Efficient System Research Articles

Exploiting beam search confidence for energy-efficient speech recognition

AbstractWith mobile and embedded devices getting more integrated in our daily lives, the focus is increasingly shifting toward human-friendly interfaces, making automatic speech recognition (ASR) a central player as the ideal means of interaction with machines. ASR is essential for many cognitive computing applications, such as speech-based assistants, dictation systems and real-time language translation. Consequently, interest in speech technology has grown in the last few years, with more systems being proposed and higher accuracy levels being achieved, even surpassing human accuracy. However, highly accurate ASR systems are computationally expensive, requiring on the order of billions of arithmetic operations to decode each second of audio, which conflicts with a growing interest in deploying ASR on edge devices. On these devices, efficient hardware acceleration is key for achieving acceptable performance. In this paper, we propose a technique to improve the energy efficiency and performance of ASR systems, focusing on low-power hardware for edge devices. We focus on optimizing the DNN-based acoustic model evaluation, as we have observed it to be the main bottleneck in popular ASR systems, by leveraging run-time information from the beam search. By doing so, we reduce energy and execution time of the acoustic model evaluation by 25.6 and 25.9 %, respectively, with negligible accuracy loss.

Review on Nanofluids: Preparation, Properties, Stability, and Thermal Performance Augmentation in Heat Transfer Applications.

Nanoparticles play a crucial role in enhancing the thermal and rheological properties of nanofluids, making them a valuable option for increasing the efficiency of heat exchangers. This research explores how nanoparticle characteristics, such as concentration, size, and shape, impact the properties of nanofluids. Nanofluids' thermophysical properties and flow characteristics are essential in determining heat transfer efficiency and pressure loss. Nanoparticles with high thermal conductivity, such as metallic oxides like MgO, TiO2, and ZnO, can significantly improve the heat transfer efficiency by around 30% compared to the base fluid. The stability of nanofluids plays a crucial role in their usability. Various methods, such as adding surfactants, using ultrasonic mixing, and controlling pH, have been employed to enhance the stability of nanofluids. The desired thermophysical properties can be achieved by utilizing nanofluids to enhance the system's heat transfer efficiency. Modifying the size and shape of nanoparticles also considerably improves thermal conductivity, affecting nanofluid viscosity and density. Equations for determining heat transfer rate and pressure drop in a double-pipe heat exchanger are discussed in this review, emphasizing the significance of nanofluid thermal conductivity in influencing heat transfer efficiency and nanofluid viscosity in impacting pressure loss. This Review identifies a trend indicating that increasing nanoparticle volume concentration can enhance heat transfer efficiency to a certain extent. However, surpassing the optimal concentration can reduce Brownian motions due to higher viscosity and density. This Review offers a viable solution for enhancing the thermal performance of heat transfer equipment and serves as a fundamental resource for applying nanofluids in heat transfer applications.

A Reconfigurable Phase-Shifted Full-Bridge DC–DC Converter with Wide Range Output Voltage

This paper analyzes, designs and implements a reconfigurable phase-shifted full-bridge (PSFB) converter. It adopts the topology of the traditional PSFB converter and incorporates clamping circuits to solve some fundamental problems of conventional topology. In addition, auxiliary switches are employed for output reconfiguration, which allows expanding the output voltage range without compromising the system efficiency. Single pole double throw (SPDT) mechanical switches are used to realize series and parallel connections. In this paper, the characterization of the PSFB converter with clamping circuit and its design considerations are discussed. A 10 kW prototype with a power density of 0.485 W/cm3, 900 V input voltage and 400/800 V nominal output voltage was manufactured. The experimental results validated the analysis and confirmed the high conversion efficiency for a wide load range; an efficiency of 96.69% was obtained for the full load condition.

Root causes of first-case start time delays for elective surgical procedures: a prospective multicenter observational cohort study in Ethiopia

BackgroundDelays in surgery start times can lead to poor patient outcomes and considerable increases in healthcare expenditures. This is especially true in developing countries that often face systemic inefficiencies, such as a shortage of operating rooms and trained surgical personnel. With substantial effects on patient outcomes, healthcare efficiency, and resource allocation, identifying delays in first-case elective surgery is a crucial area of research.MethodsA multicenter observational study was conducted at three comprehensive and specialized hospitals in the Amhara region of Ethiopia from May 1 to October 30, 2023. The primary aim of the study was to determine the occurrence of late first-case start times, defined as a patient being in the operating room at or after the hospital’s incision time of 2:30 a.m. The secondary aim was to discover potential root causes of delayed first-case start times. All patients scheduled for elective surgery as the first case on the operating list throughout the study period were included in the study. Every emergency, day case, after-hours case, and canceled case was excluded.ResultsA total of 530 surgical patients were included during the study window from May 1 to October 1, 2023. Of these, 41.5% were general surgeries, 20.4% were gynecology and obstetrics surgeries, and 13.2% were orthopedic surgery procedures. Before the procedure started, nine (1.7%) of the participants had prolonged discussion with a member of the surgical team. Patients who arrived in the operating room waiting area at or after 2:30 a.m. were 2.5 times more likely to experience a first-case start time delay than those who arrived before or at 2:00 a.m. (AOR = 2.50; 95% CI: 1.13–5.14). Furthermore, participants with abnormal investigation results were 2.4 times more likely to have a late first-case start time (AOR = 2.41; 95% CI: 1.06, 5.50). Moreover, the odds of a late first-case start time were increased by 10.53 times with the surgeon being in the operating room at or after 2:30 a.m. (AOR = 10.53; 95% CI: 5.51, 20.11).ConclusionThe research highlights a significant occurrence of delayed start times for the first elective surgical procedures. Therefore, directing attention to aspects such as ensuring patients and surgical teams arrive promptly (by or before 2:00 a.m.) and timely evaluation and communication of investigative findings before the scheduled surgery day could facilitate efforts to maximize operating room efficiency and enhance patient health outcomes.

Integrating solar-driven biomass gasification and PV-electrolysis for sustainable fuel production: Thermodynamic performance, economic assessment, and CO2 emission analysis

Biomass gasification provides a promising pathway for sustainable fuel production. Nevertheless, its development is hindered by lower efficiencies in biomass–to–fuel energy conversion and carbon utilization, along with restricted scale due to economic collection radius. To tackle these challenges, a solar–biomass hybrid gasification system is proposed for sustainable fuel production. The system employs parabolic trough and tower concentrators to generate solar heat, driving the biomass pyrolysis and pyrolysis products gasification reactions to produce bio–solar syngas. The high–density bio–oil and char produced in distributed pyrolysis units can be economically transported to the centralized gasification plant. Moreover, PV–electrolysis water is utilized to generate H2 and O2, which are used to adjust syngas composition and substitute for air separation O2, respectively. Consequently, the energy consumption for water–gas shift, CO2 separation, and air separation units can be reduced. Thermodynamic, economic, and CO2 emission performance are analyzed for a typical case of methanol production using corn residue. The total energy conversion efficiency of the hybrid system can reach 65.01 %, representing an improvement of 6.57 % compared to the conventional biomass gasification system. The fuel production cost is estimated to be $354.1 per ton, falling within the market price range. Additionally, the greenhouse gas emissions to produce unit kg methanol can be reduced by 0.63 kg CO2eq. Furthermore, we analyzed the performance of six representative fuel production scenarios involving different types of biomass feedstocks. Finally, the limitations of this work and the feasibility of its practical applications are discussed. This study offers an innovative approach to bio-solar fuel production, promoting the development of circular bio-economy and the application of sustainable fuel.

Metaverse‐based remote support system with smooth combination of free viewpoint observation and hand gesture instruction

AbstractIn field operations with large machines, onsite large task spaces have been typically required. In these cases, remote skilled workers have to provide a step‐by‐step guide by observing the onsite situation around the large task spaces in three dimensions, instructing onsite unskilled workers on how to perform the tasks with the correct hand gestures at the right position, and switching between observation and instruction frequently during the remote support. In this study, we developed a Metaverse‐based remote support system with a seamless user interface for switching between free viewpoint observation and hand gesture instruction. The proposed system enables remote skilled workers to observe the onsite field from any viewpoint, transfer hand gesture instruction to onsite workers, and seamlessly switch between free viewpoint observation and free hand gesture instruction without having to change devices. We compared the time efficiency of the proposed system and a conventional system through experiments with 28 users and found that our system improved the observation time efficiency by 65.7%, the instruction time efficiency by 27.9%, and the switching time efficiency between observation and instruction by 14.6%. These results indicate that the proposed system enables remote skilled workers to support onsite workers quickly and efficiently.

Experimental and numerical simulation research on the transport process of bubble clusters in aeration system

Improving gas-liquid mass transfer efficiency in aeration systems contributes to energy savings, cost reduction, and enhanced efficiency in wastewater treatment. However, due to the complex nonlinear interactions among bubbles in turbulence, understanding the transport mechanisms of non-uniform bubble clusters in turbulence remains unclear. This study employs a combined approach of experimental research and numerical simulations to investigate the shape, diameter distribution, trajectory, and velocity of bubbles under different aeration port sizes and flow rates. The diameter distribution of bubble clusters exhibits a bimodal distribution. Bubble trajectories during ascent mainly exhibit two types of motion patterns: “Z” shaped and linear. Increasing aeration port size and flow rate both lead to an increase in the maximum bubble diameter. Higher initial flow rates and smaller port sizes induce greater lateral velocity fluctuations in bubbles. The proposed numerical simulation method serves as a reference for simulating the transport of non-uniform bubble clusters.

Experimental study on improving the thermal performance of isobutane refrigeration system by parameter optimization

Improvement of thermal efficiency for isobutane refrigeration system could match well with the building requirements of low-carbon, and sustainable development. The electric radiant heater (ERH) is widely used for the freeze and cold storage (FCS) system, but it has problems of high electric consumption and high freezer compartment temperature rise (FCTR) as a result of low heat-transfer efficiency under defrosting. Therefore, a novel FCS system with an additional electric radiant heater (AERH) based on the heat required for frost melted and synchronous defrosting is proposed. The defrosting consumption and the FCTR of the novel FCS system are comprehensively evaluated by a novel evaluation method. Besides, the effect of the thermal parameters (i.e., the defrosting pause temperature, the position, and electric power of the AERH) on the heat transfer characteristics are compared and optimized by the experimental method. Finally, a novel method is presented to predict the optimum thermal conditions. The results show that the optimum system thermal performance is obtained, the defrosting duration and defrosting consumption are reduced by 44.02 % and 37.03 %, and the defrosting efficiency and energy efficiency could be increased by 17.92 % and 9.96 %, respectively, as compared to the conventional FCS system. The proposed FCS system has better economic performance and heat transfer efficiency. Meanwhile, 30.54 kg of CO2 emissions could be avoided during the annual operation period, and the environmental benefits are also considerable. This study not only reaffirms the benefit of using the AERH for defrosting in the FCS system but also provides a reference for the promotion and application of efficient heat transfer technology in building refrigeration engineering.

The Optimization of Urban Traffic Routes Using an Enhanced Genetic Algorithm: A Case Study of Beijing South Railway Station

Optimizing travel routes in urban transportation networks is essential for enhancing traffic efficiency in major cities. This study focuses on optimizing the combined subway and taxi travel routes from Beijing Union University to Beijing South Railway Station, a critical route for students and staff in Beijing. To address this, we propose three genetic algorithms: the Standard Genetic Algorithm (SGA), the Multipoint Crossover and Elitist Selection Genetic Algorithm (MPEGA), and the Improved Dynamic Crossover and Mutation Rate Genetic Algorithm (IDCMGA). Experimental results indicate that MPEGA reduces the mean travel cost by 15.21%, the variance by 81.72%, and the standard deviation by 57.25% compared to SGA. Additionally, IDCMGA reduces the average by 1.76%, the variance by 63.16%, and the standard deviation by 39.30% compared to MPEGA. The improved IDCMGA algorithm demonstrates significant advantages over the other two algorithms in terms of global optimization capability, convergence speed, and stability, and is more adept at adapting to new traffic conditions to identify the optimal route. Optimizing this route not only reduces commuting time and costs but also alleviates traffic congestion, thereby enhancing the overall efficiency of the urban transportation system.

Appling machine learning for estimating total suspended solids in BFT aquaculture system

Biofloc Technology (BFT) systems are used to improve water quality and the production of aquatic organisms, and they influence dissolved oxygen, alkalinity, and pH, directly affecting the efficiency and success of this production system. Measuring total suspended solids (TSS) in water demands substantial investments and involves a time-consuming process to obtain results. This delay in obtaining results poses a significant challenge to the operations of these farms. In this study, we applied Artificial Neural Networks (ANN) and Support Vector Machine (SVM) methods based on artificial intelligence and water quality parameters (easy to measure, low cost, and quick response) to identify the most accurate method for measuring TSS. The best TSS estimate was achieved with SVM using nitrite and turbidity as predictive variables, which tended to overestimate the real value by 19 %, presenting a potential for application in estimating TSS in the BFT aquaculture system.

Development and assessment of a floating photovoltaic-based hydrogen production system integrated with storage options

The integrated system approach utilized in the current study represents an innovative approach to harnessing solar energy through a floating photovoltaic-based integrated plant featuring a diverse array of energy storage options. As part of this research, a solar energy system integrating both floating and concentrating solar technologies was designed at the specified site. Despite the constraints presented by the cold temperature at the chosen location, particularly during the winter months when solar irradiation is restricted, strategies are employed, such as exploiting the high albedo effect caused by the freezing of the water body, optimizing the application of solar radiation, and assuring the system's resilience and energy efficiency. Floating photovoltaic and concentrated solar panels are integral components of this advanced system, which is supplemented by underground hot and cold storage units, underground hydro-pumped storage, a multi-effect desalination system with freshwater storage, a lithium bromide absorption cooling system, and an alkaline electrolysis system for hydrogen and oxygen storage. This comprehensive energy strategy includes diverse storage and production technologies. The thermodynamic analyses and assessments employing the Engineering Equation Solver and the System Advisor Model provide some quantitative performance evaluations. The study considers time-dependent operational characteristics, illustrates the water withdrawal rates, energy and exergy efficiencies of the heating space temperature, inverter efficiency, GHI irradiance, mass, and volume values of the heat transfer fluid in both hot and cold tanks within thermal energy storage, annual cooling generation over a year, power production, hydropower storage, and hydrogen storage over a year. The system's concentrated solar panels are projected to generate an annual AC output of 180.79 GWh, with a yearly water usage of 14,055 m3, while floating panels are predicted to provide 7000 kWh with a 0.85 performance ratio. The overall energy efficiency of the current system is determined to be 51.76 %, and the exergy efficiency is found to be 55.41 %, respectively. Optimizing energy efficiency, utilizing diverse storage solutions, and utilizing aquatic environments minimizes environmental impact, and time-dependent analysis enhances perceptions of performance throughout different times and circumstances.

Solar energy powered biodiesel synthesis from linseed oil – A novel experimental study

In developing countries such as India, there is a significant dependency on fossil fuels, which make up a substantial 70 % of their overall energy requirements. Nevertheless, this reliance becomes increasingly precarious as global reserves of fossil fuels continue to deplete due to their extensive consumption. Biodiesel offers a sustainable alternative to conventional fossil fuels, contributing to reduced greenhouse gas emissions and enhanced energy security. This research centres on developing a solar energy powered transesterification system for biodiesel production using a KOH catalyst. The main goal is to address technological, economic, and sustainability challenges in biodiesel manufacturing. Extensive experiments were conducted over five days to thoroughly assess the efficiency of this innovative solar reactor. The innovative solar biodiesel synthesis system consistently achieves an impressive average biodiesel conversion rate of 90.8 % when operated under specific reaction conditions. Furthermore, the system's energy efficiency, calculated at 9.08×10−5g/J, outperforms the energy efficiency of traditional methods. Additionally, the properties of the biodiesel produced fall well within the specified limits defined by the ASTM D6751 standards. These collective findings underscore the considerable potential of proposed novel reactor as an eco-friendly and sustainable approach to biodiesel production.

Thermal performance evaluation of the parabolic trough solar collector using nanofluids: A case study in the desert of Algeria

The use of Parabolic Trough Solar Collector (PTSC) is currently the best option for widespread application in industries operating at temperatures from 60 to 400 °C. Numerous studies have been conducted to enhance the thermal performance of the PTSC using synthetic oils as heat transfer fluids. In this study, the thermal performance of parabolic collectors was enhanced using Metallic Oxide Nanofluids (CuO, SiO2, Al2O3, TiO2) based on Therminol VP-1™ at 4 % volumetric concentration as heat-transmitting fluids. A thermal model was developed and validated through experimental and theoretical study, while the results showed good compatibility in the outlet temperature with an error rate of 0.184 % for experimental and 0.29 % for theoretical studies. Moreover, various theoretical models of the thermal properties of nanofluids were analyzed to determine the model that matches and simulates this study. The findings indicated that nanofluids enhanced the thermal efficiency of the PTSC system compared to pure Therminol VP-1™. Specifically, CuO/Therminol VP-1™ demonstrated the most significant improvement, increasing thermal efficiency by 1.03 %. Furthermore, the results also showed that the addition of CuO, TiO2, Al2O3, and SiO2 nanoparticles led to an increase in outlet temperature by 9.57 %, 6.04 %, 5.21 %, and 3.08 %, respectively.

Thermodynamic performances of a novel multi-mode solar-thermal-assisted liquid carbon dioxide energy storage system

Liquid carbon dioxide energy storage is an efficient and environmentally friendly emerging technology with significant potential for integration with renewable energy sources. However, the heat recovery and utilization during compression and expansion are not implemented well. This paper proposes a multi-mode solar-thermal-assisted liquid carbon dioxide energy storage system integrated with the organic Rankine cycle. Three operation modes of normal operation mode, heat distribution operation mode, and solar thermal power generation mode are developed to achieve flexible control of the system under both normal and extreme environmental conditions. Thermodynamic performance analysis of the system under normal operation mode shows that compared to traditional system with energy storage density of 8.55 kWh/m3, the overall efficiency of the coupled system increases from 49.5 % to 62.1 %, with an energy storage density reaching 21.74 kWh/m3. The impact of key parameters such as temperature and pressure on system performance is discussed. Furthermore, an analysis of the heat flow distribution ratio under the heat distribution mode was conducted, indicating optimal system performance at a heat flow ratio of 6:4. Comparative analysis of the system performance under various operating conditions for the three operation modes was performed, elucidating the operational strategies of each mode.

Degradation of bromothymol blue and methyl green from aqueous media by Photo-Fenton: comparison between UV-lamp and sun irradiation

Abstract The degradation of two textile dye molecules was studied using photochemical processes, both in the absence and presence of light. Various methods were employed, including photolysis/UV, combined H2O2/UV photolysis, Fe2+/UV treatment, Photo-Fenton/UV at 350 nm and Photo-Fenton with solar irradiation. The decolorization efficiency of dyes in aqueous solution was evaluated for two specific dyes: Bromothymol Blue (BTB) and Methyl Green (MG). These experiments were carried out in batch mode. The results demonstrated a synergy between light irradiation and the presence of Fenton’s reagents, such as hydrogen peroxide and divalent iron. In addition, it was demonstrated that direct solar irradiation can be used without specific devices to achieve high efficiency at low cost. In the first part, we checked the impact of the various operating parameters. Reaction efficiencies were compared for the same system in the dark and under the assistance of an artificial or solar light source. In the second part, we studied the parameters of the Photo-Fenton process, such as the initial pH of the solution, the initial concentrations of oxidant, iron catalyst, and dye under irradiation from either light source. Whereas the mere photolysis without Fenton’s reagents allowed decolorization yields below 26 %, addition of the oxidant (H2O2) or the catalyst (Fe(II) species amplified the treatment efficiency. However, the presence of both H2O2 and Fe(II) under light irradiation was shown synergetic with yields ranging from 72 to 85 % depending on the dye worked and the light source: because of its broader spectrum in the UV domain, solar irradiation led to the highest decolorization yields. The above results were obtained for well-defined proportions of dye and reagents: for a 20 mg/l dye solution, Fe(II) catalyst concentration equal to 10−3 M, peroxide concentration of 5.10−2 M and a pH of 3. These conditions allowed optimal production of OH· radicals, allowing high efficiency in systems using solar irradiation.

Thermodynamic analysis of waste heat in a combined super-critical CO2 Brayton cycle for power and hydrogen production

The current investigation aims to propose a novel cycle to generate power and hydrogen using waste heat. For this purpose, super-critical carbon dioxide Brayton cycle, Organic Rankine Cycle (ORC) and proton exchange membrane (PEM) electrolyser systems are consideredin the cycle. Energy, exergy analyses along with parametric study are performed in the research. The best organic working fluid is selected for ORC based on the obtained results. Zero-dimensional modeling for components is performed and results are presented. Results show that the net power generation is 245.5 MW, thermal efficiency is 40.97 %, exergy efficiency is 56.73 %, and hydrogen and oxygen production is 9.04 kg/h and 74.2 kg/h, respectively. The optimum working pressure ratio and evaporator temperature are calculated. The effect of different working parameters on the system performance is obtained. It is shown that increasing the isentropic efficiency of the main and recompression compressors increases power generation, hydrogen production and system efficiency. Furthermore, increasing the turbine’s inlet temperature increases the power generation of the system.

Translation as a linguistic act in the context of artificial intelligence: the impact of technological changes on traditional approaches

The purpose of this article is to study translation as a human speech act in the context of artificial intelligence. Using the method of analysing the related literature, the article focuses on the impact of technological changes on traditional approaches and explores the links between these concepts and their emergence in linguistics and automatic language processing methods. The results show that the main methods include stochastic, rule-based, and methods based on finite automata or expressions. Studies have shown that stochastic methods are used for text labelling and resolving ambiguities in the definition of word categories, while contextual rules are used as auxiliary methods. It is also necessary to consider the various factors affecting automatic language processing and combine statistical and linguistic methods to achieve better translation results. Conclusions - In order to improve the performance and efficiency of translation systems, it is important to use a comprehensive approach that combines various techniques and machine learning methods. The research confirms the importance of automated language processing in the fields of AI and linguistics, where statistical methods play a significant role in achieving better results. Keywords: technological changes, linguistics, innovations, language technologies, automatic translation

Дослідження процесу перевезення пасажирів з моделюванням роботи зупинок громадського транспорту

Public transport is characterized by its accessibility and sharing and is intended for a wide range of people, regardless of social status or income. The main function is to provide the ability to move people from one place to another within the city. Bus stops are a strategic place to ensure territorial accessibility from central to peripheral neighborhoods. They maintain order and organization in the operation of public transport. It is the study of the network of public transport routes and stops that is crucial for improving the quality of service, increasing the efficiency of transport systems and ensuring convenience for users. However, in each case, it is necessary to use an individual approach to organizational and planning decisions. The article describes the peculiarities of the functioning of public transport in the city of Dubno, Rivne region, in the context of research on infrastructure, route network, passenger flow, location and modeling of stops, taking into account the future development of new neighborhoods. It was found that the route network in Dubno includes 22 public transport routes with 64 stops. On average, 19544 passengers use public transport and get off at bus stops every day - 54% of all city residents. The rapid development of the city requires the arrangement of new public transport stops with changing routes, the operation of which in the overall transportation system was investigated by simulation modeling. The results obtained will make it possible to develop schedules and routes for public transport and to perform technical and economic calculations for the modern arrangement of stops. The research reported in this article was conducted at the National University of Water and Environmental Engineering with the support of the Department of Economics and Property of the Dubno City Council.

Determinants of technical efficiency of pig production systems in northern Uganda: a Stochastic Frontier approach

Determinants of technical efficiency of pig production systems in northern Uganda: a Stochastic Frontier approach

Selective adsorption of high ionization potential value organic pollutants in wastewater

It is imperative to devise effective removal strategies for high ionization potential (IP) organic pollutants in wastewater as their reduced electron-donating capacity challenges the efficiency of advanced oxidation systems in degradation. Against this backdrop, leveraging the metal-based carbon material structure meticulously, we employed metal-pyridine-N (M-N-C, M=Fe, Co, and Ni) as the electron transfer bridge. This distinctive design facilitated the ordered transfer of electrons from the adsorbent surface to the surface of high IP value pollutants, acting as a "supplement" to compensate for their deficient electron-donating capability, thereby culminating in the selective adsorption of these pollutants. Furthermore, this adsorbent also demonstrated effective removal of trace emerging contaminants (2 mg/L), displayed robust resistance to various salts, exhibited reusability, and maintained stability. These findings carry substantial implications for future carbon-based material design, offering a pathway toward exceptional adsorption performance in treating water pollution.