Analysis of microclimate temperature and relative humidity distribution of local poultry house in a subtropical area of Nigeria

The design of the ventilation system to ensure microclimate condition are optimum in poultry houses in the Nigerian context requires knowledge of the microclimate parameter distribution, which is lacking in the literature. This study investigated the patterns of temperature and RH distributions in a typical local poultry house. The specific objectives were to (i) analyse the vertical and horizontal distributions of the microclimate parameters in battery cage poultry housing and deep litter poultry housing, (ii) identify whether the distribution is homogenous or heterogeneous, and (iii) identify the data spread of parameters. An experimental intensive naturally ventilated local poultry house was used for this study. It consisted of deep litter (DL) and battery cage (BC) poultry housing systems partitioned by an air wall. Daytime, nighttime, rainy, and dry season temperature and RH distributions in the BC and DL poultry housing were analysed. Approximately 1.2 °C temperature difference was recorded between the poultry house and the ambient environment during the day and night. The temperature and RH distributions in the poultry housing were heterogeneous. Approximately 5% and 67%–73% of the daytime and nighttime temperature data, respectively, and 37%–41% of daytime RH fell within the optimum values

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

Background Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications. Methods We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC). Findings In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683–0·717]). Interpretation In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required. Funding British Journal of Surgery Society

Determinants of urban and peri-urban farming in Akwa Ibom State, Nigeria

No Abstract. Global Journal of Agricultural Sciences Vol. 5(1) 2006: 13-1

A Harmonic Suppression Scheme for Open-End Winding Split-Phase IM Drive Using Capacitive Filters for the Full Speed Range

Abstract—Voltage source inverter (VSI)-fed six-phase induction motor (IM) drives have high 6n ± 1, n = odd-order harmonic currents. This is because these currents, driven by the correspond- ing harmonic voltages in the inverter output, are limited only by the stator leakage impedance, as these harmonics are absent in the back electromotive force of the motor. To suppress the har- monic currents, either bulky inductive harmonic filters or complex pulsewidth modulation (PWM) techniques have to be used. This paper proposes a harmonic elimination scheme using switched capacitor filters for a VSI-fed split-phase IM drive. Two 3-phase inverters fed from capacitors are used on the open-end side of the motor to suppress 6n ± 1, n = odd-order harmonics. A PWM scheme that can suppress the harmonics as well as balance the capacitor voltage is also proposed. The capacitor fed inverters are switched so that the fundamental voltage is not affected, and the fundamental power is always drawn from the main inverters. The proposed scheme is verified with a detailed experimental study. The effectiveness of the scheme is demonstrated by comparing the results with those obtained by disabling the capacitor fed inverters

Multilevel dodecagonal space-vector generation for induction motor drives by cascading three-level and two-level inverters

This study proposes an inverter circuit topology capable of generating multilevel dodecagonal (12-sided polygon) voltage space vectors by the cascaded connection of two-level and three-level inverters. By the proper selection of DC-link voltages and resultant switching states for the inverters, voltage space vectors whose tips lie on three concentric dodecagons, are obtained. A rectifier circuit for the inverter is also proposed, which significantly improves the power factor. The topology offers advantages such as the complete elimination of the fifth and seventh harmonics in phase voltages and an extension of the linear modulation range. In this study, a simple method for the calculation of pulse width modulation timing was presented along with extensive simulation and experimental results in order to validate the proposed concept