Current Reference Values Research Articles

A Comparison of Global Lung Initiative 2012 with Third National Health and Nutrition Examination Survey Spirometry Reference Values. Implications in Defining Obstruction.

Obstructive lung disease is diagnosed by a decreased ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC); however, there is no universally accepted lower limit of normal for the FEV1/FVC ratio. Current established reference values use the Third National Health and Nutrition Examination Survey (NHANES III) database. In 2012, the Global Lung Initiative (GLI) introduced GLI12, which is a compilation reference set that uses standard deviation values to define normal spirometry. To evaluate the changes in classification of obstructive spirometry with use of GLI12 compared with NHANES III in a heterogeneous, multiracial population. We evaluated the spirometry studies conducted in our pulmonary function laboratory between January 2005 and December 2015. NHANES III reference equations were calculated to predict lower limits of normal for FEV1, FVC, and FEV1/FVC. GLI12 values were established using European Respiratory Society published computer software. FEV1 severity was graded using 2005 American Thoracic Society guidelines for NHANES III and using z-score-based criteria for GLI12. Asymmetric partition analysis evaluated agreement between the reference sets. A total of 11,888 studies were evaluated. Obstruction was diagnosed in 2,857 studies using NHANES III versus 2,489 studies using GLI12. Agreement regarding the presence or absence of obstruction occurred in 2,483 of studies with obstruction and 9,025 studies without obstruction (agreement, 96.8%; κ = 0.91). Of the studies with obstruction, 1,595 had agreement in severity grading. Overall, agreement regarding obstruction and severity grading occurred in 10,620 studies, representing 89.3% of all studies. A total of 380 studies (3.2%) had discordance regarding the presence or absence of obstruction, 34.0% (844 of the 2,483 obstruction studies) had a one-degree of change in FEV1 disease severity scoring, with 44 cases (1.8%) that had changes of two categories in FEV1 severity scores. No studies had greater than two degrees of change. Asymmetric partition analysis suggested that the highest clinically significant changes were seen in older individuals, particularly African American men older than 65. Our evaluation suggests that there is moderate overall agreement between NHANES III and GLI12. We found a 3.2% change in classification of obstruction when transitioning from NHANES III to GLI12. When incorporating a z-score-based FEV1 and GLI12 reference set, 10.7% of the spirometry studies had a change in their categorization. The disagreement between the two datasets was most pronounced in elderly subjects. Although we cannot endorse one reference set over the other, we highlight the potential implications of adopting the GLI12 reference sets and suggest caution when interpreting spirometry in the elderly.

Endothelium: A Target for Harmful Actions of Metals.

The use of heavy metals is closely linked to the history of mankind. They have been used as important materials in a wide variety of human activities such as manufacturing utensils and tools. Such extended use has significantly increased professional and environmental exposure to mercury, lead and cadmium. These metals are known to produce hypertension in humans and animals and, among other effects, they can also affect endothelial function. Results described here suggest that mercury, lead and cadmium affect vascular reactivity, even at low doses or concentrations. Several vascular actions are mediated by the endothelium via increasing the production of free radicals and angiotensin II by local ACE stimulation. These results provide further evidence that these toxic metals, even at low doses, are an environmental risk factor to the exposed population. These results also suggest that continuous exposure to these metals, followed by their absorption and progressive accumulation in the body, may be hazardous to cardiovascular function. Therefore, the current reference values, which are considered safe, need to be reduced.

Design of Hybrid Control Algorithm for Fault Ride-Through of Photovoltaic System

This paper proposes a novel control algorithm to enhance the fault ride-through (FRT) capability of a photovoltaic (PV) system. In this method, the overcurrent of the grid-tied inverter is suppressed to a preset value using model current predictive control (MCPC) algorithm, and its DC-link overvoltage is removed using a non-maximum power point tracker (non-MPPT) algorithm. Therefore, the inverter overcurrent and its DC-link overvoltage problems can be placed under decoupling control using a DC/AC converter controller and DC/DC converter controller, respectively. Using eight switching modes for the three-phase inverter, the MCPC of DC/AC converter controller establishes a value function between the current reference value and output current value. Then, by introducing the switching mode (corresponding to the minimum value function) into the DC/AC converter controller, if the current reference is set at the rated value, the inverter’s output current can be inhibited to the rated value under fault conditions. Moreover, a balanced three-phase rated current can always be obtained under either a symmetric or asymmetric fault. However, together with the MCPC, a DC-link overvoltage will appear. To remove this DC-link overvoltage quickly, based on the grid system voltage sag level, the non-MPPT algorithm is used to calculate the adjusted power for PV arrays. Then, based on the calculated power, the amended duty cycle can be obtained and immediately introduced into the DC/DC converter controller to tune the PV arrays’ output power, which significantly decreases the power imbalance between the inverter’s AC and DC sides, thus inhibiting the DC-link overvoltage. In addition, to inhibit DC-link voltage fluctuations further, DC-link voltage feedforward compensation is introduced into the DC/DC converter controller. In particular, under an asymmetric fault condition, with the help of the voltage feedforward compensation, the second harmonic frequency components of the DC-link voltage can also be removed. Finally, based on the theoretical derivation and simulation results, it can be proved that the major problems troubling a PV system’s FRT technologies can be resolved by the proposed method, especially the problem related to the harmonic components of the DC-link voltage.

Current Reference Control for Shunt Active Power Filters Under Unbalanced and Distorted Supply Voltage Conditions

This paper proposes a current reference control method for shunt active power filter under unbalanced and distorted supply voltage conditions. The method uses the Kalman filter and the symmetrical component method to obtain the fundamental sequence component of the supply voltage. The Fryze-Buchholz-Dpenbrock method is used to decompose the load current under the reference of the fundamental positive-sequence voltage to obtain the reference value of the compensation current. The method is characterized without need of coordinate transformation, simple calculation, and clear physical meaning. The harmonic current, reactive current and negative sequence current can be compensated at the same time even under the condition of unbalanced supply voltage. The proposed method is compared with the traditional method under various experimental conditions to prove the validity and accuracy of the proposed method. The results show that the proposed method has wider applicability.

Coordinate Control of Power/Current for Grid‐Connected Inverter Based on PCI Controller under Unbalanced Grid Conditions

The oscillations on output power and distortion of the inverter currents will occur in the case of unbalanced grid voltage faults. Constant output power and good current quality cannot be achieved simultaneously. Aiming at these problems, a coordinate control strategy for suppressing power fluctuations and current harmonics is proposed by analyzing instantaneous power control and current balance control. The proposed control is achieved by adjusting the weight coefficient of current reference values to change the current harmonic contents based on proportional complex integral (PCI) controller and proportional multiple complex integral (PMCI) controller. The control strategy with a simple control structure neither needs to detect harmonic components of the inverter currents, nor needs to separate the positive and negative components of voltage and current, which is easy to be realized. The feasibility and effectiveness of the proposed control are verified by the comparison and analysis of simulation.

Clinical and hematological profile in a newborn cohort with hemoglobin SC

ObjectivesHemoglobin SC is the second most common variant of sickle‐cell disease worldwide, after hemoglobin SS. The objectives of the study were to describe the clinical and laboratory characteristics of hemoglobin SC disease in children from a newborn screening program and treated at a blood center. MethodologyThis study assessed a cohort of 461 infants born between 01/01/1999 and 12/31/2012 and followed‐up until 12/31/2014. Clinical events were expressed as rates for 100 patient‐years, with 95% confidence intervals. Kaplan–Meier survival curves were created. ResultsThe median age of patients was 9.2 years; 47.5% were female. Mean values of blood tests were: hemoglobin, 10.5g/dL; reticulocytes, 3.4%; white blood cells, 11.24×109/L; platelets, 337.1×109/L; and fetal hemoglobin, 6.3%. Clinical events: acute splenic sequestration in 14.8%, blood transfusion 23.4%, overt stroke in 0.2%. The incidence of painful vaso‐occlusive episodes was 51 (48.9–53.4) per 100 patient‐years and that of infections, 62.2 episodes (59.8–64.8) per 100 patient‐years. Transcranial Doppler ultrasonography (n=71) was normal given the current reference values for SS patients. Hydroxyurea was given to ten children, all of whom improvement of painful crises. Retinopathy was observed in 20.3% of 59 children who underwent ophthalmoscopy. Avascular necrosis was detected in seven of 12 patients evaluated, predominantly in the left femur. Echocardiogram compatible with pulmonary hypertension was recorded in 4.6% of 130 children, with an estimated average systolic pulmonary artery pressure of 33.5mmHg. The mortality rate from all causes was 4.3%. ConclusionsClinical severity is variable in SC hemoglobinopathy. Several children have severe manifestations similar to those with SS disease.

Possible Scenarios of Winter Wheat Yield Reduction of Dryland Qazvin Province, Iran, Based on Prediction of Temperature and Precipitation Till the End of the Century

The climate of the Earth is changing. The Earth’s temperature is projected to maintain its upward trend in the next few decades. Temperature and precipitation are two very important factors affecting crop yields, especially in arid and semi-arid regions. There is a need for future climate predictions to protect vulnerable sectors like agriculture in drylands. In this study, the downscaling of two important climatic variables—temperature and precipitation—was done by the CanESM2 and HadCM3 models under five different scenarios for the semi-arid province of Qazvin, located in Iran. The most efficient scenario was selected to predict the dryland winter wheat yield of the province for the three periods: 2010–2039, 2040–2069, and 2070–2099. The results showed that the models are able to satisfactorily predict the daily mean temperature and annual precipitation for the three mentioned periods. Generally, the daily mean temperature and annual precipitation tended to decrease in these periods when compared to the current reference values. However, the scenarios rcp2.6 and B2, respectively, predicted that the precipitation will fall less or even increase in the period 2070–2099. The scenario rcp2.6 seemed to be the most efficient to predict the dryland winter wheat yield of the province for the next few decades. The grain yield is projected to drop considerably over the three periods, especially in the last period, mainly due to the reduction in precipitation in March. This leads us to devise some adaptive strategies to prevent the detrimental impacts of climate change on the dryland winter wheat yield of the province.

Pharmaceuticals and endocrine disruptors in raw and cooked seafood from European market: Concentrations and human exposure levels

Pharmaceuticals (PhACs) and endocrine disrupting compounds (EDCs) are chemicals of emerging concern that can accumulate in seafood sold in markets. These compounds may represent a risk to consumers through effects on the human reproductive system, metabolic disorders, pathogenesis of breast cancer or development of microbial resistance. Measuring their levels in highly consumed seafood is important to assess the potential risks to human health. Besides, the effect of cooking on contaminant levels is relevant to investigate. Therefore, the objectives of this research were to study the presence and levels of PhACs and EDCs in commercially available seafood in the European Union market, to investigate the effect of cooking on contaminant levels, and to evaluate the dietary exposure of humans to these compounds through seafood consumption. A sampling survey of seafood from 11 European countries was undertaken. Twelve highly consumed seafood types were analysed raw and cooked with 3 analytical methods (65 samples, 195 analysis). PhACs were mostly not detectable or below quantification limits in seafood whereas EDCs were a recurrent group of contaminants quantified in the majority of the samples. Besides, cooking by steaming significantly increased their levels in seafood from 2 to 46-fold increase. Based on occurrence and levels, bisphenol A, methylparaben and triclosan were selected for performing a human exposure assessment and health risk characterisation through seafood consumption. The results indicate that the Spanish population has the highest exposure to the selected EDCs through seafood consumption, although the exposure via seafood remained below the current toxicological reference values.

Design and Experimental Verification of 400-W Class LED Driver with Cooperative Control Method for Two-Parallel Connected DC/DC Converters

This paper deals with a design and experimental verification of 400-W class light-emitting diode (LED) driver with cooperative control method for two-parallel connected DC/DC converters. In the cooperative control method, one DC/DC converter is selected to supply the output current for the LED, based on the reference value of the LED current. Thus, the proposed cooperative-control strategy achieves wide dimming range operation. The discontinuous current conduction mode (DCM) operation improves the total harmonic distortion (THD) value on the AC side of the LED driver. The standard of Electrical Applications and Materials Safety Act in Japan has defined the flicker frequency and minimum optical output. The smoothing capacitors are designed by considering the power flow and LED current ripple for satisfying the standard. A prototype LED driver is constructed and tested. Experimental results demonstrate that a wide dimming operation range from 1 to 100% is achieved with a THD value less than 10% on the AC side, by the proposed control strategy. The authors compare the power conversion efficiency between Si- and SiC-metal-oxide-semiconductor field-effect transistors (MOSFETs) based LED driver. The maximum power conversion efficiency by using SiC-MOSFETs based LED driver is 91.4%. Finally, the variable switching frequency method is proposed for improving the power conversion efficiency for a low LED current region.

Reference values of left atrial size and function according to age: should we redefine the normal upper limits?

Different cut-offs have been proposed for left atrial (LA) size. Furthermore, conflicting results have been reported about the influence of age on LA size and data on the impact of age on LA myocardial function are scanty. The aim of this study was to derive references values for LA size and function in healthy subjects and to evaluate the impact of age. We conducted a systematic literature search of MEDLINE database. We included only studies evaluating healthy subjects, with age ranged between 18 and 80years. Parameters were compared among four age groups, < 30, 30-45, > 45-60, > 60years. Three hundred twenty-six studies met the inclusion criteria and the final population consisted of 62,821 subjects. LA volume index (LAVi) did not differ among different age groups (p = 0.21). The normal upper limit of LAVi was 24mL/m2. LA reservoir function, measured by strain, did not differ among age groups (38 ± 3%, 32-43%; p = 0.74). Left ventricular (LV) size and function were not different among groups, except LV mass index. A decrease in E/A ratio and an increase in E/e' ratio were found with advancing age (p < 0.0001 and p = 0.001, respectively). In healthy subjects the normal upper limit of LAVi was lower than that recommended and is not influenced by advancing age. Furthermore, also LA function measured by strain was not affected by age. The current reference values of LAVi should be used with caution when applied to healthy subjects.

Avaliação e Gerenciamento de Riscos dos Campos Eletromagnéticos em Plataforma de Petróleo

Os equipamentos de telecomunicações operam na faixa de radiofrequência do espectro eletromagnético, portanto são considerados emissores de radiações não ionizantes (RNI). A exposição a campos eletromagnéticos pode causar impactos à saúde e ao meio ambiente. A pesquisa de campo revelou que na plataforma de petróleo avaliada as exposições a RNI encontram-se abaixo dos limites estabelecidos pela legislação. No entanto, os estudos que estabelecem tais limites não são conclusivos o suficiente para garantir ausência de malefícios tanto para o homem, quanto para o meio ambiente considerando os atuais valores de referência.

Improvement of the method for analysis of nonlinear electrotechnical systems based on the small parameter method

The small parameter method, implemented in frequency domain, was used for the analytical analysis of nonlinear electrical circuits of electrotechnical systems. To have the possibility of calculations in frequency domain, the automated method of forming orthogonal harmonic components of electrical magnitudes based on the algorithm of discrete convolution was used. The characteristic of a nonlinear element was represented by the polynomial function of third degree. It was shown that application of the small parameter method with its realization in frequency domain makes it possible to simplify the process of analyzing electrical circuits with nonlinear elements by automating calculations in the mathematical package. Analytical and numerical calculations of a circuit with actively inductive load demonstrated sufficient accuracy of the proposed method, the relative error for the main harmonic of current did not exceed 6 %. The conducted comparative analysis of the proposed small parameter method with the classic small parameter method on the example of calculation of an electrical circuit with RL load showed that the developed method provides better adequacy of results and high calculation accuracy in comparison with the existing one. Relative error by amplitude of first and third harmonics of current does not exceed 2.5 %, and by phase, it does not exceed 1.042·10 -3 %. The method of numerical structural modeling was used to determine the reference values of current of the researched circuit. The results of the research can be used in calculations of electrotechnical devices, containing semiconductor components and electrical devices with nonlinear characteristics. In addition, the obtained results will make it possible to improve the processes of active compensation of harmonics of current in electrical networks with nonlinear load and to develop the tools of passive compensation

A Novel Line Current Control Strategy to Control the Real Power Flow at PCC using H-bridge Inverter

&lt;p class="abstract"&gt;This paper presents the power flow control between the main grid and the microgrid in low-voltage distribution network using H-bridge inverter. Controlling the real power flow in the line using the H-bridge inverter is investigated by implementing the line current control strategy. The feasibility of the proposed H-bridge inverter and its control strategy is validated by varying the line current reference. Hence, the H-bridge inverter will operate in its inductive or capacitive operation mode depending on the reference current value and the output of the PI controller in the control unit. The control strategy of the microgrid distributed generators has also been investigated in which P/V droop characteristics is applied to the power control of each DG in the microgrid. The effectiveness of the proposed approaches is validated through simulations. &lt;/p&gt;

Fungal contamination of paintings and wooden sculptures inside the storage room of a museum: Are current norms and reference values adequate?

Abstract Biodeterioration is a topic of ever-growing concern and is particularly relevant in the context of cultural heritage conservation, since artworks and monuments provide diversified ecological niches for microorganism colonization. Despite all the gathered knowledge in recent years, current established norms and accepted contamination thresholds have a prominent focus on human health and air quality preservation. Nonetheless they still are not enough or are not adequately applied for cultural heritage preservation. In the light of this study within a very important Museum from Coimbra (Portugal), the current knowledge and accepted norms are discussed. Despite the meticulous control of environmental parameters inside this art repository, the presence of fungal colonies was unexpectedly detected on wooden sculptures and paintings that were deposited inside a custom-built room. Contaminated art objects were sampled for fungal isolation and identification, along with seasonal indoor air sampling, for a one-year period. Molecular biology methods complemented with morphological observation were used for the identification of fungal organisms. Direct sampling of 8 contaminated paintings allowed the retrieval of 10 fungal isolates (3 different genera and 4 different species). In addition, 19 fungal isolates (5 different genera and 9 different species) were retrieved from 7 contaminated wooden sculptures. The air sampling process provided a total of 150 isolates (24 different genera and 43 different species), from which the most common genera were Aspergillus, Cladosporium and Penicillium, and the most frequent species were Aspergillus versicolor, Cladosporium cladosporioides, Penicillium copticola and P. corylophilum. Although the number of airborne CFU was considerably low in all seasons, some fungal species with known biodeterioration capability and adverse human health effects were found. The relevance of air contamination monitoring as a single tool for biodeterioration risk assessment is discussed, as are the currently available norms and recommendations. Preventive measures are advised and considerations are made regarding potentially more effective approaches.

New pediatric percentiles of liver enzyme serum levels (alanine aminotransferase, aspartate aminotransferase, γ-glutamyltransferase): Effects of age, sex, body mass index, and pubertal stage.

Current reference values of ALT, AST, and GGT serum levels were calculated for children between 11 months and 16.0 years, using modern analytical and statistical methods. This study extends the current knowledge about transaminases by revealing influences of age, sex, BMI, and puberty on serum concentrations of all three parameters and has for these parameters one of the largest sample sizes published so far. (Hepatology 2017).

Effects of the chloro-s-triazine herbicide terbuthylazine on DNA integrity in human and mouse cells.

Terbuthylazine belongs to the chloro-s-triazine group of herbicides and acts primarily as a photosynthesis inhibitor. The mechanisms of action related to its exposure, relevant both in animals and humans, are still insufficiently investigated. This comprehensive study focused on the outcomes of terbuthylazine exposure at cell level in vitro, and a mice model in vivo. Experiments in vitro were conducted on whole human peripheral blood, isolated lymphocytes, and HepG2 cells exposed for 4h to terbuthylazine at 8.00, 0.80, and 0.58ng/mL, which is comparable with current reference values set by the European Commission in 2011. Terbuthylazine cytotoxicity was evaluated using dual fluorescent staining with ethidium bromide and acridine orange on lymphocytes, and CCK-8 colorimetric assay on HepG2 cells. The levels of DNA damage were measured using alkaline and hOGG1-modified comet assays. The potency of terbuthlyazine regarding induction of oxidative stress in vitro was studied using a battery of standard oxidative stress biomarkers. The in vivo experiment was conducted on Swiss albino mice exposed to terbuthlyazine in the form of an active substance and its formulated commercial product Radazin TZ-50 at a daily dose of 0.0035mg/kgbw for 14days. Following exposure, the DNA damage levels in leukocytes, bone marrow, liver, and kidney cells of the treated mice were measured using an alkaline comet assay. In vitro results suggested low terbuthylazine cytotoxicity in non-target cells. The highest tested concentration (8.00ng/mL) reduced lymphocyte viability by 15%, mostly due to apoptosis, while cytotoxic effects in HepG2 cells at the same concentration were negligible. Acute in vitro exposure of human lymphocytes and HepG2 cells to terbuthylazine resulted in low-level DNA instability, as detected by the alkaline comet assay. Further characterization of the mechanisms behind the DNA damage obtained using the hOGG1-modified comet assay indicated that oxidative DNA damage did not prevail in the overall damage. This was further confirmed by the measured levels of oxidative stress markers, which were mostly comparable to control. Results obtained in mice indicate that both the active substance and formulated commercial product of terbuthylazine produced DNA instability in all of the studied cell types. We found that DNA in liver and kidney cells was more prone to direct toxic effects of the parent compound and its metabolites than DNA in leukocytes and bone marrow cells. The overall findings suggest the formation of reactive terbuthylazine metabolites capable of inducing DNA cross-links, which hinder DNA migration. These effects were most pronounced in liver cells in vivo and HepG2 cells in vitro. To provide a more accurate explanation of the observed effects, additional research is needed. Nevertheless, the present study provides evidence that terbuthylazine at concentrations comparable with current reference values possesses toxicological risk because it caused low-level DNA instability, both at cellular and animal organism level, which should be further established in forthcoming studies.

New mesh-type phantoms and their dosimetric applications, including emergencies.

Committee 2 of the International Commission on Radiological Protection (ICRP) has constructed mesh-type adult reference computational phantoms by converting the voxel-type ICRP Publication 110 adult reference computational phantoms to a high-quality mesh format, and adding those tissues that were below the image resolution of the voxel phantoms and therefore not included in the Publication 110 phantoms. The new mesh phantoms include all the necessary source and target tissues for effective dose calculations, including the 8-40-µm-thick target layers of the alimentary and respiratory tract organs, thereby obviating the need for supplemental organ-specific stylised models (e.g. respiratory airways, alimentary tract organ walls and stem cell layers, lens of the eye, and skin basal layer). To see the impact of the new mesh-type reference phantoms, dose coefficients for some selected external and internal exposures were calculated and compared with the current reference values in ICRP Publications 116 and 133, which were calculated by employing the Publication 110 phantoms and the supplemental stylised models. The new mesh phantoms were also used to calculate dose coefficients for industrial radiography sources near the body, which can be used to estimate the organ doses of the worker who is accidentally exposed by an industrial radiography source; in these calculations, the mesh phantoms were deformed to reflect the size of the worker, and also to evaluate the effect of posture on dose coefficients.

Summary of grip strength measurements obtained in the 2011-2012 and 2013-2014 National Health and Nutrition Examination Surveys

Study DesignCross-sectional and descriptive study. IntroductionSupported by the Centers for Disease Control and Prevention, the National Health and Nutrition Examination Survey (NHANES) began collecting grip strength data from nationally representative samples in 2011. Purpose of the StudyTo examine the stability of the grip strength values across 2 data release cycles and provide updated US population-based grip strength values for 6 to 80 year olds. MethodsHandgrip data from 13,676 participants aged 6-80 years were extracted from the NHANES 2011-2014 database. The muscle strength/grip test component measured the isometric grip strength using a Takei digital handgrip dynamometer (Takei Scientific Instruments, Shinagawa-Ku, Tokyo). Grip strength values (best of 3 trials for each hand) were summarized by gender, dominant side, and age group. Grip data from 2 data release cycles (2011-2012 vs 2013-2014) were compared. ResultsDifferences between 2 data release cycles were negligible. Hence, we summarize grip strength values across the entire 2011-2014 period. The mean grip strength ranged from 50.3 kg for the dominant hand of 30- to 34-year-old men to 10.0 kg for the nondominant hand of 6-year-old girls. DiscussionThe summary data we present provide relatively current reference values to which tested individuals can be compared. However, clinicians and/or researchers should be aware that the instrumentation and procedures may influence the values. ConclusionsResults supported the stability of the NHANES grip strength values across data release cycles.

A New Robust Analog Maximum Power Point Tracker for a PV Battery Charger

Maximum power point tracking (MPPT) is an inevitable part of new controller design for PV connected voltage converters used to extract energy. To simplify the implementation of the algorithm, in this paper, an analog circuit for MPPT of a PV battery charger is proposed which works in a full range condition with constant switching frequency. Besides this, a new robust controller parameter is introduced. As discussed in the paper, conventional MPPT algorithms provide PV current or voltage reference value as output controller parameter, which fast climate changes may cause system instability. Here, a new variable is defined to eliminate the problem and improve the stability of the system. To compare the presented circuit with a conventional system, perturb and observe MPPT algorithm which is well-known in PV systems is implemented on the same system. The proposed system is also compared with a recently developed current-mode system. Simulation results for both simulations are presented and compared which demonstrate performance and effectiveness of the proposed analog MPPT circuit.

Top tether effectiveness during side impacts

ABSTRACTObjective: Few studies have looked at the effectiveness of the top tether during side impacts. In these studies, limited anthropomorphic test device (ATD) data were collected and/or few side impact scenarios were observed. The goal of this study was to further understand the effects of the top tether on ATD responses and child restraint system (CRS) kinematics during various side impact conditions.Methods: A series of high-speed near-side and far-side sled tests were performed using the FMVSS213 side impact sled buck and Q3s ATD. Tests were performed at both 10° and 30° impacts with respect to the pure lateral direction. Two child restraints, CRS A and CRS B, were attached to the bench using flexible lower anchors. Each test scenario was performed with the presence and absence of a top tether. Instrumentation recorded Q3s responses and CRS kinematics, and the identical test scenarios with and without a top tether attachment were compared.Results: For the far-side lateral (10°) and oblique (30°) impacts, top tether attachment increased resultant head accelerations by 8–38% and head injury criterion (HIC15) values by 20–140%. However, the top tether was effective in reducing lateral head excursion by 5–25%. For near-side impacts, the top tether resulted in less than 10% increases in both resultant head acceleration and HIC15 in the lateral impact direction. For near-side oblique impacts, the top tether increased HIC15 by 17.3% for CRS A and decreased it by 19.5% for CRS B. However, the injury values determined from both impact conditions were below current injury assessment reference values (IARVs). Additionally, the top tether proved beneficial in preventing forward and lateral CRS rotations.Conclusions: The results show that the effects of the top tether on Q3s responses were dependent on impact type, impact angle, and CRS. Tether attachments that increased head accelerations and HIC15 values were generally counterbalanced by a reduction in head excursion and CRS rotation compared to nontethered scenarios.