Search

OBJECTIVES: This study was designed to assess the prevalence of malnutrition in terms of wasting and stunting in children between 3- and 5 years of age and to analyze the risk factors associated with malnutrition among them in the district of Peshawar. METHODOLOGY: This cross-sectional study was conducted in the district of Peshawar. Multi-staging simple random probability sampling selected a sample of 225 children between 3 and 5 years. The data was collected through a structured questionnaire containing demographic, risk factors and anthropometry. RESULTS: In a sample of 225 children, the prevalence of malnutrition was quite alarming. Stunting and wasting were observed in the age group 3-5 years. Low weight- for height was observed at 20%, and leanness through mid-arm circumference among children between 3-5 years of age in Peshawar district was 28%, although the mean values for all the indicators fell at the 50th percentile. About 76.9% were exclusively breastfed, and 29.8% of children were partially vaccinated. The association of low MUAC with breastfeeding (chi-square value of 28.9 & P=

To improve the recognition ability of computer-aided breast mass classification among mammographic images, in this work we explore the state-of-the-art classification networks to develop an ensemble mechanism. First, the regions of interest (ROIs) are obtained from the original dataset, and then three models, i.e., XceptionNet, DenseNet, and EfficientNet, are trained individually. After training, we ensemble the mechanism by summing the probabilities outputted from each network which enhances the performance up to 5%. The scheme has been validated on a public dataset and we achieved accuracy, precision, and recall 88%, 85%, and 76% respectively., Comment: SMA 2021: The 10th International Conference on Smart Media and Applications Gunsan Saemangeum Convention Center and Kunsan National University Gunsan-si, South Korea, September 9-11, 2021

People in scores migrate from the developing countries to the developed countries for finding employment and making a better living which in many cases, is hard for them in their own countries. In this article, we tried to explore the varying dimensions of migrants from sub-division Darra, Kohat. This study utilized qualitative approach while interpretive paradigm was explored to explore the problems of migrants through the eyes of migrants themselves. A total of 15 migrants of different age and experiences were recruited through purposive sampling. The collected data was analysed through thematic analysis technique. It was concluded that migrants face numerous problems but one of the most important problem is related to housing or living conditions. The accommodation provided by the employers are usually overcrowded or non-liveable therefore, they have to pay for their own accommodation in order to live peacefully. Furthermore, migrants often experience the issue of delayed wages and discrimination from supervisory as well as managerial staff.

The present study comprises experimental investigation on heat transfer and hydrodynamic characteristics of TiO2 nanofluid as coolant in wavy channel heat sinks having three different channel configurations. The performance of TiO2 nanofluids having concentrations of 0.006, 0.008, 0.01 and 0.012 vol% is compared with that of distilled water under laminar regime at heating powers of 25 W, 35 W and 45 W. Results indicated that for all heat sinks, nanofluids showed better heat transfer characteristics than distilled water. With an increase in heating power, TiO2 nanofluid thermal performance was decreased. Using 0.012% TiO2 nanofluids, minimum wall base temperature and maximum enhancement in Nusselt number are noted as 33.85 °C and 40.57%, respectively, for heat sink with wavelength of 5 mm and amplitude of 0.5 mm corresponding to Reynolds number of 894 at heating power of 25 W. Pumping power requirement is function of flow rate and pressure drop, and its maximum value of 0.0284 W is associated with heat sink with minimum wavelength. Moreover, variation in wavelength of channel is found to have dominating effect on heat transfer performance of heat sink as compared to the width of channel.

The novel coronavirus disease 2019 (COVID-19) continues to plague the world. Hence, there is been an effort to mitigate this virus and its effects with several means including vaccination which is one of the most effective ways of controlling the virus. However, efforts at getting people to vaccinate have met several challenges. To help with understanding the reasons underlying an individual's willingness to take COVID-19 vaccine or not, a scale called Motors of COVID-19 Vaccination Acceptance Scale (MoVac-COVID19S) was developed. To expand its usability worldwide (as it has currently been limited to only China and Taiwan), data were collected in other countries (regions) too. Therefore, this MoVac-COVID19S data is from five countries (that is, India, Ghana, Afghanistan, Taiwan, and mainland China) which cut across five regions. A total of 6053 participants across the stated countries completed the survey between January and March 2021 using a cross-sectional survey design. The different sections of the survey solicited sociodemographic information (e.g., country, age, gender, educational level, and profession) and the MoVac-COVID19S data from the participants. The data collected from this survey were analyzed using descriptive statistics, which were carried out using the IBM SPSS version 22.0.

OBJECTIVES: To determine the association between diabetic retinopathy (DR) and severity of coronary artery disease (CAD) and evaluate the relation of stage of DR with severity of CAD.METHODS: This cross-sectional study was conducted in Cardiology Unit, Lady Reading Hospital, Peshawar from January-June, 2017. Patients with diabetes mellitus for >5years who underwent coronary angiography (CA) were included. All patients underwent fundoscopy and categorized into: No-DR, pre-proliferative-DR and proliferative-DR. CA was performed to assess the severity of CAD and patients were categorized into: none, mild, moderate and severe CAD on the basis of number of vessels involved or left main stem (LMS) disease. The correlation between DR and CAD was determined by chi-square test and prevalence odd ratios (POR) were calculated by using logistic regression model.RESULTS: A total of 166 patients with mean age of 55.5±8.8years were included in the study, of which 79 were males, 35 had no-DR, 110 had pre-proliferative-DR and 21 had proliferative-DR while 63 patients had mild CAD, 50 had moderate CAD and 18 had severe CAD. By using Chi square test, association between DR and severity of CAD was calculated to be 86.68 (p-0.000). After adjustments for various risk factors, PORs for severity of CAD with increasing stage of DR were found to be significantly increased from 0.27 times for no-DR to 4.27 times for pre-proliferative-DR and 6.33 times for proliferative-DR.CONCLUSION: DR is not only strongly associated with CAD but higher stage of retinopathy predicts a more severe CAD increasing the odds of CAD by 2.27 times.KEYWORDS: Coronary Artery Disease (MeSH); Diabetic Retinopathy (MeSH); Diabetes Mellitus (MeSH).

Background: The outbreak of corona virus diseases (COVID-19) has rabidly spread all over the world. Community responses are important for outbreak management during the early phase when preventive interventions are the major options. Therefore, this study aimed to investigate perceived susceptibility and severity and behavioral responses at the early phase of the COVID-19 epidemic in Afghanistan population. Methods: A cross-sectional online survey was performed after confirmed COVID-19 in Afghanistan. The population of the study was 500 residents of the in provinces of Afghanistan that were randomly surveyed. The research tool was demographic and perceived threat questionnaire. The data analyzed using the SPSS statistical version (V.20). Findings: The means of age participants was 26.44± 7.64. Many respondents reported their health status were very good or good (95.6 %; 430/450). About 12.4 (n- 56) participants had respiratory symptoms in the past 14 days and 16.2 % had a history of travelled outside their city where they live. The means of perceived susceptibility and Perceived severity was 4.09±2.21 and 11.02±1.82 respectively. Interpretation: Perceived susceptibility the research community was very low and perceived severity toward COVID-19 in the community of Afghanistan Provinces was very high. Most participants are alert to disease progression. It seems that psychological and behavioral outcomes to COVID-19 had been considered during the phase of the outbreak. This study suggested timely behavioral assessment of the community is beneficial and effective to inform the next intervention, and risk communication strategies in at epidemic disease. Funding Statement: No funding. Declaration of Interests: All authors stated that there is no conflict of interest for this manuscript. Ethics Approval Statement: This study has been approved by the Ethics Committee of Afghanistan National Charity Organization for Special Diseases (ANCOSD) (ID: AF. ANCOSD. HREC. 016, 25/04/2020).

The spread of infectious diseases such as COVID-19, flu influenza, malaria, dengue, mumps, and rubella in a population is a big threat to public health. The infectious diseases spread from one person to another person through close contact. Without proper planning, an infectious disease can become an epidemic and can result in large human and financial losses. To better respond to the spread of infectious disease and take measures for its control, the public health authorities need models and simulations to study the spread of such diseases. In this paper, an agent-based simulation engine is presented that models the spread of infectious diseases in the population. The simulation takes as an input the human-to-human interactions, population dynamics, disease transmissibility and disease states and shows the spread of disease over time. The simulation engine supports non-pharmaceutical interventions and shows its impact on the disease spread across locations. A unique feature of this tool is that it is generic, therefore, it can simulate a wide variety of infectious disease models (SIR), susceptible-infectious-susceptible (SIS) and susceptible-infectious (SI). The proposed simulation engine will help the policy-makers and public health authorities study the behavior of disease spreading, thus, allowing for better planning.

In this paper, a detailed design procedure is presented for a bidirectional CLLLC-type resonant converter for a battery charging application. This converter is similar to an LLC-type resonant converter with an extra inductor and capacitor in the secondary side. Soft-switching can be ensured in all switches without additional snubber or clamp circuitry. Because of soft-switching in all switches, very high-frequency operation is possible; thus, the size of the magnetics and the filter capacitors can be made small. To reduce the size and cost of the converter, a CLLC-type resonant network is derived from the original CLLLC-type resonant network. First, in this paper, an equivalent model for the bidirectional converter is derived for the steady-state analysis. Then, the design methodology is presented for the CLLLC-type resonant converter. Design of this converter includes determining the transformer turns ratio, design of the magnetizing inductance based on ZVS condition, design of the resonant inductances and capacitances. Then, the CLLC-type resonant network is derived from the CLLLC-type resonant network. To validate the design procedure, a 3.5-kW converter was designed following the guidelines in the proposed methodology. A prototype was built and tested in the laboratory. Experimental results verified the design procedure presented.

State-of-the-art low-power-level metal-oxide-semiconductor field-effect transistor (MOSFET)-based transformerless photovoltaic (PV) inverters can achieve high efficiency by using latest super junction MOSFETs. However, these MOSFET-based inverter topologies suffer from one or more of these drawbacks: MOSFET failure risk from body diode reverse recovery, increased conduction losses due to more devices, or low magnetics utilization. By splitting the conventional MOSFET-based phase leg with an optimized inductor, this paper proposes a novel MOSFET-based phase leg configuration to minimize these drawbacks. Based on the proposed phase leg configuration, a high efficiency single-phase MOSFET transformerless inverter is presented for the PV microinverter applications. The pulsewidth modulation (PWM) modulation and circuit operation principle are then described. The common-mode and differential-mode voltage model is then presented and analyzed for circuit design. Experimental results of a 250 W hardware prototype are shown to demonstrate the merits of the proposed transformerless inverter on nonisolated two-stage PV microinverter application.

In this paper, a T-equivalent circuit for loosely coupled transformer, which does not involve magnetic coupling, is presented. A detailed dynamic analysis based on extended describing function technique is presented for a series–series compensated inductive power transfer system. The continuous-time large-signal model, the steady-state operating point, and the small-signal model are derived in an analytical closed-form. This model includes both the frequency and the phase-shift control. Simulation and experimental verification results of the derived models are presented to validate the presented analysis.

In this paper, a contactless charging system for an electric vehicle (EV) battery is proposed. The system consists of three parts: 1) a high-frequency power supply from a full-bridge inverter with frequency modulation; 2) a loosely coupled transformer that utilizes series resonant capacitors for both the primary and secondary windings; and 3) a rectification output circuit that uses a full-bridge diode rectifier. With carefully selected compensation network parameters, zero-voltage switching can be ensured for all the primary switches within the full range of an EV battery charging procedure, which allows the use of low ON-state resistance power MOSFETs to achieve high-frequency operation and system efficiency. The design of loosely coupled transformer is simulated and verified by finite element analysis software. For a 4-kW hardware prototype, the peak dc–dc efficiency reaches 98% and 96.6% under 4- and 8-cm air gap conditions, respectively. The prototype was tested with an electronic load and a home-modified EV to verify the performance of constant current and constant voltage control and their transitions.

This paper presents a new overall control strategy for small-scale wind energy conversion systems (WECS). The purpose of the proposed strategy is to utilize a maximum power point tracking control (MPPT) to maximize the captured energy when the wind speeds are below the rated speed. For high wind speed region; two stall controllers are developed: The constant speed stall controller which will limit the rotational speed of the generator to its rated value, and the constant power stall controller, which will regulate the captured power to be within the system rating. For the MPPT control, a modified perturb and observe (P&O) algorithm is utilized, where the dc side current is used as a perturbation variable and the dc-link voltage slope information is used to enhance the tracking speed and stability of the algorithm. For the speed and power regulation operation during high wind speeds, the system is controlled in the stall region to limit the rotational speed and the power of the generator. A stabilizing control loop is proposed to compensate for the stall region instability. A new mode transfer control strategy is developed to effectively control the transition between different modes of operation while ensuring the system stability without using any preknowledge of the system parameters. A 1 kW hardware prototype is developed and tested to validate the proposed new control strategy.

This paper proposes a maximum power point tracking (MPPT) algorithm for small-scale wind energy conversion systems. The proposed algorithm uses the dc current as the perturbing variable. The algorithm detects sudden wind speed changes indirectly through the dc-link voltage slope. The voltage slope is also used to enhance the tracking speed of the algorithm and to prevent the generator from stalling under rapid wind speed slowdown conditions. The proposed method uses two modes of operation: A perturb and observe (P&O) mode with adaptive step size under slow wind speed fluctuation conditions, and a prediction mode employed under fast wind speed change conditions. The dc-link capacitor voltage slope reflects the acceleration information of the generator, which is then used to predict the next step size and direction of the current command. The proposed algorithm shows enhanced stability and fast tracking capability under both high and low rate of change wind speed conditions and is verified using a 1.5 kW prototype hardware setup.

A bidirectional on-board charger (BODC) using a full-bridge bidirectional dc-ac inverter and a bidirectional CLLLC dc-dc converter has been designed and built for electric vehicle (EV) on-board charger applications. The dc-ac inverter can be operated in ac-dc with power factor correction (PFC) function. The CLLC dc-dc converter is modified from LLC converter with two separate resonant capacitors on both side of the transformer. A 3.3 kW bidirectional on-board charger prototype has been designed and built. Experimental results show al different operating modes including (1) battery charging mode, (2) vehicle to grid (V2G) mode, and (3) vehicle to house (V2H) mode.

This paper presents a new maximum power point tracking (MPPT) algorithm for thermoelectric generators (TEG). The proposed method is based on implementing an innovative way for indirect detection of the open circuit voltage and short circuit current, which will be used to directly steer the TEG interface converter to the MPP in very small number of steps. The proposed algorithm uses two modes of operation, namely perturb and observe (P&O) mode, in which, a fine-tuning to the MPP is taking place with fine step size. The second mode of operation is the transient mode, in which the TEG shifts its operating point due to a change in the temperature gradient through the structure. During this mode, the open circuit voltage and short circuit current of the TEG are estimated indirectly without the need to disconnect the converter, and the estimated variables are used to move the operating point directly to the vicinity of the targeted MPP, where the P&O mode is activated again for fine-tuning.

In this paper, a detailed design procedure is presented for a bidirectional resonant converter for battery charging application. This converter is similar to the LLC resonant converter with an extra inductor and capacitor in the secondary side. Soft-switching can be ensured in all switches without additional circuitry, and because of that, very high frequency operation is possible, hence; the size of the magnetics and the capacitors can be reduced. In this manuscript, first, an equivalent model for the bidirectional converter is derived for the steady-state analysis. Then, the design methodology is presented. Design of a converter includes finding the transformer turns ratio, design of magnetizing inductance based on ZVS condition, design of resonant inductances and resonant capacitances. To validate the design procedure, a 3.3 kW converter was designed following the guidelines in the proposed methodology as a design example. A prototype was built and tested in the lab. Experimental results verified the design procedure presented.

This paper discusses the characteristics of a series-series compensated inductive power transfer system (IPT) with theoretical analysis and experimental results. To maximize system efficiency, two-stage structure, which includes a PFC stage and a resonant DC-DC stage operating in ZVS region, is proposed. One of the major design challenges in implementation of a practical contactless EV charger is the variation of the coupling condition of the loosely coupled transformer. This combined with the battery charger's wide range load variation makes parameters design of the resonant DC-DC stage more complex. To optimize the parameter design for all coupling and load conditions, a parameter sweeping method is proposed. The design procedure searches parameters set to minimize the averaged primary current while keeping the voltage stress across the primary capacitor below the preset limit; both the high coupling and low coupling conditions are considered. To validate the analysis, a 4 kW resonant DC-DC prototype was built and tested. At 4 cm gap distance with 0.526 coupling coefficient, an efficiency of 97% for the DC-DC stage was achieved with output power range from 0.8 kW to 4 kW.

In this paper, the small-signal model of LLC resonant converter is derived using extended describing function (EDF) methodology and the dynamics of the LLC resonant converter are studied based on the small signal model taking into account the circuit parasitic resistance. When designing the controller, this damping effect induced by the parasitic resistance is usually neglected. While it will be shown in this paper that for large transformer turns ratio, the secondary side parasitic resistance introduces significant damping in the resonant tank. A controller is designed for an example LLC circuit. It is shown that the control loop phase margin and the cross over frequency are highly dependent on the damping factor, which should be considered in the control loop design to have the desired transient performance. The experimental verification is provided as well.

In this paper, the design procedure for a single stage transformer isolated multi-element resonant converter for an Electric Vehicle (EV) battery charging application with a large air-gap of 8cm and wide-range output voltage is proposed. Instead of having the same resonant frequency on both primary and secondary tank circuits as have been proposed in the literature, different resonant frequencies are used to meet the system specifications. This gives a number of advantages for wide-range output voltage application including simple control and ensures ZVS on the primary side switches and ZCS on the rectifying diodes, which gives high efficiency. A systematic procedure is proposed to design controllers for both current loop and voltage loop to meet the transient performance requirements. To validate the design procedure and controller design, a 1.8 kW system was built and tested. The efficiency was found to be 96.6% for a large air-gap of 8 cm during the constant current mode.

This paper presents a new overall control strategy for small scale wind energy conversion systems (WECS). The purpose of the proposed strategy is to utilize a maximum power point tracking (MPPT) control to maximize the captured energy when the wind speeds are below the rated maximum and when the wind speeds are above the rated value, the captured power is regulated to protect the system from over-power operation. For the MPPT control, a modified perturb and observe (P&O) algorithm is utilized, where the dc side current is used as a perturbation variable and the dc link voltage slope information is used to enhance the tracking speed and stability of the proposed algorithm. For the power regulation operation during high wind speeds, the system is controlled in the stall region to limit the rotational speed of the generator. A stabilizing control loop is proposed to compensate for the stall region instability. And a new mode transfer control strategy is developed to effectively control the transfer between the two modes of operation while ensuring the system stability. A 1.5KW hardware prototype is developed and tested to prove the proposed new control strategy.

In this paper, a contactless charging system for an electric vehicle (EV) battery is proposed. The system is composed of three parts, a high frequency power supply from a full-bridge inverter with frequency modulation, a loosely coupled transformer that utilizes series resonant capacitors for both the primary and secondary windings, and a rectification output circuit that uses a full-bridge diode rectifier. With carefully selected compensation network parameters, zero-voltage switching (ZVS) can be ensured for all the primary switches within the full range of an EV battery charging procedure, which allows the use of low on-state resistance power MOSFETs to achieve high frequency operation and system efficiency. The design of loosely coupled transformer is simulated and verified by finite element analysis (FEA) software. A peak efficiency of 96.6% is achieved with a 4 kW prototype with an 8 cm air gap transformer and 156 kHz switching frequency.