Computational Modeling of Passive and Active Cooling Methods to Improve PV Panels Efficiency

This paper presents the computational modeling of three cooling systems based on three different methods (passive, active, and hybrid), to improve the efficiency of PV panels when operating beyond the recommended temperature under standard test conditions. All simulations were implemented using the COMSOL Multiphysics software. In the passive method, through-holes were made in the solar panel, to allow the transfer of heat by convection due to the air flow. In the active method, water was used to cool the solar panel, spraying it on the front when the operating temperature reaches a threshold value. The analysis includes both fluid dynamics and heat transfer effects. In addition, a hybrid method that uses both passive and active cooling methods simultaneously was implemented. Finally, a mathematical model for the PV panel is presented, which allowed obtaining the changes in the output power from the reduction in the operating temperature. Results demonstrated improvements in the performance of the solar panel with the implementation of the three cooling systems, showing better performance in the active and hybrid methods compared to the passive method.

Issues of developing receiving equipment for the passive method of induced polarization

The article deals with the design of receiving equipment for the passive method of induced polarization (IP). It is shown that the best option for recording this kind of signals is a circuit with an input analogue part and amplification of 50-100 times, as well as an input gain of at least 3 MΩ and a digital part based on a modern twenty-four-bit analogue-to-digital converter (ADC). In this case, it is preferable to use one ADC per channel without multiplexing, for better suppression of inter-channel interference. Signal processing is performed using modern microcontrollers based on the Cortex M4 core, and then the data is transmitted via Bluetooth to a laptop or tablet, where visualization and post-processing is carried out. Thus, the proposed scheme for the implementation of the receiving equipment meets all the requirements for the receiving equipment for the passive IP method, and can be introduced into the practice of field work.

Mathematical assessment of the depth of the passive method of induced polarization based on experimental data

The article discusses a numerical model for assessing the depth for the passive method of induced polarization based on previously obtained experimental data at the Samson field (Republic of Khakassia). The model is based on the mathematical model of Komarov, who derived equations for the anomalous polarizability of a sphere observed on the Earth’s day surface, the proposed model for estimating the depth of the anomaly depends on the size of the proposed field and the induced polarization coefficient observed on the surface. In the course of the numerical assessment, it was shown that there is a convergence of data from field observations, exploration drilling and mathematical modeling.

Partner Notification Services (PNS) Among HIV Positive Key Populations: An Important Strategy Towards Achieving UNAIDS 95.95.95 Goals by the Year 2030

Key Populations are the major drivers of the HIV epidemic in most settings; thus, identifying positive KPs and their sexual partners becomes a strong strategy in the effort to achieve the first UNAID 95 goal. This study describes the level of acceptability and outcome of PNS among HIV-positive KPs using the various approaches for PNS. A descriptive study of all HIV positives KPs initiating ART in 7 One-Stop-Shop facilities that accepted PNS was conducted over 3 months. With the consent of patients who accepted PNS, their partners were reached using any of the PNS approaches. Partners who consented for HTS were tested, and positives partners were linked to ART services. Data were analyzed to describe the acceptability and outcome of PNS among KPs. Only 846/2,486 (34%) positive KPs accepted PNS. The 846 KPs elicited 941 partners, out of which 938 (99.6%) accepted HTS. 421/938 (45%) of the partners tested positive compared to PWIDF (15%), MSM (7%), FSW (4%) and PWIDM (4%). 129/421 (31%) of the positive partners were already known positives, with 61% already on ART. The commonest method of PNS accepted among KPs was the passive method (54%), followed by the contract method (22%), provider-initiated (19%), and dual method (5%). There was poor acceptance of PNS among KPs and, the HIV positivity rate was much higher among their partners than any of the KPs sub-groups. The passive approach was the most preferred method of PNS among KPs. This should be considered strongly as we scale up PNS in Nigeria. Keywords: HIV/AIDS, Key Populations in Nigeria, Partner notification services, UNAIDS 95-95-95 targets.

Research on Detection Technology of 235U Enrichment and Loading Uniformity for Nuclear Fuel Rods

To ensure that fuel rods operate in nuclear reactors safely and reliably, UO2 pellets with different enrichment levels of 235U in the same production line are manufactured in batches and divisionally managed to avoid confusion or the potential misloading of UO2 pellets with different enrichment levels. At the same time, nondestructive tests for their enrichment levels and loading uniformity and all UO2 pellets must be nondestructively tested during production. By studying the enrichment detection mechanism of the UO2 pellets of 235U, the design of an integral standard rod was carried out, and a single integral standard rod was used to achieve the calibration of the enrichment measurement curve, as well as the detection and calibration of abnormal pellets. This study undertook a comparison test of 235U enrichment between the neutron activation method and the array multi-probe passive method. The test results showed that the array multi-probe passive method had higher detection efficiency and equal accuracy.

Numerical Study of Airfoil Tonal Noise Reduction using Segmented Elastic Panel Configuration

In this paper, a novel passive method for airfoil tonal noise reduction is proposed using a configuration of two segmented elastic panels mounted on the airfoil. Numerical investigation using perturbation evolution method is carried out at a low Reynolds number based on airfoil chord of 5x10 and an angle of attack of 5. The passive method of employing a single panel has shown promising tonal noise reduction capabilities where the resonating panel located just ahead of the sharp growth of boundary layer instability within the airfoil separation bubble provided the strongest reduction of instabilities and noise reduction up to 3 dB has been achieved. The idea is extended in the present study by employing a two-panel configuration based on the localized flow characteristics over the airfoil surface. Five different panel configurations are designed and their effectiveness in terms of tonal noise reduction is evaluated and compared with baseline configuration. The azimuth and spectral analyses indicate the different extent of noise reduction for each configuration and even noise amplification in one of them. A significant noise reduction up to 8 dB is observed for the optimum configuration indicating the effectiveness of this novel method for devices operating at low Reynolds number.