Search Results (100)

A transformation method was applied to the biconfluent (BHE), doubly confluent (DHE), and triconfluent (THE) Heun equations to generate and classify exactly solvable quantum mechanical potentials derived from them. With this, the range of potentials solvable in terms of the confluent hypergeometric function can be extended. The resulting potentials contained five independently tunable terms and two terms originating from the Schwartzian derivative that depended only on the parameters of the $z\left(x\right)$ transformation function. The polynomial solutions of these potentials contain expansion coefficients obtained from three-term (BHE and DHE) and four-term (THE) recurrence relations. For the simplest $z\left(x\right)$ transformation functions, the Lemieux–Bose potentials have been recovered for the BHE and DHE. The coupling parameters of these potentials and also of five potentials derived from the THE have been expressed in terms of the parameters of the respective differential equations. The present scheme offers a general framework into which a number of earlier results can be integrated in a systematic way. These include special cases of potentials obtained from less general versions of the Heun-type equations and individual solvable potentials obtained from various methods that do not necessarily refer to the Heun-type equations considered here. Several potentials derived here were found to coincide with or reduce to potentials found earlier from the quasi-exactly solvable (QES) formalism. Based on their mathematical form, their physically relevant features (domain of definition, asymptotic behaviour, single- or multi-well structure) were discussed, and possible fields of applications were pointed out. Full article

Helicobacter pylori infection is a primary cause of gastritis and gastric ulcers. It is crucial to find alternative therapies for H. pylori infection due to the significant side effects of current antibiotics. Heyndrickxia coagulans is an ideal probiotic due to its functionality and stability in production and storage. This study explored the anti-bacterial effects of H. coagulans BHE26 in vitro and in vivo. H. coagulans BHE26 showed notable tolerance to simulated gastric juice (pH 3.0) and 1% bile salts, highlighting its potential suitability for gastrointestinal survival. H. coagulans BHE26 was resistant to ceftriaxone but sensitive to penicillin, ampicillin, erythromycin, gentamicin, ciprofloxacin, ceftriaxone, lincomycin, tetracycline and chloramphenicol. These characteristics showed that H. coagulans BHE26 is a potential probiotic bacterium. In vitro assays demonstrated that H. coagulans BHE26 inhibited H. pylori, reduced urease activity, and displayed notable auto-aggregation and co-aggregation abilities. In vivo, administration of H. coagulans BHE26 alleviated H. pylori-induced gastric mucosal damage, significantly lowered serum anti-bacterial IgG levels, and modulated gastric microbiota composition, including an increase in Turicibacter and a decrease in Lactobacillus abundance. These results indicate that H. coagulans BHE26 alleviated H. pylori-induced inflammation, offering a novel therapeutic strategy against H. pylori infection. Full article

Thermal [2+2] cycloaddition (22CA) reactions of perfluorobicyclo[2.2.0]hex-1(4)-ene (PFBHE) and bicyclo[2.2.0]hex-1(4)-ene (BHE) with ethylene, benzene and styrene were investigated through the Molecular Electron Density Theory (MEDT) at the UM06-2X/6-311G(d,p) level in benzene. Scrutiny of the DFT-based reactivity indices indicates that the presence of the eight fluorines in PFBHE notably expands the electrophilic nature of this species, participating in polar reactions. These 22CAs proceed through a stepwise mechanism, while the non-polar 22CA reaction of BHE with ethylene requires high energy around 26.6 kcal·mol⁻¹, the polar 22CA reaction of PFBHE with styrene requires a low activation energy of 13.2 kcal·mol⁻¹. The polar 22CA reaction of PFBHE with benzene presents the highest activation energy, 28.3 kcal·mol⁻¹, because of the loss of its aromatic character. Scrutiny of the electron localization function (ELF) at the TSs associated with the first step points that the creation of the C1–C3 bond set about, while that at the TSs associated with the ring-closure means that the creation of the C2–C4 bond has not started yet. At the end, a Relative Interacting Atomic Energy (RIAE) study of these thermal 22CA processes shows that while at the non-polar TS1a-I both interacting frameworks are electronically destabilized, at the polar TS1a-IV, the hefty global electron density transfer (GEDT) goes ahead towards PFBHE, causing a strong electronic stabilization of this framework, markedly reducing the RIAE activation energy. Full article

In cold regions, performance reduction in a Ground-Coupled Heat Pump (GSHP) system has been frequently reported. Many operational strategies have been adopted to mitigate such an undesirable phenomenon. However, these strategies have limited effects because the specific heat rate of Borehole Heat Exchangers (BHEs) is usually treated as constant. In this study, eight BHEs were installed in typical loess areas in Northwestern China to investigate how borehole depth affects its thermal performance. Thermal response tests (TRTs) showed that deeper boreholes led to a higher fluid outlet temperature. Compared to 150 m and 100 m boreholes, the energy coefficient factor (η) for a 200 m borehole increased by 18.02% and 45.0%, respectively. Numerical simulation also confirmed that deeper BHEs perform better. In addition, the initial ground temperature influences the thermal performance sensitively, but in the opposite way for heating and cooling modes. These findings offer valuable insights for installing GSHP systems to achieve sustainable and high thermal performance in cold regions. Full article

It is well known that the operation of a Borehole Heat Exchanger (BHE) can thermally induce groundwater convection in aquifers, enhancing the thermal performance of the BHE. However, the effect on the thermal performance of BHEs installed in low-permeable rock formations remains unclear. In this study, two BHEs were installed in a silty sandstone formation, one backfilled with high-permeable materials and the other grouted with sand–bentonite slurry. A Thermal Response Test (TRT) showed that the fluid outlet temperature of the high-permeable-material backfilled BHE was about 2.5 °C lower than that of the BHE refilled with sand–bentonite slurry, implying a higher thermal efficiency. The interpreted borehole thermal parameters also show a lower borehole thermal resistance in the high-permeable-material backfilled BHE. Physical model tests reveal that groundwater convective flow was induced in the high-permeable-material backfilled BHE. A test of BHEs with different borehole diameters shows that the larger the borehole diameter, the higher the thermal efficiency is. Thus, the thermal performance enhancement was attributed to two factors. First, the induced groundwater flow accelerates heat transfer by convection. Additionally, the increment of the thermal volumetric capacity of the groundwater stored inside a high-permeable-material refilled borehole stabilized the borehole’s temperature, which is key to sustaining high thermal efficiency in a BHE. The thermal performance enhancement demonstrated here shows potential for reducing reliance on fossil-fuel-based energy resources in challenging geological settings, thereby contributing to developing more sustainable geothermal energy solutions. Further validation in diverse field conditions is recommended to generalize these findings. Full article

The central role of heating and cooling in energy transition has been recognised in recent years, especially with geopolitical developments since February 2022 which demand an acceleration in deploying local energy sources to increase the resilience of the energy sector. Geothermal energy is a promising and vital option to optimize heating and cooling systems, promoting sustainability of urban environments. To this end, a proper design is of paramount importance to guarantee the energy performance of the whole system. This work deals with the optimization of the technical and geometrical characteristics of borehole heat exchangers (BHEs) as part of a shallow geothermal plant that is assumed to be integrated in an already operating gas-fired DH grid. Thermal performances of three different configurations were analysed according to the geological information that revealed an aquifer at −36 m overlying a poorly permeable marly succession. Numerical simulations validated the geological, hydrogeological, and thermo-physical models by back-analysing the experimental results of a thermal response test (TRT) on a pilot 150 m deep BHE. Five-year simulations were then performed to compare 150 m and 36 m polyethylene 2U, and 36 m steel coaxial BHEs. The coaxial configuration shows the best performance both in terms of specific power (74.51 W/m) and borehole thermal resistance (0.02 mK/W). Outcomes of the study confirm that coupling the best geological and technical parameters ensure the best energy performance and economic sustainability. Full article

Medium-deep borehole heat exchanger (BHE) systems represent an emerging form of ground source heat pump technology. Their heat transfer process is significantly influenced by geothermal gradient and soil stratification, typically simulated using segmented finite line source (SFLS) models. However, this approach involves computationally intensive procedures that hinder practical engineering implementation. Building upon an SFLS model adapted for complex geological conditions, this study proposes a comprehensive simplified algorithm: (1) For soil stratification: A geothermally-weighted thermal conductivity method converts layered heterogeneous media into an equivalent homogeneous medium; (2) For geothermal gradient: A temperature correction method establishes fluid temperatures under geothermal gradient by superimposing correction terms onto uniform-temperature model results (g-function model). Validated through two engineering case studies, this integrated algorithm provides a straightforward technical tool for heat transfer calculations in BHE systems. Full article

With the rapid urbanization and increasing development of underground spaces, foundation pit groups in complex geological environments encounter considerable challenges in deformation control. These challenges are especially prominent in cases of adjacent constructions, complex geology, and environmentally sensitive areas. Nevertheless, existing research is lacking in systematic analysis of construction sequencing and the interaction mechanisms between foundation pit groups. This results in gaps in comprehending stress redistribution and optimal excavation strategies for such configurations. To address these gaps, this study integrates physical model tests and PLAXIS 3D numerical simulations to explore the Nanjing Jiangbei New District Phase II pit groups. It concentrates on deformations in segmented and adjacent configurations under varying excavation sequences and spacing conditions. Key findings reveal that simultaneous excavation in segmented pit groups optimizes deformation control through symmetrical stress relief via bilateral unloading, reducing shared diaphragm wall displacement by 18–25% compared to sequential methods. Sequential excavations induce complex soil stress redistribution from asymmetric unloading, with deep-to-shallow sequencing minimizing exterior wall deformation (≤0.12%He). For adjacent foundation pit groups, simultaneous excavation achieves minimum displacement interference, while phased construction requires prioritizing large-section excavation first to mitigate cumulative deformations through optimized stress transfer. When the spacing-to-depth ratio (B/He) is below 1, horizontal displacements of retaining structures increase by 43% due to spacing effects. This study quantifies the effects of excavation sequences and spacing configurations on pit group deformation, establishing a theoretical framework for optimizing construction strategies and enhancing retaining structure stability. The findings are highly significant for underground engineering design and construction in complex urban geological settings, especially in high-density areas with spatial and geotechnical constraints. Full article

This study addresses the sentiment classification of short texts in teaching evaluations. To mitigate concerns regarding data security in cloud-based sentiment analysis and to overcome the limited feature extraction capacity of traditional deep-learning methods, we propose a distributed symmetric approximate homomorphic hybrid sentiment classification model, denoted BHE+ALBERT-Mixplus. To enable homomorphic encryption of non-polynomial functions within the ALBERT-Mixplus architecture—a mixing-and-enhancement variant of ALBERT—we introduce the BHE (BERT-based Homomorphic Encryption) algorithm. The BHE establishes a distributed symmetric approximation workflow, constructing a cloud–user symmetric encryption framework. Within this framework, simplified computations and mathematical approximations are applied to handle non-polynomial operations (e.g., GELU, Softmax, and LayerNorm) under the CKKS homomorphic-encryption scheme. Consequently, the ALBERT-Mixplus model can securely perform classification on encrypted data without compromising utility. To improve feature extraction and enhance prediction accuracy in sentiment classification, ALBERT-Mixplus incorporates two core components: 1. A meta-information extraction layer, employing a lightweight pre-trained ALBERT model to capture extensive general semantic knowledge and thereby bolster robustness to noise. 2. A hybrid feature-extraction layer, which fuses a bidirectional gated recurrent unit (BiGRU) with a multi-scale convolutional neural network (MCNN) to capture both global contextual dependencies and fine-grained local semantic features across multiple scales. Together, these layers enrich the model’s deep feature representations. Experimental results on the TAD-2023 and SST-2 datasets demonstrate that BHE+ALBERT-Mixplus achieves competitive improvements in key evaluation metrics compared to mainstream models, despite a slight increase in computational overhead. The proposed framework enables secure analysis of diverse student feedback while preserving data privacy. This allows marginalized student groups to benefit equally from AI-driven insights, thereby embodying the principles of educational equity and inclusive education. Moreover, through its innovative distributed encryption workflow, the model enhances computational efficiency while promoting environmental sustainability by reducing energy consumption and optimizing resource allocation. Full article

The study presents the first application of the Connected Linear Network (CLN) package implemented in MODFLOW-USG to an existing Ground-Source Heat Pump (GSHP) system. The numerical element was specifically adapted by the authors in a previous study to simulate vertical Borehole Heat Exchangers (BHEs) and is here applied for the first time to evaluate the heat transfer in Milano subsurface induced by a GSHP system. The evaluation of interference between geothermal systems and wells is an important topic, especially in densely populated areas, which has scarcely been explored in the literature. Specifically, the aim is to evaluate the thermal perturbation and the possible interference between BHE systems and the drinkable water wells of the Armi pumping station managed by MM S.p.A. The simulation results show moderate groundwater thermal perturbation: approximately 3 °C at 100 m downgradient of the borefield and, furthermore, a limited impact (maximum 1 °C) in just two wells of the Armi pumping station. After 3 years of GSHP system operation, the thermal perturbation can extend for kilometers, but with limited variation in groundwater temperature (lower than 1 °C). Although the predicted groundwater temperature variation is not critical, the real-time monitoring of temperatures coupled with numerical modeling is essential to prevent thermal interference and optimize GSHP system performance. Full article

In this work, the seasonal performance of a dual-source heat pump (DSHP) prototype, able to exploit aerothermal and geothermal energy, was assessed experimentally. The unit, operated under the working conditions of two representative heating days (RDs), was coupled to a real undersized borehole heat exchanger (BHE) field. A distributed temperature sensing (DTS) system, installed in the borefield, was adopted to monitor the ground thermal response during the DSHP operation. In order to compare the DSHP performance to that of a traditional air-source heat pump (ASHP), the same RDs were reproduced in the test rig operating the DSHP in air mode only, and then exploiting both heat sources. Comparing the efficiency of the DSHP and ASHP, it is noticed that the additional exploitation of geothermal energy can increase system efficiency by up to 3% on a seasonal basis. Indeed, the DSHP coupled to an undersized BHE can operate in ground mode until it is energy-efficient; then, the required building load is supplied by exploiting the aerothermal energy source. In this way, the BHE investment cost can be reduced, and the ground temperature drift originating from unbalanced building loads can be limited through the smart exploitation of both sources. Full article

Energy transition is a challenge for remote northern communities mainly relying on diesel for electricity generation and space heating. Solar-assisted ground-coupled heat pump (SAGCHP) systems represent an alternative that was investigated in this study for the Kuujjuaq Forum, a multi-activity facility in Nunavik, Canada. The energy requirements of community buildings facing a subarctic climate are poorly known. Based on energy bills, technical documents, and site visits, this study provided an opportunity to better document the energy consumption of such building, especially considering the recent solar photovoltaic (PV) system installed on part of the roof. A comprehensive model was developed to analyze the building’s heating demand and simulate the performance of a ground-source heat pump (GSHP) coupled with PV panels. The air preheating load, accounting for 268,200 kWh and 47% of the total heating demand, was identified as an interesting and realistic load that could be met by SAGCHP. The GSHP system would require a total length of at least 8000 m, with boreholes at depths between 170 and 200 m to meet this demand. Additional PV panels covering the entire roof could supply 30% of the heat pump’s annual energy demand on average, with seasonal variations from 22% in winter to 53% in spring. Economic and environmental analysis suggest potential annual savings of CAD 164,960 and 176.7 tCO₂eq emissions reduction, including benefits from exporting solar energy surplus to the local grid. This study provides valuable insights on non-residential building energy consumption in subarctic conditions and demonstrates the technical viability of SAGCHP systems for large-scale applications in remote communities. Full article

The increasingly severe energy crisis and associated environmental issues pose new challenges for the efficient and rational utilization of renewable energy. The solar-assisted ground-source heat pump (SAGSHP) system is a novel heating system that effectively combines the advantages of both solar and geothermal energy. In this study, an SAGSHP system was established through TRNSYS simulation software to provide winter heating and year-round domestic hot water for a residential building. By varying the area of solar collectors (A) and the number (n) and the depth (H) of the borehole heat exchangers (BHEs), the system operational performance, including the system energy consumption, ground temperature attenuation, and heat pump efficiency, was investigated. A comparison with a single ground-source heat pump (GSHP) system was also conducted. After 20 years of operation, the parameter optimization resulted in a reduction of approximately 60 MWh and 70 MWh in system energy consumption, equivalent to saving 7.37 t and 8.60 t of standard coal, respectively. At the same time, the total costs over 20 years can be reduced by 48.20% and 33.77%, respectively. The proposed design method and simulation results can serve as the reference for designing and analyzing the performance of the SAGSHP system. Full article

The storage of thermal energy within the ground serves as a method to balance irregular energy consumption for heating throughout the year. This principle revolves around the accumulation of thermal energy during the summer months, allowing for its utilization for heating buildings during the winter months. This paper focuses on the technique of storing heat energy in the ground, known as borehole thermal energy storage (BTES), via borehole heat exchangers (BHE), which are designed to harness shallow geothermal energy for heating and cooling purposes. The model of regenerating heat in rocks, after subcooling of the ground in winter months, could be conducted by storing solar energy using a panel collector. The method of solar heat regeneration on a real building with a high number of BHEs was analyzed, with special attention on certain restrictions. In climates such as northern Croatia with cold winters and warm to hot summers, where besides heating loads there are certain cooling loads present, the implementation of this ground temperature regeneration method on the cooling and heating efficiency of heat pumps was studied. This paper presents research on the possibility of using this field as a BTES system coupled with solar collectors in a climate with both heating and cooling loads present. Full article

The performance of a conventional Ground-Source Refrigeration and Air Conditioning (GSRAC) system with a borehole heat exchanger (BHE) can be enhanced by addressing the soil thermal imbalance issue that affects these systems. This study proposes a novel concept for seasonal cold energy storage using a Thermal Diode Tank (TDT). The TDT consists of an insulated water tank fitted with an array of heat pipes. By integrating the TDT into a conventional GSRAC system, “cold” energy can be passively collected from ambient air during winter, injected into the BHE, and stored in the soil. The stored “cold” energy can then be retrieved in the summer, facilitating cross-seasonal cold energy storage (CS). Thus, a conventional GSRAC system can be transformed into a GSRAC system with cross-seasonal cold energy storage capability, i.e., GSRAC + CS system. The validated BHE model previously developed by the authors is used to predict the performance improvements achieved using the GSRAC + CS system. The results indicate that the Annual Net Cold Energy Storage Efficiency (ANESE) increased from 5.7% to 10.7% over a ten year period. The average Borehole Performance Improvement (BPI) due to the addition of cold storage capability is 11% over the same timeframe. This study also discusses the impacts of varying design and operational parameters on ANESE and BPI. The results demonstrate that GSRAC + CS systems not only mitigate the soil thermal imbalance issue faced by conventional GSRAC systems, but also require less BHE depth to achieve equivalent performance. Full article