Heating Period Research Articles

Experimental Study on Flow and Thermal Transport in Additively Manufactured Lattices Based on Cube-Shaped Unit Cell

Abstract This paper presents the convective heat transfer coefficient of cubic lattices under both buoyancy-induced and forced convection. Additionally, it examines the effective thermal conductivity, permeability, and inertial coefficient of a cubic unit cell of porosity ∼0.87. The test specimens were additively manufactured using stainless steel 420 (with 40% bronze infiltration) using the binder jetting technique. In the buoyancy-driven convection experiments, three different aspect ratios (width/height) varying from 0.5 to 2 were tested across three different heating orientations, viz., bottom wall (0 deg), side wall (90 deg), and top wall (180 deg). The lattice with the lowest aspect ratio had the highest convective heat transfer coefficient in all three heating orientations. The forced convection heat transfer coefficient was determined for an additively manufactured part comprising 10 × 10 cubic unit cell array in the plane perpendicular to the flow and 20 unit cells in the streamwise direction. Additionally, the flow characteristics of the cubic lattice were characterized through permeability (K) and inertial coefficient (Cf), determined by conducting separate pressure drop experiments over a wide range of flow velocities. The thermal hydraulic performance (THP) of the cubic lattice was assessed by combining the periodic regime convective heat transfer coefficient with the pressure drop data obtained from the experimentally determined values of K and Cf. The comprehensive characterization of flow and thermal transport, including K and Cf, along with hsf, keff, presented in this paper, provides a robust foundation for their application in volume-averaged computations for detailed parametric study.

Effect of Rhei Radix Et Rhizome on treatment of polycystic ovary syndrome by regulating PI3K/AKT pathway and targeting EGFR/ALB in rats

Ethnopharmacological relevanceAbnormal endocrine metabolism caused by polycystic ovary syndrome (PCOS) poses a serious risk to reproductive health in females. According to Traditional Chinese Medicine (TCM) theories, the leading causes of PCOS include turbid phlegm, blood stasis and stagnation of liver Qi. Rhei Radix Et Rhizome is widely used in TCM to attack stagnation, clear damp heat, relieve fire. Rhei Radix Et Rhizome is an important part of the TCM formulas for the treatment of PCOS, which has a long history of medicinal use. However, the specific effect and mechanisms of Rhei Radix Et Rhizome on PCOS have yet to be elucidated. Aim of the studyThe object of this study aimed to investigate the effect and its pharmacological mechanism of Rhei Radix Et Rhizome on the treatment of polycystic ovary syndrome. MethodsPCOS was induced in female Sprague Dawley (SD) rats by administering letrozole (1 mg/kg, per orally, p.o.) for 21 days, then treated with Rhei Radix Et Rhizome at doses of 0.6g/kg or 1.2g/kg. Rats weight, blood glucose and estrus period are measured, and serum hormone include free testosterone (T), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and ovarian lesions were observed to determine the effects of Rhei Radix Et Rhizome. Network pharmacology and molecular docking predicted the targets of Rhei Radix Et Rhizome on PCOS. Epidermal growth factor receptor (EGFR), albumin (ALB), PI3K and P-AKT/AKT protein expression levels in ovarian tissues were assessed by Western blot. ResultsRhei Radix Et Rhizome reduce abnormal weight and fasting blood glucose induced by letrozole (n=5, p < 0.01), and improve the disturbed estrus cycle, reduce T, LH levels and LH/FSH ratio of PCOS rats (n=4, p < 0.01). In addition, it alleviates the polycystic changes of ovaries in PCOS rats and reduces ovarian histopathological damage (n=4, p < 0.01). Additionally, the core active components of Rhei Radix Et Rhizome for PCOS include Sennoside D_qt, Procyanidin B-5,3'-O-gallate, and Mutatochrome, which strongly bind to core therapeutic targets ALB and EGFR. Furthermore, the treatment reduces the increase of EGFR and ALB induced by letrozole (n=4, p < 0.01). KEGG pathway enrichment analysis highlights endocrine resistance and prolactin signaling pathway, in both of which the PI3K/AKT pathway plays a crucial role. Our results show Rhei Radix Et Rhizome rescue the abnormal expression of PI3K/AKT pathway in PCOS rats (n=4, p < 0.01). However, no significant dose-dependent relationship was observed in the tested dose range for the above experiments. ConclusionThese findings suggest that Rhei Radix Et Rhizome can regulate the PI3K/AKT pathway and target EGFR and ALB to treat polycystic ovary syndrome in rats. This study provides a scientific basis for the use of Rhei Radix Et Rhizome in the treatment of PCOS and highlights its potential mechanism through modulation of the PI3K/AKT pathway.

Tips and tricks for fluidproducing mares

Mares susceptible to persistent mating-induced or infectious endometritis, with delayed uterine clearance and abnormal reproductive anatomy, or mares with failure of cervical relaxation commonly present with excessive intrauterine fluid either pre-or post-breeding. One of the challenges faced with endometritis is accurately diagnosing clinical cases to ensure appropriate and timely therapy is instigated. Treatment includes improving the physical clearance of inflammatory by-products following breeding, eliminating any potential pathogens (mechanical pathway) and modulating the ongoing inflammatory response (immunological pathway). Correction of abnormal perineal conformation is also critical. Key management recommendations include breeding the mare only once during the oestrus period to limit further inflammation, performing uterine lavage and administering ecbolic agents 4–6 hours after insemination and the use of targeted post-breeding treatments. It is vital to have a non-infected, uninflamed uterine environment before the embryo entering the uterus in order to optimise embryonic survival.

Non-optimal temperature-attributable mortality and morbidity burden by cause, age and sex under climate and population change scenarios: a nationwide modelling study in Japan

Future temperature effects on mortality and morbidity may differ. However, studies comparing projected future temperature-attributable mortality and morbidity in the same setting are limited. Moreover, these studies did not consider future population change, human adaptation, and the variations in subpopulation susceptibility. Thus, we simultaneously projected the temperature-related mortality and morbidity by cause, age, and sex under population change, and human adaptation scenarios in Japan, a super-ageing society. We used daily mean temperatures, mortality, and emergency ambulance dispatch (a sensitive indicator for morbidity) in 47 prefectures of Japan from 2015 to 2019 as the reference for future projections. Future mortality and morbidity were generated at prefecture level using four shared socioeconomic pathway (SSP) scenarios considering population changes. We calculated future temperature-related mortality and morbidity by combining baseline values with future temperatures and existing temperature risk functions by cause (all-cause, circulatory, respiratory), age (<65 years, ≥65 years), and sex under various climate change and SSP scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). Full human adaptation was simulated based on empirical evidence using a fixed percentile of minimum mortality or morbidity temperature (MMT), while no adaptation was simulated with a fixed absolute MMT. A future temporal decline in mortality burden attributable to non-optimal temperatures was observed, driven by greater cold-related deaths than heat-related deaths. In contrast, temperature-related morbidity increased over time, which was primarily driven by heat. In the 2050s and 2090s, under a moderate scenario, there are 83.69 (95% empirical confidence interval [eCI] 38.32-124.97) and 77.31 (95% eCI 36.84-114.47) all-cause deaths per 100,000 population, while there are 345.07 (95% eCI 258.31-438.66) and 379.62 (95% eCI 271.45-509.05) all-cause morbidity associated with non-optimal temperatures. These trends were largely consistent across causes, age, and sex groups. Future heat-attributable health burden is projected to increase substantially, with spatiotemporal variations and is particularly pronounced among individuals ≥65y and males. Full human adaptation could yield a decreasing temperature-attributable mortality and morbidity in line with a decreasing population. Our findings could support the development of targeted mitigation and adaptation strategies to address future heat-related impacts effectively. This includes improved healthcare allocations for ambulance dispatch and hospital preventive measures during heat periods, particularly custom-tailored to address specific health outcomes and vulnerable subpopulations. Japan Science and Technology Agency and Environmental Restoration and Conservation Agency and Ministry of the Environment of Japan.

Increased angiopoietin-1 improves nailfold capillary morphology in patients with systemic sclerosis

ObjectiveRaynaud's phenomenon is a common symptom of systemic sclerosis. We previously reported that elbow heating increases angiopoietin-1 in the fingertips and alleviates Raynaud's phenomenon. Angiopoietin-1 levels decrease in patients with systemic sclerosis with severe capillary damage. We aimed to conduct a prospective study to confirm whether the increase in angiopoietin-1 caused by heating modifies capillary morphology. MethodsThe left ring fingers of 19 patients with systemic sclerosis were monitored six times at 4-week intervals using capillaroscopy, during which both elbows were heated using disposable heating pads for 8 weeks. Blood samples were collected from the same fingertips four times—before heating, twice during heating, and once after heating—to measure angiopoietin-1. ResultsIn six patients, the peak increase in angiopoietin-1 occurred 4 weeks after the start of heating, whereas in seven patients, the peak value was observed 4 weeks after the termination thereof. No change in the density of the front-row capillaries was observed by capillaroscopy. The proportion of hairpin-shaped capillaries increased from 20.2 % during the preheating period to 26.6 % during the heating period (p = 0.00107). When a correlation coefficient of 0.6 or higher was set as significant, there was a strong correlation between changes in fingertip angiopoietin-1 levels and changes in the proportion of hairpin-shaped capillaries in six patients. ConclusionIncreased angiopoietin-1 levels in the fingertip due to elbow heating may improve the peripheral capillary morphology in patients with systemic sclerosis.

A rapid response process for evaluating causes of extreme temperature events in the United States: The 2023 Texas/Louisiana heat wave as a prototype

Abstract As climate attribution studies have become more common, routine processes are now being established for attribution analysis following extreme events. This study describes the prototype process being developed through a collaboration across National Oceanic and Atmospheric Administration (NOAA), including monitoring tools as well as observational and model-based analysis of causal factors. The prolonged period of extreme heat in summer 2023 over Texas, Louisiana and adjacent areas provided a proving ground for this emerging capability. This event posed unique challenges to the initial process. The extreme heat lasted for most of the summer while most heat wave metrics have been designed for 3–7 d events. The eastern portion of the affected area also occurred within the so-called summer-time daytime warming hole where the warming trend in maximum temperatures has been mitigated wholly or in part by increased precipitation. The extreme temperature coincided with a strong—but not record—precipitation deficit over the region. Both observations and climate model simulations illustrate that the temperatures for a given precipitation deficit have warmed in recent decades. In other words, meteorological droughts today are hotter than their historical analogs providing a stronger attribution to anthropogenic forcing than for temperature alone. These findings were summarized in a prototype plain language report that was distributed to key stakeholders. Based on their feedback, the monitoring and assessment tools will continue to be refined, and the project is exploring other climate model large ensembles to increase the robustness of attribution for future events.

Monitoring the heating energy performance of a heat wheel in a direct expansion air handling unit

This study presents an on-site examination of the heating energy performance of a real ventilation system, running on the flat roof of a shopping complex building in Hungary. The main focus of this study is to delve into the heating energy efficiency of specific air handling elements, such as the air-to-air rotary heat wheel and the direct expansion heating coil supplied by a variable refrigerant volume outdoor unit under real operation conditions. Additionally, an investigation was carried out during the heating season to scrutinize the potential occurrence of CO2 transfer from the exhaust airflow to the supply airflow within the heat wheel, which issue highlights a notable limitation of the heat recovery system. Based on the monitored and measured data, the energy saving impact of the heat wheel was 20.5 % on the electric power consumption of the variable refrigerant volume outdoor unit throughout the entire heating period, compared to operation without heat wheel. Furthermore, the relative average of CO2 cross-contamination is recorded as 3.8 % in the investigated heating season.

Assessment of the Risk of Crack Formation at a Hybrid Bonding Interface Using Numerical Analysis

Hybrid bonding technology has recently emerged as a promising solution for advanced semiconductor packaging technologies. However, several reliability issues still pose challenges for commercialization. In this study, we investigated the possibility of crack formation caused by chemical mechanical polishing (CMP) defects and the misalignment of the hybrid bonding structure. Crack formation and thermomechanical stress were analyzed for two common hybrid bonding structures with misalignment using a numerical simulation. The effects of annealing temperature and dishing value on changes in the non-bonding area and peeling stress were systematically analyzed. The calculated peeling stresses were compared to the bonding strength of each bonding interface to find vulnerable regions prone to cracking. The non-bonding area in the bonding structure increased with a decreasing annealing temperature and an increasing dishing value. To achieve a sufficient bonding area of more than 90%, the annealing temperature should be greater than 200 °C. During the heating period of the annealing process, the SiCN-to-SiCN bonding interface was the most vulnerable cracking site with the highest peeling stress. An annealing temperature of 350 °C carries a significant risk of cracking. On the other hand, an annealing temperature lower than 250 °C will minimize the chance of cracking. The SiCN-to-SiO2 bonding interface, which has the lowest adhesion energy and a large coefficient of thermal expansion (CTE) mismatch, was expected to be another possible cracking site. During cooling, the SiCN-to-Cu bonding interface was the most vulnerable site with the highest stress. However, the simulated peeling stresses were lower than the adhesion strength of the bonded interface, indicating that the chance of cracking during the cooling process was very low. This study provides insights into minimizing the non-bonding area and preventing crack formation, thereby enhancing the reliability of hybrid bonding structures.

Temperature and Precipitation Synergistically Affect Yield, Harvesting Time and Post-Processing Quality of Tropical Macadamia Nuts

In response to climate change challenges and to ensure stable macadamia nut production, this study analyzed empirical data on macadamia nut yield, climate factors, harvesting time, and post-processing quality from 2020 to 2022. Key findings include: (1) During the flowering to fruit growth stage, 2020 had the highest average temperature, followed by 2021, and then 2022. Conversely, 2022 had the highest precipitation, followed by 2021, and then 2020. (2) Lower temperatures and higher precipitation during the flowering to fruit growth stage contributed to a significant increase in macadamia nut yield, which indirectly extended the harvesting time. In 2022, the average yield of the eight macadamia growers was 8.04 t ha−1, significantly higher than the yields of 6.60 t ha−1 and 6.16 t ha−1 in 2021 and 2020, respectively. Furthermore, the average harvesting time for the eight macadamia growers in 2022 was 8.88 days longer than that in 2021, and 12.50 days longer than that in 2020. (3) Temperature and precipitation had a significant impact on the post-processing quality of macadamia nuts. Lower temperature and higher precipitation during the flowering to fruit growth stage significantly increased the proportion of first-grade fruit, as well as the incidence of mildewed and insect-infested fruits. In conclusion, although a lower temperature and higher precipitation can improve macadamia nut yield, they also lead to delayed harvesting and decreased post-processing quality. Given the observed yield sensitivity to temperature and precipitation, targeted water supplementation strategies during peak heat periods emerge as vital. This approach should be integrated with broader climate resilience planning, including the timing of pest control and disease management, to safeguard macadamia nut production against the multifaceted challenges posed by climate change.

Extreme Heat and Specific-Cause Mortality during Summer 2018 in Mainland Portugal

Abstract Climate change has led to increased frequency and duration of extreme heat periods, impacting human health and mortality. During the 2003 heatwave, it was estimated that there were between 25,000 and 70,000 excess deaths in Western Europe. Specific-cause mortality analysis was conducted in Portugal that year and has not been assessed since. The goal of this study is to estimate the impact of an extreme heat period in 2018 on specific-cause mortality in mainland Portugal. An ecological study was conducted comparing observed and expected deaths, from August 2 to 9, 2018, in Portugal. Two comparison periods were chosen: from July 19 to 26, 2018 (C1) and the average deaths from August 2 to 9 in 2017 and 2019 (C2). Excesses, ratios, and respective 95% confidence intervals were calculated in R. Analyses were stratified by sex, age group, and district. Consistent excess deaths were observed between comparators, showing a greater impact in circulatory diseases (C1: 283, 95% CI: 210; 356 and C2: 239, 95% CI: 164; 314) and respiratory diseases (C1: 98, 95% CI: 55; 141 and C2: 95, 95% CI: 52; 138). Regarding death ratios, with C1, the highest death ratios were observed for exposure to excessive natural heat (50.00, 95% CI: 37.11; 65.92) and ischemic stroke (4.00, 95% CI: 2.07; 6.99). With C2, the highest death ratios were observed for exposure to excessive natural heat (50.00, 95% CI 37.11; 65.92) and atherosclerosis (2.71, 95% CI 1.63; 4.24). The excesses and ratios of deaths were higher in more urbanized districts, females, and age groups above 75 years. The results suggest that the extreme heat in 2018 had an impact on mortality. Elevated death ratios and excesses were observed for various causes of death with considerable statistical magnitude and significance. These findings align with other national and international studies. Public health action is increasingly critical to mitigate the observed rise in mortality during periods of extreme heat. Key messages • Specific-cause mortality analysis during extreme heat suggests a greater impact in circulatory and respiratory diseases, in residents of urbanized districts, females, and individuals of 75+ years. • Understanding these specific causes can better inform public health actions and planning, thereby mitigating the adverse effects of extreme heat.

Melting and solidification in periodically modulated thermal convection

Melting and solidification in periodically time-modulated thermal convection are relevant for numerous natural and engineering systems, for example, glacial melting under periodic sun radiation and latent thermal energy storage under periodically pulsating heating. It is highly relevant for the estimation of melt rate and melt efficiency management. However, even the dynamics of a solid–liquid interface shape subjected to a simple sinusoidal heating has not yet been investigated in detail. In this paper, we offer a better understanding of the modulation frequency dependence of the melting and solidification front. We numerically investigate periodic melting and solidification in turbulent convective flow with the solid above and the melted liquid below, and sinusoidal heating at the bottom plate with the mean temperature equal to the melting temperature. We investigate how the periodic heating can prevent the full solidification, and the resulting flow structures and the quasi-equilibrium interface height. We further study the dependence on the heating modulation frequency. As the frequency decreases, we found two distinct regimes, which are ‘partially solid’ and ‘fully solid’. In the fully solid regime, the liquid freezes completely, and the effect of the modulation is limited. In the partially solid regime, the solid partially melts, and a steady or unsteady solid–liquid interface forms depending on the frequency. The interface height can be derived based on the energy balance through the interface. In the partially solid regime, the interface height oscillates periodically, following the frequency of modulation. Here, we propose a perturbation approach that can predict the dependency of the oscillation amplitude on the modulation frequency.

Time-Dependent Resistance of Sol–Gel HfO2 Films to In Situ High-Temperature Laser Damage

Laser damage in films under long-term high-temperature conditions is a significant concern for advancing laser applications. This study focused on HfO2 films prepared using the sol–gel method with HfCl4 as a precursor. It examined the effects of temperature on various properties of the films, including their optical properties, microstructure, surface morphology, absorption, and laser-induced damage threshold (LIDT). The prepared film demonstrated desirable characteristics at the high temperature of 423 K, such as high transmittance, low absorption, and high LIDT. As the duration of its high-temperature exposure increased, the LIDT of the films gradually decreased. An intriguing finding was that the film’s LIDT exhibited an exponential decay pattern with prolonged heating time. This observation could be attributed to the power-law increase in defects on both the internal and surface areas of the film as the duration of high-temperature exposure lengthened. Moreover, even after a 15-day heating period at 423 K, the film maintained an LIDT of 12.9 J/cm2, indicating its potential applicability in practical high-temperature environments. This study provided a general pattern and a universal formula for understanding the laser damage of sol–gel films at high temperatures over time. Furthermore, it opened possibilities for future developments of laser films suitable for extreme environments.

The Effect of Hive Type on Colony Homeostasis and Performance in the Honey Bee (Apis mellifera).

The colonies of honey bees are mostly sessile organisms. Consequently, the type of nest boxes that beekeepers provide to their bees should impact a colony's ability to maintain homeostasis, which is a key determinant of performance and fitness. Here, we used European honey bees (Apis mellifera) and provided them with two hive setups widely used and known as Langstroth and Warré. We compared colony performance in a Mediterranean climate for five months from late spring to early autumn, which covered the most active time of bees and included periods of heat and drought. We found that irrespective of hive type or season, honey bees kept hive temperature and humidity within a remarkably narrow range. Nevertheless, the hive type impacted the daily fluctuations in temperature and humidity. In Warré hives, where bees have more autonomy to build and maintain their combs, we found that bees were able to reduce daily fluctuations in temperature and humidity and kept both measures closer to the overall average. This increase in colony homeostasis found in Warré hives negatively correlated with other hive performance indicators, such as immunocompetence. We conclude that different hive types affect key areas, such as the central part of the colony with frames of developing brood or the queen, which are the most susceptible individuals. This implies that climatic changes resulting in extreme weather events are expected to impact colony performance and fitness, especially in non-managed honey bees that are limited by available nesting sites. For managed bees, adaptations to existing hive setups could be provided to help bees minimize the effects of abiotic stress.

Investigation of periodic heat transfer on the transient thermal characteristics of fully wet moving semi-spherical porous fin composed of functionally graded material

This study investigates the thermal behaviour of a fully wet, moving semi-spherical porous fin made of linear Functionally Graded Material (FGM). This investigation examines the fin response to convective-radiative heat transfer under periodic variations in base temperature across three different FGM scenarios: Homogeneous material (HM), Functionally Graded Material I (FGM I) and Functionally Graded Material II (FGM II). The resultant nonlinear partial differential equation is accurately solved using the Finite Difference Method (FDM) and outcomes are benchmarked against existing literature. This research pioneers an investigation into the effects of periodic heat transfer on the detailed thermal profiles of FGM fin, an area not been explored in existing literature. It significantly enhances understanding of the influence of oscillatory base temperatures on thermal management within FGMs, uncovering pivotal insights into the interaction between material grading, amplitude of temperature oscillation and their collective effects on thermal efficiency. Additionally, this research assesses the influence of variables such as the amplitude of input temperature, frequency of oscillation, thermal conductivity grading parameter and others on temperature distribution along the fin length and over dimensionless time. Notably, periodic heat transfer induces a dynamically wavy thermal profile in the fin over time, attributable to oscillating base temperatures. Moreover, the analysis demonstrates that FGM II fin exhibit the most significant temperature distribution, followed by FGM I and HM. The fin heat transfer rate is profoundly influenced by the amplitude of input temperature and the thermal conductivity grading parameter. These insights are pivotal for optimizing fin designs in critical applications, including electronics cooling, HVAC systems, automotive engine cooling and solar energy collection, substantially improving upon traditional designs.

ПРИСКОРЕНИЙ ЕКСПЕРИМЕНТАЛЬНИЙ МЕТОД ВСТАНОВЛЕННЯ ФУНКЦІОНАЛЬНОЇ ЗАЛЕЖНОСТІ МІЖ ПУСКОВИМ МОМЕНТОМ АСИ- НХРОННОГО ДВИГУНА ТА НАПРУГОЮ СТАТОРНОГО КОЛА

The features of obtaining the experimental dependence of the starting torque of an induction motor on the supply voltage of the stator have been studied. It is shown that when determining this dependence, the motor operates in short-circuit mode, which leads to rapid overheating of its windings. An accelerated experimental method for determining the functional dependence of the starting torque on the supply voltage has been proposed and justified. This approach allows for a complete series of measurements of the starting torque at different values of stator circuit voltage within a time frame that does not exceed the heating period of the windings from the initial to the rated temperature. A design for the experimental setup has been developed. Mathematical models describing the thermal behavior of the stator windings and the mechanical movement of the analog part of the starting torque measurement channel have been developed, confirming the validity of the proposed method for determining the functional dependence of the starting torque of an induction motor on the stator circuit voltage.

Pollution Characteristics and Source Apportionment of Volatile Organic Compounds in Typical Solvent-using Industrial Parks in Beijing

The BCT-7800A PLUS VOC online monitor system was employed to measure ambient volatile organic compounds （VOCs） in a typical solvent-using industrial park in Beijing. From January to June 2023, the pollution characteristics, source apportionment, and ozone formation potential（OFP）of VOCs were studied, and the results of a comparative analysis were also discussed between heating and non-heating periods. The results indicated that VOC concentrations from January to June 2023 were （104.21 ± 91.31） μg·m-3 on average. The concentrations of TVOCs under the influence of southerly and northerly winds were （214.18 ± 202.37） μg·m-3 and （197.56 ± 188.3） μg·m-3, respectively. Alkanes were the species with the highest average concentration and proportion, respectively （45.53 ± 41.43） μg·m-3. The VOC concentration during the heating period was higher than those during the non-heating period, with values of （111.57 ± 83.96） μg·m-3 and （87.92 ± 75.03） μg·m-3, respectively. Propane and ethane were the species with the highest average concentration during the heating period. Compared with those in the non-heating period, the average concentrations of three species （propane, ethane, and n-butane） in the top ten species increased during the heating period, with average concentrations increasing by 51.94%, 54.64%, and 26.32%, respectively. The source apportionment results based on the positive matrix factorization （PMF） model indicated that the major sources of VOCs in the park during the monitoring period were printing emission sources （4.95%）, oil and gas evaporation sources （9.52%）, fuel combustion sources （15.44%）, traffic emissions sources （18.97%）, electronic equipment manufacturing （24.59%）, and industrial painting sources （26.52%）. Therefore, industrial painting sources, electronic equipment manufacturing sources, and traffic emissions sources were the emission sources that the park should focus on controlling. Compared with those during non-heating periods； industrial painting, traffic emission, and fuel combustion sources contributed more during the heating period, with VOC concentrations increasing by 15.02%, 16.53%, and 24.98%, respectively. The average OFP of VOCs from May to June during the monitoring period was 198.51 μg·m-3 and OVOCs, olefins, and aromatic hydrocarbons contributed the most to OFP, which were 47.41%, 22.15%, and 18.41%, respectively. The electronic equipment manufacturing source was the largest contributor to the summer OFP of the park and its contribution rate was 30.11%, which should be strengthened in the future.

Electrostatic self‐assembly of barnacle‐like modified BN@ND hetero‐structured fillers to synergistic enhanced thermal conductivity of PI composite films

AbstractHigh‐integration microelectronic equipment cannot dissipate heat for long periods of time, which enormously damages the efficiency and service life of electronic devices. Developing polymer‐based composite film exhibiting admirable thermal conductivity (TC), mechanical, dielectric and insulation performances has been pursued by researchers. Polyimide (PI) materials are generally used in progressive electronic systems. In this research, we constructed unique thermally conductive fillers to improve the TC of PI composites. Specifically, boron nitride nanosheets (BNNS) and nanodiamond (ND) were modified to impart them different charging properties. The barnacle‐like hetero‐structured fillers (MBN@FND) were assembled by electrostatic self‐assembly, and then introduced into PI to prepare PI composites. MBN@FND‐2 (MBN/FND, 1/1, wt/wt) fillers exhibited optimal morphology. The results showed that MBN@FND formed tightly stacked structure in composites, availing the densification of the thermal network and improving the heat transfer efficiency. Under 25 wt% MBN@FND loading, the in‐plane TC of MBN@FND/PI composite was 9.73 W/mK, and the through‐plane TC was 0.72 W/mK. The MBN@FND/PI composite remained at a low level in terms of dielectric properties. Moreover, MBN@FND/PI composites had flexibility, good tensile strength (47.9 MPa), and volume resistivity of 1.05 × 1013 Ω cm. This work provides a versatile approach for the preparation of hybrid materials.Highlights Hetero‐structured fillers were prepared by electrostatic self‐assembly. The in‐plane TC and through‐plane TC of PI composite was improved. The composites had insulation, flexibility, and low dielectric properties.

The development of undercut and bulge on a solidified surface

Abstract This study numerically investigates the development of undercuts and bulges parallel to the scanning direction on the surface solidified from a thermocapillary molten pool. The analysis considers various parameters, including power-off time, active solute concentration, beam power and radius, surface tension, liquid thermal conductivity, viscosity, and density. The formation and shapes of undercuts and bulges directly impact the yield, fatigue, fracture strength, and stress concentration in the solidified region. Unsteady two-dimensional fluid flow and heat transfer, which drive surface deformation in metals containing surface-active solutes (e.g., iron with sulfur), are solved using COMSOL Multiphase version 5.6. The development of the undercut, bulge, and molten pool is identified in six stages, based on whether the peak temperature is below the melting temperature, between the melting and critical temperatures, or above the critical temperature during heating and power-off periods. The critical temperature, determined as a function of solute content and temperature, leads to inward surface flow in the undercut near the pool edge, while the bulge in the central region can form due to either inward or outward surface flow. The predicted undercut depth and bulge height align well with previous scaling analyses and experimental data from laser polishing. These findings are relevant to various processes, including welding, additive manufacturing, polishing, melting, and solidification.

Comparative Phenotypic Traits and Performances of Native Sheep in Naikhongchhari Hilly Area of Bangladesh

Background: Many studies have been conducted to investigate the performance of native sheep in plains and coastal regions, but no studies have been conducted in hilly regions of Bangladesh. Considering this fact, Coastal, Barind and Jamuna River Basin sheep were evaluated for their phenotypic traits, productive and reproductive abilities to gain insights into their performance in the hilly region. Methods: The Coastal, Barind and Jamuna River Basin sheep were collected from Bangladesh Livestock Research Institute (BLRI), Savar, Dhaka for the first time to Regional Station, Naikhongchhari, BLRI and separated based on their phenotypic characteristics. A breeding program was established to ensure purity, using independent culling levels and selection indexes. Ewes were allowed to lamb throughout the year, mated with rams in a 15-20 to 1 ratio. The sheep were kept in a semi-intensive system. Result: The highest lamb birth weight was observed in coastal Region sheep, both male (1.43 kg) and female (1.22 kg), followed by Barind males (1.36 kg) and females (1.15 kg), respectively. The highest average daily gain was found in coastal region sheep (41.87 g/d), which was significantly higher compared to others. The lowest age at first heat, gestation length, age at first lambing, post-partum heat period, days open, lambing interval was observed in Barind sheep. Finally, the study offers valuable insights into the potentialities of native sheep in hilly regions, guiding future research and extension efforts for sheep farming in these areas.

Experimental study of performance of building heating system based on HPS and equipped with thermal potential recovery system and heat load prediction

The results of experimental studies of the heating system performance of a building located in the area of temperate continental climate with temperatures in the heating period down to −30 °C are discussed. The studied heating system comprises an air–liquid heat pump, a liquid–liquid heat pump with a ground circuit, and an electric boiler for peak demands.The paper presents the results of the influence of the ground thermal potential recovery system on the liquid–liquid heat pump performance. Also the influence of the used method of heat load prediction on the system efficiency and indoor air temperature stability is shown.Implementation of the thermal potential recovery system allows to increase the average value of the transformation coefficient for the liquid–liquid heat pump from 2.7 to 2.9 during three years of operation.Heat load prediction leads to stable indoor air temperature in the range of 22 ± 1 °C. Also it allows to level out the dependence of indoor temperature fluctuations on outdoor air temperature fluctuations.