Minimum Area Research Articles

Effects of airflow direction on the thermal-hydraulic performance of louvered fin-common flow up vortex generator

To improve the thermal-hydraulic performance of the louvered fin and flat tube heat exchangers (LFHEs), this paper innovatively proposes the louvered fin-common flow up vortex generator (LF-CFUVG). Then, numerical simulations are conducted to study the effects of airflow direction γ on the thermal-hydraulic performance of the LF-CFUVG. The corresponding results indicate that the flow resistance of the LF-CFUVG is always greater than the Baseline (the LFHE without CFUVGs), as the CFUVGs reduce the minimum free flow area while forming low-speed wake zones behind them. The heat transfer capacity of the LF-CFUVG exceeds the Baseline as well, this is attributed to the longitudinal vortices induced by the CFUVGs, which is helpful to homogenize the temperature field and transport the high-speed and low-temperature airflow. And the thermal-hydraulic performance of LF-CFUVG also outperforms the Baseline. In comparison to the working condition of γ is 0°, the pressure drop Δp for the LF-CFUVG declines with increase of γ from 0° to 30°, thus a larger angle helps to reduce flow resistance. However, the heat transfer coefficients hLF and performance evaluation criteria (PEC) of the LF-CFUVG deteriorate with the increasing γ, so a smaller angle is recommended to obtain an intenser heat transfer and better PEC.

STRENGTH DESIGN OF REINFORCED CONCRETE SECTIONS BASED ON A NUMERICAL OPTIMIZATION METHOD

Reinforced concrete structures are widely used in construction of civil infrastructures. Classical methods are available for the analysis and design of reinforced concrete members, such as beams or columns, which are typically done by hand or using a spreadsheet program. In this study, an analysis and design approach of reinforced concrete sections is developed based on a numerical optimization method, and applied in accordance with the latest concrete design code. The basic idea of the proposed approach is to derive an optimization formulation in order to determine the minimum steel area required to support a given factored load combinations applied on a concrete section. A rigorously derived analysis and design framework of general beam sections is presented. For practical applications by civil and structural engineers, the readily-available optimization solver in Microsoft Excel spreadsheet is used. To illustrate the applicability of the approach, a numerical example with different analysis and design cases is studied. The proposed analysis and design approach using numerical optimization and spreadsheet solver works very well and is easy to implement in the Excel environment. The analysis and design results compare well with hand calculation results based on the classical method.

STRENGTH DESIGN OF REINFORCED CONCRETE SECTIONS BASED ON A NUMERICAL OPTIMIZATION METHOD

Reinforced concrete structures are widely used in construction of civil infrastructures. Classical methods are available for the analysis and design of reinforced concrete members, such as beams or columns, which are typically done by hand or using a spreadsheet program. In this study, an analysis and design approach of reinforced concrete sections is developed based on a numerical optimization method, and applied in accordance with the latest concrete design code. The basic idea of the proposed approach is to derive an optimization formulation in order to determine the minimum steel area required to support a given factored load combinations applied on a concrete section. A rigorously derived analysis and design framework of general beam sections is presented. For practical applications by civil and structural engineers, the readily-available optimization solver in Microsoft Excel spreadsheet is used. To illustrate the applicability of the approach, a numerical example with different analysis and design cases is studied. The proposed analysis and design approach using numerical optimization and spreadsheet solver works very well and is easy to implement in the Excel environment. The analysis and design results compare well with hand calculation results based on the classical method.

Study on the difference in subcooling flow boiling of materials in a vertical rectangular channel at a low flow rate

Alloy materials with excellent properties are widely used in different industrial fields. Conducting flow boiling studies on alloy surfaces will help explore their applications in flow boiling, especially in heat exchange equipment. Five alloys were selected, including 304SS, Inconel600, Monel400, Zr4 and FeCrAl. Bubble dynamics in a vertically upward-flowing rectangular channel were observed using a high-speed camera under the condition of atmospheric pressure, 400 kg·m^-2·s^-1 mass flowrate and 5 K inlet subcooling. Results show that roughness and wettability cannot individually define material-sensitive heat transfer coefficient (HTC) and critical heat flux (CHF). Thermal effusivity shows a linear relationship to HTC. Material-sensitive CHF seems to be a power-law function of the nondimensional parameter of the product of the maximum nucleation site density and the minimum bubble nucleation area.

Impact of coronary calcium morphology on intravascular lithotripsy.

Coronary calcification negatively impacts optimal stenting. Intravascular lithotripsy (IVL) is a new calcium modification technique. We aimed to assess the impact of different calcium morphologies on IVL efficacy. This was a prospective, multicentre study (13 tertiary referral centres). Optical coherence tomography (OCT) was performed before and after IVL, and after stenting. OCT-defined calcium morphologies were concentric (mean calcium arc >180°) and eccentric (mean calcium arc ≤180°). The primary outcomes were angiographic success (residual stenosis <20%) and the presence of fracture by OCT in concentric versus eccentric lesions. Ninety patients were included with a total of 95 lesions: 47 concentric and 48 eccentric. The median number of pulses was 60 (p=1.00). Following IVL, the presence of fracture was not statistically different between groups (79.0% vs 66.0% for concentric vs eccentric; p=0.165). The number of fractures/lesion (4.2±4.4 vs 2.3±2.8; p=0.018) and ≥3 fractures/lesion (57.1% vs 34.0%; p=0.029) were more common in concentric lesions. Angiographic success was numerically but not statistically higher in the concentric group (87.0% vs 76.6%; p=0.196). By OCT, no differences were noted in final minimum lumen area (5.9±2.2 mm2 vs 6.2±2.1 mm2; p=0.570), minimum stent area (5.9±2.2 mm² vs 6.25±2.4 mm2; p=0.483), minimum stent expansion (80.9±16.7% vs 78.2±19.8%), or stent expansion at the maximum calcium site (100.6±24.2% vs 95.8±27.3%) (p>0.05 for all comparisons of concentric vs eccentric, respectively). Calcified nodules were found in 29.5% of lesions; these were predominantly non-eruptive (57%). At the nodule site, dissection was more common than fracture with stent expansion of 103.6±27.2%. In this prospective, multicentre study, the effectiveness of IVL followed by stenting was not significantly affected by coronary calcium morphology.

Computational fluid dynamics simulations of single-bubble evolution under synergy of ultrasound and an electrostatic field

In the study reported here, a two-phase flow model was developed for the evolution of a single bubble under ultrasonic irradiation coupled with an electrostatic force. We started with the following assumptions: (I) the liquid is incompressible, (II) the effect of gravity is negligible in the liquid, (III) the bubble is insulating, and no free charges are distributed on the liquid–gas interface, and (IV) the liquid contains only one bubble. Using computational fluid dynamics, we analyzed how the bubble shape evolves under various conditions, and the main findings are as follows: (1) With increasing electric field strength, the bubble reaches a larger maximum area and a smaller minimum area. Furthermore, during the positive phase of ultrasound, a higher electric field strength leads to faster compression and a more slender bubble. (2) As the initial bubble radius is increased from 3 to 5 μm, the cavitation becomes significantly stronger, but when the initial bubble radius reaches 10 μm, the cavitation intensity decreases instead because of greater compression resistance caused by there being more gas in the bubble. (3) Cavitation cannot be triggered under an excessively low acoustic pressure amplitude, and an excessively high acoustic pressure amplitude results in weaker cavitation; the appropriate acoustic pressure amplitude is considered to be 1.35 atm.

Assessing the Theoretical, Minimal Intervention Potential of Floating Solar in Greece: A Policy-Oriented Planning Exercise on Lentic Water Systems of the Greek Mainland

According to the recent revision of the Greek National Energy and Climate Plan, the country sets out to accomplish an ambitious target concerning the integration of renewables in the local electricity mix during the ongoing decade, at the levels of 80% by 2030. This implies the need to more than double the existing wind and PV capacity at the national level, which in turn introduces numerous challenges. Amongst them, spatial planning for new RES installations seems to be the most demanding, with the adoption of novel technological solutions in the field of RES potentially holding a key role. New technologies, like offshore wind and floating solar, are gradually gaining maturity and may offer such an alternative, challenged at the same time however by the need to entail minimum disruption for local ecosystems. To that end, we currently assess the theoretical potential of floating PVs for lentic water systems of the Greek mainland. We do so by looking into 53 different lentic water systems across the Greek territory that meet the constraint of 1 km2 minimum surface area, and we proceed with the estimation of the relevant floating PV capacity per system under the application of a minimal intervention approach, assuming PV coverage of 1% over the total lentic water system area. In this context, our findings indicate a maximum, aggregate theoretical capacity that could exceed 2 GWp at the national level, with the respective annual energy yield reaching approximately 4 TWh or, equivalently, &gt;6% of the country’s anticipated annual electricity consumption in 2030. Finally, our results extend further, offering a regional level analysis and a set of policy directions and considerations on the development of floating solar in Greece, while also designating the energy merits of floating PVs against similar, land-based installations.

3D analysis of upper airway morphology related to obstructive sleep apnea severity

BackgroundObstructive sleep apnea (OSA) is the most common sleep-related breathing disorder characterized by repetitive collapse of the upper airway during sleep. However, little evidence is available on the differences between the sub-regions of the upper airway morphology and OSA severity. Since orthodontists frequently perform cone beam computed tomography (CBCT) in the neck area, we aimed to investigate the relationship and the differences between upper airway morphology and OSA severity using CBCT. Materials and methodsThe medical records, CBCT imaging of 21 OSA patients diagnosed by polysomnography, and the apnea-hypopnea index (AHI) results were included to classify OSA severity as mild, moderate, or severe. The minimum cross-sectional areas (MCA) and volumes of the upper pharyngeal airway boundaries in four sub-regions: nasopharynx, retropalatal, retroglossal, and hypopharynx were measured. Dolphin Imaging software was used for upper airway segmentation. The correlation coefficient (r), one-way ANOVA, and the least significant difference post hoc multiple comparison test were applied to fulfill the objectives. ResultsA statistically significant relationship was found between the MCA of the nasopharynx and the AHI (r = −0.473, P < 0.05). Furthermore, a difference was found between mild and moderate and moderate and severe OSA severity in the MCA results of the retroglossal region (P < 0.05). However, no relationship was found between the upper airway volume and OSA severity. ConclusionsMCA was moderately negatively correlated to AHI only in the nasopharynx subregion. Moderate OSA presented significantly less MCA than mild and severe OSA only in the oropharynx and retroglossal subregions.

Advancement in Thermoelectric Innovation: Crafting a Portable Climate Control System

Greenhouse gas emissions are on the rise globally due to increasing demands for electricity, vehicle usage, desertification, and inadequate waste management practices. In response to these challenges, a portable heater and cooler utilizing the thermoelectric effect have been developed. This device comprises four thermoelectric Peltier modules, a heat sink with four fans, two batteries, a charge controller, and a solar panel. The four Peltier modules, each capable of 50 watts, are interconnected in series and parallel configurations on the cover of a thermocol box. To ensure effective heating and cooling throughout the workspace, all modules are equipped with heat sinks and fans operating at 12V and 0.28A. To optimize thermal transfer, the Peltier modules are sandwiched between heat sinks using thermal paste, resulting in one side becoming hot and the other cold when power is supplied. These sandwich configurations are placed atop the thermocol box. Testing of the portable cooler and heater was conducted under various load conditions, including no load, 1 liter of water, and 2 liters of water, with batteries, for both cooling and heating. The fully charged batteries can power the entire experimental setup for 21 hours in each scenario. During cooling, the device achieved a minimum working area temperature (thermocol box) of 18.8°C under no load conditions and a minimum water temperature of 18.6°C for 1 liter of water. In heating mode, the experimental setup reached a maximum working area temperature of 42.4°C and a maximum water temperature of 33.3°C for 1 liter of water.

Coronary laser with simultaneous contrast injection for the treatment of stent underexpansion.

Stent underexpansion is a challenge in interventional cardiology. Some off-label treatments, such as rotational atherectomy, intravascular lithotripsy (IVL) and coronary lasing, have been used to overcome the problem. The purpose of this study is to evaluate the safety and efficacy of coronary laser atherectomy with simultaneous contrast injection and subsequent balloon dilation to optimize stent expansion. Coronary laser atherectomy with simultaneous contrast injection was used. After lasing, non-compliant balloon dilation at high pressure was performed to overcome the underexpanded point. The average increase in the minimum stent area (MSA) was measured by intravascular ultrasound (IVUS), and any complication related to the technique was evaluated. Additionally, major adverse cardiovascular events (MACE), consisting of death from any cause, new myocardial infarction (MI) and target lesion revascularization (TLR), were scrutinized in a long-term follow-up. Sixteen underexpanded stents were treated with laser between August 2017 and November 2022. In all cases but one, IVUS was used to evaluate the MSA before and after lasing. The MSA showed an average increase of 2.34 ± 1.57 mm² (95% confidence interval [CI]: 1.47-3.21; p < 0.001) after laser application and balloon inflation. No complication related to the technique was detected. During a follow-up period of a median (interquartile range) of 457 (50-973) days, the combined MACE assessed by Kaplan-Meier estimator showed an event-free rate of 0.82 (95% CI: 0.59-1). Coronary laser with simultaneous contrast injection is a safe method to optimize a stent underexpansion, with an acceptable event-free rate in long-term follow-up.

Correlation between oral cavity volume and upper airway changes in skeletal Class III patients undergoing bimaxillary orthognathic surgery: a pilot cone-beam computed tomography study.

To evaluate changes of the upper airway and oral cavity volumes in patients with skeletal Class III malocclusion undergoing bimaxillary orthognathic surgery, and to analyze the correlation between postoperative upper airway decrease and the amount of jaw movement and oral cavity volume reduction. Thirty patients (16 males and 14 females) undergoing bimaxillary surgery were included. Three-dimensional reconstruction of the upper airway and oral cavity were performed using preoperative (T0) and postoperative (T1) (6 months) cone-beam computed tomography scans. The volume, sagittal area and minimum cross-sectional area of the upper airway were diminished (P < .001). The decrease in volume and minimum cross-sectional area in the oropharyngeal region of the upper airway were weakly correlated with B-point posterior movement (P < .05). Total oral cavity volume was decreased, with maxillary oral volume increasing and mandibular oral volume decreasing (P < .001). Upper airway decrease was highly correlated with total oral volume reduction and mandibular oral volume reduction, with the most significant correlation being with total oral volume reduction (P < .001). Class III bimaxillary surgery reduced the volume, sagittal area, and minimum cross-sectional area of the upper airway as well as oral cavity volume. Upper airway changes were weakly correlated with anterior-posterior mandibular movement but significantly correlated with oral cavity volume changes. Thus, oral cavity volume reduction is a crucial factor of upper airway decrease in patients with skeletal Class III malocclusion undergoing bimaxillary orthognathic surgery.

Automated treatment planning for whole breast irradiation with individualized tangential IMRT fields.

This study aimed to develop and validate algorithms for automating intensity modulated radiation therapy (IMRT) planning in breast cancer patients, with a focus on patient anatomical characteristics. We retrospectively selected 400 breast cancer patients without lymph node involvement for automated treatment planning. Automation was achieved using the Eclipse Scripting Application Programming Interface (ESAPI) integrated into the Eclipse Treatment Planning System. We employed three beam insertion geometries and three optimization strategies, resulting in 3600 plans, each delivering a 40.05Gy dose in 15 fractions. Gantry angles in the tangent fields were selected based on a criterion involving the minimum intersection area between the Planning Target Volume (PTV) and the ipsilateral lung in the Beam's Eye View projection. ESAPI was also used to gather patient anatomical data, serving as input for Random Forest models to select the optimal plan. The Random Forest classification considered both beam insertion geometry and optimization strategy. Dosimetric data were evaluated in accordance with the Radiation Therapy Oncology Group (RTOG) 1005 protocol. Overall, all approaches generated high-quality plans, with approximately 94% meeting the acceptable dose criteria for organs at risk and/or target coverage as defined by RTOG guidelines. Average automated plan generation time ranged from 6 min and 37 s to 9 min and 22 s, with the mean time increasing with additional fields. The Random Forest approach did not successfully enable automatic planning strategy selection. Instead, our automated planning system allows users to choose from the tested geometry and strategy options. Although our attempt to correlate patient anatomical features with planning strategy using machine learning tools was unsuccessful, the resulting dosimetric outcomes proved satisfactory. Our algorithm consistently produced high-quality plans, offering significant time and efficiency advantages.

GROWTH AND YIELD RESPONSES OF RED AMARANTH TO LOCALLY SOURCED LIQUID MANURE

The experiment was conducted at Horticultural farm, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period of September to November 2023. The experiment was laid out with single factor experiment using a completely randomized design with three replications to study the Growth and Yield responses of Red Amaranth (Amaranthus cruentus L) to liquid manure. The treatments under this study were; T1: Control (Only Water), T2: Vermi Tea; T3: SAU- MLM, T4: SAU-NLM, T5: SAU-PLM. Significant variation of growth and yield parameters were found among the treatments. Among the treatments. The tallest plant (44.3 cm), maximum root length was (13.3cm), maximum leaf area (38.2 sq. cm), maximum leaf number (14.0), maximum fresh weight per plant (22.1g), highest weight of plants per 506.25 sq. cm (274.9 g) and highest yield per ha (54.3 ton) was found in T5 while shortest plant (25.1 cm, minimum root length (4.8cm), minimum leaf area (16.4 sq. cm), minimum leaf number (8.6), minimum weight of plants/506.25 sq.cm. (77.5 g) and the lowest yield per ha (15.6 t) was found in T1 at final harvest (30 days after showing). Considering the overall analysis, it becomes evident that T5 consistently exhibits superior outcomes when compared to the other treatments. The superior performance of T5 suggests that it could be the optimal choice for maximizing agricultural productivity while maintaining a focus on human well-being and environmental sustainability. This treatment option not only results in higher yields, indicating potential economic benefits, but it also contributes to the overall safety and health considerations for individuals involved in the agricultural processes.

Off-design characteristics of a scoop-type streamline-tracing scramjet inlet

This study investigates the off-design characteristics of a scoop-type streamline-tracing inlet, focusing on identifying its operable envelope using numerical and experimental methods, with experiments primarily conducted for validation purposes. The fixed geometry of streamline-tracing inlets necessitates this research, and a scoop-type inlet is targeted because it has the minimum viscous drag owing to the minimum wetted area between the streamline-tracing inlet variants. A scoop inlet with a cruise Mach number (M) of 6 and contraction ratio of 4.14 was designed, with three different values of M and various angles of attack (AoAs) used to simulate its flight in on- and off-design freestream conditions. Computational results were used to delineate the unstart boundaries with regard to AoA for each tested M. Predictably, the inlet exhibited the widest operable range for the on-design M. The flow fields for the on- and off-design conditions were compared, as were the contraction ratio, captured mass flow rate, pressure ratio, inlet exit, M, and total pressure recovery. The results indicated that the inlet performance deteriorated when the flow condition deviated from the on-design condition. However, the scoop-type inlet maintained its performance for a relatively wide range of off-design conditions, confirming its potential versatility for various flight missions.

Association Between Soft Tissue Measures From Computed Tomography and Upper Airway Collapsibility on Drug-Induced Sleep Endoscopy.

Positive airway pressure (PAP) titration during drug-induced sleep endoscopy (DISE) provides objective measures of upper airway collapsibility. While skeletal measurements relate to collapsibility measures on DISE, the influence of soft tissue dimensions on upper airway collapsibility is not known. We analyzed the relationship of measures of upper airway soft tissue volumes, specifically soft palate, pharyngeal lateral walls, and tongue, with metrics of collapsibility. Cross-sectional analysis from a prospective cohort. Academic medical center. Patients seeking PAP alternative therapies for obstructive sleep apnea (OSA) underwent standardized supine computed tomography (CT) acquisition and DISE protocols. The CT analysis primarily focused on soft tissue volumes and, secondarily, on airway and skeletal volumetric measures. DISE with PAP administration (DISE-PAP) enabled the determination of the pressure at which inspiratory airflow first commenced (pharyngeal critical pressure, PcritA) and the pressure at which inspiratory flow limitation was abolished (pharyngeal opening pressure, PhOP). Both unadjusted and adjusted correlation analyses were performed to understand the relationship between upper airway anatomy and either PcritA or PhOP. One hundred thirty-nine subjects completed both CT and DISE-PAP. On average, patients were male (70.5%), white (84.2%), middle-aged (56.6 ± 13.5 years), and overweight (29.6 ± 4.7 kg/m2), with moderate-severe apnea-hypopnea index (29.7 ± 21.3 events/h). Adjusted for age, sex, body mass index, and skeletal volumes, soft palate, and lateral pharyngeal wall volumes were not associated with PhOP or PcritA, but a larger tongue was associated with more positive PhOP (⍴ = 0.20, P = .02), and more positive PcritA (⍴ = 0.16, P = .07). Exploratory analyses revealed smaller minimum cross-sectional retropalatal area and intramandibular volume were also associated with increased collapsibility measures. After controlling for clinical factors and skeletal volume, greater tongue volume was associated with more severe collapsibility during DISE. These results, in concert with previous work, suggest that greater tongue volume in a smaller skeletal dimensions contribute to the severity of airway collapsibility, a key driver of OSA pathogenesis.

Three-dimensional assessment of upper airway changes associated with mandibular positional deviations following fibula free flap reconstruction

ObjectivesFibula free flaps (FFF) are the standard approach to mandibular reconstruction after partial resection, with the goal of restoring aesthetics and masticatory function. The graft position affects both and must be carefully selected. Correlations between sagittal positioning and upper airway anatomy are known from orthognathic surgery. This study aims to evaluate changes in mandibular position and upper airway anatomy after reconstructive surgery with FFF and corresponding correlations.Materials and methodsMandibular position after reconstruction was evaluated using three-dimensional datasets of pre- and postoperative computed tomography scans of patients treated between 2020 and 2022. Three-dimensional measurements were performed on both condyles and the symphyseal region. Changes in upper airway volume and minimum cross-sectional area (minCSA) were analysed. Intra-rater reliability was assessed. Correlations between changes in upper airway anatomy and sagittal mandibular position were tested.ResultsThe analysis included 35 patients. Intra-rater reliability was good to excellent. Condylar deviations and rotations were mostly rated as small. Changes in symphyseal position were considerably greater. Median airway volume decreased in the oropharynx and hypopharynx. Posterior deviation of the symphysis was associated with a decreasing minCSA in the hypopharynx and vice versa.ConclusionsThe overall accuracy of mandibular reconstructions with FFF is high, but there is room for optimization. The focus of research should be extended from masticatory to respiratory rehabilitation.Clinical relevanceEffects on respiratory function should be considered prior to graft positioning. The clinical relevance of upper airway changes within the complex rehabilitation of reconstructive surgery patients needs to be further investigated.

Edge history modulates the depth of edge influence: Evidence from ground beetles with different feeding traits

Anthropogenic habitat loss and fragmentation are major concerns to conservationists, since these processes lead to species decline and extinction. Edge effect is one of the most important causes of biodiversity losses in fragmented habitats. The depth of edge influence, the distance over which the edge effect penetrates into the adjacent habitat is a central issue, as it fundamentally determines whether the habitat fragment has any remaining core habitat, which is essential for the survival of habitat specialist species. We reviewed 204 edge studies on ground beetles (Coleoptera: Carabidae) of different feeding habits, in forests, one of the habitats most impacted by humans. Meta-analysing 1814 abundance data of 351 ground beetle species from forest edges and their adjoining interiors, we showed that forest edges had significantly higher abundance of herbivorous, omnivorous, and predatory ground beetles than their interiors. Edge history considerably affected the depth of edge influence which on all trophic groups was similar in natural edges and those maintained by agriculture (≤ 10–20 m), while it was wider (> 300 m) when created by forestry or other anthropogenic activities. Consequently, the minimum area of a forest fragment should be ∼ 330 ha in order to keep half of it as core habitat to preserve forest-interior species.

Energy-Space-Time Plateau-Rayleigh Instability, Quantum Phenomenon &amp; the Fundamental Interactions

In general, fluids in motion or at rest tend to minimize their surface area due to their surface tension. It is shown that kinetic energy flow through space-time experience the same Plateau-Rayleigh instability observed in fluid dynamics. Energy, space-time act like fluids, and the space-time reaction to the energy action is the equivalent of an interface tension between energy and space-time. Energy cannot continuously flow through space-time due to an energy-space-time Plateau-Rayleigh instability, space-time compression (contraction) on kinetic energy direction of motion induces an energy wave like motion (a space-time compression wave acting as kinetic energy waveguide), the particle or energy packet must follow when moving through space-time, the reason for the observed wave - particle duality. Quantum phenomenon is simply a consequence of the space-time compression on kinetic energy direction of motion. Kinetic energy and space-time are fluids and energy quanta can reach a critical point when energy quanta can change from linear to circular motion and assume a spherically symmetrical shape (the minimum surface area possible to minimize the tension at the space-time energy interface) and so it condensates as mass energy. It is shown that energy quanta to mass transformation occurs via Plateau–Rayleigh energyspace-time instability and it is governed by an energy-space-time Young-Laplace equation. Electric field lines are described as space contraction energy shock waves induced by a dynamic space-time phase transition at maximum kinetic energy space- time interface tension which is the “charge”. Space-time always reacts to the presence of energy and that reaction is the interface tension at the energy-space-time boundary: gravitational &amp; electric energy fields are consequences of energyspace-time interface tension (at either rest or kinetic energy boundary) also governed by an energy-space-time instability Young-Laplace equation. Gravitational constant G and the fine structure constant ∝ are respectively, the energy interface field’s interaction constants. The Strong force is a consequence of a direct contact between the nucleon's energy-space-time interface tension fields and has no interaction constant. The range and variation in the strength of the Strong force is due to Heisenberg’s uncertainty principle

ТЕХНИКО-ЭКОНОМИЧЕСКОЕ ОБОСНОВАНИЕ УСТАНОВКИ СОЛНЕЧНЫХ КОЛЛЕКТОРОВ ДЛЯ ИНДИВИДУАЛЬНЫХ ДОМОВ

The hot water supply system of Perm uses solar energy. The aim of the study was to substantiate the economic efficiency of solar collectors and determine their payback period taking into account climatic conditions, equipment cost and economic criteria. The proposed technical solutions of solar energy using were analyzed and compared with electric heating. During the study, the authors defined the required minimum solar collector area for a household (taking into account the hot water standard for Perm) as a functional dependence of the amount of incoming solar insolation on the amount of using heat energy. We evaluated domestic and imported solar collectors on the required parameters. The value of the reduction in the payment for electric energy was taken as the income for the households. The economic efficiency was calculated based on the forecasted average electricity tariff, taking into account inflation from 2 to 16 %. The payback of a solar hot water heating system depends primarily on the cost of purchase, installation of equipment and on the discount rate. The practical significance is to substantiate the economic efficiency of solar collectors for consumers. The methodology and results of the study can be used in private residential construction and in justification of the use of alternative energy sources for Russian regions with low insolation.

Mapping the all-day radiative sky-cooling potential of India for a sustainable environment

Radiative cooling is one of the passive methods of cooling by exchanging radiative heat between a surface and the cold universe through an atmospheric window (8 to 13 µm). The effectiveness of radiative cooling depends on the optical properties of the surfaces and the local meteorological conditions. It is essential to determine the local cooling potential to implement radiative cooling strategies. In this research, India’s annual and seasonal average radiative cooling potential was computed for 437 locations from meteorological data and the map has been developed to meet the energy-efficient cooling requirements of the Indian Cooling Action Plan (ICAP) 2019 and to fulfil the targets of Sustainable Development Goals (SDG). The results show that most locations in India have a cooling potential between 60 to 140 W/m2. The minimum area required for radiative cooling to meet India’s cooling demand is also evaluated. These results will help disseminate radiative cooling technologies in India to achieve ICAP and SDG targets.