Search Results (82)

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

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 mechanism of the DA cycloaddition reaction between the pyridine adduct of borabenzene and acetylene has been investigated using topological analysis of the electron localization function (ELF) and catastrophe theory (bonding evolution theory, BET). The study focuses on the differences in the electronic structures of C-C and C-B bonds during their formation. Additionally, the influence of electron density functionals with different constructions (B3LYP, CAM-B3LYP, B2PLYP, M06, M062X, and M052X) on the BET results was examined. The reaction proceeds through ten distinct phases. The B-C bond forms first, followed by the C-C bond. Significant differences were observed in the behavior of the non-bonding basins V(C) and V(B) compared to the V(C), V(C) basins, which precede the formation of the bonding basins V(B,C) and V(C,C). The use of different functionals results in quantitative variations in the lengths and positions of the reaction phases—for example, relative to the transition state structure. A possible qualitative influence on the overall picture of the reaction mechanism is suggested by the results obtained using the CAM-B3LYP and B2PLYP functionals, particularly in phases VI and VII. Full article

Background: PC has become a significant global health challenge, with incidence and mortality rates rising over the past three decades. While traditionally associated with aging, recent data indicate an increasing burden among younger populations. This study aims to analyze global trends in PC incidence and mortality and to identify key contributing factors, particularly modifiable risk factors such as obesity, diabetes, and smoking. Methods: Using data from the Global Burden of Disease Study (GBD) 2021, population-based cancer registries globally and nationally, systematic reviews and analysis trends in PC incidence, mortality and survival were analyzed. To assess epidemiological shifts, we utilized previously published annual percentage change (AAPC) values stratified by region, age group, and sex, as reported in the cited literature. Additionally, the influence of modifiable risk factors was evaluated to determine their contribution to rising incidence rates. Results: Between 1990 and 2021, the global incidence of PC increased by 8.9%, from 5.47 to 5.96 per 100,000, with the highest rates observed in high-Sociodemographic-Index (SDI) regions (10.00 per 100,000) and the lowest in low-SDI regions (1.59 per 100,000). Significant increases in incidence were noted in several countries, particularly among men in Iceland (AAPC 8.85) and women in Malta (AAPC 6.04). Early-onset PC is becoming more prevalent, especially among younger women. Modifiable risk factors, including obesity, diabetes, and smoking, play a critical role, with excess body weight contributing to 17.9% of PC cases and smoking to 13.9% in the United States (U.S.). Conclusions: The rising burden of PC, particularly among younger populations, highlights the need for targeted prevention strategies, early detection efforts, and further research into the underlying mechanisms driving these trends. Addressing modifiable risk factors could be key to mitigating the increasing incidence of this highly lethal cancer. Full article

In this work, novel sodium-intercalated vanadium oxide nanowire electrode materials (NaXV@CC) were successfully designed as cathode materials for Aqueous Zinc-Ion Batteries (AZIBs) through a two-step electrochemical process. The optimized electrode material, Na30V@CC, exhibited superior capacity, excellent rate capability, and outstanding stability. The intercalation of sodium ions into the nanowire lattice induced a significant transformation in the overall nanostructure, leading to altered nanowire morphology. This unique structural design provided abundant active sites and efficient ion transport pathways, thereby enhancing the overall electrochemical performance. The charging and discharging capacities were 343.3 and 330.4 mAh·g⁻¹ at 0.2 A·g⁻¹, respectively, and the capacity was maintained at 90 mAh·g⁻¹ at 8 A·g⁻¹. The battery demonstrated exceptional capacity retention over 3000 cycles at 5 A·g⁻¹, highlighting its long-term electrochemical stability. Moreover, the overall battery reaction was governed by a combination of diffusion and surface processes. The Na30V@CC battery system demonstrated reduced reaction impedance and improved zinc ion diffusion rates. This study offers valuable insights into enhancing the electrochemical performance of vanadium-based cathodes in AZIBs. Full article

The frequency of publications on value co-creation (VCC) in marketing has significantly increased. However, in business-to-business (B2B), it is underexplored, and there is no consensus regarding its antecedents and consequences. This systematic literature review (SLR) aims to identify, define, and categorize the antecedents and consequences to have a better comprehension of VCC in B2B. We conducted a comprehensive search for the keyword value co-creation, B2B, relationships, antecedents, consequences, and relationship quality in the Web of Science (WoS) core collection database and Scopus. By following Denyer and Tranfield’s five-step approach for SLR, we established research questions and selected, analyzed, and synthesized the relevant studies. We also followed Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA 2009, 2020) guidelines for screening articles, which led us to the analysis of 39 relevant articles. Our findings contribute to the research of VCC through the identification and categorization of antecedents and consequences of VCC into 20 initial groups, respectively, which provided a holistic view. Furthermore, notably, we revealed that the 39 papers employed 30 theoretical frameworks and models, which guided us to the presentation of the Theories Context Methods—Antecedents Value Co-creation Consequences model (TCM-AVC). The model further reduced the initially identified 20 groups into 6 and 5 categories of antecedents and consequences, respectively. Additionally, the findings extracted from those papers were segregated into eight novel streams, which opened fresh avenues for future research. These findings collectively enrich our understanding and provide practical implications for business practitioners in regards to the implementation of short-, medium-, and long-term sustainable VCC strategies to be effective and sustainable co-creators. Full article

As application conditions become increasingly demanding and usage becomes more aggressive, the performance of traditional insulated gate bipolar transistor (IGBT) and fast recovery diode (FRD) systems can no longer meet the required specifications. In these systems, FRDs are required to carry load current and allow current to return from the load to the IGBTs. Consequently, the reverse recovery performance of the FRDs significantly restricts the overall efficiency of the system. Therefore, how to predict the reverse recovery characteristics of the FRDs with greater precision has attracted considerable attention. In this context, this paper presents an in-depth investigation of the high-level injection carrier distribution and reverse recovery characteristics of punchthrough P-I-N (PT-PIN) FRD with a buffer layer. Specifically, the research explores the physical properties of the materials, doping concentrations, and the geometric structure of the devices. Furthermore, it takes into account the complex interactions among carrier recombination, diffusion, and drift, leading to the development of a model that delineates the spatial distribution of carriers and their influence on current conduction. Building upon the traditional step-wise analysis method, subsequently, the temporal aspects of the FRDs reverse recovery process were further segmented. Utilizing the derived carrier distribution model, a reverse recovery analytical model was constructed. The model was validated using a 1200 V, 100 A IGBT with 1200 V, 60 A FRD configured in a reverse parallel arrangement, which demonstrated a 5% improvement in prediction accuracy of V_R compared with previous models that employed the lumped charge method. Finally, a range of experiments with varying R_G, V_CC and I_F confirmed the broad applicability of this analytical model. Full article

Variable-Speed Hydropower Plants (VSHP) are becoming more promising for stabilising power grids with the increasing integration of renewable energy sources. This research focuses on improving fault ride-through capabilities and delivering efficient ancillary services for VSHPs to support the grid by developing a comprehensive control strategy. The control system proposed integrates a machine-side controller, a Frequency Support Controller (FSC), a Virtual Synchronous Machine (VSM), a Vector Current Controller (VCC) for the grid-side converter, a turbine governor for regulating turbine speed, and a DC-link controller. PID with an anti-windup scheme and a Model Predictive Controller (MPC) were employed for the turbine governor. The MPC turbine governor results demonstrate the potential of advanced control methods for enhanced performance of the VSHP. A benchmarking between the MPC and the PID governor was made. The benchmarking results have reported that the MPC can achieve reference tracking improvements up to $99.42\%$. Tests on a diverse set of grid scenarios were conducted, and the graphical results showed significant improvements in mitigating the frequency drops through the effective governor response. The synthetic inertia provision is swift, completing within seconds of a frequency drop. Compared to the fixed-speed approach, the VSHP improves the grid’s overall stability by minimising frequency dipping and achieving steady-state recovery remarkably faster. The fixed-speed approach only begins to recover minutes after the VSHP reaches the settling time. By effectively providing critical ancillary services such as frequency support, synthetic inertia, and smooth fault ride-through capability, the VSHP can become a transformative solution for future power grids, which are estimated to be more reliant on renewable energy sources. Full article

The paper proposes an original single-phase transformerless three-level (S-PT) photovoltaic (PV) inverter in the cascade H bridge (CHB) configuration. The DC-link voltage of the inverter is created by two serial voltage sources with a voltage twice as low as the DC-link voltage. An appropriate V_CC DC-link voltage is generated by a two-phase DC-DC boost converter, fed from the string panel output at a level determined by the maximum power point tracking (MPPT) algorithm. Two symmetrical sources with V_CC/2 are formed by a divider of two series-connected capacitors of large and the same capacitance. The common mode (CM) voltage of the proposed inverter is constant, and the voltage stresses across all switches, diodes and gate drive circuits are half of the DC-link voltage. The principles of operation of the S-PT inverter, an implementation of a complete gate control system with galvanic isolation for all IGBTs, are also presented. The proposed inverter topologies have been implemented using high-speed IGBTs and simulated in PSPICE, as well as being experimentally validated. Full article

The increasing demand for sustainable energy solutions has spurred significant interest in cogeneration technologies. This study introduces a novel integrated organic Rankine cycle (ORC) and vapor compression cycle (VCC) system, specifically designed to enhance energy efficiency and reduce greenhouse gas emissions in industrial applications and district heating systems. The key innovation lies in the development of an advanced coupling mechanism that seamlessly connects the ORC and VCC, enabling more efficient utilization of low-grade heat sources. By optimizing working fluid selection and implementing a shared shaft connection between the ORC turbine and VCC compressor, the system achieves dual functionality—simultaneous electricity generation and cooling—with higher efficiency than conventional methods. Thermodynamic analyses and experimental results demonstrate that the proposed ORC–VCC system can significantly reduce operational costs and decrease reliance on fossil fuels by leveraging renewable energy sources and industrial waste heat. Additionally, the study addresses integration challenges by introducing specialized components and a modular design approach that simplifies installation and maintenance. This innovative system not only enhances performance but also offers scalability for various industrial applications. By providing a detailed evaluation of the ORC–VCC integration and its practical implications, this work underscores the system’s potential to contribute substantially to a sustainable energy transition. The findings offer valuable insights for future research and development, highlighting pathways to overcome existing barriers in cogeneration technologies. Full article

Due to developments in vehicle engineering and communication technologies, vehicular networks have become an attractive and feasible solution for the future of electric, autonomous, and connected vehicles. Electric autonomous vehicles will require more data, computing resources, and communication capabilities to support them. The combination of vehicles, the Internet, and cloud computing together to form vehicular cloud computing (VCC), vehicular edge computing (VEC), and vehicular fog computing (VFC) can facilitate the development of electric autonomous vehicles. However, more connected and engaged nodes also increase the system’s vulnerability to cybersecurity and privacy breaches. Various security and privacy challenges in vehicular cloud computing and its variants (VEC, VFC) can be efficiently tackled using machine learning (ML). In this paper, we adopt a semi-systematic literature review to select 85 articles related to the application of ML for cybersecurity and privacy protection based on VCC. They were categorized into four research themes: intrusion detection system, anomaly vehicle detection, task offloading security and privacy, and privacy protection. A list of suitable ML algorithms and their strengths and weaknesses is summarized according to the characteristics of each research topic. The performance of different ML algorithms in the literature is also collated and compared. Finally, the paper discusses the challenges and future research directions of ML algorithms when applied to vehicular cloud computing. Full article

The urgent need for environmentally sustainable cooling technologies, driven by global regulatory constraints, has intensified the search for natural refrigerants with low global warming potential. This study evaluates the potential of natural refrigerants, specifically butane and isobutane, in advanced single- and dual-fluid Organic Rankine Cycle–Vapor Compression Cycle (ORC–VCC) systems to enhance energy efficiency and environmental sustainability. Using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) within a multi-objective framework, the optimization maximizes key performance metrics such as coefficient of performance (COP) and cooling power, while the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method enables a refined ranking of optimal solutions. Findings reveal that the isobutane (ORC)–butane (VCC) dual-fluid configuration achieves the highest overall COP of 0.447 and a cooling capacity of 35.517 kW, surpassing the reference fluid R1233zd, which attains a COP of 0.374 and a cooling capacity of 30.361 kW. Isobutane-based configurations consistently deliver higher COP and cooling capacities than R1233zd, highlighting isobutane’s suitability for applications demanding high energy efficiency. Pressure analysis revealed that R1233zd exhibits the highest pressure ratio of 4.10, necessitating more complex compressor designs. In contrast, isobutane configurations offer favorable pressure ratios and similar pressure parameters in both single and dual setups, simplifying compressor design requirements. This research provides valuable guidance for developing sustainable ORC–VCC systems by combining effective fluid selection and advanced multi-objective optimization techniques to meet both environmental and operational criteria. Full article

This research evaluated the impact of Lactobacillus starter cultures on post-acidification, viable cell counts (VCC), antioxidant activities (such as DPPH radical scavenging, Ferric Reducing Antioxidant Power (FRAP), and Ferrous Ion Chelating (FIC) activity), and sensory attributes of fermented camel milk (FCM) over a 21-day period at 4 °C. FCM was prepared with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. lactis (control), as well as with three different Lactobacillus starter cultures individually: Lacticaseibacillus rhamnosus, Lacticaseibacillus casei, and Lactiplantibacillus plantarum, in co-cultures with S. thermophilus and L. delbrueckii subsp. lactis. The findings indicated that FCM with L. rhamnosus experienced the most significant pH decrease (p < 0.05) throughout the storage period. L. plantarum-FCM maintained the highest VCC (p < 0.05) compared with the other samples. Additionally, all three Lactobacillus strains showed significantly higher (p < 0.05) DPPH radical scavenging and FRAP compared with the control by the end of the storage. However, L. casei exhibited the greatest FIC activity. Among the samples, L. plantarum was rated highest in taste, flavor, and overall preference. In conclusion, the incorporation of these Lactobacillus strains into camel milk during fermentation improved bacterial viability, enhanced antioxidant properties, and boosted sensory qualities, especially for flavor and texture, positioning it as a promising functional food product. Full article

In light of the intensifying global climate crisis and the increasing demand for efficient electricity and cooling systems, the exploration of advanced power generation technologies has become crucial. This paper presents a comprehensive analysis of Organic Rankine Cycle–Vapor Compression Cycle (ORC-VCC) systems utilizing low-grade waste heat for the dual purpose of electricity and cooling production. The study focuses on systems that harness waste heat below 90 °C with thermal inputs up to 500 kW. An in-house Python code was developed to calculate cycle parameters and perform multi-objective optimization targeting the maximization of both ORC-VCC efficiency and power output. The optimization was conducted for 10 different cases by evaluating five working fluids across two different ambient temperatures. The analysis reveals that the optimized system achieved an impressive overall cycle efficiency exceeding 90%, demonstrating the significant potential of ORC-VCC technology in waste heat recovery applications. The Non-Dominated Sorting Genetic Algorithm II (NSGA-II) multi-objective optimization approach was found to be particularly effective at navigating the multi-dimensional solution space and identifying the global optimum. This study provides valuable insights into system performance across a range of operating conditions and design parameters. Sensitivity analyses highlight key factors influencing cycle efficiency and power output. These findings have important implications for the development and deployment of ORC-VCC systems as a sustainable and efficient solution to meet growing energy needs while reducing greenhouse gas emissions. Full article

The increasing global demand for energy-efficient cooling systems, combined with the need to reduce greenhouse gas emissions, has led to growing interest in using low-GWP (global warming potential) refrigerants. This study conducts a multi-objective optimization of a small-scale organic Rankine cycle–vapor compression cycle (ORC-VCC) system, utilizing refrigerants R1233zd, R1244yd, and R1336mzz, both individually and in combination within ORC and VCC systems. The optimization was performed for nine distinct cases, with the goals of maximizing the coefficient of performance (COP), maximizing cooling power, and minimizing the pressure ratio in the compressor to enhance efficiency, cooling capacity, and mechanical reliability. The optimization employed the Non-dominated Sorting Genetic Algorithm III (NSGA-III), a robust multi-objective optimization technique that is well-suited for exploring complex, non-linear solution spaces. This approach effectively navigated trade-offs between competing objectives and identified optimal system configurations. Using this multi-objective approach, the system achieved a COP of 0.57, a pressure ratio around 3, and a cooling capacity exceeding 33 kW under the specified boundary conditions, leading to improved mechanical reliability, system simplicity, and longevity. Additionally, the system was optimized for operation with a cooling water temperature of 25 °C, reflecting realistic conditions for contemporary cooling applications. Full article