Severe Cold Conditions Research Articles

Temperature Maintenance of Proton Exchange Membrane Fuel Cell System Based on Genetic Algorithm

Temperature is one of the main factors affecting proton exchange membrane fuel cells(PEMFC). In severe cold conditions, when equipment with PEMFCs is shut down for a short period of time, the battery temperature will drop to below zero degrees Celsius. Under this condition, the generation of ice will increase the battery start-up time, and cold start of PEMFC often requires additional heat sources. At the same time, repeated cold starts will seriously reduce the lifespan of proton exchange membrane fuel cells. Aiming at this problem, a temperature maintenance strategy is proposed for short-term low-power output of PEMFCs in severe cold conditions based on the temperature dynamic model of PEMFCs, which reduces energy loss through genetic algorithm effectively.

The Effects of Weather Conditions on Hematological and Biochemical Parameters in Dogs: A Field Study

Although animals have adaptation abilities to different environmental conditions, various physiological changes may occur. The present research aimed to evaluate the effects of severe winter conditions on hematological and biochemical parameters in dogs kept outside all year. The research was carried out in the province of Kars, which is known for its severe cold conditions in Türkiye. Vital signs, hematological, and biochemical parameters of 12 adult dogs aged 1-8 years old (mixed breed, 8 males and 4 females) included in the study were compared in winter and summer seasons. The results indicated a significant effect of the winter season on the body temperature, respiration, and pulse rate of the dogs. In addition, it was observed that some hematological, including White blood cell (WBC), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) Hemoglobin (HB), and biochemical parameters (urea, TP, albumin, cholesterol, glucose, creatinine) of dogs differed in winter from those in summer. It should be considered that the vital values of dogs living outdoors in intense winter differed from those in mild winter or summer. It is also concluded that veterinarians should consider these differences in routine clinical examinations of these animals.

The Physiological Response of Apricot Flowers to Low-Temperature Stress.

The growth and development of apricot flower organs are severely impacted by spring frosts. To better understand this process, apricot flowers were exposed to temperatures ranging from 0 °C to -8 °C, including a control at 18 °C, in artificial incubators to mimic diverse low-temperature environments. We aimed to examine their physiological reactions to cold stress, with an emphasis on changes in phenotype, membrane stability, osmotic substance levels, and antioxidant enzyme performance. Results reveal that cold stress induces significant browning and cellular damage, with a sharp increase in browning rate and membrane permeability below -5 °C. Soluble sugars and proteins initially rise as osmoprotectants, but their content decreases at lower temperatures. Proline content consistently increases, suggesting a protective role. Antioxidant enzyme activities, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), exhibit a complex pattern, with initial increases followed by declines at more severe cold conditions. Correlation and principal component analyses highlight the interplay between these responses, indicating a multifaceted adaptation strategy. The findings contribute to the understanding of apricot cold tolerance and inform breeding efforts for improved crop resilience.

Stable isotopes show Homo sapiens dispersed into cold steppes ~45,000 years ago at Ilsenhöhle in Ranis, Germany

The spread of Homo sapiens into new habitats across Eurasia ~45,000 years ago and the concurrent disappearance of Neanderthals represents a critical evolutionary turnover in our species’ history. ‘Transitional’ technocomplexes, such as the Lincombian–Ranisian–Jerzmanowician (LRJ), characterize the European record during this period but their makers and evolutionary significance have long remained unclear. New evidence from Ilsenhöhle in Ranis, Germany, now provides a secure connection of the LRJ to H. sapiens remains dated to ~45,000 years ago, making it one of the earliest forays of our species to central Europe. Using many stable isotope records of climate produced from 16 serially sampled equid teeth spanning ~12,500 years of LRJ and Upper Palaeolithic human occupation at Ranis, we review the ability of early humans to adapt to different climate and habitat conditions. Results show that cold climates prevailed across LRJ occupations, with a temperature decrease culminating in a pronounced cold excursion at ~45,000–43,000 cal bp. Directly dated H. sapiens remains confirm that humans used the site even during this very cold phase. Together with recent evidence from the Initial Upper Palaeolithic, this demonstrates that humans operated in severe cold conditions during many distinct early dispersals into Europe and suggests pronounced adaptability.

Analysis of the ion current in misfiring and firing cycles during the cold starting of a compression ignition engine

Compression ignition engines will continue to power heavy-duty, long-haul vehicles, and heavy machinery in the future, while batteries become more prevalent in powering light-duty vehicles. However, compression ignition engines face problems when started under severe cold conditions. These problems include combustion instability, misfiring, and higher emissions of unburnt hydrocarbons. Feedback of an engine’s performance to its control unit can be used to improve the fuel injection strategy in real time and mitigate these problems. The ion current signal, being reflective of the combustion and emissions characteristics, has already been proven as a reliable feedback signal under warmed-up conditions. This paper investigates the ion current signal as potential feedback during the cold starting and the warm-up period. Cold starting experiments were conducted in a VW’s 2.0-L, direct injection, four-cylinder compression ignition engine at ambient temperatures of −10°C, 0°C, 10°C, and 20°C. The engine experienced misfiring cycles at the ambient temperatures of −10°C and 0°C. In some misfiring cycles, the ion current was detected even though the pressure trace did not show a distinct combustion event, indicating that the autoignition occurred but the combustion failed to sustain. This means the ion current can identify un-sustained combustion events in misfiring cycles. In firing cycles, an ion current characteristic could well predict the combustion phasing at ambient temperatures of 10°C and 20°C. The real-time feedback of (1) un-sustained combustion events in misfiring cycles and (2) combustion phasing in firing cycles at various ambient temperatures can be utilized to mitigate cold starting problems in compression ignition engines.

Pathology and Molecular Diagnosis of Respiratory Disease Outbreak due to PCV-2 in a Pig Farm in Goa, India

Background: Pig farming is an important source of income and nutrition for rural farmers in Goa. Pig production is threatened by many infectious diseases. The present study reports a respiratory disease outbreak in a total of 200 pigs including adults and piglets with 40% mortality in a pig herd of Large white Yorkshire and crossbreds in South Goa during the winter period in January 2022. Method: The farm was visited and recorded clinical signs and post mortem findings and and samples were collected for bacterial isolation, PCR confirmation of bacterial and viral pathogens and histopathology. Result: The affected pigs showed high fever, reduced feed intake, staggering gate, huddling, difficulty in breathing, cough, and brown to greenish diarrhea followed by death within a span of 3 weeks. Major gross lesions were non-collapsed lungs with severe congestion and localized areas of consolidation, severe congestion of viscera, and enlargement, and presence of multifocal areas of necrosis in the liver. Histopathology of lungs focal or diffuse bronchointerstitial pneumonia and the lymphoid organs showed lymphoid depletion. Pasteruella multocida could be isolated from heart blood and tissues from 3 cases and PCR of the tissue DNA confirmed the presence of P. multocida and Porcine Circo Virus-2 (PCV-2) infection. The study confirms the presence of PCV-2 infection in pig herds in Goa for the first time. The acute mortality can be attributed to the co-infection of the herd with PCV-2 and P. multocida and sudden change in weather patterns with prevailing severe cold conditions during time of outbreak. Sequencing and Phylogenetic analysis of the PCV-2 ORF-2gene showed the PCV-2 virus from Goa is more related to isolates from southern Indian states.

Study on Power Frequency Breakdown Characteristics of Nano-TiO2 Modified Transformer Oil under Severe Cold Conditions

With 45# transformer oil as the base fluid, different concentrations of TiO2 nanomodified transformer oil were prepared via the thermal oscillation method. Nanomodified transformer oil with a concentration of 0.01 g/L was selected for evaluation via the breakdown test. Then, 0.01 g/L nanomodified transformer oil and ordinary 45# transformer oil were subjected to the variable control of different moisture contents and different temperatures, and breakdown tests under different types of electrodes were performed within the temperature range of −30 °C to 30 °C. The test results showed the following: Under severe cold conditions, the improvement effect of the breakdown voltage in different temperature ranges was different. Within the temperature range of −30 °C to −10 °C, the enhancement effect could reach 13% to 15%. Within the temperature range of −10 °C to 0 °C, the enhancement effect could reach 8% to 9%. Within the temperature range of 0 °C to 30 °C, the enhancement effect could reach 18% to 21%. Compared with the test results at high water contents, the improvement in the breakdown voltage amplitude of transformer oil by nanomaterials was more obvious at low water contents. In addition, nanomaterials could reduce the dispersion of the breakdown voltage to make the breakdown voltage more stable. Lastly, COMSOL was used to simulate the polarization process of nanoparticles under a uniform electric field and the influence of the trajectory of charged particles in the oil to further analyze the mechanism of the influence of nanoparticles in oil on the breakdown voltage of the oil gap. The simulation results showed that, when the particles were accelerated by the electric field, they moved irregularly. After adding nanoparticles, the charged particles were adsorbed by the nanoparticles when passing through the nanoparticles, which reduced the migration rate of charged particles in the oil. The breakdown voltage of the oil gap increased.

Investigation of energy recovery performance and frost risk of membrane enthalpy exchanger applied in cold climates

The membrane enthalpy exchanger (MEE) is a viable energy recovery device to alleviate building energy consumption. In this paper, a quasi-counter-flow MEE's energy-saving effect and frost risk under severe cold conditions is investigated experimentally and numerically. The experimental results demonstrate that frost occurs when the outdoor air temperature falls below −14 °C. At an outdoor temperature of −26 °C, the enthalpy effectiveness decreases from 63.8% to 43.3% after one hour of frosting, accompanied by a significant increase in the exhaust air's pressure drop by 2.7 times. Furthermore, the simulation results reveal that the lower latent effectiveness compared to sensible effectiveness contributes to the highest risk of saturation near the exhaust air outlet. Moreover, this study analyzes the influence of MEE's geometrical and physical characteristics on its recovery effectiveness and frost risk. The findings indicate that increasing the membrane spacing can prolong MEE's operation duration at the expense of recovery effectiveness. Specifically, the MEE's total energy recovery during the whole heating season in Shenyang, China, increases by 18% when the membrane spacing is extended from 2 mm to 5 mm with a membrane thickness of 70 μm. This study provides insights into the MEE design.

Ice collars around freezing in the ice hydrotechnical structures

Arctic engineering projects pose unique challenges due to severe cold conditions and the presence of ice. Among the critical factors affecting offshore constructions in these regions, ice loads stand out as a primary concern. Accurate estimation of ice loads is essential to ensure safe and cost-effective operation of marine structures in icy environments. One specific ice formation that significantly influences the total design load on marine structures is the ice collar. Ice collars are thicker thermodeveloped ice formations that occur around marine structures with high thermal conductivity when level ice stops moving. The presence of ice collars can considerably alter the total load on the structure, demanding careful consideration during the design process. Various methods to manage ice collars’ impact on marine structures exist, including mechanical removal, specialized cover layers, heating systems, and design adaptations. Numerical modeling proves valuable in predicting ice collar growth and its influence on load distribution. Implementing appropriate mitigation strategies ensures the continuous operability and structural integrity of marine installations in ice-prone regions.

Managing Thermal Effects in Waterproofed Concrete with Multi-Crystallization Enhancer

Thermal effects in concrete are associated with a heat release from the exothermic cement hydration reactions during concrete curing under normal conditions or under severe cold conditions, or when it is subjected to cycles of freezing and thawing. These thermal effects may cause cracking, impact concrete porosity and affects its thermal, mass and hydraulic conductivities, and hence create major durability problems. This paper presets an experimental study of the thermal management ability of an aqueous waterproofing solution (the Multi-Crystallization Enhancer (MCE)) that is intermixed with water at the time of batching. The experiments were performed according to the applicable ASTM procedures for measuring the rate of heat release, temperature profiles, compressive and flexural strengths, temperature-time factor and thermal and electrical conductivities. Additionally, the impact of cycles of freezing and thawing on the percentages of mass change, length change and relative dynamic modulus were investigated. The findings indicate that the addition of the MCE at a dosage of 2% of cement weight has the potential to mitigate the thermal effects during cement hydration and during curing concrete under freezing conditions providing a solution for thermal problems of mass concrete. The findings demonstrate that the MCE can delay the exothermic heat release and can reduce its rate at the initial stage. It can also increase the resistance of concrete against cycles of freezing and thawing by achieving 92% reduction in the percentage mass change, 15% reduction in the percentage length change and 17% enhancement in the relative dynamic modulus, after 300 cycles. These thermal impacts of the MCE are also associated with 16% reduction in the thermal conductivity and 90.7% reduction in the total charge passage through concrete.

Systematic Methods to Increase the Lifetime of Mechanical Products Such as Refrigerators by Employing Parametric Accelerated Life Testing

This investigation practically explains the implementation of parametric accelerated life testing (ALT) as an algorithm to recognize design imperfection and rectify it in creating a reliable quantitative (RQ) statement by sample size equation. It covers: (1) a module BX life that X% of a collection of system items is unsuccessful with an ALT plan, (2) design for fatigue, (3) ALTs with alterations, and (4) discernment as to if the final design(s) obtains the targeted BX lifetime. A (generalized) life–stress formulation by the linear transport process is recommended for the mathematical work of the parametric model. As a case study, an ice-maker including gear system in a refrigerator was utilized. The gear teeth made of cast iron (carbon, 3 wt% and silicon, 2 wt%) was fracturing in a refrigerator ice-maker. To reproduce the field failure and rectify the problematic designs in the marketplace, a parametric ALT was carried out. At the first ALT, the gear teeth made of cast iron partly cracked and fractured under severe cold conditions (below −20 °C) in the freezer. It was modified by changing the material from cast iron to a sinter-hardened powder metallurgy nickel steel because high fatigue strength in the low temperature was required. At the second ALT, we discovered the fractured helix made of polycarbonates (PC). As a modification, strengthened rib on the front and side of the helix the thickness of gear teeth was attached. At the third ALT, there was no concern, and the life of the auger motor including gear system was manifested to have a B1 life 10 years.

Ventilation status of the residential kitchens in severe cold region and improvement based on simulation: A case of Shenyang, China

ABSTRACT Residents tend to close the doors and windows of their residential kitchens in severe cold conditions, making insufficient outdoor air supply and aggravating indoor air pollution. In order to understand the ventilation and pollution status of the residential kitchens in a severe cold region and improve the ventilation system, this study used questionnaires, on-site tests, and Computational Fluid Dynamics (CFD) simulation to analyze a pollution and ventilation case in Shenyang, China. The method of using ceiling openings to compensate for outdoor air supply was proposed and optimized to improve air distribution in the residential kitchen. The average CO2 concentration in the breathing region, air velocity, and temperature levels in the kitchen, before and after the improvement, were compared. The results indicated that the kitchen pollution in severe cold area of Shenyang is serious, and the ventilation habit has regional characteristics. Furthermore, the overall kitchen environment including air velocity, temperature, pollutant levels, static pressure, CO2 concentration, indoor airflow fluctuation, and cooking fire were obviously improved for the ceiling make-up air cases. These findings provide a basis for improving the reasonable air distribution of residential kitchens in cold regions and for building a thermally comfortable environment. Implications: In order to understand the ventilation and pollution status of the residential kitchens in a severe cold region and improve the ventilation system, this study used questionnaires, on-site tests, and Computational Fluid Dynamics (CFD) simulation to analyze one pollution and ventilation case in Shenyang, China. The method of ceiling openings to compensate for outdoor air supply was proposed and optimized to improve air distribution in the residential kitchen. The average CO2 concentration in the breathing region, air velocity, and temperature levels in the kitchen, both before and after the improvement, were compared. The results indicated that the kitchen’s air velocity, temperature, and pollutant levels are much better for the ceiling make-up air case compared with permeation and opening window cases. The static pressure, CO2 concentration, indoor airflow fluctuation, and cooking fire showed remarkable improvement in the residential kitchens. These findings provide a basis for improving the reasonable air distribution of residential kitchens in cold regions and for building a thermally comfortable environment.

Comparative transcriptome analysis reveals regulatory genes involved in cold tolerance and hypoxic adaptation of high-altitude Tibetan bumblebees

China has many habitats supporting a wide diversity of bumblebees, some species of which are limited in distribution to the Tibet Plateau. The high-altitude Tibet Plateau, which has low air density as well as extremely low temperatures, strains the energy requirements for flight in most insects. However, high-altitude bumblebees have adapted to the harsh conditions of this type of habitat. Bumblebees are a particular group of insect pollinators that exclusively utilize carbohydrates from flowers for energy to sustain flight. Here, gene expression was compared between low-altitude species and Bombus longipennis, and the genes upregulated in B. longipennis were involved in aerobic metabolism, such as the oxidative phosphorylation and citric acid cycle (TCA cycle) pathways. Furthermore, a conjoint analysis of the transcriptomes of six bumblebee species from the high-altitude Tibet Plateau and two bumblebee species from the low-altitude North China Plain showed that 19 genes were commonly upregulated in high-altitude species. Among these 19 commonly upregulated genes, Pfk1 was enriched in multiple glycometabolic pathways, which are the main energy pathways in bees; this upregulation enhanced the aerobic and anaerobic glycolysis processes to produce more ATP molecules to supply energy for high-altitude bumblebee flight under severe cold conditions. In addition, glycolysis was enhanced by two other genes, Rac1 and AAC2. Relative quantitative real-time PCR was used to verify that the three genes Pfk1, Rac1, and AAC2 were upregulated in the six main bumblebee species inhabiting the Tibet Plateau.

Effect of long-term thermal history on physiological acclimatization and prediction of thermal sensation in typical winter conditions

Thermal history plays an important role in thermal comfort of occupants. In this study, climate chamber experiments were conducted in winter using two groups of total 32 subjects who have different indoor thermal histories. The cold-adapted (CA) group consisted of subjects who long lived in naturally ventilated buildings (approximately 11.8 ± 3.4 °C in winter) in the hot summer and cold winter climate zone of China. The warm-adapted (WA) group consisted of subjects who long lived in heated space in winter. Two kinds of thermal conditions were investigated: the temperature dropping (24-16 °C) and constant severe cold (12 °C) conditions. Results show the thermal sensation vote and heart rate of the CA group were significantly different from that of the WA group in a short period when temperature just dropping to 16 °C and in most time of severe cold condition of 12 °C. However, there were no difference in skin temperatures and blood pressure between the CA and WA groups during the whole experiment period in both conditions. Thus, a cold-adapted basal heart rate was proposed to calculate metabolic rate for the CA group. Results show the accuracy of predicted thermal sensation model could be improved while considering the factor of cold acclimatization.

Effects of local body heating on thermal comfort for audiences in open-air venues in 2022 Winter Olympics

The snow events of the 2022 Winter Olympic Games will be held in Chongli, Hebei Province, China, where the outdoor temperature is predicted to be lower than that of recent Winter Olympics hosts. The audiences of snow events watch the competitions in open-air building venue, where it is usually cold and windy. To reduce the negative impact of outdoor severe cold conditions on the viewing feelings, the effectiveness of several body heating measures (cushion, footpad, and gloves) were studied at temperature condition between – 10 °C and – 15 °C in a cryogenic chamber, with an air velocity of 0.9 m/s. Eight male subjects participated in this experiment, whose subjective evaluations and physiological parameters were recorded and analyzed. Additionally, the energy consumption of each heating measure was also monitored. The results show that the heating cushion is the most effective measure in improving the overall thermal evaluation, while the heating gloves has the highest ratio of thermal comfort improvement and energy consumption. The heating footpad is not ideal for either thermal comfort improvement or energy consumption, due to the high thermal resistance of the shoes.

How far in advance can we predict changes in large‐scale flow leading to severe cold conditions over Europe?

The potential of early warning for severe cold conditions is explored using the Subseasonal to Seasonal (S2S) Prediction research project data archive. We explore the use of a two‐dimensional phase space based on the leading empirical orthogonal functions (EOFs) of mid‐tropospheric flow computed over the Euro‐Atlantic region in order to study the time evolution of flow patterns associated with high‐impact temperature anomalies. We find that the phase space is an effective tool for monitoring predictions of regime transitions at medium and extended ranges. We show that a number of S2S systems have some skill in the prediction of cold spells over Europe, even beyond the medium range. In particular, the ECMWF (European Centre for Medium‐Range Weather Forecasts) model represents well the observed preferential transition paths. We reveal that the impact of the Madden–Julian Oscillation (MJO) on the predictive skill of large‐scale flow over Europe is asymmetric. The impact of the MJO on the Brier skill scores and reliability is significantly positive for predictions of the negative phase of the North Atlantic Oscillation (NAO): beyond week one, forecasts with the MJO in their initial state are significantly more reliable than forecasts with no MJO in their initial conditions. In contrast, the predictive skill for positive NAO shows little sensitivity to the MJO.

The complete mitochondrial genome of Sanhe horse (Equus caballus)

The present study reports the whole mitochondrial genome sequence of Sanhe horse (Equus caballus). Sanhe horse adapts quickly to severe cold conditions, which might be attributed to the unique genetic characteristics for acclimatizing to the harsh environment. However, the number of Sanhe horses has decreased sharply in recent years. Developing reasonable conservation and utilization measures for Sanhe horse requires a deeper understanding of molecular genetics. Because animal mitochondrial DNA evolves faster than the nuclear genetic markers, it is used as a powerful tool in the study of biodiversity conservation and sustainable utilization of biological resources. In this study, the complete mitochondrial genome of Sanhe horse was determined. The circular mitogenome sequenced by the Illumina HiSeq 2500 platform retrieved 16,504-bp-long sequences, containing 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and a non-coding control region. The 32-bp initiation site of the L-strand replication origin was located between the tRNA-Asn and tRNA-Cys. The overall base composition of the genome was A (32.3%), C (28.5%), G (13.3%), and T (25.9%). The phylogenetic tree was constructed using MEGA 7 with the neighbor-joining method, demonstrating that the Sanhe horse was clustered closely with the breeds in northern Europe, although it was relatively independent.

Reduced North American terrestrial primary productivity linked to anomalous Arctic warming

Warming temperatures in the Northern Hemisphere have enhanced terrestrial productivity. Despite the warming trend, North America has experienced more frequent and more intense cold weather events during winters and springs. These events have been linked to anomalous Arctic warming since 1990, and may affect terrestrial processes. Here we analyse multiple observation data sets and numerical model simulations to evaluate links between Arctic temperatures and primary productivity in North America. We find that positive springtime temperature anomalies in the Arctic have led to negative anomalies in gross primary productivity over most of North America during the last three decades, which amount to a net productivity decline of 0.31 PgC yr−1 across the continent. This decline is mainly explained by two factors: severe cold conditions in northern North America and lower precipitation in the South Central United States. In addition, United States crop-yield data reveal that during years experiencing anomalous warming in the Arctic, yields declined by approximately 1 to 4% on average, with individual states experiencing declines of up to 20%. We conclude that the strengthening of Arctic warming anomalies in the past decades has remotely reduced productivity over North America. Anomalous Arctic warming has been linked to colder North American winters. Analyses of weather and productivity observations reveal that Arctic–North American teleconnections reduce gross primary productivity in the US.

Freshening of the Labrador Sea as a trigger for Little Ice Age development

Abstract. Arctic freshwater discharges to the Labrador Sea from melting glaciers and sea ice can have a large impact on ocean circulation dynamics in the North Atlantic, modifying climate and deep water formation in this region. In this study, we present for the first time a high resolution record of ice rafting in the Labrador Sea over the last millennium to assess the effects of freshwater discharges in this region on ocean circulation and climate. The occurrence of ice-rafted debris (IRD) in the Labrador Sea was studied using sediments from Site GS06-144-03 (57.29° N, 48.37° W; 3432 m water depth). IRD from the fraction 63–150 µm shows particularly high concentrations during the intervals ∼ AD 1000–1100, ∼ 1150–1250, ∼ 1400–1450, ∼ 1650–1700 and ∼ 1750–1800. The first two intervals occurred during the Medieval Climate Anomaly (MCA), whereas the others took place within the Little Ice Age (LIA). Mineralogical identification indicates that the main IRD source during the MCA was SE Greenland. In contrast, the concentration and relative abundance of hematite-stained grains reflects an increase in the contribution of Arctic ice during the LIA. The comparison of our Labrador Sea IRD records with other climate proxies from the subpolar North Atlantic allowed us to propose a sequence of processes that led to the cooling that occurred during the LIA, particularly in the Northern Hemisphere. This study reveals that the warm climate of the MCA may have enhanced iceberg calving along the SE Greenland coast and, as a result, freshened the subpolar gyre (SPG). Consequently, SPG circulation switched to a weaker mode and reduced convection in the Labrador Sea, decreasing its contribution to the North Atlantic deep water formation and, thus, reducing the amount of heat transported to high latitudes. This situation of weak SPG circulation may have made the North Atlantic climate more unstable, inducing a state in which external forcings (e.g. reduced solar irradiance and volcanic eruptions) could easily drive periods of severe cold conditions in Europe and the North Atlantic like the LIA. This analysis indicates that a freshening of the SPG may play a crucial role in the development of cold events during the Holocene, which may be of key importance for predictions about future climate.

A MATHEMATICAL MODEL FOR THE ESTIMATION OF THERMAL STRESS AND DEVELOPMENT OF COLD INJURIES ON THE EXPOSED ORGANS OF HUMAN BODY

The severe ambient temperature always disrupts the normal thermoregulatory system of the human body. The decrease in core temperature leads to hypothermia and the development of cold injuries takes place at the exposed shells of the human body. The intensity of the cold exposure and its duration leads to various degrees of frostbites and resulting cell damage and fluid passage from the necrotic regions. In this paper, variational finite element has been employed to estimate the thermal damage due to severe cold conditions. The formulation of the model is based on Pennes’ bioheat equation and mass diffusion equation. Moreover, the fluid passage from the cold injuries at the peripheral tissues of the human body with respect to extreme cold conditions has been analyzed in relation with other parameters.