Search Results (634)

Since the hydrogen-production process is not yet fully efficient, this paper proposes a poly-generation system that is driven by a geothermal energy source and utilizes a combined Kalina/organic Rankine cycle coupled with an electrolyzer unit to produce, simultaneously, power and green hydrogen in an efficient way. A comprehensive thermodynamic analysis and an exergetic evaluation are carried out to assess the effect of key system parameters (geothermal temperature, high pressure, ammonia–water concentration ratio, and terminal thermal difference) on the performance of concurrent production of power and green hydrogen. Thereby, two configurations are investigated with/without the separation of turbines. The optimal ammonia mass fraction of the basic solution in KC is identified, which leads to an overall optimal system performance in terms of exergy efficiency and green hydrogen production rate. In both configurations, the optimal evaluation is made possible by conducting a genetic algorithm optimization. The simulation results without/with the separation of turbines demonstrate the potential of the suggested cycle combination and emphasize its effectiveness and efficiency. Exemplary, for the case without the separation of turbines, it turns out that the combination of ammonia–water and MD2M provides the best performance with net power of 1470 kW, energy efficiency of 0.1184, and exergy efficiency of 0.1258 while producing a significant green hydrogen amount of 620.17 kg/day. Finally, an economic study allows to determine the total investment and payback time of $3,342,000 and 5.37 years, respectively. The levelized cost of hydrogen (LCOH) for the proposed system is estimated at 3.007 USD/kg H₂, aligning well with values reported in the literature. Full article

Background/Objectives: Soft tissues are essential for maintaining the function and long-term success of dental implants. In many cases, implant placement necessitates soft tissue augmentation procedures such as free gingival grafts (FGGs) or connective tissue grafts (CTGs) to restore lost gingival architecture. Nevertheless, a significant challenge associated with FGG and CTG is postoperative pain, largely due to morbidity at the palatal donor site. To address this issue, various approaches have been proposed to reduce patient discomfort and promote improved wound healing at the donor site. This study aimed to compare the effectiveness of four different methods for protecting the palatal donor site following free gingival graft harvesting. Methods: A total of 76 patients undergoing implant therapy with an indication for free gingival grafting were selected and divided into four groups based on the method used to protect the palatal donor site: an absorbable gelatin sponge secured with sutures (GS); an absorbable gelatin sponge with sutures and cyanoacrylate tissue adhesive (GS+CTA); oxidized regenerated cellulose combined with cyanoacrylate tissue adhesive (ORC+CTA); and an absorbable gelatin sponge covered with a flowable resin composite and stabilized with sutures (GS+FRC). The effectiveness of each method was evaluated in terms of postoperative pain, bleeding, and wound healing. Results: Although the differences in pain intensity among the groups were not statistically significant throughout the observation period (p > 0.05), the GS+FRC group consistently exhibited the lowest mean pain scores. No statistically significant differences were observed between the groups regarding the incidence of secondary bleeding. The highest mean wound healing rate was recorded in the GS+FRC group (75.95 ± 18.75%), whereas the ORC+CTA group demonstrated the lowest rate (43.66 ± 25.74%). Conclusions: The use of an absorbable gelatin sponge covered with a flowable resin composite and secured with sutures, despite the presented limitations, appears to be a promising approach for palatal wound protection. While this group consistently demonstrated the lowest mean pain scores, differences in pain intensity among the groups were not statistically significant. Nonetheless, it achieved the most favorable outcomes in terms of wound epithelialization. Full article

This study investigates the exergoeconomic performance of a milk pasteurization system powered by geothermal energy, operating across geothermal source temperatures (GSTs) ranging from 80 °C to 110 °C. The system uses geothermal heat as its primary energy source, while the cooling process is supported by a vapor compression refrigeration cycle driven by electricity generated through an Organic Rankine Cycle (ORC). The analysis was carried out in three stages: determining system parameters for each GST level, conducting detailed energy and exergy analyses, and performing an exergoeconomic evaluation using the specific exergy costing (SPECO) method. The results show that both energy and exergy efficiencies decline as GST increases. Energy efficiency varies between 88.30% and 78.53%, while exergy efficiency ranges from 72.86% to 58.02%. In parallel, unit-specific manufacturing costs increase with higher GST. Electricity production costs range from 610 to 900 USD·MWh⁻¹, and the cost of pasteurized milk varies between 3.76 and 6.53 USD·ton⁻¹. These findings offer practical insights into how geothermal source temperature affects the thermodynamic and economic performance of such systems, contributing to the broader understanding of sustainable dairy processing technologies. Full article

The article discusses the current challenges facing the energy sector in the context of climate policy, technological transformation, and the urgent need to increase energy efficiency while reducing greenhouse gas emissions. Modern thermal energy conversion technologies are analyzed, including supercritical steam and gas–steam cycles, as well as distributed systems using renewable fuels and microturbines. Particular attention is given to innovative systems with isothermal expansion, which theoretically allow operation close to the efficiency limit defined by the Carnot cycle. The study presents calculation results for conventional systems (steam, gas with regeneration, and Organic Rankine Cycle) and proposes a novel isothermal air turbine cycle. In a combined gas–steam configuration, the proposed cycle achieved an efficiency exceeding 43% at a relatively low heat source temperature of 700 K, clearly outperforming conventional steam and ORC systems under the same thermal conditions. The use of a simple working medium (air), combined with the potential for integration with renewable energy sources, makes this concept a promising and viable alternative to traditional Rankine and Brayton cycles in thermally constrained applications. Full article

Introduction: The role of urethrectomy at the time of Robotic-Assisted or Open Radical Cystectomy (RARC, ORC) is controversial. Whether urethrectomy should be performed at the time of RARC/ORC or delayed up to a 3–6 month interval is unclear. We performed a retrospective cohort analysis of perioperative and survival outcomes in patients with high-risk NMIBCs or non-metastatic MIBCs at our institution who underwent either concomitant or deferred urethrectomy after RC. Materials and Methods: cTis-T1 or cT2-T4, N0-1, M0 BC patients who underwent RARC or ORC from 2009 to 2024 were reviewed. Clinical, demographic, tumour, and patient characteristics and perioperative variables were assessed across concomitant and delayed urethrectomy groups. Multivariate logistic analysis was performed to estimate the impact of significant variables on intraoperative and postoperative outcomes. Univariable Kaplan–Meier and multivariable Cox regression modelling was implemented to explore the relative effect of time of urethrectomy on progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS). Results: A total of n = 58 patients (n = 47 delayed vs. n = 11 concomitant) with similar demographic characteristics were included. The concomitant urethrectomy group experienced longer operative time and greater blood loss (379 ± 65 min and 430 ± 101 mL vs. 342 ± 82 min and 422 ± 125 mL, with p = 0.049 and p = 0.028, respectively). Hospital readmission rates were higher in the concomitant urethrectomy group (36.4% vs. 8.5%, p = 0.016; OR: 17.9; 95% CI 1.2–265; p = 0.036). In Cox regression analysis, the timing of urethrectomy had no influence on PFS, CSS, or OS (all p > 0.05). Conclusions: Our study suggests that urethrectomy can be safely deferred unless urothelial disease is clearly present pre- or intraoperatively without compromising survival outcome and with the advantage of reducing surgical morbidity at the time of RC. Full article

This research introduces a two-stage, low-carbon industrial heating process, leveraging advanced waste heat recovery (WHR) technologies and exploiting waste heat (WH) to drive decentralised hydrogen production. This study is supported by a data-driven analysis of individual technologies, followed by 0D modelling of the integrated system for technical and feasibility assessment. Within 10 years, the EU industry will be supported by two main strategies to transition to low-carbon energy: (a) shifting from grid-mix electricity towards fully renewable sources, and (b) expanding low-carbon hydrogen infrastructure within industrial clusters. On the demand side, process heating in the industrial sector accounts for 70% of total energy consumption in industry. Almost one-fifth of the energy consumed to fulfil the process heat demand is lost as waste. The proposed heating solution is tailored for process heat in industry and stands apart from the dual-mode residential heating system (i.e., heat pump and gas boiler), as it is based on integrated and simultaneous operation to meet industry-level reliability at higher temperatures, focusing on WHR and low-carbon hydrogen. The solution uses a cascaded heating approach. Low- and medium-temperature WH are exploited to drive high-temperature heat pumps (HTHPs), followed by hydrogen burners fuelled by hydrogen generated on-site by electrolysers, which are powered by advanced WHR technologies. The results revealed that the deployment of the solution at scale could fulfil ~14% of the process heat demand in EU/UK industries by 2035. Moreover, with further availability of renewable energy sources and clean hydrogen, it could have a higher contribution to the total process heat demand as a low-carbon solution. The economic analysis estimates that adopting the combined heating solution—benefiting from the full capacity of WHR for the HTHP and on-site hydrogen production—would result in a levelised cost of heat of ~EUR 84/MWh, which is lower than that of full electrification of industrial heating in 2035. Full article

With the widespread application of unmanned aerial vehicle technology in navigation mark inspection, path planning algorithm efficiency has become crucial to improve inspection effectiveness. The traditional self-organizing mapping (SOM) algorithm suffers from dual limitations in UAV inspection path optimization, including insufficient global exploration during early training stages and susceptibility to local optima entrapment in later stages, resulting in limited inspection efficiency and increased operational costs. For this reason, this study proposes two improved self-organizing mapping algorithms. First, the ORC_SOM algorithm incorporating a generalized competition mechanism and local infiltration strategy is developed. Second, the ORCTS_SOM hybrid optimization model is constructed by integrating the Tabu Search algorithm. Validation using two different scale navigation mark datasets shows that compared with traditional methods, the proposed improved methods achieve significantly enhanced path planning optimization. This study provides effective path planning methods for unmanned aerial vehicle navigation mark inspection, offering algorithmic support for intelligent maritime supervision system construction. Full article

The present study reports the outcome of an experimental study of organic vapor trailing edge flows. As a working fluid, the organic vapor Novec 649 was used under representative pressure and temperature conditions for organic Rankine cycle (ORC) turbine applications characterized by values of the fundamental derivative of gas dynamics below unity. An idealized vane configuration was placed in the test section of a closed-loop organic vapor wind tunnel. The effect of the Reynolds number was assessed independently from the Mach number by charging the closed wind tunnel. The airfoil surface roughness and the trailing edge shape were evaluated by experimenting with different test blades. The flow and the loss behavior were obtained using Pitot probes, static wall pressure taps, and background-oriented schlieren (BOS) optics. Isentropic exit Mach numbers up to 1.5 were investigated. Features predicted via a simple flow model proposed by Denton and Xu in 1989 were observed for organic vapor flows. Still, roughness affected the downstream loss behavior significantly due to shockwave boundary-layer interactions and flow separation. The new experimental results obtained for this organic vapor are compared with correlations from the literature and available loss data. Full article

Using waste biomass as a raw material for the combined production of electricity and heat offers corresponding energy, economic, environmental and resource efficiency benefits. The study examines both the performance of a system for combined energy production based on the Organic Rankine Cycle (ORC) utilizing wood biomass and the market interest in its deployment within Bulgaria. Its objective is to propose a technically and economically viable solution for the recovery of waste biomass through the combined production of electricity and heat while simultaneously assessing the readiness of industrial and municipal sectors to adopt such systems. The cogeneration plant incorporates an ORC module enhanced with three additional economizers that capture residual heat from flue gases. Operating on 2 t/h of biomass, the system delivers 1156 kW of electric power and 3660 kW of thermal energy, recovering an additional 2664 kW of heat. The overall energy efficiency reaches 85%, with projected annual revenues exceeding EUR 600,000 and a reduction in carbon dioxide emissions of over 5800 t/yr. These indicators can be achieved through optimal installation and operation. When operating at a reduced load, however, the specific fuel consumption increases and the overall efficiency of the installation decreases. The marketing survey results indicate that 75% of respondents express interest in adopting such technologies, contingent upon the availability of financial incentives. The strongest demand is observed for systems with capacities up to 1000 kW. However, significant barriers remain, including high initial investment costs and uneven access to raw materials. The findings confirm that the developed system offers a technologically robust, environmentally efficient and market-relevant solution, aligned with the goals of energy independence, sustainability and the transition to a low-carbon economy. Full article

This paper discusses a thorough analysis, as well as the design, of an environmentally friendly, single-stage Organic Rankine Cycle (ORC) system, particularly optimized for untapped geothermal applications in Pakistan that are secluded and off-grid, to tackle the severe energy crises choking this country and its resources. Keeping in mind its Global Warming Potential (GWP), as well as its performance in the ORC, r600a was chosen as the operating fluid. This study focuses on varying the temperature, pressure, and mass flow rate of not only the geothermal reservoir but that of the operating fluid in the ORC as well. The impacts of adjusting these parameters on the net power output, cycle efficiency, and component-wise exergy destruction, as well as the total exergy destruction, are examined extensively. Analyses of the component-wise exergy destruction found that the maximum exergy destruction occurred in the evaporator, whereas it was discovered that decreasing the condenser pressure below 350 kPa led to negative exergy destruction values, although the total exergy destruction remained positive. Full article

Combining Organic Rankine Cycles (ORC) with cooling cycles offers a promising approach to achieving greater outputs within a single system. In this study, a novel directly combined ORC-VCC system has been designed to not only meet the cooling demand using a geothermal heat source but also generate power. The proposed novel ORC-VCC system has been analyzed for its energetic performance using four selected fluids: R290, R600a, R601, and R1234ze(E). Parametric analysis has been conducted to investigate the effects of parameters of heat source temperature, heat source mass flow rate, cooling capacities, condenser temperature, ORC evaporator temperature, pinch point temperature difference and isentropic efficiencies on net power production. Among the working fluids, R290 has provided the highest net power production under all conditions in which it was available to operate. Additionally, the results have been analyzed concerning a reference cycle for comparative evaluation. The proposed novel cycle has outperformed the reference cycle in all investigated cases in terms of net power production such as demonstrating an improvement of approximately from 8.7% to 57.8% in geothermal heat source temperature investigations. Similar improvements have been observed over the reference cycle at lower heat source mass flow rates, where net power increases by up to 50.8%. Full article

Background/Objectives: While robot-assisted radical cystectomy (RARC) has shown potential benefits over open radical cystectomy (ORC), such as reduced blood loss and quicker recovery, its adoption has been limited because of its complexity and long learning curve, especially for urinary diversion. We assessed whether a RARC program with fully intracorporeal urinary diversion could be safely implemented in a hospital with no prior experience in RARC, but with expertise in ORC and other robotic surgeries. We also compared perioperative outcomes and complications between RARC and ORC during the implementation phase. Methods: This retrospective comparative study included 50 consecutive patients who underwent RARC between June 2023 and January 2025 and 50 patients previously treated with ORC. All RARC cases were performed with intracorporeal urinary diversion. A structured proctoring program guided two surgeons through a stepwise training approach by an expert RARC surgeon. Perioperative outcomes and 90-day complications were compared. Results: All RARC procedures were completed fully intracorporeally with no conversions to open surgery. Compared with ORC, RARC was associated with significantly shorter operative times (for ileal conduit diversion) and hospital stays, lower estimated blood loss, and fewer postoperative complications. There were no differences in intraoperative complications. Worst single grade ≥ 3 complications were significantly less frequent in the RARC than the ORC group (11 [11%] versus 21 [21%], p = 0.045). On multivariable analysis, the robotic approach independently predicted fewer any-grade complications (odds ratio 0.81, 95% confidence intervals 0.65–0.95, p = 0.01). Conclusions: A RARC program can be safely and effectively implemented in a previously RARC-naïve centre with existing surgical expertise. The robotic approach offers clear perioperative benefits and may represent a favourable alternative to open surgery. Full article

The worldwide need for energy as well as environmental challenges have promoted the creation of sustainable power solutions. The combination of different working fluids is used for an organic Rankine cycle-powered vapor compression cycle (ORC-VCC) to deliver cooling applications. The selection of an appropriate working fluid significantly impacts system performance, efficiency, and environmental impact. The research evaluates possible working fluids to optimize the ORC-VCC system. Firstly, Artificial Neural Network (ANN)-derived models are used for exergy destruction ( E d t o t ) and heat exchanger total heat transfer capacity ( U A t o t ). Later on, multi-objective optimization was carried out using the acquired models for E d t o t and U A t o t using the Genetic Algorithm (GA) followed by the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The optimization results showcase Decane ORC-R600a VCC as the best candidate for the ORC-VCC system; the values of E d t o t and U A t o t were found to be 24.50 kW and 6.71 kW/K, respectively. The research data show how viable it is to implement biogas-driven ORC-VCC systems when providing air conditioning capabilities. Full article

The organic Rankine cycle (ORC) is a key technology for the recovery of low-grade waste heat, but its efficient and stable operation is challenged by complex kinetic coupling. This paper proposes a model partitioning strategy based on gap measurement to construct a high-fidelity ORC system model and combines the setting of observer decoupling and multi-model switching strategies to reduce the coupling impact and enhance adaptability. For control optimization, the reinforcement learning method of deep deterministic Policy Gradient (DDPG) is adopted to break through the limitations of the traditional discrete action space and achieve precise optimization in the continuous space. The proposed DDPG-MGPC (Hybrid Model Predictive Control) framework significantly enhances robustness and adaptability through the synergy of reinforcement learning and model prediction. Simulation shows that, compared with the existing hybrid reinforcement learning and MPC methods, DDPG-MGPC has better tracking performance and anti-interference ability under dynamic working conditions, providing a more efficient solution for the practical application of ORC. Full article

Background: Epigenomic instability accelerates mutations in tumor suppressor genes and oncogenes, contributing to malignant transformation. Histone modifications, particularly methylation and acetylation, significantly influence tumor biology, with chromo-, bromo-, and Tudor domain-containing proteins mediating these changes. This study investigates how genes encoding these domain-containing proteins affect colorectal cancer (CRC) prognosis. Methods: Using CRC data from the GSE39582 and TCGA datasets, we identified domain-related genes via GeneCards and developed a prognostic signature using LASSO-COX regression. Patients were classified into high- and low-risk groups, and comparisons were made across survival, clinical features, immune cell infiltration, immunotherapy responses, and drug sensitivity predictions. Single-cell analysis assessed gene expression in different cell subsets. Results: Four domain-related genes (AKAP1, ORC1, CHAF1A, and UHRF2) were identified as a prognostic signature. Validation confirmed their prognostic value, with significant differences in survival, clinical features, immune patterns, and immunotherapy responses between the high- and low-risk groups. Drug sensitivity analysis revealed top candidates for CRC treatment. Single-cell analysis showed varied expression of these genes across cell subsets. Conclusions: This study presents a novel prognostic signature based on domain-related genes that can predict CRC severity and offer insights into immune dynamics, providing a promising tool for personalized risk assessment in CRC. Full article