Ambient Temperature Research Articles

Chance-Constrained Optimal Design of PV-Based Microgrids under Grid Blackout Uncertainties

A grid blackout is an intractable problem with serious economic consequences in many developing countries. Although it has been proven that microgrids (MGs) are capable of solving this problem, the uncertainties regarding when and for how long blackouts occur lead to extreme difficulties in the design and operation of the related MGs. This paper addresses the optimal design problem of the MGs considering the uncertainties of the blackout starting time and duration utilizing the kernel density estimator method. Additionally, uncertainties in solar irradiance and ambient temperature are also considered. For that, chance-constrained optimization is employed to design residential and industrial PV-based MGs. The proposed approach aims to minimize the expected value of the levelized cost of energy (LCOE), where the restriction of the annual total loss of power supply (TLPS) is addressed as a chance constraint. The results show that blackout uncertainties have a considerable effect on calculating the size of the MG’s components, especially the battery bank size. Additionally, it is proven that considering the uncertainties of the input parameters leads to an accurate estimation for the LCOE and increases the MG reliability level.

Dry-Cooled Rankine Cycle Operated With Binary Carbon Dioxide Based Working Fluids

The dry-cooled Rankine cycle working with a zeotropic mixture of CO2+C6F6 is influenced by the ambient temperature as air is used as the heat sink. Varying heat sink temperatures allow for operating the cycle under sliding condensation pressure which may benefit a hybrid PV-CSP plant. The study demonstrates the effect of this operation mode on composition shift and condensation pressure and investigates the cycle performance. The results show that defining the turbine design conditions significantly impact whether the system´s thermodynamic performance behaves acceptably in off-design conditions. Operating the turbine which was designed for a big pressure ratio in part-load especially if both, inlet and outlet pressure are at off-design conditions, is not favorable and leads to deteriorated efficiencies. Under some constraints for turbine and heat exchanger design, the proposed cycle enhances the hybrid PV-CSP system.

Evaluation of storage stability of dietary fibre incorporated aerobically packaged spent hen meat snacks at ambient temperature

Purpose The purpose of the study was to produce a healthier, convenient and traditional ready-to-eat (RTE) snack option with increased nutritional value, using spent hen meat, dietary fibre (DF) and simple technological methods. The product was designed to be stable without refrigeration and be easily adoptable by local self-help groups, rural women and youth and entrepreneurs in urban and semi-urban areas. Design/methodology/approach Conventional binder used for making snacks, i.e. rice flour was partially replaced by different sources of antioxidant DFs, i.e. oat flour (T1 – 10%), finger millet flour (T2 – 5%) and amaranth flour (T3 –15%) to prepare spent hen snack sticks (SHSS). The snacks were then packaged in low density polyethylene (LDPE) pouches and evaluated for their storage stability at ambient temperature for a period of 35 days. Their physico-chemical, sensory and microbiological quality was evaluated at a regular interval of 7 days. The proximate composition of developed SHSS was compared to commercially available snack products (chakli/murukku – snacks without meat). Findings The fibre-enriched SHSS showed significant improvement in nutritive value, as they contained more fibre (p = 0.001) and protein (p = 0.029) than control SHSS. When compared to commercially available snack product SHSS showed three-fold significant increase in protein (p = 0.000) and ash content (p = 0.001) and only 11%–12% total fat as compared to 31% fat in the market-available product. The most acceptable treatment in terms of overall sensory quality and nutritional aspects was T3; however, T2 was more shelf-stable during the storage period. The study showed that fibre-enriched snacks can be stored at ambient temperature for up to 35 days without substantial loss in physico-chemical, sensory and microbial quality. Hence, substituting rice flour with DFs can lead to the development of products with better sensory attributes and improved functionality. Social implications The simplicity of the product in terms of composition, machinery and low production costs makes it an easily adoptable one by small-scale entrepreneurs, especially those belonging to semi-urban areas. Originality/value Incorporation of spent hen meat, a relatively cheap but abundant source of protein, in RTE products can serve as an effective way to alleviate protein malnutrition, whereas addition of fibre further improves the functionality of the product. The methodology can be easily taken up by small-scale entrepreneurs and create a market for snack-based functional meat products.

First Report of Globisporangium (Pythium) mastophorum causing Damping-off / Root Rot on Parsley in Slovenia.

Pythium-like species cause damping-off symptoms of various hosts, including umbelliferous crops. In April 2023, parsley plantlets (Petroselinum crispum), showing stunted growth, yellowing, decayed roots and damping-off, were obtained from a nursery in central Slovenia, where parsley was grown in polystyrene trays in a greenhouse. Nearly 30% of plants were symptomatic. Sampled roots of ten plants contained ornamented oogonia (avg. 33.3 ± 1.4 µm in diam) with conical projections (5.2 ± 0.5 µm long) (Figure S1 A, B) in microscopically analyzed squash mounts. The pathogen was isolated from root pieces treated for surface disinfection with 0.5% sodium hypochlorite for 30 s, and washed with sterile water. Four 1-2 mm root pieces were taken from each of 10 plants, plated on the selective medium P5ARP, and incubated at 21 °C. Mycelia emerging from root pieces were transferred to carrot piece agar (CPA). Twenty-two equally looking oomycetous colonies were obtained; all sampled plants were infested. Oogonia formed by all colonies were similar to those observed on decayed roots and suggested that Globisporangium (Pythium) mastophorum is the causal disease agent. Analyses of partial β-tubulin (Kroon et al. 2004) and mitochondrial cytochrome c oxidase I (COI) gene sequences (Robideau et al. 2011) confirmed the identification. Obtained COI (Genbank accession number OR725417) sequence was 100% identical to that from G. mastophorum strain CBS 375.72 (EU350523), whereas the β-tubulin sequence (OR725416) corresponded to 99.6 % pairwise identity (KJ595502). Further, pathogenicity of an obtained isolate was tested on 4 wk-old curly leaf (cv. Petra F1) parsley. Half of a 7 d-old CPA culture, consisting of mycelium and oogonia, was finely cut and mixed with ca 50 ml of nonsterile commercial substrate (Potgrond H, AGRO-FertiCrop) in each of six 400 ml pots. Pots were filled with ca 300 ml additional substrate, into which 5 parsley seedlings were planted. Control plants were treated equally but with sterile CPA. Plantlets were watered with sterile tap water and held at ambient light conditions and temperature (night 18 °C - day 23 °C). After 14 d, inoculated plants started wilting and yellowing and showed stunted growth. After 21 d, roots were severely decayed and the seedlings damped-off (Figure S1 C). Four pieces each from 10 decayed roots were plated. Thirty-one pieces revealed pythium-like colonies. Obtained isolates were morphologically identical to the strain used for inoculation and identified as G. mastophorum. Control plants developed no foliar or root symptoms and no pythium-like species was obtained. Agricultural advisors observed occurrence of parsley damping-off also in other nurseries in Slovenia what may lead to spreading the pathogen to parsley in production fields and private gardens. The case emphasizes the need for implementing phytosanitary measures in order to eliminate primary inoculum. Reports from field-infected plants showed that G. mastophorum is a pathogen of parsley in Australia (Petkowski et al. 2013) and the USA (Tsuchida et al. 2018), and celery in the Czech Republic (Šafránková and Holková 2017). Others isolated G. mastophorum from parsley in The Netherlands (online database of the Westerdijk Fungal Biodiversity Institute, strain CBS 243.86). However, the here described case is, to the best of our knowledge, one of the rare documentations of damping-off due to G. mastophorum in Europe (Šafránková and Holková 2017) and the first in Slovenia. Funding: The work was funded by the Ministry of Agriculture, Forestry and Food of Slovenia, and Slovenian Research and Innovation Agency (ARIS Programs P4-0431 and P4-0072).

Optimizing large-scale hydrogen storage: A novel hybrid genetic algorithm approach for efficient pipeline network design

As hydrogen production technologies continue to advance, efficient and high-capacity hydrogen storage solutions become increasingly crucial. To address the complex optimization challenges in the design of large-scale hydrogen storage pipeline networks, the study introduces a mixed integer nonlinear optimization model inspired by hydrogen pipeline design optimization theory. The model not only focuses on optimizing network design parameters but also aims to minimize investment costs. To achieve this, the study proposes an innovative hybrid genetic algorithm that combines the Modified Feasible Directions Method (MFDM) and Genetic Algorithm Theory (GAT), specifically targeting the optimization of pipeline diameter's discrete distribution challenges. Comparative analyses with SUMT and GA algorithms demonstrate the superiority of the approach. In continuous space, the algorithm achieves a lower convergence cost of 232.4437 × 104 Yuan, while in discrete space, the cost further decreases to 212.1636 × 104 Yuan. Additionally, the study delves into the sensitivity of the HGA-MFDM algorithm to ambient temperature and wellhead temperature in hydrogen storage facilities. The analysis reveals that wellhead temperature has a more significant impact on pipeline network investment, whereas ambient temperature exhibits a more pronounced effect on iteration curves. The findings provide valuable insights for the precise adjustment and optimization of hydrogen storage pipeline networks in practical applications.

Sustainable 3D printing with alkali-treated hemp fiber-reinforced polycarbonate composites

AbstractThe study investigated the properties of alkali-treated hemp fiber-reinforced polycarbonate (PC) composites that can be formed by 3D printers for architectural applications. To determine the optimum alkali treatment to be applied to the fibers, the properties of the samples treated with 5% and 7% sodium hydroxide (NaOH) at both ambient temperature (AT) and 120 °C (HT) were determined by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). It was determined that the alkali treatment that gave the optimum result was 5% HT. Composite specimens with fiber/matrix ratios of 10/90, 20/80, and 30/70 were prepared in filament form to be printed in a 3D printer as alkali-treated and untreated. These composites were characterized by conducting tensile strength, FTIR, differential scanning calorimetry (DSC), TGA, and scanning electron microscopy (SEM) analyses. Tensile strength results revealed the highest mechanical performance for 5% NaOH alkali-treated and 10 wt.% hemp fiber-reinforced PC composites. DSC results showed that slight changes occurred in the glass transition temperature values. Furthermore, SEM analysis showed that 5% NaOH-treated hemp fibers have better interfacial bonding with the PC matrix than untreated fibers. As a result, more natural and sustainable materials have been obtained for architectural applications without significantly decreasing in PC properties.

Low-Protein Diets Differentially Regulate Energy Balance during Thermoneutral and Heat Stress in Cobb Broiler Chicken (Gallus domesticus)

The objective was to assess whether low-protein (LP) diets regulate food intake (FI) and thermogenesis differently during thermoneutral (TN) and heat stress (HS) conditions. Two-hundred-day-old male broiler chicks were weight-matched and assigned to 36 pens with 5–6 chicks/pen. After 2 weeks of acclimation, birds were subjected into four groups (9 pens/group) including (1) a normal-protein diet under TN (ambient temperature), (2) an LP diet under TN, (3) a normal-protein diet under HS (35 °C for 7 h/day), and (4) an LP diet under HS, for 4 weeks. During HS, but not TN, LP tended to decrease FI, which might be associated with a lower mRNA abundance of duodenal ghrelin and higher GIP during HS. The LP group had a higher thermal radiation than NP under TN, but during HS, the LP group had a lower thermal radiation than NP. This was linked with higher a transcript of muscle β1AR and AMPKα1 during TN, but not HS. Further, LP increased the gene expression of COX IV during TN but reduced COX IV and the sirtuin 1 abundance during HS. The dietary protein content differentially impacted plasma metabolome during TN and HS with divergent changes in amino acids such as tyrosine and tryptophan. Compared to NP, LP had increased abundances of p_Tenericutes, c_Mollicutes, c_Mollicutes_RF9, and f_tachnospiraceae under HS. Overall, LP diets may mitigate the negative outcome of heat stress on the survivability of birds by reducing FI and heat production. The differential effect of an LP diet on energy balance during TN and HS is likely regulated by gut and skeletal muscle and alterations in plasma metabolites and cecal microbiota.

Effect of NASCION‐Type ceramic dispersion in PAN/PVA‐based blend polymer electrolyte: A structural, thermal, and electrical study

AbstractSolid flexible separators having adequate ion conductivity at ambient temperature along with good thermal and voltage stability are potential candidates for separators in all solid‐state ion batteries. In the present work, zirconium and niobium‐doped Li1.3Al0.3Ti1.7 (PO4)3 ceramic particles have been incorporated into a polyvinyl alcohol (PVA) and polyacrylonitrile (PAN)‐based blend that served as a flexible matrix to create a flexible polymer–ceramic framework and have been examined for conductivity, dielectric properties, voltage stability, thermal stability, and electrochemical performance. The flexible polymer–ceramic framework shows high thermal stability, improved conductivity, and a high‐voltage window. Optimized dc conductivity of 9.8 × 10−5 S cm−1 has been observed among all investigated samples, with an improved voltage stability of 4.94 V. Further, the Trukhan model has been used to understand the effect of filler loading on ion migration properties. The optimized solid polymer electrolyte (SPE) shows improved ion mobility (μ) of 5.13 × 10−2 cm2 V−1 s, number density (n) = 2.39 × 1015 cm3, and diffusion coefficient (D) of 2.09 × 10−3 cm2 s−1. It also shows a very high specific capacitance of ~10−4 Fg−1, excellent cycling stability, and 93.75% capacity retention after 100 cycles.

Photo Switchable 4D Printing Remotely Controlled Responsive and Mimetic Deformation Shape Memory Polymer Nanocomposites

AbstractPhoto‐triggered shape morphing structures can be found in myriads of areas. Utilizing light as a switch can effectively control and regulate the precise deformation of structures. However, the integration of photo‐switching functions in shape‐morphing structures with complex geometries remains a challenge. Here, photoswitchable digital light processing based 4D printing high‐resolution and highly complex geometries, based on UV curable WO2.9 nanoparticle doped shape memory polymer nanocomposites is reported, which are highly deformable (stretchability up to ≈1000% at rubbery state) and fatigue resistant (repeatedly loaded >1200 times at ambient temperature). The presence of just trace WO2.9 nanoparticles (<0.20 wt.‰) contributes to the controlled photothermal property of nanocomposite via selective absorption of light, which enables reversibly photoswitchable (>50 times), spatial and remote control of 4D printing shape morphing structures. These findings offer a promising approach to expanding the applications of photo‐triggered shape‐morphing structures.

Stress corrosion tests for prestressing steels—Part 1: The influence of surface condition and test solution composition on hydrogen charging

AbstractTests for assessing prestressing steels' susceptibility to hydrogen‐induced stress corrosion cracking are essential for approvals, in‐house monitoring, and third‐party material testing. According to ISO 15630‐3, the time to brittle fracture by constant load under corrosive conditions in thiocyanate test solutions (A or B) at 50°C is measured. In the literature, a high scattering in stress corrosion tests is reported, which questions the integrity of the test procedure. This paper shows the results of studies about the influence of solution composition on hydrogen charging in electrochemical and permeation measurements. Electrochemical experiments show that polished steel surfaces without common drawing layers have more consistent free corrosion currents, polarization resistances, and B‐values in solution A with low scattering compared to the solution B experiments. The influence of temperature at 50°C and an ambient temperature of 22°C was also tested.

Efficacy ofhydroxypropyl-guar dropsin improving tear film index and ocular surface dynamicsusing two treatment methods under a controlled desiccating environment.

This study aimed to assess the efficacy of hp-guar eye drops on tear film index and ocular surface dynamics under desiccating conditions using protection and relief treatment modalities. The 12 normal, non-dry eye participants were subjected to adverse environmental conditions using a Controlled Environment Chamber (CEC) where the relative humidity (RH) was 5% and the ambient temperature was 21°C. The participants were screened for ocular symptoms, tear osmolarity, ocular surface temperature (OST), tear production using the Ocular Surface Disease Index questionnaire (OSDI), OcuSense TearLab Osmometer, FLIR System ThermaCAM P620, and Schirmer strips. Tear production was calculated by the Tear Function Index test (TFI). The mean tear film osmolarity decreased significantly from 296mOsm/L at 40% RH to 285mOsm/L at 5% RH (p = 0.01). Conflicting responses were seen for osmolarity in protection and relief. Mean tear osmolarity was significantly higher in the protection method in comparison to the relief method (p = 0.005). The mean TFI increased from 557 at 40% to 854 at 5% (p = 0.02). A significant increase in TFI was observed in the relief method in comparison with both 40% (p = 0.001) and 5% (p = 0.04). In the relief method, the mean TFI score went up to 1139 when hp-guar was installed. A significant improvement in ocular comfort was experienced in both the protection (p = 0.041) and relief (p = 0.010) methods at 5% RH. The instillation of hp-guar drops in the relief method resulted in a significant reduction in OST. The mean OST dropped to 33.01 ºC, significantly lower than the recorded OST for both normal (p = 0.040) and dry (p = 0.014) environmental conditions. Hp-guar drops significantly improve tear film parameters under a desiccating environment, however, tear film parameters respond differently to the management modalities. In the protection method, tear film osmolarity was protected against a dry environment, while in the relief mode, an improvement in tear production and a decrease in ocular surface temperature were seen. Hp-guar performance could be maximized for the management of exposure to adverse environments by using a treatment protocol that targets the most affected parameters in each group of patients. Using CEC has the potential to provide researchers with a readily available method to evaluate the efficiency of tear supplementation.

Infrared Thermography in Assessment of Facial Temperature of Racing Sighthound-Type Dogs in Different Environmental Conditions

The aim of the study was to assess the usefulness of IRT measurements of selected regions of interest (ROI), i.e., the eyeball and the nose of whippet dogs, before and after coursing competitions taking place in various environmental conditions, thereby enabling the assessment of well-being and the level of heat stress. The research was carried out over two different periods with different thermal humidity indexes (THIs). In the first period, the THI was 59.27 (Run 1), while in the second period, the THI was 63.77 (Run 2). The experimental subjects comprised 111 sighthound-type dogs—whippets—that were photographed with a thermal imaging camera to determine their eye temperature (ET) and nose temperature (NT). The average minimum and maximum eye temperatures were statistically lower after running in both measurements. Increased minimum and maximum nose temperatures were also demonstrated after both runs. The nasal temperature values were statistically higher for Run 2, for which the THI was higher, compared to Run 1. Eyeball temperature may be a marker of thermoregulation ability, regardless of the ambient temperature. The value of ETmax decreased on average by 2.23 °C and 0.4 °C, while NTmax increased uniformly by 2 °C after both runs. A correlation was found between the IRT measurements and physiological indicators.

Changes in temperature in preheated crystalloids at ambient temperatures relevant to a prehospital setting: an experimental simulation study with the application of prehospital treatment of trauma patients suffering from accidental hypothermia

BackgroundAccidental hypothermia is common in all trauma patients and contributes to the lethal diamond, increasing both morbidity and mortality. In hypotensive shock, fluid resuscitation is recommended using fluids with a temperature of 37–42°, as fluid temperature can decrease the patient’s body temperature. In Sweden, virtually all prehospital services use preheated fluids. The aim of the present study was to investigate how the temperature of preheated infusion fluids is affected by the ambient temperatures and flow rates relevant for prehospital emergency care.MethodsIn this experimental simulation study, temperature changes in crystalloids preheated to 39 °C were evaluated. The fluid temperature changes were measured both in the infusion bag and at the patient end of the infusion system. Measurements were conducted in conditions relevant to prehospital emergency care, with ambient temperatures varying between − 4 and 28 °C and flow rates of 1000 ml/h and 6000 ml/h, through an uninsulated infusion set at a length of 175 cm.ResultsThe flow rate and ambient temperature affected the temperature in the infusion fluid both in the infusion bag and at the patient end of the system. A lower ambient temperature and lower flow rate were both associated with a greater temperature loss in the infusion fluid.ConclusionThis study shows that both a high infusion rate and a high ambient temperature are needed if an infusion fluid preheated to 39 °C is to remain above 37 °C when it reaches the patient using a 175-cm-long uninsulated infusion set. It is apparent that the lower the ambient temperature, the higher the flow rate needs to be to limit temperature loss of the fluid.

Biophysical Breakthroughs Projected for the Phage Therapy of Bacterial Disease

Past anti-bacterial use of bacteriophages (phage therapy) is already well reviewed as a potential therapeutic response to the emergence of multidrug-resistant, pathogenic bacteria. Phage therapy has been limited by the following. (1) The success rate is too low for routine use and Food and Drug Administration (FDA) approval. (2) Current strategies of routine phage characterization do not sufficiently improve the success rate of phage therapy. (3) The stability of many phages at ambient temperature is not high enough to routinely store and transport phages at ambient temperature. In the present communication, we present new and previous data that we interpret as introductory to biophysically and efficiently transforming phage therapy to the needed level of effectiveness. Included are (1) procedure and preliminary data for the use of native gel electrophoresis (a low-cost procedure) for projecting the therapy effectiveness of a newly isolated phage, (2) data that suggest a way to achieve stabilizing of dried, ambient-temperature phages via polymer embedding, and (3) data that suggest means to increase the blood persistence, and therefore the therapy effectiveness, of what would otherwise be a relatively low-persistence phage.

Recovery of engine waste heat in low temperature environment of plug-in hybrid electric vehicle

The performance and life of electric vehicle power batteries will be reduced at low temperatures, and the lower temperature in the electric vehicle will also affect the comfort of drivers and passengers. Taking into account the winter temperatures and the unique drive structure of the plug-in hybrid electric vehicle, a specially designed driving mode for low-temperature environment is implemented. Based on this drive mode, a plug-in hybrid electric vehicle (PHEV) integrated thermal management structure is proposed to heat the battery and the passenger compartment, thereby improving energy efficiency. A mathematical model is used to establish the entire vehicle thermal management system, which is then experimentally validated. Under the NEDC (New European Driving Cycle) at ambient temperatures of −5°C, −10°C, −15°C, and −20°C, the calculation results of engine waste heat utilization and PTC (Positive Temperature Coefficient) heating are compared and analyzed. The results show that the average heating rate of the thermal management system proposed in this study is 23% faster than that of PTC heating at low temperature. The SOC decreases to 63.43% when engine waste heat utilization is adopted. When PTC heating is used, the SOC decreases to 49.18%. However, the advantage of the faster rate of engine waste heat compared to PTC heating becomes less pronounced as the ambient temperature decreases.

Influence of recycled coarse aggregate on properties of fly ash and slag-based geopolymer concrete cured under oven and ambient temperature

Purpose The purpose of this paper is to investigate the effect of the replacement of natural coarse aggregate (NCA) with different percentages of recycled coarse aggregate (RCA) on properties of low calcium fly ash (FA)-based geopolymer concrete (GPC) cured at oven temperature. Further, this paper aims to study the effect of partial replacement of FA by ground granulated blast slag (GGBS) in GPC made with both NCA and RCA cured under ambient temperature curing. Design/methodology/approach M25 grade of ordinary Portland cement (OPC) concrete was designed according to IS: 10262-2019 with 100% NCA as control concrete. Since no standard guidelines are available in the literature for GPC, the same mix proportion was adopted for the GPC by replacing the OPC with 100% FA and W/C ratio by alkalinity/binder ratio. All FA-based GPC mixes were prepared with 12 M of sodium hydroxide (NaOH) and an alkalinity ratio, i.e. sodium hydroxide to sodium silicate (NaOH:Na2SiO3) of 1:1.5, subjected to 90°C temperature for 48 h of curing. The NCA were replaced with 50% and 100% RCA in both OPC and GPC mixes. Further, FA was partially replaced with 15% GGBS in GPC made with the above percentages of NCA and RCA, and they were given ambient temperature curing with the same molarity of NaOH and alkalinity ratio. Findings The workability, compressive strength, split tensile strength, flexural strength, water absorption, density, volume of voids and rebound hammer value of all the mixes were studied. Further, the relationship between compressive strength and other mechanical properties of GPC mixes were established and compared with the well-established relationships available for conventional concrete. From the experimental results, it is found that the compressive strength of GPC under ambient curing condition at 28 days with 100% NCA, 50% RCA and 100% RCA were, respectively, 14.8%, 12.85% and 17.76% higher than those of OPC concrete. Further, it is found that 85% FA and 15% GGBS-based GPC with RCA under ambient curing shown superior performance than OPC concrete and FA-based GPC cured under oven curing. Research limitations/implications The scope of the present paper is limited to replace the FA by 15% GGBS. Further, only 50% and 100% RCA are used in place of natural aggregate. However, in future study, the replacement of FA by different amounts of GGBS (20%, 25%, 30% and 35%) may be tried to decide the optimum utilisation of GGBS so that the applications of GPC can be widely used in cast in situ applications, i.e. under ambient curing condition. Further, in the present study, the natural aggregate is replaced with only 50% and 100% RCA in GPC. However, further investigations may be carried out by considering different percentages between 50 and 100 with the optimum compositions of FA and GGBS to enhance the use of RCA in GPC applications. The present study is further limited to only the mechanical properties and a few other properties of GPC. For wider use of GPC under ambient curing conditions, the structural performance of GPC needs to be understood. Therefore, the structural performance of GPC subjected to different loadings under ambient curing with RCA to be investigated in future study. Originality/value The replacement percentage of natural aggregate by RCA may be further enhanced to 50% in GPC under ambient curing condition without compromising on the mechanical properties of concrete. This may be a good alternative for OPC and natural aggregate to reduce pollution and leads sustainability in the construction.

Investigating urban canyons, façade albedo, and pedestrian thermal comfort using microclimate model calculations

Previous studies have shown a strong relationship between heat-related fatalities and ambient air temperature. This problem is expected to increase due to constant urbanization and the threat of global warming. Therefore, designing urban street canyons (USC) to be thermally comfortable is essential for a healthy urban life. This paper investigates the correlation between an urban street canyon’s aspect ratio and the albedo material of its surrounding buildings. The aim is to study which combination can successfully mitigate urban heat stress and create a thermally comfortable pedestrian microclimate. This research uses a comparative analysis that suggests the optimum albedo for different USC geometries. An ENVI-met model was used to simulate 9 scenarios for an idealized 2D USC with varying aspect ratios and albedo values. Air temperature, mean radiant temperature and Universal Thermal Climate Index (UTCI) were analyzed. Results show that a medium albedo value performs best thermally in all USCs. High albedo had 13.2% more combined thermal stress compared to medium albedo. However, high albedo performed much better in deep canyons than wider ones, with the average UTCI decreasing by about 4.8%-5.7% when used in deep canyons. Medium albedo should be exclusively used in wide canyons for minimal thermal stress. Practical application: This study provides a reference to the use of materials in urban street canyons of different aspect ratios to achieve good outdoor thermal comfort for pedestrians.

Investigation of maximum temperatures in lithium-ion batteries by CFD and machine learning

Alternative fuels are becoming more popular as awareness of fossil fuel depletion, pollution, and climate change grows. Numerous industrial companies are producing electric automobiles for use worldwide. Electric vehicles’ battery packs’ cooling causes firing due to high temperatures. In this study, the surface temperatures of a single electric battery with dimensions of 160 mm × 210 mm within a battery pack were investigated using computational fluid dynamics and, subsequently, Levenberg-Marquardt machine learning as a function of ambient temperature, convective heat transfer coefficient, nominal capacity of the electric battery, and discharge rate. The transport coefficient has been calculated for a rechargeable electric battery with a nominal capacity ranging from 14.6 to 20 Ah and a discharge rate varying between 1 and 15, taking into account conditions of stagnant air at temperatures ranging from 20°C to 35°C and values between 5 and 20 W/m2.K. Insufficient or absent cooling of battery temperatures can lead to them reaching combustion temperatures of electric vehicle batteries, typically from 50°C to 80°C, depending on the operational circumstances. An artificial neural network was utilized in machine learning to forecast maximum temperatures based on operating conditions without requiring simulation. The neural network achieved an estimated mean squared error of 0.00552 and a calculated coefficient of determination of 0.99. The neural network model can predict outputs with mean and standard deviation rates below 0.237. The anticipated artificial neural network model can accurately forecast the maximum surface temperature of an electric vehicle battery.

A DFT calculation of electronic structures, magnetic, and thermoelectric properties of the new equiatomic quaternary Heusler alloy RuTiCrSi

AbstractThe stabilities, mechanical, electronic, and magnetic properties of the new equiatomic quaternary Heusler alloy (EQHA) RuTiCrSi were investigated using the Kohn‐Sham DFT (KS‐DFT) calculations within the generalized gradient approach (GGA), the modified version of the exchange potential introduced by Becke and Johnson in addition to the GGA (mBJ‐GGA), and Heyd‐Scuseria‐Ernzerhof (HSE06) hybrid functional. The ground‐state equilibrium energy reveals that the ferromagnetic with type 2 structure is the more stable. The RuTiCrSi is energetically, mechanically, and dynamically stable. The calculated self‐consistent total magnetic moment is 2 μB and agrees well with the Slater‐Pauling rule of . The electronic structure results from mBJ‐GGA and HSE06 functionals show a half‐metallic behavior. A high Curie temperature is obtained using the mean‐field approximation. The thermoelectric response was calculated using the semi‐classical Boltzmann transport equation under constant relaxation time. The maximum value of Seebeck coefficient is observed at the ambient temperature of . It was also observed that the power factor increases significantly as temperature rises. Therefore, the new EQHA RuTiCrSi seems to be a potential candidate for spintronic thermoelectric applications.

Comparative Analysis of Current-Voltage Characteristics of Photovoltaic (PV) Systems in Selected Climatic Regions in Cross River State, Nigeria

This study investigated the effect of solar radiation’s intensity and ambient temperature on the current-voltage (I-V) characteristics of monocrystalline and polycrystalline photovoltaic (PV) systems in the generation of electricity in Calabar and Okuku, Cross River State, Nigeria. Appropriate measuring devices were employed to record daily readings of these parameters at the study locations, from July to August 2022. The data were collected and results graphically analyzed and calculated. The results indicate that current (Isc), voltage (Voc) as well as the maximum power (Pmax) of both module types increased positively with increase in solar radiation and ambient temperature. Results from collected and computed data also show average daily readings across the locations for solar radiation ranging between 271Wm-2 and 409Wm-2 and ambient temperature between 320C and 370C. The calculated Pmax ranges between 49W and 63W from the 130W solar modules used for the investigation. Another notable result is that the polycrystalline module exhibits higher Pmax than the monocrystalline module in both locations. In spite of the low solar radiation and ambient temperature obtained during this study period, which is considered the worst climatic period of the year (July and August), it is desirable and recommendable to employ solar modules as an alternative power generation in Calabar and Okuku, Cross River State, Nigeria.