Severe Cold Environment Research Articles

Adaptation of clinical bacteriology techniques for remote polar research.

Antimicrobial resistance (AMR) represents one of the key global public health threats currently facing humanity. The recent UN High-Level Meeting on AMR highlighted the need for greater knowledge generation on its environmental aspects while also considering the potential adverse effects of climate change. The polar regions of the world offer a unique opportunity for AMR research in a near-pristine environment while also holding the potential for novel resistance mechanisms and/or antimicrobial peptide discovery within melting permafrost or glacial ice. Despite considerable technological advances in microbiology, operating in severe cold environments continues to present significant operational challenges. Our report here offers a basis for adaptations to enable both environmental and clinical antimicrobial resistance, microbiome, and discovery research for operating in the harshest of remote environments.

Construction and performance of an aluminum-water system for real-time hydrogen production in a severe cold environment

To achieve real-time hydrogen delivery in a severe cold environment with temperatures between 253.15 K and 233.15 K, a unique aluminum-water system composed of Al-Ga-In-SnCl2 (AGISc)/NaBH4/g-C3N4 composite and CoCl2 methanol solution are logically designed and constructed in this study. The final hydrogen generation from AGISc/NaBH4/1g-g-C3N4 composite in a 0.04 M CoCl2 methanol aqueous solution is 1185 mL·gAl−1, and the conversion efficiency is 85.6% at 253.15 K. Even at 233.15 K, a 0.06 M CoCl2 methanol aqueous solution may generate 1133 mL·gAl−1 of total hydrogen. With a maximum hydrogen generation rate (HGR) of 14 mL·gAl−1·s−1 and a conversion efficiency of 81.8%, real-time hydrogen production under extremely cold conditions is effectively possible. The microstructure and phase characterization of samples reveal that g-C3N4 can facilitate mechanical alloying in the preparing process, while NaBH4 can release a large amount of heat and create a mildly alkaline environment during hydrolysis, both of which enhance the hydrolysis activity. Moreover, CoCl2 solvents in solution acting as the catalysts is essential to the reaction system by forming micro-cells of Al–Co or Al–Co2B.

Road use and electrothermal performance of graphene-conductive asphalt-recycled pervious concrete under severe cold environment

Conductive-asphalt-recycled pervious concrete alleviates the urban “heat island effect” and “rain island effect” to realize the resourceful and efficient use of waste concrete and also reduces the probability of urban snow and ice disasters to ensure the safety of winter operation of asphalt pavements in cold areas. This study presents a theoretical and technical basis for ensuring the winter operational safety of asphalt pavements in cold regions. First, we compound graphene and carbon fiber as conductive phase materials and prepare graphene-conductive asphalt-recycled permeable concrete using recycled coarse aggregates with straight top and bottom holes. Then, we analyzed the electrical conductivity, road performance, and electrothermal performance of the specimens prepared using different recycled coarse aggregate substitution rates under different snowfall levels to determine their snow melting efficiency and verify their application in cold regions. The results indicate that the quality of the recycled aggregates is high, the optimal conductive filler ratio is 0.3% polyacrylonitrile-based carbon fiber and 1.5% graphene by mass of asphalt, and the resistivity of the specimens is only 3.2 Ω·m. Moreover, the conductivity and road performance of the graphene-conductive asphalt-recycled concrete decreases with an increase in the replacement rate of the recycled coarse aggregate, and the artificially prefabricated upper and lower through holes affect the conductivity of the specimens to a certain extent. Further, the graphene-conductive asphalt-recycled pervious concrete shows excellent snow melting potential, and as the required snow melting thickness and snow melting time increase, the effect of pervious asphalt slabs for snow melting efficiency becomes more significant. Moreover, when the replacement rate of the recycled concrete aggregate is within the range of 0–50%, it can be completed in 2–3 h under different snowfall levels of snow melting requirements.

Freeze-thaw resistance of concrete containing azodicarbonamide expansive agent

Azodicarbonamide expansive agent (ADC) and air-entraining agent (AEA) have similarities in introducing pores into concrete and can both be applied in constructions served in severe cold environments. This paper investigates the effect of ADC on the freeze-thaw resistance of concrete and compares the differences between ADC and AEA in the anti-freezing mechanism. The results show that ADC improves the freeze-thaw resistance of concrete, while its effect is weaker than that of AEA. The non-hydrophobic bubble shell formed by ADC cannot reduce the freezing temperature and delay freezing time as well as the shell consisted of hydrophobic calcium salt formed by AEA. A rosette-shaped pore structure and non-dense shell of air voids formed by ADC have both positive and negative effects on freeze-thaw resistance: they release hydraulic pressure to improve freezing resistance, while they reduce the suction force resulting in weakened freezing resistance. The air-void spacing factor instead of the air content at fresh stage is more suitable for assessing the freeze-thaw resistance of concrete with ADC.

Effects of Inter- and Intra-Specific Interactions on Moose Habitat Selection Limited by Temperature

Habitat selection and daily activity patterns of large herbivores might be affected by inter- and intra-specific interaction, changes of spatial scale, and seasonal temperature. To reveal what factors were driving the habitat selection of moose, we collected moose (Alces alces) and roe deer (Capreolus pygargus bedfordi) occurrence data, analyzed the multi-scale habitat selection and daily activity patterns of moose, and quantified the effects of spatial heterogeneity distribution of temperature, as well as the occurrence of roe deer on these habitat selection processes. Our results suggested that moose and roe deer distribution spatially overlap and that moose habitat selection is especially sensitive to landscape variables at large scales. We also found that the activity patterns of both sexes of moose had a degree of temporal separation with roe deer. In the snow-free season, temperatures drove moose habitat selection to be limited by threshold temperatures of 17 °C; in the snowy season, there were no similar temperature driving patterns, due to the severe cold environment. The daily activity patterns of moose showed seasonal change, and were more active at dawn and nightfall to avoid heat pressure during the snow-free season, but more active in the daytime for cold adaptation to the snow season. Consequently, this study provides new insights on how the comprehensive effects of environmental change and inter- and intra- specific relationships influence the habitat selection and daily activity patterns of moose and other heat sensitive animals with global warming.

Mechanical properties and its reliability prediction of engineered /strain-hardening cementitious composites (ECC/SHCC) with different moisture contents at negative temperatures

The mechanical properties of cement-based materials with different moisture contents are very sensitive to temperature. It is well known that engineered/strain-hardening cementitious composites (ECC/SHCC) are a high ductility cementitious composite material. The current research on SHCC is limited to room temperature and high temperature, and there is still a gap in the research on negative temperature. This study aims to explore the mechanisms of compressive strength and tensile properties of SHCC serving in cold environments. The effects of key parameters such as temperature (20 °C, −20 °C, −40 °C, and −60 °C) and moisture content (0%, 50%, 80%, and 100%) on the properties of SHCC were investigated comprehensively. With decreasing temperature and increasing moisture content, the compressive and tensile strengths of SHCC increased, while the tensile strain capacity decreased significantly. However, the tensile strain capacity of SHCC is still greater than 2% even at −60 °C. Micromechanical model parameters were obtained by fracture toughness and single fiber pullout tests, and the Pseudo Strain Hardening Behavior (PSH) criterion was calculated to explain the strain properties deterioration of SHCC at negative temperatures. Reliability prediction of the tensile strain capacity of SHCC at negative temperatures was made based on the Weibull distribution. The predicted results agree well with the experimental results. The predicted method can guide the design and engineering applications of SHCC in severe cold environments.

Ergonomic design and evaluation of carbon nanotube film (CNTF) and metal wire based flexible electrically heated gloves

Electric heating gloves are essential for people working in severe cold environments which could protect their hands warm efficiently. Existing electric heating gloves, however, tend to restrict the movement of the fingers and have limited thermal protection, affecting the working efficiency of the wearers. Here, we report on the development and evaluation of carbon nanotube film (CNTF) and metal fiber based electric heating gloves. The electric heating elements were placed in the back of the gloves, and we tested the electric heating properties of the gloves. They showed great electrothermal performance and it had a certain repeatability and stability through multiple experiments. Then the electro-thermal and ergonomic performance of the gloves were evaluated under the severe cold outdoor environment of −20 ± 2°C. In comparison with conventional single layer polar fleece gloves and carbon fiber electric heating gloves that purchased from the market, CNTF based gloves and metal fiber-based gloves demonstrated outstanding advantages in terms of faster heating speed, great warmth retention, and enhanced finger agility, which is attributed to the electrothermal properties of CNTF and metal fiber as well as the structural design of the gloves.

Performance and economic evaluation of a solar-air hybrid source energy heating system installed in cold region of China

This paper proposes a solar-air source energy storage heating system (SASES-HS), which can solve the problems of high energy consumption and difficult defrosting when the ambient temperature is low. By coupling solar energy,air energy and phase change energy, the system heats the end of the user through a two-stage heat pump. In order to analyze the feasibility of the system, the mathematical model of the system is established, and an experimental platform is built. A typical experimental condition was chosen to analyze the performance of the system in detail. The results show that the system can continuously provide high-temperature hot water of nearly 60°C for buildings in a severe cold environment of −20°C for 24 h, and the heat exchange temperature difference is as high as 80°C. In addition, the system operates with a higher coefficient of performance than a single-stage heat pump system. The COP can reach the level of 4.1 during the day and as low as 2.5 at night. The operating cost of the system only accounts for 65.8% and 88.4% of the coal-fired boiler and the air source phase change heat pump, respectively. And the CO2 emissions of this system only account for 57.5% and 88.4% of the coal-fired boiler and the air source phase change heat pump, respectively. In view of the analysis of operational performance and economic and environmental benefits, it is found that the system is worth popularizing and using in the northern cold regions.

Seismic performance of reinforced concrete beams under freeze-thaw cycles

Previous studies have shown that freeze-thaw cycle (FTC) action in severe cold environments is a durability issue that seriously threatens the seismic performance of concrete members. However, research on the seismic resistance of reinforced concrete (RC) beams under FTC action is still scarce. This paper presents an experimental study of six undamaged and frost-damaged RC beams subjected to a low-cycle reciprocating load. The paper aims to investigate the influences of FTC number and concrete strength on the seismic resistance of damaged beams. The paper reports on frost damage at different levels, cyclic damage process, hysteresis response, strength, ductility, shear deformation, and energy dissipation. The test results demonstrate that as the FTCs rose, the width and number of frost-heave cracks on the surface of the beam gradually increased. Moreover, frost action had a significant negative effect on strength, deformation, and energy dissipation, especially when the beams were highly frost-damaged. Further, the shear deformation and shear component to whole deformation gradually increased. Based on the experimental results, a time-dependent evaluation model is proposed to estimate the residual capacity of key elements of RC frame structures in severe cold climates, taking into account the effects of FTCs, concrete strength, and uneven distribution of freeze-thaw damage.

Snow Melting Performance of Graphene Composite Conductive Concrete in Severe Cold Environment.

The use of conductive concrete is an effective way to address snow and ice accretion on roads in cold regions because of its energy saving and high efficiency without interruption of traffic. Composite conductive concrete was prepared using graphene, carbon fiber, and steel fiber, and the optimum dosage of graphene was explored with resistivity as the criterion. Subsequently, under the conditions of an initial temperature of −15 °C and a wind speed of 20 km/h, the extremely severe snow event environment in cold regions was simulated. The effects of electrode spacing and electric voltage on snow melting performance of conductive concrete slab were explored. Results showed that graphene can significantly improve the conductivity of conductive concrete; the optimal content of graphene was 0.4% of cement mass in terms of resistivity. The snow-melting power of conductive concrete slab decreased with increase in electrode spacing and increased with increase in on-voltage. For an optimal input voltage of 156 V and an optimal electrode spacing of 10 cm, the time required to melt a 24 h snow thickness (21 cm), accumulated during a simulated severe snow event, was only 2 h, which provides an empirical basis for the application of graphene composite conductive concrete to pavement snow melting in cold regions.

Preparation and Application of Self-Curing Magnesium Phosphate Cement Concrete with High Early Strength in Severe Cold Environments.

The early strength of magnesium phosphate cement (MPC) decreases sharply in severe cold environments ≤−10 °C, with the 2 h compressive strength falling to 3.5 MPa at−20 °C. Therefore, it cannot be used as a repair material for emergency repair construction in such environments. In this study, MPC is adapted for use in such cold environments by replacing part of the dead-burned magnesia (M) in the mixture with a small amount of light-burned magnesia (LBM) and introducing dilute phosphoric acid (PA) solution as the mixing water. The heat released by the highly active acid–base reaction of PA and LBM stimulates an MPC reaction. Moreover, the early strength of the MPC significantly improves with the increase in the Mg2+ concentration and the initial reaction temperature of the MPC paste, which enables MPC hardening in severe cold environments. Although the morphology of the reaction products of the MPC is poor and the grain plumpness and size of the struvite crystals are remarkably reduced, the early strength of MPC prepared in the severe cold environment is close to that of MPC prepared under normal temperature. Furthermore, the increases in the early reaction temperature and early strength of magnesium phosphate cement concrete (MPCC) are significantly improved when the PA concentration in the mixing water and the LBM/M ratio are 10% and 4–6% at −10 °C and 20% and 6–8% at −20 °C, respectively. Moreover, self-curing of MPCC can be realized even at −20 °C, at which temperature the 2 h and 24 h compressive strength of MPCC reach 36 MPa and 45 MPa, respectively.

Operation improvement measures of dry type air-core reactor in severe cold environment

In severe cold environment, the surface of dry type air-core reactor would easily be cracked, once natural contamination accumulated on the cracks, surface flashover would have more possibility to happen, leading to more serious reactor faults. The most commonly used methods to avoid reactor surface discharge includes RTV coating and surface decontamination using water-based cleaning agent, yet the effects of these methods, as well as possible impact on reactor performance have not been fully studied. In this paper, RTV coating and decontamination tests were carried out to evaluate the effect of the methods, also the impact of these two methods on reactor electrical performance were analyzed. The research result showed that: (1)Water-based cleaning agent was effective in removing contamination on insulation paint surface, but less effective in removing contamination on RTV coated surface; However, the water-based cleaning agent would cause damping between the winding strands, and damping recovery degree was not easy to control. Therefore, water-based cleaning agent was not suitable to solve surface flashover problem of dry type air-core reactors. (2) The overall coating for reactor surface and air duct could be realized by special spraying equipment. The adhesion test showed that RTV was of good covering and adhesion performance, and had little impact on reactor temperature rise, indicating that RTV could be an effective measure to improve operation quality of dry type air-core reactor in extreme cold environment.

Fault Investigation and Operation Strategy of Dry Type Air-core Reactor in Severe Cold Environment

The influence of extreme climate such as severe cold temperature on power transmission system can not be ignored, the low temperature could cause complicated mechanical and dielectric deterioration to electrical materials and devices. In China’s recent operation experience of reactors, it is found the burning fault rate of dry type air-core reactors in cold northeast region was obviously higher than that of other regions, which had inflicted negative impact on substation equipment and personnel safety. To tackle with the problems and prevent potential faults, typical fault characteristics and mechanism at low temperature, the specific influence of low temperature on materials and reactor performance, as well as corresponding operation strategies would be studied and proposed in this paper.

Adiabatic Temperature Rise Test of Cemented Sand and Gravel (CSG) and Its Application to Temperature Stress Prediction of CSG Dam

An adiabatic temperature rise test of cemented sand and gravel (CSG) is conducted, a model for temperature rising of CSG is proposed, and its application to temperature stress prediction of CSG dam is presented. Adiabatic temperature rise tests are first conducted to investigate the temperature rise properties of CSG material with different cementing agent contents. The results demonstrate that the hydration reaction time is longer for CSG material with higher cementing agent content, and a linear relationship is presented between cementing agent contents and final value of adiabatic temperature rise. Then, a calculation model considering different cementing agent contents is developed based on the regression analysis of the test data. The proposed model is implanted into the ANSYS software platform for predictions of temperature distributions and stress fields of a typical CSG dam. The results show that the distributions of temperature and temperature stress are similar to those of roller compacted concrete (RCC) dam. Due to the high temperature stress at the long intermittent surface and downstream surface of the dam, the thermal insulation measures on the surface of the dam should be considered in the CSG dam with high cementing agent contents and in the severe cold environment. Therefore, it cannot be generally considered that the temperature control of the CSG dam does not need to be considered, and it should be determined according to the specific working conditions.

Research on Ventilation Plan of Summer in Kangding

Indoor thermal environment in kangding was tested on a typical day of summer, it was found that due to outdoor severe cold environment conditions, even in summer 66.4percent of local residents used heating equipments to keep warm with doors and windows closed, thus causing unhealthy indoor air quality (IAQ). So with a local typical apartment as an example, the air changes under the condition of local window tightness was calculated. Results showed that when the doors and windows were closed, indoor air changes was mostly between 0.13-1∼0.24h-1, far from required 0.5h-1 of relevant standard specification. Proper ventilation was an effective measure to improve IAQ. Therefore the required ventilation time with different opening areas was calculated. Results showed that required ventilation time was respectively 5.42∼24.30mins with full opening areas, 15.89∼49.09mins with opening scale of 1/2 and 31.30∼100.22mins with opening scale of 1/4. And proper period of ventilation time which was affected by local residents’ living habits, rooms’ function, outdoor environment conditions and the required ventilation time was discussed.