Paul Schumaker

University Press of Kansas eBooks • 1990

A central question in political science is who governs and how. Typically political scientists attempt to answer this question by relying upon either empirical analysis, which explains existing political practices, or normative analysis, which prescribes ideal political practices. Political scientist Paul Schumaker rejects this distinction between empirical and normative theory. Instead, he weds the two approaches to create the new analytical mode he calls critical pluralism. With it he can measure variances in government from pluralist/democratic ideals and still provide theoretical explanations of why the variances occurred. Schumaker uses critical pluralism to describe, explain, and evaluate variations in three key measures of democratic performance: responsible representation, complex equality, and principle-policy congruence. To test his framework and methodology he analyzes 29 community issues that arose in Lawrence, Kansas, between 1977 and 1987. The results of his study—one of the most comprehensive databases ever in the study of community politics—will be of interest to those who study community power. The conceptual framework itself and methodology used in assessing democratic performance will have a lasting impact on the way community government is studied.

AutoGas Filling Complex + Alternative fuel • 2019

The actuality of the article is due to the need to improve the toxicity indicators of dieselengines exhaust gases. One of the modern ways to achieve the required indicators of exhaustgas toxicity is to add eco-friendly additives to the fuel. An opportunity of using carbonnanotubes as eco-friendly additives to petroleum diesel fuel is considered. Experimentalstudies of the D-243 diesel engine running on petroleum diesel fuel with the addition of 125,250 and 500 mg/l nanotubes were carried out. Mixing of petroleum diesel fuel with nanotubeswas performed with the usage of an ultrasonic apparatus. A possibility of improving theenvironmental performance of a diesel engine when adding nanotubes to the fuel is shown. Ina full-load mode, the addition of 500 mg/l carbon nanotubes to the fuel reduced the exhaustsmoke from 26.0 % to 11.2 % according to the Hartridge scale. Keywords diesel engine; petroleum diesel fuel; carbon nanotubes; exhaust gas toxicity indicators; exhaust gas smokiness

P. Arjun, Saravanan Natarajan, Manikandan Chinnathambi et al.

SAE Technical Paper Series • 2024

<div class="section abstract"><div class="htmlview paragraph">In farm tractors, the available drawbar power, and Power Take-Off (PTO) power are generally lower than the engine power due to parasitic losses. These losses are caused by engine-driven auxiliary loads such as cooling fans, hydraulic pumps for power steering, alternators, etc. Minimizing these parasitic losses can increase the available drawbar power and PTO power, resulting in direct fuel savings by reducing fuel consumption. The continuous increase in fuel costs and the environmental impact of emitted gases from burned fuel into the atmosphere have necessitated the replacement of hydraulic power steering and mechanical fans with Electric Power Steering (EPS) and electric fans, respectively, to improve efficiency. The existing battery has been replaced with a higher capacity battery to provide power to the electric fan, electric power steering, and other electrical components. Additionally, the existing alternator has been replaced with a higher capacity alternator to meet the increased power requirements. The developed system was installed on a 45 hp 2-wheel drive tractor, and its performance was evaluated. Field trials were conducted at three testing sites (Sindhanur, Jaitsar, and Tindivanam), resulting in an average fuel efficiency improvement of 8.34%. Haulage trials were completed at MSPT (Mahindra SUV Proving Track), Cheyyar, and achieved an average fuel efficiency improvement of 8.5%.</div></div>

Monika Kloch, Renata Toczyłowska-Mamińska

Energies • 2020

Microbial fuel cell (MFC) has the potential to become a promising sustainable technology of wastewater treatment. Usually, the investigations on MFCs are aimed at maximized power production in the system. In this article, we focused on the optimization of wood industry wastewater treatment in MFC, in combination with municipal wastewater as a source of microorganisms. We investigated the influence of different external resistance (2000 Ω, 1000 Ω, 500 Ω, and 100 Ω) on power density and wastewater treatment efficiency (chemical oxygen demand (COD) removal) in 1-month MFC operation time. We found that the highest COD removal was for MFCs under R = 1000 Ω after 22 days of MFC operation, while the highest current density was obtained for the lowest applied resistance. The results imply that wastewater treatment parameters such as resistance and time of MFC operation should be a subject of optimization for each specific type of wastewater used, in order to maximize either wastewater treatment efficiency or power production in MFC. Thus, optimization of power production and COD removal efficiency in MFCs need to be run separately as different resistances are required for maximizing these two parameters. When COD removal efficiency is a subject of optimization, there is no universal value of external resistance, but it should be set to the specific wastewater characteristics.

M A Bustomi, F B Setiawan, B Indarto et al.

Journal of Physics: Conference Series • 2024

Abstract Brushless Direct Current (BLDC) generators have many advantages over DC generators that use brushes. In this research, the advantages of the BLDC generator are applied as a generator for a micro-hydro power plant (MHPP) that uses an Archimedes screw turbine. The study aims to test the performance of the BLDC generator as a generator on the Archimedes screw turbine MHPP. The MHPP specifications for the Archimedes screw turbine used in this research are an Archimedes screw turbine with three blades, an elevation angle of 40° and a transmission gear ratio of 2.8:1. The screw turbine has an inner diameter of 14.02 cm, an outer diameter of 23.9 cm, a pitch of 25.67 cm and a length of 51.34 cm. The generator used is a 3-phase Brushless Direct Current (BLDC) generator. The load used is a 12 Volt LED lamp with a 5 to 20 Watts power. The test results at a discharge of 0.00634 m3/s showed that the mechanical power was (36.408 ± 0.202) Watts and the highest electrical power was (7.86 ± 0.03) Watts. Based on these results, the efficiency of electrical power on mechanical power is around 22%.

Steve Ingistov

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration • 2000

Ambient air temperature plays significant role in performance of a Gas Turbine. Frequently Gas Turbines in electrical power generation are single rotor and are directly coupled to the Electrical Generators. These machines normally operate 8,000 hours per calendar year under the 100% load. The control of the combustion air flow is achieved by modulating compressor Inlet Guide Vanes (IGV). The single shaft axial compressor consumes as a rule of thumb more than 50% of turbine useful expansion work. Axial compressor is high-volume, moderate discharge pressure machine. Its power demand to discharge ambient air to the turbine combustion system is very dependent on ambient conditions such as pressure, temperature and relative humidity. The optimization of the axial compressor aerodynamic loading under various ambient conditions is therefore mandatory. During the hot and humid summer days, especially from the noon time to 6:00 PM, the demand for the power is at its maximum. This Paper describes selection, design and installation of the Inlet Air Cooling System. (IACS). The selected IACS is fine water mist, FOG. FOG System (FS) was selected because of its efficiency and because the clean water was available. FS incorporates Fog Generating Skid (FGS) and Fog Curtain (FC). FC is comprised of lateral lines with equally spaced. FOG Nozzles (FN). The FN is specially designed to generate individual “Fog Cones” that efficiently dissipate the water particles in the space. Fine water particles are atomized by incoming air in the Inlet Air (IA) duct. The homogenous mixture of FOG and IA is required to enhance the water mist particles evaporation process. In cases when the FS works in tandem with Evaporative Cooler (EC) most of the FOG particles are “injected” into the compressor suction. The injected FOG particles start to evaporate during the IA compression process. The water evaporation process simultaneously causes cooling of the IA being compressed. The result is reduced compression work and improved performance of GT.

S. Can Gulen, Raub W. Smith

Volume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric Power • 2007

A significant portion of the new electrical generating capacity installed in the past decade has employed heavy-duty gas turbines operating in a combined cycle configuration with a steam turbine bottoming cycle. In these power plants approximately one third of the power is generated by the bottoming cycle. To ensure that the highest possible combined cycle efficiency is realized it is important to develop the combined cycle power plant as a system. Doing so requires a solid understanding of the efficiency entitlement of both, topping and bottoming, cycles separately and as a whole. This paper describes a simple but accurate method to estimate the Rankine bottoming cycle power output directly from the gas turbine exhaust exergy utilizing the second law of thermodynamics. The classical first law approach, i.e. the heat and mass balance method, requires lengthy calculations and complex computer-based modeling tools to evaluate Rankine bottoming cycle performance. In this paper, a rigorous application of the fundamental thermodynamic principles embodied by the second law to the major cycle components clearly demonstrates that the Rankine cycle performance can be accurately represented by several key parameters. The power of the second law approach lies in its ability to highlight the theoretical entitlement and state-of-the-art design performances simultaneously via simple, fundamental relationships. By considering economically and technologically feasible upper limits for the key parameters, the maximum achievable bottoming cycle power output is readily calculable for any given gas turbine from its exhaust exergy.

, Venkata Naga Likhith Peruri

• 2021

This research investigates bioelectrochemical system technology. The study demonstrates with focus on energy conversion efficiency. Experimental validation provides insights into system behavior. Results contribute to the development of sustainable bioelectrochemical technologies.

Salvatore A. Della Villa, Carlos Koeneke

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Education; Electric Power; Manufacturing Materials and Metallurgy • 2010

Since its inception the gas turbine market has been driven by an emphasis on improved operating efficiency, greater megawatt output, with reduced environmental impact through technology advancement. The technology advances that have taken place include; higher firing temperatures and pressure ratios, improved cooling schemes with advanced metallurgy and coatings for hot gas path parts, consideration for tighter clearances, low emissions combustion systems, and fuels flexibility. Contemporaneously, there has been a commensurate focus on ensuring that the achievable levels of availability and reliability of these evolving product offerings would be optimized for various duty cycles, applications, and plant arrangements. In fact, as product evolution and advancement has taken place, there has been an expectation that availability and reliability performance would be consistent with the best achievable levels experienced by existing and more mature technologies. The purpose of this paper is to address the industry focus on availability and reliability (from EPRI to DOE), and to discuss the current and historical availability and reliability performance of gas turbines based on class; specifically “E” and “F” class. Additionally, this paper will also address the positive impact that “remote monitoring” has had; through the automation and computation of availability and reliability metrics. “Remote monitoring” has been introduced to provide an extra level of protection and diagnostic capability; providing an emphasis on performance, operability, and availability of the power generation equipment. The fact that “remote monitoring” has facilitated rapid data acquisition has had a positive impact on the calculation of availability and reliability metrics, making them more timely and accurate. This important point will also be discussed. With the permission of Mitsubishi Power Systems America (MPSA), specific data for the M501F fleet is presented. These comparisons will assist in establishing benchmarks for equipment performance based on duty cycle and other meaningful segmentations. Data available from SPS’s ORAP® (Operational Reliability Analysis Program) and other industry sources will be used to provide valid references for consideration.

Ken R. Parker, Jeff Allen, Anupam Sanyal

ASME 2006 Power Conference • 2005

For a 500 MW unit, a 1 % reduction in boiler efficiency equates to a coal cost in the order of $ 1/2 million/annum, while a 5 % unit derate, needed to meet emission compliance, can equate to an annual revenue loss of up to $ 12 million. Many software products are in use, which based on the present plant performance, identify and optimize the operational parameters for the best plant capacity, utilization and efficiency. While they are effective in tuning up the unit, they are applied to an operating plant firing a given coal for the given performance. But what if there were a means of predicting how a coal will perform with respect to slagging, fouling and every other single parameter involved in the use of that coal for capacity, efficiency maximization and emission control without firing even a lb of coal? This would enable the operator to know in advance what to expect and thereby, adjust the operating variables to get the best out of that coal. Such a software product – SCES (Steam Coal Evaluation & Services) has been developed based on the fundamental principles of combustion, mineral matter transformation and emission of particulates, NOx, SO2 and mercury, based on only the standard ASTM coal and ash analyses. The operational parameters evaluated are: Slagging and fouling as well as Grindability, Abrasion of the grinding elements; Combustibility & Unburnt carbon, Corrosion and Erosion; Emission of particulates, the oxides of sulfur and nitrogen (both primary and secondary DeNOx) as well as mercury when data are available. Its advantage over the existing products is its ability to predict, amongst others parameters, corrosion, erosion of convective tubes and the life of grinding elements none of which are discernible from the existing software products or from a limited test burn. These parameters however play important roles in the bottom line O & M costs. The implementation of SCES in providing meaningful rankings alerts the plant operators to the performance they can expect and any measures that need to be taken to be able the plant to operate at its highest load factor and efficiency while under emission compliance with minimum impact on O & M cost. No separate coal sample or small-scale laboratory evaluation work is required in the derivation of the rankings. Because of its simplicity of use and immediate availability of results, SCES can also be used as a routine analytical tool, accompanying the coal analyses by the plant or supplied with each delivery of coal. It is applicable to all coals irrespective of rank and country of origin, it has been used and validated on coals from the US, UK, Russia, Columbia and India. The paper describes the fundamental properties coal used in the development of the software and cites case histories of its validation on US (Bituminous & Sub-bituminous) coals.

Lamyae Oulmaati, Salima El Amrani, Khalid Bouziane et al.

Applied Sciences • 2023

An efficient quantum cutting mechanism was observed in a system comprising Tb3+−Yb3+ codoped silica hafnia glass and glass-ceramic. Thin films were deposited on silicon substrates using the dip-coating method and photoluminescence dynamics revealed a quantum efficiency of up to 179% at 980 nm. These films can efficiently convert light to lower energy levels and can easily be integrated into silicon-based solar cells, increasing their photoelectric conversion efficiency at a low cost. This was demonstrated through electrical characterization, which revealed a boost in solar cell efficiency when the film was utilized. It was specifically noted that the efficiency of Si solar cells increased by 10.79% and 10.78% when covered with 70SiO2−30HfO2−3Tb3+−12Yb3+ glass and glass ceramic, respectively. Furthermore, an evaluation of the additional external quantum efficiency, derived from this optical system, revealed an improvement ranging from 2.64% to 3.44%. This finding highlights the enhanced light conversion capabilities of the quantum cutting mechanism within the system.

Shakkira Erimban, Matias Factorovich, Ignacio Bombau et al.

ChemRxiv • 2025

Anion exchange membranes (AEMs) are integral to fuel cells and water electrolysis systems but suffer from poor durability under alkaline conditions. Ether cleavage is an important failure pathway of poly(arylene ether) based AEMs that compromises both mechanical stability and ion transport. While this degradation pathway is often studied in terms of polymer fragmentation, the role of newly formed hydrophilic groups has been largely overlooked. We show that polymer scission leads to reduced mechanical rigidity, while the introduction of hydrophilic groups partially mitigates this loss. Under alkaline conditions, phenoxide groups formed during ether cleavage neutralize the polymer cations, leading to a previously unreported loss of ion exchange capacity (IEC). This IEC loss mechanism exacerbates the reduction in ionic conductivity, emphasizing the severity of ether cleavage as a degradation pathway. Recognizing that ether cleavage introduces significant chemical changes beyond polymer fragmentation provides critical insights into its interplay with other degradation mechanisms, such as the direct reduction of cationic sites by E2 and SN2 and provides molecular-level interpretations for the concurrent effects of polymer scission and increased hydrophilicity on membrane performance.

Grzegorz Pasternak, John Greenman, Ioannis Ieropoulos

Scientific Reports • 2019

Abstract Microbial electrochemical technology is emerging as an alternative way of treating waste and converting this directly to electricity. Intensive research on these systems is ongoing but it currently lacks the evaluation of possible environmental transmission of enteric viruses originating from the waste stream. In this study, for the first time we investigated this aspect by assessing the removal efficiency of hepatitis B core and surface antigens in cascades of continuous flow microbial fuel cells. The log-reduction (LR) of surface antigen (HBsAg) reached a maximum value of 1.86 ± 0.20 (98.6% reduction), which was similar to the open circuit control and degraded regardless of the recorded current. Core antigen (HBcAg) was much more resistant to treatment and the maximal LR was equal to 0.229 ± 0.028 (41.0% reduction). The highest LR rate observed for HBsAg was 4.66 ± 0.19 h −1 and for HBcAg 0.10 ± 0.01 h −1 . Regression analysis revealed correlation between hydraulic retention time, power and redox potential on inactivation efficiency, also indicating electroactive behaviour of biofilm in open circuit control through the snorkel-effect. The results indicate that microbial electrochemical technologies may be successfully applied to reduce the risk of environmental transmission of hepatitis B virus but also open up the possibility of testing other viruses for wider implementation.

Fang-Yi Lin, Tzu-Yin Liu, Han-Yi Chen

ECS Meeting Abstracts • 2020

Developing clean and sustainable energy sources is important as it deals directly with energy shortage and environmental pollution problems caused by fossil fuels. Plant microbial fuel cells (PMFCs) is a novel technology that can convert solar energy into electrical energy by the microbes at the region of rhizosphere of the plants. Without producing any harmful byproducts during the energy generation process, PMFCs seems to be a promising choice as a renewable power supply technique. Green carbon materials, utilizing agro-industrial waste as precursors, has attracted lots of interest in research recently on account of them being environmental friendly materials and mitigating bio-wastes. To combine the advantages of PMFCs and green carbon materials, the aim of this study is to optimize the electrochemical performance of our designed PMFCs by utilizing biowaste-derived activated carbon materials as the electrode materials. The biowaste-derived activated carbon materials were characterized by Brunauer-Emmett-Teller (BET) surface area analyzer, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance of PMFCs devices developed by ourselves were analyzed through linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). This study set out to examine the relationship between the properties of activated carbon and the electrochemical performance of PMFCs, expecting to develop a high power density PMFCs device.

, Sin Hoi Phang

• 2017

This research investigates bioelectrochemical system technologyfocusing on performance optimization and reactor design. Results contribute to the development of sustainable bioelectrochemical technologies.

, Sirawit Witpathomwong

• 2017

This research investigates bioelectrochemical system technology. Results contribute to the development of sustainable bioelectrochemical technologieswith potential for distributed power generation.

Melkamu Bezabih Yitbarek

Research Square • 2022

Abstract Background Effective Microorganisms is the mixed cell culture composed of photosynthetic bacteria, actinomyces, yeast, lactobacillus and fungi which improves growth rate, feed efficiency, egg production and increases the health status of poultry. The experiment was conducted to evaluate the economic efficiency of effective microorganism’s supplementation to Bovans Brown laying hens. Results The result revealed that layers fed in T4 (124.07g) was significantly higher (P < 0.05) than T1 (119.67g), T2 (122.36g) and T3 (122.37g). The total egg production during the experimental period (week 20 to week 67) was 241,242,249 and 268 for T1, T2, T3 and T4, respectively. The highest (P < 0.05) feed conversion ratio was observed in T4 (2.23). The total feed cost was T1 > T2 > T3 > T4. The highest net revenue was obtained from T4 and the lowest was T1 and T2. The economic efficiency was ranged from 0.66 to 0.90 and the feed cost ratio was ranged from 1.66 to 1.90 ETB. Conclusion Therefore, from this study it can be concluded that supplementation of EM with drinking water and in feed (T4) had the best production performance indices among the treatment groups.

David Gardner, Roger Fontes, Richard Casey

2003 International Joint Power Generation Conference • 2002

Fifteen municipal electric utilities are jointly studying the feasibility of developing a 500 MW to 1,000 MW coal-fired generation project. The project will combine advanced technologies seeking maximum performance, minimal risk and outstanding environmental acceptability. This paper describes engineering and financial studies comparing coal-firing technology alternatives such as Pulverized Coal (PC), Circulating Fluidized Bed and Integrated Gasifier Combined Cycle, and PC refinements including supercritical steam conditions and innovative use of gas turbine feedwater heating. The paper also examines options to minimize environmental impact. Use of high-efficiency steam plant technologies is found to be an environmental advantage. A prudent combination of sophisticated technologies is found to be cost-effective. Finally, the paper describes the project’s innovative joint development process.

Justin Zachary, Alex Khochafian

ASME 2007 Power Conference • 2006

Based on the present revival of coal as the fossil fuel of choice for power generation, there is a high probability that several IGCC projects will materialize in the near future. One of the challenges facing the Owners, EPC Contractors and OEM’s will be to define the performance commercial guarantees and the practical means to determine them. In addition following the current huge upturn in conventional supercritical coal fired power plants, a large number of facilities will conduct thermal performance tests. The proper conductance of the test, data collection and correction to reference conditions, have many technical implications and could affect drastically the commercial outcome of a project both for the Contractor and the Owner. For IGCC plants, in anticipation of this probability, ASME Performance Test Committee had developed a Performance Test Code for such type of plant — PTC 47, which was published in January 2007. In the first part, the paper will provide details about the specific challenges facing the implementation of the Code, in particular the proposed use of the input/output method (mass and energy balance). The presentation will cover other highlights of the code recommendations. The methodology is fully applicable to conventional power plants, since they use same type of fuel. The determination of the heat input based on actual continuous measurement of the mass flow and composition of the coal will be discussed in details. The practicality and the measurement uncertainty associated with fuel composition will also be analyzed. A comparison with the indirect method for determination of the heat input will also be presented. The article will evaluate how the code requirements are reflected in the definition of the power plant design, configuration and instrumentation. The implications of test tolerance as a commercial issue and measurement uncertainty as a technical issue will also be presented and evaluated Other unique aspects of the entire IGCC plant performance testing will be discussed: (1) stability criteria related to the gasification and integration processes, (2) corrections from test to guarantees conditions due to complex chemical, mechanical processes. Finally, the article will indicate the progress on the development of performance evaluation methodologies for other main IGCC components: gasifier, air separation unit, gas cleaning systems and Power Island.

Beibei Zong, Zizhao Zhang, Qing Shun et al.

Advanced Electronic Materials • 2021

Abstract The photoelectric conversion efficiency of perovskite solar cells (PSCs) has rapidly developed in the past decade. However, the development of PSCs still has many limitations: for instance, the accumulation of harmful defects on their surfaces and grain boundaries limit their performance. Here, PSCs with ITO/SnO 2 /FA x MA 1− x Pb(I y Br 1− y ) 3 /Spiro‐OMeTAD/Ag structure are fabricated under air conditions, meanwhile, the effect the different masses of BaCl 2 (0, 10, 15, 20, and 25 mg) added to FA x MA 1− x Pb(I y Br 1− y ) 3 perovskite precursor solution on the performance of PSCs is investigated. The results show that the best performance is obtained when 20 mg BaCl 2 is added, and the performance parameters J sc , V oc , FF of the PSCs (those with 20 mg BaCl 2 ) are 24.43 mA cm −2 , 1137 mV, and 75.82, respectively, and their power conversion efficiency is up to 21.06%, which is ≈25% higher than that of the reference devices (those without BaCl 2 ). Test results, such as XRD, SEM, TRPL, SCLC, UV–Vis, show that right amount of BaCl 2 additive can significantly improve the crystallinity, absorbance, and interface defect state of perovskite films. It can also increase the separation and mobility of charge carriers, thus greatly improving the performance of PSCs.

Halil İbrahim DAĞ, Günnur KOCAR

Politeknik Dergisi • 2021

In this study, efficiency of water-type photovoltaic/thermal (PV/T) modules that convert solar energy into both electrical and thermal energy were investigated. By using identical photovoltaic (PV) cells, one PV module and five PV/T modules differed in thermal structure with different diameters, amount and layout of absorber tubes, and type of absorber sheets were fabricated with lamination technique. Firstly, the electrical efficiency of all samples under Standard Test Conditions was tested by a sun simulator. Efficiency values were between 12.56% and 12.68% under STC. Furthermore, outdoor tests were carried out to investigate the effect of temperature on PV modules in ambient conditions using PV/T samples. In order to determine the efficiency of the units, parameters such as solar irradiation, voltage and current values, inlet and outlet water temperature and flow rate of PV/T modules and ambient temperature were measured. It was observed that the electrical performance of PV/T modules was higher than that of the PV module due to the cooling effect of water circulation over the cells. PV/T module with the highest thermal efficiency was also determined. Total efficiency value of PV/T modules in outdoor conditions were attained between 60.68% and 67.14%.

S. Babanova, Y. Hubenova, M. Mitov et al.

Fuel Cells • 2011

Abstract The commonly used parameters characterizing fuel cells and in particular microbial fuel cells (MFCs) electrical performance are open circuit voltage (OCV), maximum power, and short circuit current. These characteristics are usually obtained from polarization and power curves. In the present study, the expanded uncertainties of operational characteristics for yeast‐based fuel cell were evaluated and the main sources of uncertainty were determined. Two approaches were used: the uncertainty budget building for sources uncertainty estimation and a statistical treatment of identical MFCs results – for operational characteristics uncertainty calculation. It was found that in this particular bioelectrochemical system the major factor contributing to operational characteristics uncertainties was the electrodes' resistance. The operational characteristics uncertainties were decreased from 19 to 13% for OCV, from 42 to 14% for maximal power, and from 46 to 13% for short circuit current with the usage of electrodes with resistance in the interval 6–7 Ω. The described approaches can be used for operational characteristics expanded uncertainties calculation of all types of fuel cells using data from polarization measurements.

Vratislav Michal

IET Power Electronics • 2016

This study presents concept of the power‐efficiency optimisation of interleaved step‐down DC/DC converter with segmented power stages. Use of segmented power stage is based on continuous adjusting of the size of power switches, and is currently exclusively employed in the single‐phase topologies. The size control use accurate peak‐efficiency detection method. Employed iterative algorithm allows to equilibrate the dissipated dynamic and Joule powers in wide range of operating parameters such as output current, input/output voltages, temperature, switching frequency, or variation of the process. By the balancing of dynamic and Joule power losses, peak efficiency is achieved in low and middle output power range. This allows to increase the power efficiency by several per cent, when compared with the phase shedding approach. Moreover, use of the segmented switches enables to maintain all power stages active during light‐load operation. This allows to benefit from reduced AC input/output currents of the multi‐phase topology. This study describes the efficiency optimisation of interleaved power converters, technique of the peak‐efficiency detection, and shows comparison of results obtained by the presented peak‐efficiency tracking and phase shedding approach.

Mohamed M. Albarghot, M. Tariq Iqbal, Kevin Pope et al.

Journal of Energy • 2019

The combination of a fuel cell and batteries has promising potential for powering autonomous vehicles. The MUN Explorer Autonomous Underwater Vehicle (AUV) is built to do mapping-type missions of seabeds as well as survey missions. These missions require a great deal of power to reach underwater depths (i.e., 3000 meters). The MUN Explorer uses 11 rechargeable Lithium-ion (Li-ion) batteries as the main power source with a total capacity of 14.6 kWh to 17.952 kWh, and the vehicle can run for 10 hours. The drawbacks of operating the existing power system of the MUN Explorer, which was done by the researcher at the Holyrood management facility, include mobilization costs, logistics and transport, and facility access, all of which should be taken into consideration. Recharging the batteries for at least 8 hours is also very challenging and time consuming. To overcome these challenges and run the MUN Explorer for a long time, it is essential to integrate a fuel cell into an existing power system (i.e., battery bank). The integration of the fuel cell not only will increase the system power, but will also reduce the number of batteries needed as suggested by HOMER software. In this paper, an integrated fuel cell is designed to be added into the MUN Explorer AUV along with a battery bank system to increase its power system. The system sizing is performed using HOMER software. The results from HOMER software show that a 1-kW fuel cell and 8 Li-ion batteries can increase the power system capacity to 68 kWh. The dynamic model is then built in MATLAB/Simulink environment to provide a better understanding of the system behavior. The 1-kW fuel cell is connected to a DC/DC Boost Converter to increase the output voltage from 24 V to 48 V as required by the battery and DC motor. A hydrogen gas tank is also included in the model. The advantage of installing the hydrogen and oxygen tanks beside the batteries is that it helps the buoyancy force in underwater depths. The design of this system is based on MUN Explorer data sheets and system dynamic simulation results.

Chih-Lung Shen, Heng Liou

Materials • 2017

In this paper, a novel step-up converter is proposed, which has the particular features of single semiconductor switch, ultra-high conversion ratio, galvanic isolation, and easy control. Therefore, the proposed converter is suitable for the applications of fuel-cell power system. Coupled inductors and switched capacitors are incorporated in the converter to obtain an ultra-high voltage ratio that is much higher than that of a conventional high step-up converter. Even if the turns ratio of coupled inductor and duty ratio are only to be 1 and 0.5, respectively, the converter can readily achieve a voltage gain of up to 18. Owing to this outstanding performance, it can also be applied to any other low voltage source for voltage boosting. In the power stage, only one active switch is used to handle the converter operation. In addition, the leakage energy of the two couple inductors can be totally recycled without any snubber, which simplifies the control mechanism and improves the conversion efficiency. Magnetic material dominates the conversion performance of the converter. Different types of iron cores are discussed for the possibility to serve as a coupled inductor. A 200 W prototype with 400 V output voltage is built to validate the proposed converter. In measurement, it indicates that the highest efficiency can be up to 94%.

Jiabin Zhang, Tao Jia, Ching-Hong Tan et al.

Solar RRL • 2021

Rapid developments in material design have led to significant breakthroughs in the power conversion efficiency (PCE) of all‐polymer solar cells (all‐PSCs) in recent years. However, most of these devices are processed using halogenated solvents. Here, nonhalogenated solvent o ‐xylene ( o ‐XY)‐processed all‐PSCs based on PBDB‐T:PJ1 are studied. Interestingly, it is found that the efficiency of the all‐PSCs can be greatly improved to 14.34% by simply increasing the spin‐coating speed during device processing. Careful studies reveal that this improvement could be attributed to the stronger centrifugal force (resulting from a higher spin‐coating speed), shorten the film formation time, and inhibit the excessive aggregation of PJ1. Consequently, a blend film with more reasonable domain size is formed. Based on these findings, another polymer acceptor PJ2, which bears a similar backbone to PJ1 but contains an additional thiophene spacer, is designed. PJ2 exhibits a much weaker aggregation ability and is used as a compatibilizer to improve the miscibility between the PBDB‐T and PJ1. Eventually, PBDB‐T:PJ1:PJ2‐based ternary all‐PSCs with a best PCE of 14.28% but processed under more mild conditions are obtained. These results may provide guidelines for future industrial fabrication of large‐area all‐PSCs.

Carlos Castillo‐Saldarriaga, Christine N. S. Santos, Stephen Sarria et al.

Microbial Biotechnology • 2024

ABSTRACT Yeast extract (YE) is a complex nutritional source associated with high performance on microbial production processes. However, its inherent compositional variability challenges its scalability. While prior efforts have focused on growth‐associated products, the dynamics of growth‐uncoupled production, which leads to higher production rates and conversion yields, still need to be explored. This production scenario is common in large‐scale applications. This study presents a systematic approach to replace YE for the production of the terpene amorpha‐4,11‐diene in Escherichia coli . Sequential processing was successfully applied to identify glutamic acid, alanine, leucine, valine, isoleucine and glycine as the key amino acids (AAs) under slow‐growth conditions. Thoroughly applying biomass retention as part of sequential processing increased production capacity by 45% using these AAs instead of YE. Further studies, including flux balance analyses, targeted pyruvate as the common AA precursor. The optimized fed‐batch process feeding pyruvate with 0.09 g Pyr h −1 enhanced amorpha‐4,11‐diene production by 37%, although adding only 1% carbon via pyruvate. Flux balance analysis revealed the criteria for optimum pyruvate feeding, for example, to prevent succinate secretion and maintain the NADH/NAD + balance. These findings illustrate the interplay between media composition and metabolic activity and provide a successful guideline for identifying lean, best‐performing media for industrial applications.

, Vasileios Karakostas

• 2016

Virtual memory improves programmer productivity, enhances process security, and increases memory utilization. However, virtual memory requires an address translation from the virtual to the physical address space on every memory operation. Page-based implementations of virtual memory divide physical memory into fixed size pages, and use a per-process page table to map virtual pages to physical pages. The hardware key component for accelerating address translation is the Translation Lookaside Buffer (TLB), that holds recently used mappings from the virtual to the physical address space. However, address translation still incurs high (i) performance overheads due to costly page table walks after TLB misses, and (ii) energy overheads due to frequent TLB lookups on every memory operation. This thesis quantifies these overheads and proposes techniques to mitigate them. In this thesis we argue that fixed size page-based approaches for address translation exhibit limited potential for improving TLB performance because they increase the TLB reach by a fixed amount. To overcome the limitations of such approaches, we introduce the concept of range translations and we show how they can significantly improve the performance and energy-efficiency of address translation. We first comprehensively quantify the address translation performance overhead on a collection of emerging scale-out applications. We show that address translation accounts for up to 16% of the total execution time. We find that huge pages may improve the application performance by reducing the time spent in page walks, enabling better exploitation of the available execution resources. However, the limited hardware support for huge pages in combination with the workloads' low memory locality leave ample space for performance optimizations. To reduce the performance overheads of address translation, we propose Redundant Memory Mappings (RMM). RMM provides an efficient alternative representation of many virtual-to-physical mappings. We define a range translation be a subset of a process's pages that are virtually and physically contiguous. RMM translates each range translation with a single range table entry, enabling a modest number of entries to translate most of the process's address space. RMM operates in parallel with standard paging and introduces a software range table and a hardware range TLB with arbitrarily large reach that is accessed in parallel with the regular L2-page TLB. We modify the operating system to automatically detect ranges and to increase their likelihood with eager paging. RMM is thus transparent to applications. We prototype RMM software in Linux and emulate the hardware. RMM reduces the overhead of virtual memory to less than 1% on average on a wide range of workloads. To reduce the energy cost of address translation, we propose the Lite mechanism and the TLB-Lite and RMM-Lite designs. Lite monitors the performance and utility of L1 TLBs, and adaptively changes their sizes with way-disabling. The resulting TLB-Lite design targets commodity processors with TLB support for huge pages and opportunistically reduces the dynamic energy spent in address translation with minimal impact on TLB miss cycles. To further provide more energy-efficient address translation, we propose RMM-Lite that adds to RMM an L1-range TLB, that is accessed in parallel with the regular L1-page TLB, and the Lite mechanism. The high hit ratio of the L1-range TLB allows Lite to downsize the L1-page TLBs more aggressively. RMM-Lite reduces the dynamic energy spent in address translation by 71% on average. Above the near-zero L2 TLB misses from RMM, RMM-Lite further reduces the overhead from L1 TLB misses by 99\%. The proposed designs target current and future high-performance and energy-efficient memory systems to meet the ever increasing memory demands of applications. La memoria virtual aumenta la productividad del programador, provee seguridad a los procesos e incrementa la utilización de la memoria. No obstante, la memoria virtual requiere de una traducción de direcciones entre los espacios de direcciones virtual y físico en cada operación de memoria. La implementación de la memoria virtual paginada divide la memoria física en páginas de tamaño fijo. El principal componente para acelerar la traducción de direcciones es la TLB (Translation Lookaside Buffer). Sin embargo, la traducción de direcciones tiene un alto coste en el rendimiento, por la necesidad de buscar en la tabla de páginas después de un fallo de TLB, y por el coste energético por las frecuentes búsquedas en la TLB (una por cada operación de memoria). En esta tesis defendemos que los mecanismos de traducción basados en páginas tienen un potencial limitado para aumentar el rendimiento de la TLB. Principalmente porque solo se puede aumentar en una cantidad limitada el conjunto de direcciones que la TLB puede traducir. Para superar esta limitaciones, introducimos el concepto de traducciones por rangos y mostramos como este mecanismo puede mejorar significativamente el rendimiento y la eficiencia energética en la traducción de direcciones. Primero, cuantificamos la pérdida de rendimiento debido a la traducción en aplicaciones emergentes que escalan bien al agregar más procesadores. Mostramos que en estas aplicaciones la traducción de direcciones es responsable de hasta el 16% del tiempo de ejecución. Además, también mostramos que las páginas grandes pueden mejorar el rendimiento de las aplicaciones, permitiendo un mejor uso de los recursos disponibles. Sin embargo, el limitado soporte del hardware para páginas grandes, combinado con cargas de trabajo con poca localidad, nos deja mucho espacio para la optimización. Para reducir los costes de rendimiento de la traducción de direcciones, proponemos RMM (Redundant Memory Mappings). RMM esta basado en rangos de páginas y ofrece una vía alternativa eficiente para representar muchas traducciones. Definimos un rango de traducción como un subconjunto de páginas contiguas de un proceso, tanto en el espacio virtual como en el físico. RMM traduce con un pequeño número de rangos la mayor parte del espacio de direcciones del proceso, y opera en paralelo con el sistema estándar de paginación, agregando una tabla de rangos implementada en software y una TLB de rangos de dimensión arbitraria, accedida en paralelo por la TLB de segundo nivel. Modificamos el sistema operativo para que automáticamente detecte los rangos y aumente su probabilidad de uso. RMM es un mecanismo transparente a las aplicaciones y reduce la pérdida de rendimiento de la memoria virtual hasta algo menos del 1% de media. Para reducir los costes energéticos en la traducción de direcciones, diseñamos el mecanismo Lite, e introducimos los diseños TLBLite y RMMLite. Lite monitora el rendimiento y la utilización de la TLB de primer nivel y adapta su tamaño apagando vías. TLBLite esta orientado a los procesadores actuales que soportan páginas grandes. TLBLite reduce el consumo de energía dinámica usado en la traducción de direcciones, con un impacto mínimo de ciclos en los fallos de TLB. Para hacer aún más eficiente energéticamente la traducción de direcciones proponemos RRMLite, el cual agrega a RMM una TLB de rango paralela a la TLB de primer nivel que tiene el mecanismo Lite. El alto ratio de aciertos en la RMM de primer nivel nos permite deshabilitar vías de la TLB de primer nivel de forma agresiva. RMMLite reduce la energía dinámica total utilizada para la traducción de direcciones en un promedio del 71%. Las técnicas propuestas están diseñadas para soportar sistemas de memoria de alto rendimiento, además de ser eficientes energéticamente, y por lo tanto podrán ser usadas tanto por las aplicaciones actuales como para las futuras que incrementarán su requerimiento a memoria.

Hwa Lin, Yun-Hsun Huang, Jung-Hua Wu

Energies • 2024

This article discusses how the introduction of corporate average fuel economy (CAFE) standards in Taiwan, whose market and industry size are much smaller than those of Europe, the United States, Japan, and China, can effectively improve vehicle energy efficiency. It examines the changes in passenger car energy efficiency under Taiwan’s CAFE framework and evaluates CAFE compliance performance to summarize its impacts and challenges. Observations indicate that the strategically flexible CAFE scheme is indeed more effective than mandatory minimum energy performance standards (MEPS) in encouraging manufacturers to comply through various methods. This approach has ultimately increased the overall average fuel efficiency of Taiwan’s passenger cars by 23.5% since 2012, while maintaining the diversity of vehicle models in the market. However, there are challenges to implementing CAFE in a small market, such as difficulties in introducing and promoting high-efficiency models, limited activity in the CAFE credit market, and the current overly favorable policy design. The design of the CAFE mechanism is crucial not only for benchmarking with larger economies but also for taking into account local market conditions and industrial capabilities. Taiwan’s next phase of CAFE must incorporate multi-dimensional adjustments to achieve higher, potentially net-zero vehicle efficiency targets.

Xiao Liu, Zhiwei Zhao, Helong Jiang

Journal of Physics: Conference Series • 2023

Abstract Sediment microbial fuel cell (SMFC) is a renewable energy source with a wide range of raw materials. They have a simple structure, low cost, and broad application prospects in the field of self-power supply, attracting the attention of many researchers. However, the output current of SMFC is weak and the output voltage is low, which does not meet the power supply requirements of general electronic devices. Therefore, it is necessary to connect multiple SMFCs to obtain the required voltage and current. Series operation can increase the output voltage, while parallel operation can increase the output current. However, voltage reversal occurs in series operation, which can affect the output performance of the battery. In this work, voltage reversal was studied by two SMFCs respectively connected in series and in parallel after their output voltage stabilized. External load of the series and parallel batteries were connected to 330 ohms, 680 ohms, 1000 ohms, 2000 ohms, and 380K ohms, respectively. It was found that batteries with poor performance in series battery packs experienced voltage reversal, which occurred at 330 ohms, 680 ohms, and 1000 ohms. When the resistances became 2000 ohms and 380K ohms, parallel battery packs did not experience similar phenomena. The reason for voltage reversal was provided in this article. In addition, voltage reversal occurred in the stage of low resistances, which indicating that the greater the current, the greater the possibility of voltage reversal.

, Jinseok Chang, Minjae Kim et al.

FISITA World Congress 2021 - Technical Programme • 2021

"The new 3L diesel engine for passenger cars has been developed as the highly-performing and environment-friendly 3rd generation engine of Hyundai Motor Group. It is the newly-developed inline – 6 cylinders 3.0L diesel engine, and its performance for power, fuel efficiency, NVH, and responsiveness has been optimized for the first SUV of the GENESIS brand, GV80 - Project code: JX1. The future trend of powertrain is that although electrification and hybridization are continuously increasing, the internal combustion engine is still expected to play a role as a powertrain with sufficient production volume even in the future after 2030. This engine is equipped with an aluminum block, a common rail of pressure 2200 bar, a ball bearing turbocharger, a water-cooled intercooler, an LP(Low Pressure) & HP (High Pressure) EGR system, and has an LNT, a DPF , and an SCR as after-treatment devices. The combustion system of this engine was newly developed in common with HMG’s new diesel 2.0, 2.2, and 3.0L module engines. The combustion chamber has been improved in shape and spray compared to HMG’s previous V6 3L engine. And configuration of Injector nozzle, NTP, and valve timing have been optimized for the new combustion chamber. The turbo-charger has also been newly optimized for the power, fuel efficiency and responsiveness of the new engine. Accordingly, the responsiveness of the engine has been remarkably improved compared to the previous engine, and the power performance of the vehicle has also been improved very well. The performance of the intake manifold was also improved through several times with focus on air and EGR distribution, and also on cost, weight reduction, and robustness. The back pressure level of the exhaust system was developed in consideration of both power and NVH performance with focus on the GENESIS brand. In consideration of this, the engine's NVH showed better results than the engines of the previous HMG’s and competitors. Its maximum power advanced 7% more than the previous HMG’s engine, and it has also become a 3L diesel engine with the highest power, overtaking competitors. The engine's fuel efficiency is improved by about 6% over the previous HMG's engine. In addition, the results were 5-10% better than competitors' engines, and vehicle fuel efficiency was 13% superior to the previous HMG’s and 8-9% superior to competitors. Through this, it has secured the world's best fuel efficiency and power performance competitiveness. For the after-treatment devices, the EMS mapping development of the exhaust heating was efficiently progressed according to the state of the after-treatment devices, and the water-cooled intercooler and the complex EGR system were developed to operate properly including the extended RDE at low temperature. The SCR system showed a high NOx conversion efficiency of over 80% in regulatory modes such as WLTC and RDE STEP2. The new 3L diesel engine’s performance accords with the world-best-class fuel efficiency and high-performance for the world-premium brand GENESIS, satisfying with the latest environmental regulation EURO6d."

Ahsan Amjad, Waqar Muhammad Ashraf, Ghulam Moeen Uddin et al.

Energy Science & Engineering • 2023

Abstract Accurately predicting fuel blends' lower heating values (LHV) is crucial for optimizing a power plant. In this paper, we employ multiple artificial intelligence (AI) and machine learning‐based models for predicting the LHV of various fuel blends. Coal of two different ranks and two types of biomass is used in this study. One was the South African imported bituminous coal, and the other was lignite thar coal extracted from the Thar Coal Block‐2 mine by Sind Engro Coal Mining Company, Pakistan. Two types of biomass, that is, sugarcane bagasse and rice husk, were obtained locally from a sugar mill and rice mill located in the vicinity of Sahiwal, Punjab. Bituminous coal mixture with other coal types and both types of biomass are used with 10%, 20%, 30%, 40%, and 50% weight fractions, respectively. The calculation and model development procedure resulted in 91 different AI‐based models. The best is the Ridge Regressor, a high‐level end‐to‐end approach for fitting the model. The model can predict the LHV of the bituminous coal with lignite and biomass under a vast share of fuel blends.

Shweta Rawat, Jyoti Rawat

International Journal of Applied Sciences and Biotechnology • 2016

Microbial fuel cell technology is a recent approach which consist renewable and sustainable technology for electricity generation. Great attentions have been paid to microbial fuel cells (MFCs). Since, it recovers energy from renewable materials that can be difficult to dispose, such as organic wastes, waste water etc. and utilize variety of biodegradable substrates as fuel. Through which, microorganisms actively catabolize substrate and generate electricity. Besides many advantages, it still faces some limitations such as low power and current density. In the present research waste water was physically, biologically and chemically tested. We found that waste water has less amount of toxicity. Thus, it was assumed as low strength waste water and used for the MFC setup for bioelectric generation.Initially, the setup was run three times in a small scale. Simultaneously voltage and current was measured at different time intervals. It was observed that in first run, the voltage and current fluctuation data was not significant but voltage generation was varied from 140.8-182.5 mV in final run, correspondingly current fluctuated from 51-352 μA and power varied from 7180.8-66439.1 nW. However, we got highest power density of 0.0215-0.042 mW when the setup was moved in higher scale.Int J Appl Sci Biotechnol, Vol 4(3): 281-287

Senthil M Kumar, A Kerihuel, J Bellettre et al.

Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy • 2005

The influence of water and methanol (W/M) fractions on the performance of a compression ignition engine fuelled with animal fat (obtained from duck) emulsions is studied. A single cylinder air-cooled, direct injection diesel engine developing a rated brake power output of 2.8 kW at 1500 r/min is tested using diesel neat animal fat, and animal fat emulsions with different fractions of W/M. Results show reduced peak pressure with neat animal fat when compared with diesel. Animal fat emulsions result in increased peak pressure with increased W/M fractions. Ignition delay is quite high with neat animal fat. Increase in W/M amounts in the emulsions further increase the ignition delay. Heat release pattern shows improved combustion rates with animal fat emulsions at all W/M fractions when compared with neat animal fat. Drastic reduction in smoke emission from 3.6 m −1 with neat animal fat to a minimum of 0.5 m −1 is achieved with the animal fat emulsion at the maximum W/M fraction. NO emission is found to be lower with neat animal fat than with neat diesel. Animal fat emulsions further reduce NO emission at all W/M fractions. Hydrocarbon and carbon monoxide emissions are also reduced significantly with animal fat emulsions at all W/M ratios when compared with neat animal fat. In general, animal fat emulsions with different W/M fractions show considerable reduction in all emissions and improvement in engine performance when compared with neat animal fat. Emulsion of 10W10M2S83 (i.e. 10 per cent of water, 10 per cent of methanol, and 2 per cent of span 83 by volume) is found to be the best among the three tested emulsions for optimum performance and emissions.

Joseph M. Staller, Robert P.M. Craven, Stephen Idem et al.

ASME Open Journal of Engineering • 2021

Abstract This paper describes a real-time performance-monitoring method based on PTC 4-2013 that was developed for determining and reporting the annual heat rate for fossil fuel power plants. Unlike for the PTC 4 test, the coal composition is typically not known in real-time, so the procedure uses a modified output-loss approach applied to a control volume that closely conforms to the boiler. A calibration approach utilizes an ultimate analysis to describe the coal being burned during the calibration, while holding the plant load and other factors steady. This permits the calculation of correction factors used during real-time performance monitoring. Based on several assumptions that are justified within, a real-time estimate of coal composition is obtained. The losses are calculated in a similar manner to PTC 4-2013. However, the losses are expressed on a per-pound of as-fired coal basis, as opposed to a percentage of higher heating value of the coal, which is not known in real-time.

Taiki Nobeshima, Kazuki Nakamura, Norihisa Kobayashi

Japanese Journal of Applied Physics • 2013

An AC-driven light-emitting cell based on the electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy) 3 2+ ] was fabricated by simply placing the electrolyte solution between transparent electrodes, and this AC-driven ECL cell was demonstrated for comparison to a DC-ECL cell. The properties of the ECL cell were dramatically improved by using the AC method. The AC-ECL cell showed the luminance of 56.4 cd/m 2 , the current efficiency of 0.78 cd/A and the turn-on response time of ca. 15 ms under application of 4 V, 50 Hz AC. We also elucidated the detailed mechanisms of the AC-ECL reaction to monitor the faradaic current. These improved properties and the frequency dependence of the AC-ECL cell were discussed in the relation to the revealed mechanisms.

Natalia Tapia, Claudia Rojas, Carlos Bonilla et al.

Sensors • 2017

Green roofs have many benefits, but in countries with semiarid climates the amount of water needed for irrigation is a limiting factor for their maintenance. The use of drought-tolerant plants such as Sedum species, reduces the water requirements in the dry season, but, even so, in semiarid environments these can reach up to 60 L m−2 per day. Continuous substrate/soil water content monitoring would facilitate the efficient use of this critical resource. In this context, the use of plant microbial fuel cells (PMFCs) emerges as a suitable and more sustainable alternative for monitoring water content in green roofs in semiarid climates. In this study, bench and pilot-scale experiments using seven Sedum species showed a positive relationship between current generation and water content in the substrate. PMFC reactors with higher water content (around 27% vs. 17.5% v/v) showed larger power density (114.6 and 82.3 μW m−2 vs. 32.5 μW m−2). Moreover, a correlation coefficient of 0.95 (±0.01) between current density and water content was observed. The results of this research represent the first effort of using PMFCs as low-cost water content biosensors for green roofs.

Shi‐Jie You, Jin‐Na Zhang, Yi‐Xing Yuan et al.

Journal of Chemical Technology & Biotechnology • 2010

Abstract BACKGROUND: Sustainable technologies need to be developed to treat saline seafood wastewater (SSW) efficiently. This study focused on the feasibility of a continuously operated microbial fuel cell (MFC) with modified anoxic/oxic (A/O) architecture (A/O–MFC) for power generation and treatment of SSW simultaneously. RESULTS: Hydraulic retention time (HRT) was shown to have an impact on polarization and power output of the A/O–MFC and the maximum power density of 16.2 W m −3 was obtained at a current density of 41.7 A m −3 and HRT of 4.2 h. High salinity together with advective flow mode enabled a low and constant internal resistance of approximately 100 Ω throughout the experiments. Besides, pH of waste stream in both compartments was found always near neutral level. Increasing HRT could improve eliminability of soluble chemical oxygen demand (sCOD) and biological nitrification. CONCLUSIONS: This study provides a proof‐in‐concept demonstration to utilize an MFC for effective and sustainable treatment of SSW along with recovery of electrical energy. Copyright © 2010 Society of Chemical Industry

Carla Isabel Flores Rodriguez, Gustavo Mockaitis

Preprints.org • 2024

PSLer is designed to utilize commercial boards and open-source code to deliver and capture voltage in microbial electrolysis systems. This applied voltage enhances microbial metabolic processes, allowing the microbial cells to generate electrical power, which the device captures and records. Effective operation, optimization, and troubleshooting of microbial electrolysis cells rely on power suppliers and multimeters with data acquisition capabilities to ensure dependable performance and efficient resource use. In this context, the manuscript describes the development of an automatic monitoring device that incorporates a Power Supply Unit, Arduino UNO, and ADS1256 boards, with an assembly cost less than $300 American dollars. This cost-effective solution empowers researchers with limited budgets to conduct dependable and efficient research. Additionally, the manuscript provides detailed instructions for assembling and using the monitoring device. This innovative prototype overcomes the limitations of costly and inflexible commercial devices and fosters interdisciplinary research, ultimately saving time and reducing costs.

, Teng Wang

• 2020

This PhD thesis provides a fast engineering approach to the design of digital predistortion (DPD) linearizers from several perspectives: i) enhancing the off-line training performance of open-loop DPD, ii) providing robustness and reducing the computational complexity of the parameters identification subsystem and, iii) importing machine learning techniques to favor the automatic tuning of power amplifiers (PAs) and DPD linearizers with several free-parameters to maximize power efficiency while meeting the linearity specifications. One of the essential parts of unmanned aerial vehicles (UAV) is the avionics, being the radio control one of the earliest avionics present in the UAV. Unlike the control signal, for transferring user data (such as images, video, etc.) real-time from the drone to the ground station, large transmission rates are required. The PA is a key element in the transmitter chain to guarantee the data transmission (video, photo, etc.) over a long range from the ground station. The more linear output power, the better the coverage or alternatively, with the same coverage, better SNR allows the use of high-order modulation schemes and thus higher transmission rates are achieved. In the context of UAV wireless communications, the power consumption, size and weight of the payload is of significant importance. Therefore, the PA design has to take into account the compromise among bandwidth, output power, linearity and power efficiency (very critical in battery-supplied devices). The PA can be designed to maximize its power efficiency or its linearity, but not both. Therefore, a way to deal with this inherent trade-off is to design high efficient amplification topologies and let the PA linearizers take care of the linearity requirements. Among the linearizers, DPD linearization is the preferred solution to both academia and industry, for its high flexibility and linearization performance. In order to save as many computational and power resources as possible, the implementation of an open-loop DPD results a very attractive solution for UAV applications. This thesis contributes to the PA linearization, especially on off-line training for open-loop DPD, by presenting two different methods for reducing the design and operating costs of an open-loop DPD, based on the analysis of the DPD function. The first method focuses on the input domain analysis, proposing mesh-selecting (MeS) methods to accurately select the proper samples for a computationally efficient DPD parameter estimation. Focusing in the MeS method with better performance, the memory I-Q MeS method is combined with feature extraction dimensionality reduction technique to allow a computational complexity reduction in the identification subsystem by a factor of 65, in comparison to using the classical QR-LS solver and consecutive samples selection. In addition, the memory I-Q MeS method has been proved to be of crucial interest when training artificial neural networks (ANN) for DPD purposes, by significantly reducing the ANN training time. The second method involves the use of machine learning techniques in the DPD design procedure to enlarge the capacity of the DPD algorithm when considering a high number of free parameters to tune. On the one hand, the adaLIPO global optimization algorithm is used to find the best parameter configuration of a generalized memory polynomial behavioral model for DPD. On the other hand, a methodology to conduct a global optimization search is proposed to find the optimum values of a set of key circuit and system level parameters, that properly combined with DPD linearization and crest factor reduction techniques, can exploit at best dual-input PAs in terms of maximizing power efficiency along wide bandwidths while being compliant with the linearity specifications. The advantages of these proposed techniques have been validated through experimental tests and the obtained results are analyzed and discussed along this thesis. Aquesta tesi doctoral proporciona unes pautes per al disseny de linealitzadors basats en predistorsió digital (DPD) des de diverses perspectives: i) millorar el rendiment del DPD en llaç obert, ii) proporcionar robustesa i reduir la complexitat computacional del subsistema d'identificació de paràmetres i, iii) incorporació de tècniques d'aprenentatge automàtic per afavorir l'auto-ajustament d'amplificadors de potència (PAs) i linealitzadors DPD amb diversos graus de llibertat per poder maximitzar l’eficiència energètica i al mateix temps acomplir amb les especificacions de linealitat. Una de les parts essencials dels vehicles aeris no tripulats (UAV) _es l’aviònica, sent el radiocontrol un dels primers sistemes presents als UAV. Per transferir dades d'usuari (com ara imatges, vídeo, etc.) en temps real des del dron a l’estació terrestre, es requereixen taxes de transmissió grans. El PA _es un element clau de la cadena del transmissor per poder garantir la transmissió de dades a grans distàncies de l’estació terrestre. A major potència de sortida, més cobertura o, alternativament, amb la mateixa cobertura, millor relació senyal-soroll (SNR) la qual cosa permet l’ús d'esquemes de modulació d'ordres superiors i, per tant, aconseguir velocitats de transmissió més altes. En el context de les comunicacions sense fils en UAVs, el consum de potència, la mida i el pes de la càrrega útil són de vital importància. Per tant, el disseny del PA ha de tenir en compte el compromís entre ample de banda, potència de sortida, linealitat i eficiència energètica (molt crític en dispositius alimentats amb bateries). El PA es pot dissenyar per maximitzar la seva eficiència energètica o la seva linealitat, però no totes dues. Per tant, per afrontar aquest compromís s'utilitzen topologies amplificadores d'alta eficiència i es deixa que el linealitzador s'encarregui de garantir els nivells necessaris de linealitat. Entre els linealitzadors, la linealització DPD és la solució preferida tant per al món acadèmic com per a la indústria, per la seva alta flexibilitat i rendiment. Per tal d'estalviar tant recursos computacionals com consum de potència, la implementació d'un DPD en lla_c obert resulta una solució molt atractiva per a les aplicacions UAV. Aquesta tesi contribueix a la linealització del PA, especialment a l'entrenament fora de línia de linealitzadors DPD en llaç obert, presentant dos mètodes diferents per reduir el cost computacional i augmentar la fiabilitat dels DPDs en llaç obert. El primer mètode se centra en l’anàlisi de l’estadística del senyal d'entrada, proposant mètodes de selecció de malla (MeS) per seleccionar les mostres més significatives per a una estimació computacionalment eficient dels paràmetres del DPD. El mètode proposat IQ MeS amb memòria es pot combinar amb tècniques de reducció del model del DPD i d'aquesta manera poder aconseguir una reducció de la complexitat computacional en el subsistema d’identificació per un factor de 65, en comparació amb l’ús de l'algoritme clàssic QR-LS i selecció de mostres d'entrenament consecutives. El segon mètode consisteix en l’ús de tècniques d'aprenentatge automàtic pel disseny del DPD quan es considera un gran nombre de graus de llibertat (paràmetres) per sintonitzar. D'una banda, l'algorisme d’optimització global adaLIPO s'utilitza per trobar la millor configuració de paràmetres d'un model polinomial amb memòria generalitzat per a DPD. D'altra banda, es proposa una estratègia per l’optimització global d'un conjunt de paràmetres clau per al disseny a nivell de circuit i sistema, que combinats amb linealització DPD i les tècniques de reducció del factor de cresta, poden maximitzar l’eficiència de PAs d'entrada dual de gran ample de banda, alhora que compleixen les especificacions de linealitat. Els avantatges d'aquestes tècniques proposades s'han validat mitjançant proves experimentals i els resultats obtinguts s'analitzen i es discuteixen al llarg d'aquesta tesi.