Water Temperature Fluctuations Research Articles

Cold thermopeaking-induced drift of nase Chondrostoma nasus larvae

Research on how intermittent water releases from hydropower plants affect the early life stages of fish has advanced in the last years, focusing not only on the direct impacts of rapid flow changes (hydropeaking), but also on the short-term fluctuations in water temperature (thermopeaking). Flow and thermal fluctuations caused by hydropeaking may affect fish movement patterns and migration at critical stages of a species’ life cycle, e.g., by inducing passive downstream drift. Using two experimental outdoor channels, we investigated how nase (Chondrostoma nasus, Cypriniformes) larvae respond to a rapid drop in water temperature during hydropeaking (simulating a cold thermopeaking event), reaching on average 5.5 °C under peak flow (maximum discharge) conditions, in comparison with a hydropeaking treatment with a constant water temperature regime. Responses of fish larvae were analyzed during acclimation, up-ramping (increase in discharge), peak flow and down-ramping (decrease in discharge) phases. Fish drift increased during peak flow in the cold thermopeaking treatment compared to hydropeaking. Higher drift rates were also negatively associated with pronounced water temperature drops during peak flow conditions. In addition, the starting temperature of the experiment influenced drift during up-ramping. Overall, the results suggest that cold thermopeaking may increase drift in the early life stages of cypriniform fish compared with hydropeaking with stable water temperature. Hence, monitoring and active water temperature adjustments following hydropower releases should be adopted as strategies to mitigate power plant-related impacts on aquatic organisms.

Uncovering the link between environmental factors and coral immunity: A study of fluorescent protein expression and phenoloxidase activity in Acropora cervicornis

Worsening environmental conditions due to climate change have profoundly affected the health of coral reefs worldwide. Thus, understanding how corals respond to fluctuating and/or extreme levels of temperature and solar irradiation will guide future protection and restoration efforts of this valuable ecosystem. Herein, we present a study of the immune responses of the endangered coral Acropora cervicornis to seasonal fluctuations in water temperature (WT), light intensity (LI), and water depth. Immune responses were observed by measuring the concentration of green and cyan fluorescent proteins (GFP and CyFP) and the activity of phenoloxidase (PO), an enzyme involved in the biosynthesis of the photoprotective protein melanin. To study these responses, visually healthy A. cervicornis fragments were placed at 8, and 12 m depth, and GFP, CyPF, and PO activity were measured at three-month intervals over a 12-month period. Seawater temperature and light intensity were also measured at each depth during this period. A general linear mixed model was used to determine the effects of seasonal variations of WT, LI, and water depth on the immune proteins. GFP, CyFP, and PO activity varied significantly across time – all higher in late summer/early fall and lower in late winter/early spring. Likewise, WT and LI significantly affected GFP, CyFP, and PO activity. On the other hand, water depth only had a significant effect on fluorescent protein concentrations but not PO activity. Our study demonstrates that corals can modulate these key immune-related proteins throughout natural seasonal fluctuations. That is, increasing in months of higher thermal and light conditions while decreasing in months with mild thermal and light conditions. The phenotypic plasticity of A. cervicornis in adapting to a changing environment underscores the importance that in future studies time of the year should be a meaningful consideration when evaluating the responses of A. cervicornis to the environment.

Impact of the Atlantic Meridional Overturning Circulation on Upper Water Temperature of the North Atlantic and the Atlantic Sector of the Arctic Ocean

In this study we investigate the impact of variability of the Atlantic Meridional Overturning Circulation (AMOC) on water temperature of the upper 100-m layer of the North Atlantic and Arctic oceans. We use three data-sets (ARMOR-3D, SODA3.4.2 и ORAS4) with different spatial resolution and covering different time periods. The temperature variability is decomposed into its natural modes using Empirical Orthogonal Functions (EOF). The second EOF, which accounts for 20–27% of dispersion of water temperature in the upper ocean, is associated with a change in the AMOC intensity. The time variability of the principal component of this mode has high correlation with the AMOC (0.6–0.9 depending on the data-set and the AMOC index used). The AMOC has the highest impact on water temperature in the Irminger and Labrador seas. The related amplitude of water temperature fluctuations reaches 1.5–2°С in the central part of the Irminger Sea, which is one of the key deep convection regions. Intensification of the AMOC leads to an increase the upper ocean temperature over most of the North Atlantic and Norwegian Sea and to a decrease of water temperature over most of the Greenland Sea, Barents Sea and in an area north of Spitsbergen.

Optimal Dietary Protein Requirement of Subadult Australian Hybrid Abalone (Haliotis rubra × Haliotis laevigata) at Different Rearing Temperatures

Australian abalone aquaculture is characterised by a prolonged culture period and slow and variable growth, and abalone is cultured in fluctuating water temperatures ranging between 10 and 25°C with distinct seasons. Temperature is a crucial environmental factor influencing abalone’s physiology and energetics, leading to a change in nutritional requirements. However, feeds are generally formulated to match the nutritional requirements at their optimal temperature. Hence, there is a need to optimise dietary protein levels to match temperature-specific requirements during extreme conditions (winter and summer). Given this, a growth trial evaluating five experimental feeds consisting of graded protein inclusion levels (320, 350, 380, 410, and 440 g·kg−1) was conducted on subadult hybrid abalone (Haliotis rubra × H. laevigata) at three different temperatures reflecting winter (12°C), summer (22°C), and the annual average water temperature (17°C) for 143 days. At lower water temperature (12°C), there was a marginal improvement in growth performance as dietary protein levels increased from 320 to 440 g·kg−1. However, at higher water temperatures (when the culture water temperature is above 17°C), there was a significant improvement in growth performance as dietary protein levels increased from 320 to 440 g·kg−1 as evidenced by an improved weight gain, specific growth rate, and feed conversion ratio. Furthermore, increasing dietary protein levels did not compromise the nutritional quality of the abalone tissue at all three tested temperatures. Therefore, during periods of higher water temperatures, feeding Australian hybrid abalone with a relatively high dietary protein level (410 g·kg−1) is expected to result in improved growth, shorter culture duration, and profit maximisation.

Interactive effects of diet and water temperature on the nutritional value, flavor, and sensory quality in hybrid abalone (Haliotis. discus hannai ♀ × H. fulgens♂) meat

In commercial aquaculture, the phenomena of diet conversion and water temperature fluctuation commonly occur in abalone farming. The meat quality of abalone is affected by diet and temperature, and this in turn directly influences consumer acceptance of abalone products and financial returns to producers. The aim of this study was to investigate the impacts of diet (Gracilaria lemaneiformis vs artificial feed) and water temperature (low, 19 °C and high, 27 °C) on growth performance, nutritional value, flavor, and sensory quality of abalone. The results showed that artificial feed led to increases in growth, content of body protein, total free amino acids (TAA), delicious amino acids (DAA), volatile compounds (alcohols, acids, aromatic compounds, and esters), and sensory quality (hardness) of abalone meat. High temperature significantly decreased the growth, body moisture, n-3 polyunsaturated fatty acids, and hardness but increased the contents of DAA, TAA, alcohols, acids, and aromatic compounds in abalone meat. Our study suggests that high temperature significantly decreases the growth and nutritional value of abalone muscle but does provide a different mouthfeel and flavor for consumers, and nutrition-balanced artificial feed as the diet at a low water temperature maximizes the growth of abalone without sacrificing meat quality. The results may help to formulate an optimal feed strategy for farming industries throughout the abalone culture period, thereby allowing farmers to harvest premium quality abalone and elevate the market value of abalone products.

Pinpointing drivers of widespread colonization of Legionella pneumophila in a green building: Roles of water softener system, expansion tank, and reduced occupancy

IntroductionLegionella pneumophila is an opportunistic pathogen that is a key contributor to drinking water-associated disease outbreaks in the United States. Prolonged water stagnation periods in building plumbing systems due to low occupancy, especially during building shutdowns, breaks, and holidays, can lead to water quality deterioration and (re)colonization of buildings with L. pneumophila. Water monitoring in buildings typically relies on grab samples with small datasets.MethodsIn this study, a larger dataset was created by sampling a Leadership in Energy and Environmental Design (LEED)-certified data-rich commercial building for L. pneumophila and physical-chemical water quality during the COVID-19 pandemic after reduced building occupancy. A proxy for human occupancy rates using WIFI logins was recorded throughout the study period.ResultsL. pneumophila was observed in grab samples taken throughout the building, where concentrations generally increased with greater distances from the building point of entry to locations throughout the building. Factors conducive to microbial growth were identified in the building including fluctuations in water temperatures, lack of chlorine residual, a low water heater setpoint, colonized water-saving fixtures, prolonged stagnation throughout the building; especially in an expansion tank designed to reduce pressure issues during demand fluctuations, and the presence of oversized softener tanks with ion exchange resin that contributed to chlorine residual removal as well as colonization of the resin with L. pneumophila.DiscussionFlushing and thermal disinfection alone did not resolve the problem, and replacement of the expansion tank ultimately resolved the L. pneumophila issue. As ad-hoc approaches are logistically- and time-intensive, more proactive approaches are needed for informing preventative and corrective actions for reducing the risk of exposure to opportunistic pathogens in the building plumbing.

Controllable adhesion behavior in underwater environments.

Microstructure adhesive pads can effectively manipulate objects in underwater environments. Current adhesive pads can achieve adhesion and separation with rigid substrates underwater; however, challenges remain in the control of adhesion and detachment of flexible materials. Additionally, underwater object manipulation necessitates considerable pre-pressure and is sensitive to water temperature fluctuations, potentially causing object damage and complicating adhesion and detachment processes. Thus, we present a novel, controllable adhesive pad inspired by the functional attributes of microwedge adhesive pads, combined with a mussel-inspired copolymer (MAPMC). In the context of underwater applications for flexible materials, the use of a microstructure adhesion pad with microwedge characteristics (MAPMCs) is a proficient approach to adhesion and detachment operations. This innovative method relies on the precise manipulation of the microwedge structure's collapse and recovery during its operation, which serves as the foundation for its efficacy in such environments. MAPMCs exhibit self-recovering elasticity, water flow interaction, and tunable underwater adhesion and detachment. Numerical simulations elucidate the synergistic effects of MAPMCs, highlighting the advantages of the microwedge structure for controllable, non-damaging adhesion and separation processes. The integration of MAPMCs into a gripping mechanism allows for the handling of diverse objects in underwater environments. Furthermore, by merging MAPMCs and a gripper within a linked system, our approach enables automatic, non-damaging adhesion, manipulation, and release of a soft jellyfish model. The experimental results indicate the potential applicability of MACMPs in underwater operations.

Study of an innovative combined absorption-adsorption cooling system employing the same evaporator and condenser

In this paper, the performance of innovative combined absorption and adsorption cooling (ABC-ADC) systems employing the same evaporating and condensing units is theoretically investigated. The generator of the absorption cooling (ABC) system is connected directly to the heat source system, and the outlet hot water is used to drive the desorber bed of the adsorption cooling (ADC) system. The performance of the proposed system is compared with a separated ABC-ADC system, combined ABD-ADC employing the parallel operation mode, conventional single-stage ADC cycle, and other integrated systems available in the literature. In the separated system, each system of ABC and ADC has its condenser and evaporator. Results showed that, at 85 °C heat source temperature, the cooling capacity and COP of the proposed combined ABD-ADC configuration are 0.344 kW and 0.623, respectively, and higher than that of the separated ABC, and ADC systems by 4.06% and 2.73%, respectively. The cooling capacity and COP of the proposed combined ABD-ADC configuration are significantly higher than that of the single-stage ADC system by 58.34% and 27.07%, respectively. The outlet chilled water temperature fluctuation of the proposed combined ABC-ADC systems (±0.88 °C) is significantly lower than that of the separated ABC-ADC system (±1.84 °C). Validation of the proposed ABC and ADS mathematical models with other published experimental data are around 0.2% and ±10% respectively.

Design and optimization of thermal strategy to improve the thermal management of proton exchange membrane fuel cells

This paper briefly recommends the working principle of the cooling system of the fuel cell engine (PEMFC), studies the control strategy of the thermostat in the cooling system, which couples the electric heater to shorten the water temperature fluctuation and save time. Cooling PEMFC is a challenge due to the small temperature differences between the stack and the environment. The fluctuation of water temperature and time transformation will lead to the change of system power, and further impact on the system's dynamic performance, reliability and life. Firstly, the simulation and experimental verification of cooling system of 30 kW fuel cell engine are presented. The influence of mechanical paraffin thermostat and electronic thermostat with certain control logic on the outlet temperature of the engine system stack is contrasted. Severe water temperature fluctuations will decrease the life of the system. Furthermore, the PID control and fuzzy PID control of temperature control valve are adopted, and the control method of coupling electric heater is used to solve the temperature fluctuation when the water temperature at the outlet of the stack is mixed. The results indicate that compared with the paraffin thermostat and PID controller, the fuzzy PID controller can obviously decrease the temperature fluctuation during the mixing of water temperature. Further, in different external environments, the fuzzy PID control coupling electric heater can reduce the temperature difference fluctuation to 0.5 °C when the system mixes large and small circulating water temperatures. The optimized coupling control strategy can decrease the water temperature fluctuation of the cooling system, thereby optimizing the temperature management of the cooling system, and significantly extending the power and reliability of the system.

Do predator (Mystus gulio) and prey (Penaeus monodon) have differential response against heatwaves? Unveiling through oxidative stress biomarkers and thermal tolerance estimation

Extreme climatic events such as heatwaves are anticipated to intensify in future and impose additional thermal stress to aquatic animals. Knowledge regarding an organism's thermal tolerance or sensitivity is therefore important in determining the effects of fluctuating water temperature on physiological responses. Thus, thermal tolerance tests can serve as a first step in understanding the present and future effects of climate warming. Climatic variability will alter prey-predator attributes differentially and impact their subsequent interactions. The key objective of this study was to compare and decode the stress responses, resistance and vulnerability of two economically important species from Sundarbans estuarine system- Penaeus monodon (prey) and Mystus gulio (predator) subjected to acute thermal challenges such as sudden heatwaves. Both the species were subjected to an increasing thermal ramp of 1°C h−1 from 22°C to 42°C. Organisms were observed continuously throughout the ramping period and changes in the locomotory behaviour were followed until their loss of equilibrium. The digestive tissue samples were dissected out from both M. gulio and P. monodon at every 2°C and also after a recovery period of 48 h. The SOD, CAT, GST, LPO were measured and integrated biomarker response (IBR) was analysed. The results from thermal tolerance maxima estimation, biomarker study, IBR responses indicated more intense stress response in fish M. gulio whereas recovery potential was greater in shrimp P. monodon. Our findings corroborate the ‘trophic sensitivity hypothesis’ which advocates predators to be less tolerant in aggravated environmental stress than their prey.

Study on the Performance of a Newly Designed Cooling System Utilizing Dam Water for Internet Data Centers

A novel energy-saving hybrid cooling system that combines a forced-cooling cycle and a free-cooling cycle was developed to increase the energy efficiency of cooling systems in year-round operation of an internet data center with high heat loads. This system effectively utilizes a dam deep water source to reduce energy consumption in internet data centers. The hybrid cooling system operates in forced-cooling mode when the entering water temperature exceeds the mode change temperature of 9 °C, but switches to free-cooling mode when the ambient temperature falls below the mode change temperature. In this paper, the cooling performance of the hybrid system was assessed under various operating conditions based on entering water temperature fluctuation. Because the cooling effectiveness of this type of system is highly dependent on the outside climate, its usefulness and suitability for different periods and zones must be investigated. The annual energy saving performance of the new system was estimated and compared to a conventional cooling system in terms of the integrated coefficient of performance, based on the hourly weather air temperature and water temperature bin data collected from 16 cities of different climate zones in South Korea. The experimental findings revealed that the novel hybrid internet data center cooling system showed a 67% annual operating performance over a conventional air source internet data center cooling system due to the adoption of a dam deep water source.

Thermal Stress Induces Metabolic Responses in Juvenile Qingtian Paddy Field Carp Cyprinus carpio var qingtianensis

Extreme fluctuations in water temperature lead to significant economic losses for the aquaculture industry. Cyprinus carpio var qingtianensis (locally called Qingtian paddy field carp), is a local variety commonly found in Zhejiang province, China. Unlike traditional aquaculture environments, the water temperature range between day and night in the rice field environment is much larger, and the high temperature in summer may exceed the growth threshold of fish because there is no manual intervention; therefore, the study of how the Qingtian paddy field carp (PF carp) adapts to high-temperature conditions can shed light how the species adapt to the rice field environment. To investigate the molecular mechanisms of this fish under thermal stress, the liver metabolomics of Qiangtian paddy field carp (PF carp) were analyzed. In this study, metabolomics was used to examine the metabolic reaction of PF carp (102 days old, 104.69 ± 3.08 g in weight, 14.65 ± 0.46 cm in length) at water temperatures of 28 °C (control group, CG), 34 °C (experimental group (EG) 34), and 38 °C (EG38). The results show that 175 expression profile metabolites (DEMs), including 115 upregulated and 60 downregulated metabolites, were found in the CG vs. EG34. A total of 354 DEMs were inspected in CG vs. EG38, with 85 metabolites downregulated and 269 metabolites upregulated. According to the pathway enrichment study, various pathways were altered by thermal stress, including those of lipid, amino-acid, and carbohydrate metabolism. Our study presents a potential metabolic profile for PF carp under thermal stress. It also demonstrates how the host responds to thermal stress on a metabolic and molecular level.

Multidecadal Fluctuations of SST and Euphotic Zone Temperature off Northwest Africa

Abstract The Atlantic multidecadal variability (AMV) switched from a cool to a warm phase in 1995 and the mean euphotic zone (EZT) and sea surface temperature (SST) shifted upward by 0.57° and 0.69°C, respectively, between 1982–91 and 2006–15 in the Atlantic region off northwest Africa. This ocean margin has many marine fisheries, and water temperature fluctuations may cause fish there to switch their habitats. Net radiation flux did not significantly change between these two decades. So, we hypothesized that the key driver of the EZT and SST increase is wind, which controls turbulent (sensible and latent) heat exchange with the atmosphere as well as bulk vertical and horizontal heat transport. Using satellite-derived SST and atmospheric and oceanic reanalyses to analyze the ocean top-200-m heat budget, we compared the relative contributions of the heat budget components to the cyclical changes in EZT and SST between these two decades. Results showed that the dominant heat source is horizontal heat flux convergence: weaker northeasterly trades and stronger southerly winds and monsoon enabled the southerly winds to drive warm water northward that subsequently warmed the domain. The dominant heat sink is latent heat loss: onshore–offshore atmospheric pressure gradients caused a complex wind adjustment that enabled the Sahara wind to accelerate evaporation over large subregions. These results highlight the important roles of ocean heat transport and atmosphere–ocean coupling for the tropical branch of the AMV. The regional EZT and SST anomalies associated with this AMV phase switch are mainly a consequence of wind-driven processes occurring at larger spatial scales.

Air-water interactions regulating water temperature of lakes: Direct observations (Agamon Hula, Israel) and analytical solutions

Air-water interactions regulate lake-water temperature by balancing the rate of change of water temperature (stored heat) with the incoming and outgoing heat fluxes, which are functions of water temperature and external forcing. Yet, there is a large knowledge gap in quantifying the thermoregulation of a lake, and especially managed lakes, which is hypothesized to be related to both external environmental forcing and management decisions on lake depth and water inflow. Here we explore the thermoregulation of a restored and managed Mediterranean lake (Agamon Hula, Israel), by direct measurements of all major heat fluxes. We interpret the results with a rigorous analysis of the thermoregulation equation, obtained by formulating the energy balance equation in terms of water temperature. The equation shows how water temperature of a lake shifts toward steady state, scaled by the lake’s response time. Where the steady-state temperature was reached, it was controlled by external environmental forcing and not by lake depth. Whereas the thermal response time to re-attain steady state, following an abrupt change in various environmental conditions, is controlled by water depth. The lake-temperature response to pre-defined oscillations of the environmental forcing showed that the amplitude of water temperature fluctuations and the time delay from steady-state are controlled by the ratio between the environmental forcing’s time period (diurnal, seasonal or other cycles) and the thermal response time of the lake. The summertime measured CO2 fluxes of Agamon Hula revealed the lake acts as a CO2 source to the atmosphere, overpassing similar water bodies from different climates.

Synchrotron µ-XRF mapping analysis of trace elements in in-situ cultured Japanese red coral, Corallium japonicum.

Precious corals belong to the family Coralliidae (Cnidaria, Octocorallia), and their axis, which consists of high magnesian calcium carbonate, has long been used in jewelry. With its low growth rate and long lifespan, precious coral is a representative taxon of the vulnerable marine ecosystem. Due to years of overfishing, coral fishery has become a controversial issue. To estimate the growth rate and clarify the uptake process of trace elements in relation to the growth of the carbonate axis, Japanese red coral (Corallium japonicum) was cultured at a depth of 135 m off Takeshima Island, Kagoshima, Japan for 98 months and analyzed by microscopic X-ray fluorescence/soft X-ray photoabsorption (µ-XRF/XAS) speciation mapping. The growth rate was estimated to be 0.37 mm/year in diameter, and 10–11 growth rings were observed in a cross section of the axis. This estimated growth-rate value is the first ever to be obtained from the in-situ culture of Japanese precious coral. The fluctuation in water temperature near the in-situ-culture site was recorded for part of the culture period and then compared with the changes in the growth ring and the distribution of trace elements in a cross section of the coral axis during the same period. When the water temperature was increasing, the growth ring was light in color, sulfur and phosphorus concentrations were low, and magnesium was high. Conversely, a dark band in the growth ring, high sulfur and phosphorus, and low magnesium concentrations were observed when the water temperature was decreasing. In a cross section of the coral axis, the distribution of sulfur and magnesium from the center to the surface corresponded, respectively, to dark and light bands in the annual growth ring. Sulfur concentration was high in the dark band and low in the light band, while magnesium was negatively correlated with sulfur.

Results of quantitative assessment of seaward migrating pink salmon fry in the Malaya Khusi river (north-east of Sakhalin) in 2021

Following the results of quantitative assessment in the Malaya Khusi river, total number of seaward migrating pink salmon fry was 0,22 mln. Extremely low number of pink salmon fry is is due to unfavorable environmental conditions during embryonic and larval development. Seaward migration of pink salmon fry started 10 days later relative to the long-term average. Previously, pink salmon alevins, physiologically unprepared for migration to the sea, were washed out of from ground affected by massive flood. The maximum of intensity of migration occurred on June 20–21. Variation in the intensity of migration under stable hydrological conditions was determined by fluctuations in water temperature. Migration of pink salmon took place at the dark time of the day. Average body length and weight of seaward migrating pink salmon fry increased slightly during migration. The proportion of fish with a residual yolk sac varied significantly. By the end of the migration period, individuals which began to feed in fresh water were found among seaward migrating fry.

Thermal stress induces expression of Nuclear protein and Parkin genes in endangered catfish, Clarias magur.

Fluctuation in water temperature can create thermal stress, which may impact many aspects of fish life, such as survival, growth, reproduction, disease occurrence etc. The endangered catfish, Clarias magur, has been reported to survive at higher thermal stress, even though the exact mechanism is unknown. The genes coding for Nuclear protein 1 (Nupr1) and Parkin E3 ubiquitin protein ligase (Park2) have been reported to protect cells from stress-induced damage and death. In this study, we characterized both the genes and assessed their quantitative expression in C. magur. Structural features of both the genes were found similar to a related catfish, Ictalurus punctatus, and model fish zebrafish. The genes were fairly conserved in fishes as observed through phylogenetic analysis. The real time expression of the two stress-associated genes were also assessed in brain, kidney, liver and muscle tissues of C. magur exposed to warm (34°C) and cold (15°C) water. RT-PCR analysis revealed up-regulation in the relative expression levels of Nupr1 and Park2 genes at both temperatures with maximum positive fold change during stress to cold water, even though the posteriori Dunnett's test after ANOVA revealed that there were significant differences between the control and challenged groups. The study indicated that Nupr1 gene plays role in muscle tissue at both high and low thermal stress, but at high thermal stress in liver, while Park2 plays role in muscle, brain and kidney at low temperature and in liver at high temperature stress in C. magur. The study has generated first-hand information under warm- and cold water, which pave the way to understand the expression response of these genes to thermal vacillations and to establish evolutionary significance in catfishes and other species.

Research on water heat coupling model of riparian zone based on soil thermal conductivity model

In recent years, the research on the process of water and heat transfer in the riparian zone has become more and more extensive, a more accurate riparian water and heat coupling model is helpful for us to understand the law of water and heat transfer in the riparian zone. The hydro thermal coupling model of riparian zone is constructed based on different soil thermal conductivity models, the simulation effects of different models are verified and compared by using the experimental data, the parameter sensitivity analysis of the built model is carried out to determine the main parameters affecting the output of model temperature field, and the influence of revetment structure on the process of hydro thermal transport in riparian zone is simulated. The results show that: 1. the Hydrothermal Coupling Model of riparian zone based on Johansen thermal conductivity model has the best simulation effect and high reliability. 2. The permeability coefficient (ks ) and porosity (n) have the most significant influence on the temperature simulation results, and the parameter sensitivity is the highest. 3. The revetment structure hinders the infiltration of surface water into the riparian zone in the horizontal direction, reduces the infiltration water level and temperature fluctuation in the riparian zone.

Identifying of Unsteady Performance of Oil to Water Heat Exchanger Integrated with Process

There are many approaches by which the heat exchanger can be modeled depending on how much information is available to start with. Grey-box model represents one of these approaches which is considered in the present study to modeling the unsteady operation heat exchanger. The available measurements of an unidentified heat exchanger integrated with a process involving oil circulation were statistically analyzed to extract the information that could aid in its identification. The proposed heat exchanger system included a hot oil stream coming from the thermal unit process and cooled by a cold-water circuit. The objective of this study is to develop a grey box model for the unspecified heat exchanger with a suitable nonlinear state-space structure and solved numerically using MATLAB-19 software and engineering equation solver (EES). Suitable parameters included oil and water inventories, heat addition, and conductance divisor factor are chosen to fully identify the heat exchanger from measured temperatures and flow rates. The parameters used to identify the oil process included the oil mass inventory within the process and the quantity of heat added. While for the heat exchanger; oil, water, and solid thermal masses were determined along with a conductance divisor to close its model. The results revealed that, comparing the model output with the measured data was satisfactory. The effect of 10% increment in the oil process heat as external excitation on a heat exchanger can only be controlled by water and oil flow rates and any fluctuation in inlet water temperature is insignificant and considered as a noise disturbance. An increment of 19% in the oil flowrate with unchanged water flowrate resulted in an increase in oil outlet temperature by about 4%. applying a noise of about ±10% on inlet water temperature to the system resulted in insignificant effects on the oil temperatures, and therefore it could be considered as uniform temperature. An effective control system to manage the heat exchanger and therefore the process can be designed according to the predictions of changing the water and oil flow rate responses.

ПРИЛИВНОЙ АПВЕЛЛИНГ НА ЮГО-ЗАПАДНОМ ШЕЛЬФЕ ОСТРОВА САХАЛИН

The materials of instrumental measurements of the current velocity and water temperature at the horizons of 100 and 10 m near the continental slope of southwestern Sakhalin Island (south of Moneron Island) are considered. At a depth of 100 m, diurnal fluctuations in water temperature with an amplitude of 0.5–1°C were revealed, depending on the intensity of tidal currents (temperature decrease when the flow is oriented southeast, towards the La Perouse Strait), interpreted as tidal upwelling. The materials of hydrological surveys on the T1 oceanological section have been analyzed, vertical distributions of water temperature, chlorophyll-a and biogenic elements have been constructed based on the measurements on April 15, 1999. They are consistent with the concept of tidal mixing.