Behaviour in Medical Profession in the Light of Quranic Ethics

This qualitative study is based on philosophical analysis (interpretive) that focuses on discussing the relationship of medical science with Islamic teachings to clarify the importance of Islamic rules and laws in the medical profession and the impact of these principles to promote good health and positive behavior. The medical profession and life sciences are proving all those facts today that came through Islam more than 1400 years ago. This study throws light on those universal golden rules given by the Quran in the perspective of medical science, health & hygiene and better mental health to be followed by the medical professionals and the fellow beings around. Quran gives easy and simple guidelines to maintain better health and behavior promoting the ultimate standards in the fields of medical and life sciences. These sciences should be based on Islamic principles to get most of the benefits out of it.

Utilization of Aircraft System Data for Air Transport Safety and Efficiency

The article is focused on aircraft’s flight and system data utilization for aviation safety and efficiency. This includes work with Performance Engineering Programs (PEP) output which is based on data recorded by Data Management Unit (DMU). Output is analyzed using tools supported by MS Office. The goal is to provide simple guidelines for operators that are unable to afford the systems for automatic data check send by the aircraft manufacturers.

Non-Structural Earthquake Risk Management for Residential Buildings

As buildings become more resilient against structural damage the cost of non-structural damage and their consequences becomes proportionally higher, giving non-structural damage greater importance in earthquake risk reduction. Providing residents with detailed guidance on how to evaluate their risk regarding non-structural earthquake damage, and what mitigation and preparedness options they have, can increase both home and societal earthquake resiliency. Earthquake damage data from destructive earthquakes in south Iceland in 2000 and 2008 were used to develop simple but detailed twelve-step risk-management guidelines for residents. The guidelines are based on a set of disaster-related objectives. A standard loss estimation study was used to develop guidelines for the fixed non-structural elements and photographs from inside homes that had sustained significant non-structural damage were used to develop guidelines for loose items. Virtually every item in the studied homes was considered to understand its importance and its relevance to the function of a home. Information in terms of financial, functional and emotional value were used in the guidelines to help residents decide which mitigation options to take. The photos provided valuable information by placing each item in context with its surroundings, for example, to understand the possibility of motion and consequences to other items. The proposed approach, although based on observations from residential buildings, is useful for facilities that have sensitive operations, such as offices, industrial facilities, hospitals and government services. As societies become more complex and reliant on non-structural elements, systematic and thorough studies such as the one outlined herein become an increasingly critical part of sound earthquake risk management.

Staging and Grading Discussion of Borderline Cases in Gray Zones

Staging and grading for chronic periodontal disease, as described in 2018, is designed to focus on key distinctions with the recognition that there is a subset of individuals who are on a different clinical trajectory of disease. The staging and grading framework aids the clinician in generating a periodontal diagnosis, however, some cases fall into gray zones in which the simple diagnostic parameters make it challenging to categorize the patient. These cases do not present with clear clinical findings and medical and dental histories that fit within the simple guidelines defined in the staging and grading tables and subsequent algorithms. Two cases are presented and demonstrate typical clinical scenarios that fall into gray zones when it comes to differentiating whether the patient will respond predictably to standard principles of care. Case 1 presents a scenario in which the patient's early history suggests the potential for disease progression and increases the likelihood that the patient may develop a need for complex rehabilitation due to periodontal breakdown. Clinical judgment was used to evaluate whether the patient remained at elevated risk and the potential implications for disease progression. Case 1 was diagnosed with generalized Stage III, Grade B. The initial presentation of Case 2 had a higher severity and complexity and therefore was diagnosed with generalized Stage IV, Grade C. The need for complex rehabilitation in Case 2, however, was not primarily due to periodontitis. Decision guidelines and algorithms help in establishing a standardized diagnosis, however cases that fall into gray zones require clinical judgment to establish the most appropriate diagnosis to guide a treatment plan that is personalized based on current knowledge.

Online Demand Fulfillment Under Limited Flexibility

We study online demand fulfillment in a class of networks with limited flexibility and arbitrary numbers of resources and request types. We show analytically that such a network is both necessary and sufficient to guarantee a performance gap independent of the market size compared with networks with full flexibility, extending the previous literature from the long chains to more general sparse networks. Inspired by the performance bound, we develop simple inventory allocation rules and guidelines for designing such network structures. Numerical experiments including one using some real data from Amazon China are conducted to confirm our findings as well as some of the flexibility principles conjectured in the literature. This paper was accepted by Chung Piaw Teo, optimization.

A Simple Formula Based on Postprandial Plasma Glucose Prediction Using 5,640 Meals Data Via GH-Method: Math-Physical Medicine (No. 301)

This article is based on the continuation of the author’s research work, a simple and practical, yet highly accurate postprandial plasma glucose (PPG) prediction formula for type 2 diabetes (T2D) patients. His methodology is the developed GH-Method: math-physical medicine (MPM) which has been utilized repeatedly in the past decade.The predicted PPG formula-based on the status of fasting plasma glucose (FPG), carbs/sugar intake amount, and post-meal walking steps are as follows: Predicted PPG = 0.97 * FPG + (carbs/sugar grams * 1.8) - (post-meal walking steps in thousand * 5). The conclusive results have the order of values m1 / m2 /m3 / prediction accuracy %. 1) Case A: 1.8 / 5.0 / 0.97 / 99.8%. 2) Case B: 2.0 / 5.0 / 0.945 / 99.9%. 3) Case C: 2.2 / 5.0 / 0.92 / 99.9%. Exercise is important, contributing ~3% higher than food, is easily achieved compared to the required knowledge of diet. As a result, the author spent four years to study food nutrition. Most T2D patients are seniors; therefore, he suggests that walking is the best form of exercise. However, the most difficult part of exercise is the behavior psychology related to the issue of “discipline and persistence”. T2D patients need to walk between 2,000 to 4,000 steps after each meal. The author walks an average of 4,300 steps after each meal. On the other hand, diet (carbs/sugar amount and nutritional balance) requires much more and deeper knowledge of food nutrition in order to control diabetes. Therefore, the author developed an AI-based tool to assist T2D patients. For non-tech patients, the following simple guidelines can assist with meal intake: 1) Starchy food: Eat an amount half of your fist or hand at most. 2) Colorful vegetables: Eat an amount limited to one fist or hand. 3) Green vegetables: Eat an amount limited to 2.5 fists or hands. Please note: you must combine two types of vegetable together in order to get the total intake limitation. The author highly recommends the patients to measure their FPG at least several times a quarter, in order to get a quarterly average FPG value. The other three PPG values can then utilize the formula-based predicted PPG to control their overall diabetes conditions. The described method mentioned above in regard to the predicted PPG formula along with the postmeal walking exercise and carbs/sugar intake amount can help patients control their diabetes without painful and troublesome finger-piercing glucose measurements. The author has been measuring his glucoses for 8.5 years (3,126 days) with finger-piercing glucose testing combined with his 10-years of diabetes research work. He hopes this article can provide useful guidelines to other diabetes patients to take back their lives from this dreadful chronic disease.

A Simple Formula Based on Postprandial Plasma Glucose Prediction Using 5,640 Meals Data Via GH-Method: Math-Physical Medicine (No. 301)

This article is based on the continuation of the author’s research work, a simple and practical, yet highly accurate postprandial plasma glucose (PPG) prediction formula for type 2 diabetes (T2D) patients. His methodology is the developed GH-Method: math-physical medicine (MPM) which has been utilized repeatedly in the past decade.The predicted PPG formula-based on the status of fasting plasma glucose (FPG), carbs/sugar intake amount, and post-meal walking steps are as follows: Predicted PPG = 0.97 * FPG + (carbs/sugar grams * 1.8) - (post-meal walking steps in thousand * 5). The conclusive results have the order of values m1 / m2 /m3 / prediction accuracy %. 1) Case A: 1.8 / 5.0 / 0.97 / 99.8%. 2) Case B: 2.0 / 5.0 / 0.945 / 99.9%. 3) Case C: 2.2 / 5.0 / 0.92 / 99.9%. Exercise is important, contributing ~3% higher than food, is easily achieved compared to the required knowledge of diet. As a result, the author spent four years to study food nutrition. Most T2D patients are seniors; therefore, he suggests that walking is the best form of exercise. However, the most difficult part of exercise is the behavior psychology related to the issue of “discipline and persistence”. T2D patients need to walk between 2,000 to 4,000 steps after each meal. The author walks an average of 4,300 steps after each meal. On the other hand, diet (carbs/sugar amount and nutritional balance) requires much more and deeper knowledge of food nutrition in order to control diabetes. Therefore, the author developed an AI-based tool to assist T2D patients. For non-tech patients, the following simple guidelines can assist with meal intake: 1) Starchy food: Eat an amount half of your fist or hand at most. 2) Colorful vegetables: Eat an amount limited to one fist or hand. 3) Green vegetables: Eat an amount limited to 2.5 fists or hands. Please note: you must combine two types of vegetable together in order to get the total intake limitation. The author highly recommends the patients to measure their FPG at least several times a quarter, in order to get a quarterly average FPG value. The other three PPG values can then utilize the formula-based predicted PPG to control their overall diabetes conditions. The described method mentioned above in regard to the predicted PPG formula along with the postmeal walking exercise and carbs/sugar intake amount can help patients control their diabetes without painful and troublesome finger-piercing glucose measurements. The author has been measuring his glucoses for 8.5 years (3,126 days) with finger-piercing glucose testing combined with his 10-years of diabetes research work. He hopes this article can provide useful guidelines to other diabetes patients to take back their lives from this dreadful chronic disease.

A Simple Formula Based on Postprandial Plasma Glucose Prediction Using 5,640 Meals Data Via GH-Method: Math-Physical Medicine (No. 301)

This article is based on the continuation of the author’s research work, a simple and practical, yet highly accurate postprandial plasma glucose (PPG) prediction formula for type 2 diabetes (T2D) patients. His methodology is the developed GH-Method: math-physical medicine (MPM) which has been utilized repeatedly in the past decade.The predicted PPG formula-based on the status of fasting plasma glucose (FPG), carbs/sugar intake amount, and post-meal walking steps are as follows: Predicted PPG = 0.97 * FPG + (carbs/sugar grams * 1.8) - (post-meal walking steps in thousand * 5). The conclusive results have the order of values m1 / m2 /m3 / prediction accuracy %. 1) Case A: 1.8 / 5.0 / 0.97 / 99.8%. 2) Case B: 2.0 / 5.0 / 0.945 / 99.9%. 3) Case C: 2.2 / 5.0 / 0.92 / 99.9%. Exercise is important, contributing ~3% higher than food, is easily achieved compared to the required knowledge of diet. As a result, the author spent four years to study food nutrition. Most T2D patients are seniors; therefore, he suggests that walking is the best form of exercise. However, the most difficult part of exercise is the behavior psychology related to the issue of “discipline and persistence”. T2D patients need to walk between 2,000 to 4,000 steps after each meal. The author walks an average of 4,300 steps after each meal. On the other hand, diet (carbs/sugar amount and nutritional balance) requires much more and deeper knowledge of food nutrition in order to control diabetes. Therefore, the author developed an AI-based tool to assist T2D patients. For non-tech patients, the following simple guidelines can assist with meal intake: 1) Starchy food: Eat an amount half of your fist or hand at most. 2) Colorful vegetables: Eat an amount limited to one fist or hand. 3) Green vegetables: Eat an amount limited to 2.5 fists or hands. Please note: you must combine two types of vegetable together in order to get the total intake limitation. The author highly recommends the patients to measure their FPG at least several times a quarter, in order to get a quarterly average FPG value. The other three PPG values can then utilize the formula-based predicted PPG to control their overall diabetes conditions. The described method mentioned above in regard to the predicted PPG formula along with the postmeal walking exercise and carbs/sugar intake amount can help patients control their diabetes without painful and troublesome finger-piercing glucose measurements. The author has been measuring his glucoses for 8.5 years (3,126 days) with finger-piercing glucose testing combined with his 10-years of diabetes research work. He hopes this article can provide useful guidelines to other diabetes patients to take back their lives from this dreadful chronic disease.

A simple formula based on postprandial plasma glucose prediction using 5,640 meals data via GH-Method: math-physical medicine (No. 301)

This article is based on the continuation of the author’s research work, a simple and practical, yet highly accurate postprandial plasma glucose (PPG) prediction formula for type 2 diabetes (T2D) patients. His methodology is the developed GH-Method: math-physical medicine (MPM) which has been utilized repeatedly in the past decade. The predicted PPG formula-based on the status of fasting plasma glucose (FPG), carbs/sugar intake amount, and postmeal walking steps are as follows: Predicted PPG = 0.97 * FPG + (carbs/sugar grams * 1.8) - (post-meal walking steps in thousand * 5) The conclusive results have the order of values m1 / m2 /m3 / prediction accuracy %. Case A: 1.8 / 5.0 / 0.97 / 99.8% Case B: 2.0 / 5.0 / 0.945 / 99.9% Case C: 2.2 / 5.0 / 0.92 / 99.9% Exercise is important, contributing ~3% higher than food, is easily achieved compared to the required knowledge of diet. As a result, the author spent four years to study food nutrition. Most T2D patients are seniors; therefore, he suggests that walking is the best form of exercise. However, the most difficult part of exercise is the behavior psychology related to the issue of “discipline and persistence”. T2D patients need to walk between 2,000 to 4,000 steps after each meal. The author walks an average of 4,300 steps after each meal. On the other hand, diet (carbs/sugar amount and nutritional balance) requires much more and deeper knowledge of food nutrition in order to control diabetes. Therefore, the author developed an AI-based tool to assist T2D patients. For non-tech patients, the following simple guidelines can assist with meal intake: Starchy food: Eat an amount half of your fist or hand at most Colorful vegetables: Eat an amount limited to one fist or hand. Green vegetables: Eat an amount limited to 2.5 fists or hands. Please note: you must combine two types of vegetable together in order to get the total intake limitation. The author highly recommends the patients to measure their FPG at least several times a quarter, in order to get a quarterly average FPG value. The other three PPG values can then utilize the formula-based predicted PPG to control their overall diabetes conditions. The described method mentioned above in regard to the predicted PPG formula along with the post-meal walking exercise and carbs/sugar intake amount can help patients control their diabetes without painful and troublesome fingerpiercing glucose measurements. The author has been measuring his glucoses for 8.5 years (3,126 days) with fingerpiercing glucose testing combined with his 10-years of diabetes research work. He hopes this article can provide useful guidelines to other diabetes patients to take back their lives from this dreadful chronic disease.

Five different solutions to mitigate overprescribing opioid medications.

The University of Colorado School of Dental Medicine took 5 distinct actions to mitigate the amount of opioids prescribed at the dental school between the years 2016-2020. This retrospective study evaluated a comprehensive 5-step quality improvement strategy which was implemented to decrease opioid prescribing. a) development of a Dental Pain Management Protocol, b) implementation of the protocol with pre-doctoral students, c) incorporating the results of a Master's project that determined the actual postoperative pain after periodontal/oral surgical procedures, d) development of a favorite electronic prescription list, and e) creation of patient instructions to allow for information on nonopioid analgesic use after dental procedures to be disseminated to the patient. There was a significant decrease (P=0.05) in the opioid prescribing trend with the implementation of these 5 actions, resulting in an overall 68.8% decrease for prescription writing of opioids and a 78.6% decrease of opioid pills over this 3 year period. Simple guidelines and protocols resulted in a drastic decrease in opioid prescribing, with limited negative feedback from faculty and patients.

The European Federation for Medicinal Chemistry (EFMC) Best Practice Initiative: Validating Chemical Probes.

As part of an initiative aimed to share best practices in Medicinal Chemistry, the European Federation for Medicinal Chemistry (EFMC) is preparing a series of webinars and slide sets focused on the early phase of drug discovery. This educational material is freely accessible through the EFMC. The main target audiences are students or early career scientists and we also believe it will be valuable for experienced practitioners. The first of the series is focused on the generation and validation of high-quality chemical probes, which are critical for drug discovery and more broadly to further our understanding of human biology and disease.

P11. How much lumbar lordosis does a patient need to reach their age-adjusted alignment target? A formulated approach predicting successful surgical outcomes

BACKGROUND CONTEXT Age-adjusted alignment targets for adult spinal deformity (ASD) patients have the potential to reduce the incidence of PJK while ensuring optimal HRQL. Previous studies demonstrated the interplay between lumbar lordosis (LL) and thoracic kyphosis (TK) and their relationship with pelvic morphology as measured by the plevic incidence (PI). In clinical practice, reaching this ideal alignment remains challenging as the relationship between lordosis and kyphosis is not clearly elucidated. PURPOSE This study aimed at developing a pragmatic formula on how much lumbar lordosis is needed based on the patient age, PI and exiting thoracic kyphosis. STUDY DESIGN/SETTING Multicenter retrospective review of a prospective database. PATIENT SAMPLE A total of 347 adult spinal deformity patients reaching age-adjusted alignment at 1-year post surgery. OUTCOME MEASURES Sagittal alignment and internal validation of predictive formula. METHODS Surgical ASD patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regressions analysis was used to identify the relationship between regional curvatures (LL &TK) permitting to reach a given global alignment (TPA) based on pelvic incidence. RESULTS The 347 patients included (60 years old, 72% female, BMI 29±6.2) had a significant improvement in all sagittal parameters from pre-op to 1Y (p CONCLUSIONS This study provides a simple guideline to identify the amount of lordosis needed to reach a given alignment (ie, age-adjusted target) based on pelvic incidence and associated thoracic kyphosis. Implementation of this predictive formula during pre-operative surgical planning can help to reduce unexpected sub-optimal post-operative alignment outcomes. These values could be integrated into pre-contoured rods for true patient specific alignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

All-in-one, reversible yellow-green color switching tungsten oxide electrochromic devices

Tungsten oxide (WO3) sol doped with carbon nanodots (CDs) was utilized for constructing an electrolyte-free, all-in-one electrochromic device (ECD). Different from the traditional WO3-based ECDs, showing the color transition between colorless and blue, the demonstrated device could realize reversible color changes between yellow and green due to the intrinsic color of CDs. The optical contrast of the optimized ECD was up to 53.6% at 650 nm and the coloration response time was 27 s. It could also be automatically bleached under 0 V with the bleaching response time of 80 s. In addition, attributing to the unique photoluminescence (PL) characteristics of CDs, the ECD could also present tunable PL under various excitation wavelengths, which potentially broadens the applications of ECDs in multiple anti-counterfeiting. These results provide simple and effective guidelines for constructing high-performance ECDs with simple architecture and extended color palette.

Understanding the diversity of the metal-organic framework ecosystem

Millions of distinct metal-organic frameworks (MOFs) can be made by combining metal nodes and organic linkers. At present, over 90,000 MOFs have been synthesized and over 500,000 predicted. This raises the question whether a new experimental or predicted structure adds new information. For MOF chemists, the chemical design space is a combination of pore geometry, metal nodes, organic linkers, and functional groups, but at present we do not have a formalism to quantify optimal coverage of chemical design space. In this work, we develop a machine learning method to quantify similarities of MOFs to analyse their chemical diversity. This diversity analysis identifies biases in the databases, and we show that such bias can lead to incorrect conclusions. The developed formalism in this study provides a simple and practical guideline to see whether new structures will have the potential for new insights, or constitute a relatively small variation of existing structures.

Guidelines for designing the antithetic feedback motif

Integral feedback control is commonly used in mechanical and electrical systems to achieve zero steady-state error following an external disturbance. Equivalently, in biological systems, a property known as robust perfect adaptation guarantees robustness to environmental perturbations and return to the pre-disturbance state. Previously, Briat et al proposed a biomolecular design for integral feedback control (robust perfect adaptation) called the antithetic feedback motif. The antithetic feedback controller uses the sequestration binding reaction of two biochemical species to record the integral of the error between the current and the desired output of the network it controls. The antithetic feedback motif has been successfully built using synthetic components in vivo in Escherichia coli and Saccharomyces cerevisiae cells. However, these previous synthetic implementations of antithetic feedback have not produced perfect integral feedback control due to the degradation and dilution of the two controller species. Furthermore, previous theoretical results have cautioned that integral control can only be achieved under stability conditions that not all antithetic feedback motifs necessarily fulfill. In this paper, we study how to design antithetic feedback motifs that simultaneously achieve good stability and small steady-state error properties, even as the controller species are degraded and diluted. We provide simple tuning guidelines to achieve flexible and practical synthetic biological implementations of antithetic feedback control. We use several tools and metrics from control theory to design antithetic feedback networks, paving the path for the systematic design of synthetic biological controllers.

Behavioral effects of guideline-provision on climate-friendly food choices – A psychological perspective

Greenhouse gas (GHG) emissions resulting from global food production are responsible for approximately 25–30% of all global GHG emissions and hence contribute to global climate change (Intergovernmental Panel on Climate Change, 2019). Promoting climate friendly (CF) food consumption can be an effective way to counter this problematic development. Aside from their individual motivation to do so, consumers’ ability to identify CF food represents the fundamental basis for their actual CF food consumption. Initial empirical findings suggest that this ability can be promoted by the provision of simple guidelines (i.e., appropriate action knowledge for CF food consumption). The main objective of the present study was to evaluate the effectiveness of such guideline-provision in promoting the consumers’ ability to identify CF food and to identify relevant preconditions for its effectiveness from a psychological perspective.Two samples of private consumers were examined by means of an online survey – consumers from Switzerland (N = 150) and from Germany (N = 229). In both samples, participants were randomly assigned to the experimental group (EG, receiving simple guidelines for CF food consumption) and the control group (CG, without any intervention).As expected, EG-participants showed higher ability to identify CF food during a conducted food choice-experiment compared to CG-participants. However, this effect was only found when the provided simple guidelines clearly indicated one food-option to be the (more) CF one (i.e., easy food choices). Guideline-provision showed no behavioral effect in more difficult food choices.Taken together, the present study provides further empirical evidence for the effectiveness of action knowledge-provision in promoting consumers’ ability to identify CF food. Furthermore, relevant preconditions for this behavioral effect were identified.

Analytical Guidelines for Designing Curvature-Induced Dielectrophoretic Particle Manipulation Systems.

Curvature-induced dielectrophoresis (C-iDEP) is an established method of applying electrical energy gradients across curved microchannels to obtain a label-free manipulation of particles and cells. This method offers several advantages over the other DEP-based methods, such as increased chip area utilisation, simple fabrication, reduced susceptibility to Joule heating and reduced risk of electrolysis in the active region. Although C-iDEP systems have been extensively demonstrated to achieve focusing and separation of particles, a detailed mathematical analysis of the particle dynamics has not been reported yet. This work computationally confirms a fully analytical dimensionless study of the electric field-induced particle motion inside a circular arc microchannel, the simplest design of a C-iDEP system. Specifically, the analysis reveals that the design of a circular arc microchannel geometry for manipulating particles using an applied voltage is fully determined by three dimensionless parameters. Simple equations are established and numerically confirmed to predict the mutual relationships of the parameters for a comprehensive range of their practically relevant values, while ensuring design for safety. This work aims to serve as a starting point for microfluidics engineers and researchers to have a simple calculator-based guideline to develop C-iDEP particle manipulation systems specific to their applications.

Analysis and Design of Self-Oscillating Resonant Converters with Loss-Free Resistor Characteristics

A general approach for the analysis and design of self-oscillating resonant converters is presented in this paper, for a particular class of circuits in which the change of input voltage polarity is caused by the zero-crossings of the input inductor current. The key features of the method are an analytical description in the time-domain of a spiral that eventually converges into an ellipse, and a frequency–domain analysis that explains the behavior of the ellipse as a limit cycle. On a theoretical basis, this class of circuits behaves as loss-free resistors (LFR) because in steady-state the input inductor current is in phase with the first harmonic of the input voltage. The proposed analytical procedure predicts accurately the amplitude and frequency of the limit cycle and justifies the stability of its generation. This accuracy is reflected in the close agreement between the theoretical expressions and the corresponding simulated and measured waveforms. Third and fourth order resonant converters are designed following simple guidelines derived from the theoretical analysis.