Experimental Work Research Articles

Differences on carboxylic acids bioproduction from soluble carbohydrates or proteins in a sequencing batch reactor: Deciphering the influence of the volumetric and specific organic loading rate

Acidogenic fermentation (AF) has been extensively explored. However, the impact of operational parameters on AF has led to inconsistent results. In this work, AF experiments were performed in a sequencing batch reactor (SBR) using simulated wastewaters solely containing soluble carbohydrates or proteins as carbon sources to independently assess the impact of the volumetric organic loading rate (OLRv) and of the specific organic loading rate (OLRs). When only carbohydrates were used, the main effluent components were acetic and butyric acids at OLRv of 6.0 g COD L−1 d−1, while changing OLRv over 11.0 g COD L−1 d−1 gave acetic acid and ethanol as main components. Conversely, if the carbon source consisted solely of proteins, increasing the OLRv or the OLRs had minimal impact on the AF performance and on the effluent composition. Also, in the case of carbohydrate experiments, increasing the OLRs from 2.3 to 3.8 g COD g−1 VSS d−1 promoted chain elongation reactions, as caproic acid formation was also observed. Besides, at the highest OLRv tested in this work for protein experiments (18.5 g COD L−1 d−1), it was obtained the maximum isocaproic acid concentration using mixed microbial cultures and without adding any external electron donor. The SBR configuration proved to be an adequate system, especially when proteins were used as carbon source, since it makes possible to keep low the OLRs and to reduce the hydrolysis limitations. Finally, the bacterial genera detected in the reactors notably changed between both substrates. Future work must be focused on identifying carboxylic acid producing-genera from proteins.

Augusto Monterroso en la UNAM

This article is an investigation, based on the historical and labor archives of the Universidad Nacional Autónoma de México (unam), of Augusto Monterro-so’s professional career at that institution. Monterroso joined unam in the 1950s as a proofreader. This job gave him the economic stability to develop a literary work of great formal experimentation, that practiced with literary genres of little popularity and diffusion at the time (minifiction, short stories, essays). His literary capital and his friendship with key figures such as Rubén Bonifaz Nuño helped him to join the Facultad de Filosofía y Letras, as a professor of a writing workshop, and the Instituto de Investigaciones Filológicas, as a researcher. The University provided Monterroso with: 1- the necessary economic stability to keep his distance from literary fashions and follow an aesthetic of formal complexity; 2- an active relationship as editor and corrector of classical works and the Western canon, which were the foundation of his poetics, and 3- the tools of literary criticism necessary for the writing of a playful literary essay with marked intertextual features. Keywords:archives; formal experimentation; academy; biography; Mexican literature

Offshore Wind Energy Validation Experiment Hierarchy

This paper provides a summary of planning work for experiments that will be necessary to address the long-term model validation needs required to meet offshore wind energy deployment goals. Conceptual experiments are identified and laid out in a validation hierarchy for both wind turbine and wind plant applications. Instrumentation needs that will be required for the offshore validation experiments to be impactful are then listed. The document concludes with a nominal vision for how these experiments can be accomplished.

Heat Transfer Performance Analysis of an E-Vehicle Cooling System Using a Hybrid Peltier System

Abstract: This research investigates the heat transfer performance of an electric vehicle (EV) cooling system utilising a hybrid Peltier as integrated system with advancements in EV battery technology, the demand for efficient cooling systems has become crucial for ensuring battery safety, longevity, and overall performance. Present research focus on the application of ethylene glycol as a coolant, exploring the thermal parameters, heat transfer rates, and overall effectiveness of the hybrid cooling system. A literature review highlights the significance of heat transfer enhancement techniques, emphasising the need for energyefficient methods in the automotive industry. The research methodology involves experimental work, analytical calculations, and the preparation of coolant samples to evaluate thermo-physical parameters. The results demonstrate the temperature drop, Overall heat transfer for different flow rates, Logarithmic Mean Temperature difference, and Comparative Power Consumption of different setup. The result showed that presence of ethylene glycol in water enhances the desirable temperature drop of the heat transfer fluid. The Overall heat transfer rate is increased by 58% for EG-100 sample as compared to pure water. Further an ANN model is also developed for prediction of temperature drop, the result showed 2 layer model with 8, 8 neurons as optimum model for prediction.

Enhancement in thermal and electrical characteristics of solar photovoltaic module through a direct contact water jacketed cooling system

Renewable energy resources are vital for addressing the universal concerns of air quality, energy security, and sustainable development. Solar energy has several benefits over other popular renewable energy sources, such as its accessibility and increased predictability. The device used for conversion of solar energy to electrical energy is known as photovoltaic panel, which is highly sensitive to the temperature. A significant reduction in efficiency is observed with an increment in temperature hence cooling of photovoltaic panel is highly desirable. Among the different cooling techniques, water cooling is attractive and widely used due to its good thermal properties and availability. Generally, panel cooling through water circulation in tubing is explored in past, however, these tubing structures are having some limitations such as heat transfer barrier, limited surface area, leakage issues, clogging and cost of material. These issues can be partially resolved by using direct contact water jacket cooling system. Therefore, the present study focuses on in enhancing the thermal and electrical characteristics of the solar photovoltaic module through a direct contact water jacketed cooling system. Initially, a 3D numerical model is developed and the outcome of the numerical model is compared with the experimental work. The results obtained are found in good agreement for solar cell temperature and water outlet temperature. The solar panel performance is investigated with different flow rates such as 0.01, 0.05, 0.1 and 1 cm/s. The direct contact water jacketed cooling system offers simplicity, light weight and cost effectiveness and is found promising over the indirect system. Temperature reduction up to 20 °C is observed over uncooled PV panel whereas enhancement in electrical efficiency up to 9.6 % is observed. The cooled PV solar cell maintain 40.2% low temperature compare to uncooled solar cell temperature.

Mechanism of scour around two piers

AbstractScour around the bridge piers is the main cause of bridge failure below any bridge pier placed within the waterways. It is more than hundred years back a number of researchers described the vortex shedding phenomenon and the resulting Aeolian tones from a circular cylinder. Since then there have been a large number of investigations dealing with various aspects of this phenomenon. In many practical works and situations, flow takes place around more than one obstruction and objects in close proximity. Invariably in all these cases, interference effects occur and the forces on the obstructions are much influenced by these effects. These effects play a key role in the structures like flow-induced vibration of TV and transmission towers, and in many other practical situations. In this research paper the changes in the flow field that occur due to the interference effects are shown, analysed and the results as given in literature are compared with the present experimental work. The features have been brought out in this paper mainly make use of stand and geometry of circular cylinders in close proximity and the flow part of geometry in side by side arrangement.

Gaskell Studies: Realism, Radicalism, and the Neoliberal Lens in Recent Scholarship on Elizabeth Gaskell

ABSTRACT Literary critics have long prized the works of Elizabeth Gaskell for their unflinching realism. They have found in her novels, in particular, artifacts of her era’s greatest injustices and the progressive spirit that animated resistance to them. In the last ten years, Gaskell scholarship has taken a different tack. Exploring her more formally radical narrative forms, including lesser-studied novellas like Lois the Witch and other Gothic tales, recent criticism has begun wrestling directly and indirectly with the concept of realism itself. Some scholars go so far as to suggest that realism as a literary critical rubric may be inadequate to the task of understanding and interpreting Gaskell’s most experimental and subversive works. This article furthermore argues that when we read for realism in Gaskell’s works, we run the risk of reading through a neoliberal lens that obscures key dimensions of her work and the social and political radicalism they espouse.

Filament-based memristor switching model

The filaments rupture and recovery in oxide-type memristors have been theoretically studied. The model is based on the kinetics of oxygen vacancies and includes Joule heating of the oxide medium, which enhances the diffusion and drift of oxygen vacancies in an external electric field. The current-voltage characteristic of the model structure was obtained. Comparison with experimental results allowed for the determination of the constants used in the modeling. The peculiarity of the current-voltage characteristic observed in experimental works is explained.

Increased cardiac vagal tone in childhood-only, adolescent-only, and persistently antisocial teenagers: the mediating role of low heart rate.

Cardiac vagal tone is an indicator of parasympathetic nervous system functioning, and there is increasing interest in its relation to antisocial behavior. It is unclear however whether antisocial individuals are characterized by increased or decreased vagal tone, and whether increased vagal tone is the source of the low heart rate frequently reported in antisocial populations. Participants consisted of four groups of community-dwelling adolescent boys aged 15.7 years: (1) controls, (2) childhood-only antisocial, (3) adolescent-only antisocial, and (4) persistently antisocial. Heart rate and vagal tone were assessed in three different conditions: rest, cognitive stressor, and social stressor. All three antisocial groups had both lower resting heart rates and increased vagal tone compared to the low antisocial controls across all three conditions. Low heart rate partially mediated the relationship between vagal tone and antisocial behavior. Results indicate that increased vagal tone and reduced heart rate are relatively broad risk factors for different developmental forms of antisocial behavior. Findings are the first to implicate vagal tone as an explanatory factor in understanding heart rate - antisocial behavior relationships. Future experimental work using non-invasive vagus nerve stimulation or heart rate variability biofeedback is needed to more systematically evaluate this conclusion.

Nozzle effects on spray combustion and emissions in compression ignition engines using waste cooking oil biodiesel: A computational fluid dynamics analysis at varying injection pressures

AbstractThis study investigates the spray combustion characteristics of waste cooking oil (WCO) in comparison between a swirl nozzle (SN) and a conventional nozzle (CN) of equal cross‐section. n‐Heptane, methyl decanoate, and methyl‐9‐decenoate were used as WCO substitutes in the simulation. The research primarily focuses on multiphase flow using the Lagrangian‐drop Eulerian‐fluid (LDEF) method, employing an equilibrium phase spray model (EP) for droplet behaviour analysis. The model's efficacy was validated through comparisons with experimental works by other engine researchers. At varying injection pressures, the study found that SN slightly reduced evaporative spray tip penetration but increased the cone angle compared to CN. This suggests early fuel jet disintegration and improved air entrainment due to SN. SN also showed a higher heat release rate and temperature, with soot reduction between 3.20 to 6.72% as injection pressure increased from 100 to 300 MPa. This indicates that SN achieves better air‐fuel mixture than CN. Further, the study discovered that the influence of SN becomes more significant as the rheological properties of WCO lessen under ultra‐high injection pressures.

Reinforcement of concrete beams using waste carbon-nanoclay-fiberglass laminate pieces

In the last few decades, strengthening of structures in need of repair with fiber reinforced polymer (FRP) composite materials produced with different fiber types has gained great importance. Within the scope of this experimental study, the usability of hybrid glass and carbon composite laminates produced for different purposes and later cut into waste was investigated for concrete reinforcement. Hybrid composite laminates were produced in the form of glass-carbon-glass and carbon-glass-carbon, and the effect was investigated in two different sequences in the study. In addition, there are 3 different rates of nanoclay (0.50%, 0.75% and 1.25%) in the production of composite materials, and the effect of nanoclay ratio was investigated. In the study, two different numbers of composite laminates were adhered to the concrete samples produced in 70x70x280 mm dimensions and subjected to flexural strength test. In the Carbon-Glass-Carbon series using triple waste laminate pieces, the highest flexural strength was reported in the CGC-0.75-3 series, which achieved an increase of approximately 55% and 42% compared to the Control and Control-E series. It was determined that the effectiveness of the reinforcement technique of concrete with laminates in flexure did not change significantly depending on the number of laminate pieces. The main mode of failure in the experimental work was due to concrete fracture.

Defect-induced properties of MoSi2/Nb(Ta)Si2 disilicide nanocomposites

Research on disilicide nanocomposites, as modern materials with promising technological applications, is very desirable these days. Our ab initio analysis concentrates on the C11b (tetragonal) MoSi2/C40 (hexagonal) NbSi2 or TaSi2 nanocomposites containing 12 types of interfaces formed by (110) planes in the C11b and (0001) planes in the C40 disilicide. The most stable nanocomposites are MoSi2(AC)/Nb(Ta)Si2(BAC), MoSi2(AB)/Nb(Ta)Si2(CAB) and MoSi2(AB)/Nb(Ta)Si2(ABC). The interfaces reveal positive formation energies, e.g. γIFBA = 0.63670 J.m−2 and γIFCA = 0.63727 J.m−2 in the Nb system and γIFBA = 0.57837 J.m−2 and γIFCA = 0.57802 J.m−2 in the Ta system. In the most stable C11b-MoSi2(AC)/C40-Nb(Ta)Si2(BAC) nanocomposite, the effect of the impurities (Al, Si), vacancies or their aggregates on the stability and structure is investigated. It turns out that (i) vacancies preferentially form at the Si positions in the third (first) layer of MoSi2 in the Nb (Ta) systems, utilising an energy of 2.259 eV.Va−1 (1.971 eV.Va−1); (ii) Al impurities prefer Si positions, and it is easier to introduce them into the Ta system than into the Nb one; however, this does not apply if Al is in the Mo position; (iii) Si impurities prefer Ta positions to Nb ones, and the bulk to interfacial ones; (iv) the Si-Si divacancy is the least destabilising among divacancies; and (v) Al impurities in both systems prevent the formation of Si vacancies, and the Si impurities simplify the formation of vacancies in the Nb system. As there is very little experimental information on the structure and properties of these interfaces, most of the present results are theoretical predictions which may motivate future experimental work.

Discovering [C4C1im][BF4] as draw solution in forward osmosis

AbstractPromising forward osmosis (FO) membrane desalination is a potentially viable energy‐efficient performance technology compared to other techniques. Searching for the ideal draw solute that creates high osmotic pressure difference and ease of regeneration is critical for water desalination using the FO system. However, many fundamental aspects still need to be adapted, such as needing more screening potential anions and cations based on the predictive method. The Group Contribution Method (GCM) was used in this study to predict the value of the van't Hoff factor denoted by (i). In the end, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([C4C1im][BF4]) was selected as a draw solution for later experimental work.

The Influence of Current Magnitudes and Profiles on the Sedimentation of Magnetorheological Fluids: An Experimental Work

Magnetorheological fluids (MRFs) are widely used for various kinds of controllable devices since their properties can be controlled by an external magnetic field. Despite many benefits of MRFs, such as fast response time, the sedimentation arisen due to the density mismatch of the compositions between iron particles and carrier oil is still one of bottlenecks to be resolved. Many studies on the sedimentation problem of MR fluids have been carried out considering appropriate additives, nanoparticles, and several carrier oils with different densities. However, a study on the effect of current magnitudes and profiles on the sedimentation is considerably rare. Therefore, this study experimentally investigates sedimentation behaviors due to different current magnitudes and different magnitude profiles such as square and sine waves in different diameters. The evaluation was performed by visual observation to obtain the sedimentation rate. It was found that the average sedimentation rate of the square type of current is slower compared to the sinusoidal type. It has also been identified that the higher intensity of the applied current results in a stronger electromagnetic field, which could slow down the sedimentation. The results achieved in this work can be effectively used to reduce particle sedimentation in the controller design of various application systems utilizing MRFs in which the controller generates a different magnitude and different profile of the external magnetic field.

The Performance of a Solar Panel with Maximum Power Point Tracking (MPPT) System

Due to the rotation of the earth and its spherical shape the availability of sunlight at a certain place is not same. At normal sky condition at a place sunlight is minimum at morning that gradually increase upto 2-3 pm then again tends to minimum. Usually, solar panels are fixed type and can’t absorb the sunlight whole day properly. In that sense, to increase the efficiency of a solar panel with its necessary accessories has been developed where maximum power point tracking (MPPT) system adopted. In this system the panel can easily move to get the maximum sunlight. The electric charges are then store in a battery that are being supplied to the electric appliances. The experimental work has been done at the roof-top of science faculty building of Chittagong University. This experimental study shows that the efficiency of the solar panel starts increasing from morning 9 am with efficiency of 16.64% and found maximum with efficiencies at 12 noon (24.92%); 1 pm (25.94%); and at 2 pm (24.68%) then again starts decreasing with the values of (22.3%) & (18.7%) at 3 and 4 pm respectively. Another, It has also been found that the peak value of average efficiency on July is (24.44%). The achieved efficiencies are more than the efficiency of (15.7%) studied on May-2017 with a fixed-type solar panel at the same place [M. A. Haque et al. 2018].

Theoretical Insight into the Palladium-Catalyzed Prenylation and Geranylation of Oxindoles with Isoprene.

This work presents a comprehensive mechanistic study of the ligand-controlled palladium-catalyzed prenylation (with C5 added) and geranylation (with C10 added) reactions of oxindole with isoprene. The calculated results indicate that the prenylation with the bis-phosphine ligand and geranylation with the monophosphine ligand fundamentally share a common mechanism. This mechanism involves the formation of two crucial species: a η3-allyl-Pd(II) cation and an oxindole carbon anion. Furthermore, the reactions necessitate the assistance of a second oxindole molecule, which serves as a Brønsted acid, providing a proton to generate the oxindole nitrogen anion. The oxindole nitrogen anion then acts as a Brønsted base, abstracting a C-H proton from another oxindole molecule to form an oxindole carbon anion. These mechanistic details differ significantly from those proposed in the experimental work. The present calculations do not support the presence of the Pd-H species and the η3, η3-diallyl-Pd(II) intermediate, which were previously suggested in experiments. The theoretical results rationalize the experimental finding that the bis-phosphine ligand favors the prenylation of oxindole, while the monophosphine ligand enables the geranylation of oxindole.

Experimental investigation of generating superheated steam using a parabolic dish with a cylindrical cavity receiver: A case study

Abstract This study uses solar energy to convert steam from a saturated to a superheated state using a solar steam superheater system. This collector system comprised a parabolic dish with a cylindrical cavity. The parabolic dish is of 2 m diameter and 0.83 m focal distance, covered with a reflective surface made of 1,283 rectangular pieces of mirrors, each of 3.5 cm × 4 cm that were fixed in place with glue type (FnTai). The receiver is a stainless-steel cylindrical cavity having a diameter of 17 cm and a length of 25 cm. A helical copper coil with a diameter of 10 mm and a length of 6 m was inserted inside the cylindrical cavity. The experimental work utilized saturated steam produced separately from an auxiliary electric boiler system, which was made along with other system components. A 0.011 kg/s of saturated steam at a temperature of 112°C enters the copper coil and is heated by the solar radiation reflected by the parabolic dish onto the receiver. As a result, the temperature of the steam is increased to 169.5°C at the receiver outlet. It was found that the collector efficiency is 55.6%. In addition, the convection and radiation heat losses are 12.14 and 10.98%, respectively. Also, the heat losses of (spillage, reflection, and conduction) were estimated to be 21.18%. The mass flow rate and pressure of the saturated steam from the boiler and entering the receiver affected the superheated steam production process. The process of superheating the steam, coupled with the subsequent improvement in thermal performance, indicates an increased efficiency of the collector. This is achieved by boosting the generation of useful heat and mitigating heat losses.

Finite Element Analysis of Solid and Hollow Roller Bearings to Predict the Influence of Contact Factors on Cage Slip

This study examines the influence of contact factors such as bearing deformation, contact width and contact pressure on cage slide in cylindrical roller bearings. A cylindrical shaped roller bearing test setup is designed in order to determine the operating speed of bearing components under varying working circumstances. Solid and hollow roller bearings are analyzed using finite element technique, and the contact parameters are obtained. The cage slip obtained by experimental work is correlated with the contact parameters of hollow and solid shaped roller bearings. The specific load acting on solid rollers at various angular positions and the corresponding bearing deflection are obtained by FEA and the bearing run out is estimated. A new methodology is developed for deriving the contact mechanics of hollow roller to predict contact pressure and contact width from the roller deflection. The effect of hollowness on these parameters is derived and the corresponding cage slip is correlated. The effect of hollowness on bending and resultant stresses is obtained by numerical and analytical methods to correlate the stability of hollow roller bearing with the percentage of hollowness.

Stability enhancement of Al2O3, ZnO, and TiO2 binary nanofluids for heat transfer applications

Abstract Primary goal of this research is to enhance stability of nanofluids which is vital for maintaining consistent thermophysical properties during various applications. Nanofluid stability is essential for obtaining the uniform thermophysical properties during its application. X-ray diffraction and zeta potential were performed to characterize three nanoparticles, namely TiO2, Al2O3, and ZnO. Experimental work was carried out under several trials to enhance the stability of nanofluids. Initially, deionized water was used as base fluid for stability analysis, but nanoparticles agglomerate within after 5 h. Second, alkaline water was selected as base fluid at different pHs ranging from 7 to 14 to analyze the stability of the nanofluids. Finally, the effect of surfactant addition on the stability of prepared nanofluids was also investigated. Observations revealed that at pH 11, nanoparticles exhibited enhanced stability compared to other pH levels. This stability can be attributed to the high zeta potential, fostering electrostatic repulsion between individual particles. It was concluded from the results that zeta potential increases in cases of (TiO2 + ZnO) and (Al2O3 + ZnO) from −44.2 to −47.8 mV and −42.4 to −44.1 mV with the addition of surfactant, respectively. In the case of (Al2O3 + TiO2), zeta potential decreases slightly from −47.7 to −44.9 mV with the addition of surfactant.

Integrating theory with the nanoreactor concept to synthesize hollow carbon sphere‐encapsulated PtNi alloys for enhanced H2 generation

AbstractThe rational design of efficient bimetallic nanoparticle (NP) catalysts is challenging due to the lack of theoretical understanding of active components and insights into the mechanisms of a specific reaction. Here, we report the rational design of nanoreactors comprising hollow carbon sphere‐confined PtNi bimetallic NPs (PtNi@HCS) as highly efficient catalysts for hydrogen generation via ammonia borane hydrolysis in water. Using both density functional theory calculations and molecular dynamics simulations, the effects of an active PtNi combination and the critical synergistic role of a hollow carbon shell on the molecule diffusion adsorption behaviors are explored. Kinetic isotope effects and theoretical calculations allow the clarification of the mechanism, with oxidative addition of an O–H bond of water to the catalyst surface being the rate‐determining step. The remarkable catalytic activity of the PtNi@HCS nanoreactor was also utilized for successful tandem catalytic hydrogenation reactions, using in situ‐generated H2 from ammonia borane with high efficiency. The concerted design, theoretical calculations, and experimental work presented here shed light on the rational elaboration of efficient nanocatalysts and contribute to the establishment of a circular carbon economy using green hydrogen.