A Control Scheme for an AC-DC Single-Stage Buck-Boost PFC Converter with Improved Output Ripple Reduction

AC-DC power factor correction (PFC) single-stage converters are attractive because of their cost and their simplicity. In these converters, both PFC and power conversion are done at the same time using a single converter that regulates the output. Since they have only a single controller, these converters operate with an intermediate transformer primary-side DC bus voltage that is unregulated and is dependent on the converters’ operating conditions and component values. This means that the DC bus voltage can vary significantly as line and load conditions are changed. Such a variable DC bus voltage makes it difficult to optimally design the converter transformer as well as the DC bus capacitor. One previously proposed single-stage AC-DC converter, the Single-Stage Buck-Boost Direct Energy Transfer (SSBBDET) converter has a clamping mechanism that can clamp the DC bus voltage to a pre-set limit. The clamping mechanism, however, superimposes a low frequency 120 Hz AC component on the output DC voltage so that some means must be taken to reduce this component. These means, however, make the converter transient slow and sluggish. The main objective of this thesis is to minimize the 120 Hz output ripple component and to improve the dynamic response of the SSBBDET converter by using a new control scheme. In the thesis, the operation of the SSBBDET converter is reviewed and the proposed control method is introduced and explained in detail. Key design considerations for the design of the converter controller are discussed and the converter’s ability to operate with fixed DC bus voltage, low output ripple and fast dynamic response is confirmed with experimental results obtained from a prototype converter

Effects of carbon nanotubes (CNTs) nano-materials on the giant freshwater prawn (Macrobrachium rosenbergii, de Man, 1879) in laboratory conditions

Carbon nanotubes (CNTs) are the most widely studied class of engineered nanoparticles due to carbon’s unique hybridization properties and they are extensively used in several fields depending on their morphology, particle size, exposure time, and concentration. These nanoparticles are released into the aquatic ecosystems through domestic and industrial wastewater and induce adverse effects on the aquatic organisms. The present study evaluated the toxicity effects of CNTs nano-particles on crustacean hyperglycemic hormone (CHH) hormone release, hematology factors, and anti-oxidative enzymes’ activity of Macrobrachium rosenbergii. This research was conducted in five treatments, including 0 (control), 5, 10, 20, and 30 mg/L CNT nanoparticles in triplicate for 28 days. The experimental units consisted of a 300-l recirculating system, stocked with, 10 prawns. The results indicated that M. rosenbergii reproductive performance, anti-oxidant enzyme activities, hematology parameters and CHH hormone release, survival rate, and growth performance were strongly affected by CNT NMs toxicity. The findings showed that SOD and CAT antioxidant enzymes activities have positive responses to the CNTS NMs in the experimental treatments and these NMs showed dose-dependent effects on the enzyme's activities. Also, CHH hormone in the experimental treatments showed significantly higher than the control treatment. The results of this work illustrate that because of the settling behavior of NMs, M. rosenbergii as a freshwater benthic decapod crustacean is an appropriate biological model to study NMs toxicity and also a suitable bio-monitor for NMs contaminations in freshwater aquatic environments

Emergency response network design for hazardous materials transportation with uncertain demand

Transportation of hazardous materials play an essential role on keeping a friendly environment. Every day, a substantial amount of hazardous materials (hazmats), such as flammable liquids and poisonous gases, need to be transferred prior to consumption or disposal. Such transportation may result in unsuitable events for people and environment. Emergency response network is designed for this reason where specialist responding teams resolve any issue as quickly as possible. This study proposes a new multi-objective model to locate emergency response centers for transporting the hazardous materials. Since many real-world applications are faced with uncertainty in input parameters, the proposed model of this paper also assumes that reference and demand to such centre is subject to uncertainty, where demand is fuzzy random. The resulted problem formulation is modelled as nonlinear non-convex mixed integer programming and we used NSGAII method to solve the resulted problem. The performance of the proposed model is examined with several examples using various probability distribution and they are compared with the performance of other existing method

Investigation of different levels of glycerol on cyst hatching percentage, total length and survival of Phallocryptus spinosa and Artemia franciscana

Artemia and fairy shrimps due to propitious size and wide distribution throughout the world, purvey ample feed resources with relatively favorable nutritional value to profitable aquatic species. Ambient water physical-chemical properties affect the biological function of zooplanctonic cysts. Glycerol is an alcoholic compound which is soluble in water and it  has three hydroxyl groups that are responsible for solubility in water. There is a relationship between the presence of free glycerol in water and cysts metabolic rate and dormancy duration. The present study aimed to investigate the effects of different levels of free glycerol in the hatchery water on hatching percentage, total length of nauplius and mortality rate of Phallocryptus spinosa and Artemia franciscana cysts. In this experiment, four triplicate treatments including 0% (control), 0.1%, 1% and 10% of glycerol were used on A. franciscana and P. spinosa hatchery water for 48 hours and 72 hours, respectively. The results revealed that 0.1% glycerol was the most efficient level for hatching percentage of P. spinosa cysts with 28.86±1.6%. Also, the size of total length of newly hatched nauplii in this treatment was 0.75±0.08 mm that was significantly greater than the other treatments (P≤0.05); there was no significant difference in the mortality percentage between this treatment and the control treatment. In A. franciscana, the highest hatching rate (68.33±4.71%) and nauplius length (0.90±0.08 mm) were recorded in the 1% glycerol treatment. According to the results, glycerol at 0.1% level for P. spinosa and 1% level for A. franciscana are suitable in the cysts hatching media to increase hatching rate and nauplii performance. Our work could contribute to a better understanding of the hatching biology of dormant life stages in zooplanctonic crustaceans

The reliability and validity of the persian version of sinonasal outcome test 22 (Snot22) questionnaires

Background: The quality of life (QOL) is an important indicator for disease-severity classification and outcome measurement in obtaining treatment sinonasal diseases. The sinonasal outcome test 22 (SNOT 22) questionnaire has been introduced as the best specific sinonasal instrument for QOL measurement. Objectives: To prepare a valid and reliable Persian language version of SNOT 22 questionnaire. Patients and Methods: After forward and backward translation of the original version of SNOT 22 questionnaire from English to Persian, a group of patients with nasal septal deviation who need septal surgery and another group of healthy volunteers answered the Persian version of the questionnaire. The responsiveness rate, validity (Pearson correlations and differential validity) and reliability (internal consistency and test-retest reliability) of the 22 items of the questionnaire was calculated. P value < 0.05 was considered significant. Results: Thirty adults with nasal septal deviation need surgical correction and 30 healthy volunteers were included (mean age 30.4 ± 7.1 vs. 33 ± 6.7, P value = 0.148). The questionnaire was introduced to subjects two times with a two-week-period gap. Total responsiveness rate for 22 items was more than 97%. The total Cronbach's Alfa coefficient was 0.898 (ranging 0.890-0.903). The Pearson correlations were 0.85 and 0.96 for patients and healthy volunteers, respectively. The mean total score were 25.6 ± 13.3 (range 6-52) and 7.6 ± 9.1 (range 0-45) in patients and healthy volunteers, respectively (P < 0.0001). The subscales scores were also significantly different between two groups. Conclusions: The Persian version of SNOT 22 questionnaire is a valid and reliable instrument for accessing sinonasal diseases in Persianspeaking people

Assessment of habitat suitability index of Capoeta species in the Caspian Sea and Namak Lake basins, Iran

Habitat suitability index (HSI) models are usually used to forecast habitat quality and species distributions and are used to develop biological studies, management priorities and anticipate possible changes under different management or climate change situations. This study was conducted to identify the habitat suitability index of three species namely, Capoeta    buhsei, C.  razii and C. alborzensis in the Kordan, Taleghan and Jajrood Rivers, respectively. At each station, environmental variables including temperature, dissolved oxygen, pH, EC, TDS and hydrological parameters such as flow velocity, depth, width, average diameter of stones and amount of phosphate, nitrate and ammonium were measured. The results showed that suitable habitats for these species are those with a high stone diameter, high temperature, low flow velocity and in areas where the width of the river is low. With respect to the abundance of fishes sampled in this study, the central and lower regions of the Jajrood and Kordan Rivers and the stations far from the dam on the Taleghan River are favorable habitats for the studied Capoeta species.

Effect of Slope Position on Soil Properties and Types Along an Elevation Gradient of Arasbaran Forest, Iran

Sustainable development by forest managing need to identify forest ecosystem elements. Forest soil is the most important element of forest ecosystem that has key roles in forest managing. Therefore, studying of soil properties and evolution under different environmental conditions is necessary for sustainable management of forest ecosystems. Spatial variation of soil properties is significantly influenced by some environmental factors that slope position is one of them. The aim of this study was evaluating effects of slope position on forest soil change which was carried out in Arasbaran forest, North-West of Iran. Nine soil profiles were dug, described and sampled in three different parts of an altitudinal transect with same environmental conditions and different slope positions. Then soil samples were analysed physicaly and chemicaly and so classified based on Soil Taxonomy 2014. Also according to obtained results One-way analysis of variance was used to test relations of soil properties and slope positions. This results revealed significant effect of slope positions on thickness of the soil profile and solum, clay, organic carbon and total nitrogen percentages and cation exchange capacity at 5% level of confidence which lead to change of type, depth and sequence of soil horizons along altitudinal transect. Finally, it has found that slope position not only has important role in soil properties changes and soil evolution but also it can't be refused the various role and influence of same forest stand in different slope positions. Therefore various soils such as Inceptisols, Alfisols and Molisols were observed under different slope positions. Then it can be achieved that, because of special forest vegetation, soil evolution along altitudinal transect of forest ecosystems are differing from other ecosystems. Thus, for forest soil management program it is necessary to consider both of topography and vegetation effect over the area, even if one of them is constant

The Combined Effect of Photobiomodulation and Curcumin on Acute Skin Wound Healing in Rats

Introduction: Abnormal wound repair is a cause for a considerable expense, as well as patient morbidity and mortality. Here, we investigated the combined impact of photobiomodulation (PBM) and curcumin on a rat experimental model of an acute skin wound.Methods: A round full-thickness wound was created on the back of each rat. We divided the rats into the following four groups. Group one was the control group. Group two received pulse wave (PW) PBM at a dose of 890 nm, 80 Hz, and 0.2 J/cm2. Group 3 received 40 mg/kg curcumin by gastric gavage and group 4 was treated with PWPBM + curcumin. We measured the wound area on days 4, 7, and 15, and performed microbiologically and tensiometry examinations.Results: There was markedly improved wound contraction in the curcumin (7.5 ± 0.57; P=0.000), PBM (8.5 ± 1.2; P=0.000), and PBM + curcumin (14.5 ± 4.3; P=0.002) groups relative to the control group (25 ± 6). PBM (100 ± 7.3; P=0.005), and PBM + curcumin (98 ± 6; P=0.005) groups meaningfully improved tensile strength relative to the control group (61 ± 8.2). On day 15, the PBM (10 ± 5; P=0.000), curcumin (14 ± 4.5, P=0.000), and PBM + curcumin (27.3 ± 8.3; P=0.000) groups meaningfully decreased microbial flora relative to the control group (95 ± 6).Conclusion: We concluded that the PBM and PBM + curcumin groups meaningfully accelerated wound healing of the acute skin wound in the rats. The results of the PBM group were statistically more effective than the curcumin alone and PBM + curcumin-treated groups. DOI:10.34172/jlms.2021.0

Evaluation of the Effects of Photobiomodulation on Partial Osteotomy in Streptozotocin-Induced Diabetes in Rats

Objective: We examined the effects of photobiomodulation (PBM) on stereological parameters, and gene expression of Runt-related transcription factor 2 (RUNX2), osteocalcin, and receptor activator of nuclear factor kappa-B ligand (RANKL) in repairing tissue of tibial bone defect in streptozotocin (STZ)-induced type 1 diabetes mellitus (TIDM) in rats during catabolic response of fracture healing. Background data: There were conflicting results regarding the efficacy of PBM on bone healing process in healthy and diabetic animals. Materials and methods: Forty-eight rats have been distributed into four groups: group 1 (healthy control, no TIDM and no PBM), group 2 (healthy test, no TIDM and PBM), group 3 (diabetic control, TIDM and no PBM), and group 4 (diabetic test, no TIDM and PBM). TIDM was induced in the groups 3 and 4. A partial bone defect in tibia was made in all groups. The bone defects of groups second and fourth were irradiated by a laser (890 nm, 80 Hz, 1.5 J/cm2 ). Thirty days after the surgery, all bone defects were extracted and were submitted to stereological examination and real-time polymerase chain reaction (RT-PCR). Results: PBM significantly increased volumes of total callus, total bone, bone marrow, trabecular bone, and cortical bone, and the numbers of osteocytes and osteoblasts of callus in TIDM rats compared to those of callus in diabetic control. In addition, TIDM increased RUNX2, and osteocalcin in callus of tibial bone defect compared to healthy group. PBM significantly decreased osteocalcin gene expression in TIDM rats. Conclusions: PBM significantly increased many stereological parameters of bone repair in an STZ-induced TIDM during catabolic response of fracture healing. Further RT-PCR test demonstrated that bone repair was modulated in diabetic rats during catabolic response of fracture healing by significant increase in mRNA expression of RUNX2, and osteocalcin compared to healthy control rats. PBM also decreased osteocalcin mRNA expression in TIDM rats

Investigation of metabonomics technique by analyze of NMR data, which method is better? Mean center or auto scale?

The factors such as disease can disrupt homeostasis, resulting in perturbations of endogenous biochemicals that are involved in key metabolic profiles. Metabonomics is useful technique to quantitative description of endogenous metabolites present in a biological sample such as urine, plasma and tissue. High resolution 1H nuclear magnetic resonance (NMR)-based metabonomics is a technique used to analyze and interpret multivariate metabolic data that correlate with changes of physiological conditions. Before any explanation for metabolite data, preprocessing the spectroscopic data is essential. In this paper, we show scaling effects in metabonomics investigation of patients diagnosed with Crohn's and Celiac disease. two techniques of scaling were applied as follows: mean centering and auto scaling. Results reveal that the mean centering is more useful to segregate patients from healthy subjects in the data set of Crohn's and Celiac disease