Differential Energy Research Articles

SPyCE: A structured and tailored series of Python courses for (bio)chemical engineers

In times of educational disruption, significant advances in adopting digitalization strategies have been accelerated. In this transformation climate, engineers should be adequately educated to face the challenges and acquire the new skills imposed by Industry 4.0. Among these, one of the most highly requested tools is Python. To tackle these aspects, this work establishes a pedagogical framework to teach Python to chemical engineers. This is achieved through a hands-on series of Python courses (sPyCE), covering topics as chemical reaction engineering and machine learning. Part of the series has been embedded in the curriculum of a Bachelor’s-level course at the Technical University of Denmark (DTU). Overall, students found the course to be useful; using Python, they solved systems of differential equations, mass and energy balances, set stoichiometric tables, regressions, simulations and more. Motivated by the large applicability and relevance of the covered topics, sPyCE is made publicly available on GitHub.

Detection and ISI mitigation in mobile molecular communication system for targeted drug delivery

This paper proposes a targeted drug delivery system based on mobile molecular communication (MMC). The system consists of a mobile transmitter and a mobile reactive receiver. The transmitter can sense the required drug concentration and send commands to the receiver for drug delivery in the extracellular fluid (ECF). The commands are sent in the form of bits and the received signal is prone to noise and inter-symbol interference (ISI). Hence, at the receiver, two detection techniques, differential amplitude detector (DAD) and differential energy detector (DED) with ISI mitigation are proposed for MMC. Manchester-coded bits are transmitted using modified concentration shift keying (MCSK). In the proposed detection mechanism, an adaptive threshold technique is used for estimating the number of signaling molecules using the maximum a posteriori probability (MAP) rule. Further in each bit interval, dynamic distance estimation, signal reconstruction, and ISI mitigation are performed. Particle-based simulation for reactive receiver is also carried out to validate the results. A low bit error rate (BER) in the MMC system signifies the promising performance of the drug delivery system.

Heat capacity changes associated with G-quadruplex unfolding.

G-quadruplexes are four-stranded DNA structures that have been found in the cell and are thought to act as elements of control in genomic events. The measurements of the thermodynamic stability, ΔG, of G-quadruplexes shed light on the molecular forces involved in the stabilization of these structures. In thermodynamic studies, the differential heat capacity, ΔCP, of the folded and unfolded states of a G-quadruplex is a fundamental property that describes the temperature dependences of the differential enthalpy, ΔH, entropy, ΔS, and free energy, ΔG. Despite its recognized importance, the ΔCP of G-quadruplex unfolding has not been measured directly. Here, we use differential scanning calorimetry to evaluate changes in heat capacity, ΔCP, accompanying the unfolding transitions of G-quadruplexes formed by modified DNA sequences from the promoter regions of the c-MYC, VEGF, and Bcl-2 oncogenes. The average value of ΔCP is 0.49 ± 0.12kcal mol-1K-1. Our analysis revealed that disregarding ΔCP leads to significant errors in extrapolated values of the differential enthalpy, ΔH, and entropy, ΔS, of the folded and unfolded DNA conformations. Although the compensation between ΔH and ΔS weakens the effect of ΔCP on the differential free energy, ΔG, neglecting ΔCP may still result in relative errors in ΔG extrapolated to room temperature as great as 140%. We emphasize the importance of proper consideration of the effect of ΔCP in conformational studies of guanine-rich DNA molecules.

A Cross-Layer Media Access Control Protocol for WBANs

Wireless body area network (WBAN) is an emerging comprehensive technology that can deeply integrate with e-health and smart sports. As a wearable network, improving the quality of network service and user experience is crucial. Due to the miniaturized design of sensors, their available energy from batteries is limited, making the extension of their lifetime a key research challenge. Existing studies have proposed methods to improve energy efficiency, but there are still limitations in addressing dynamic adaptive aspects of differential energy distribution and channel conditions. In order to further extend the lifetime of sensor nodes and networks while ensuring quality of service, and to provide a reliable transmission mechanism for heterogeneous application data, this paper presents a cross-layer optimized MAC protocol mechanism. The protocol takes into account the transmission requirements of different types of data and redesigns the superframe. To improve the lifetime of nodes, we propose an energy-adaptive adjustment mechanism considering the channel conditions. At the same time, a cooperative transmission mechanism is proposed to further enhance network lifetime. In experiments conducted on two typical networks, compared to IEEE 802.15.6, the power adjustment scheme improves the network lifetime by 2.8 to 3.7 times, and the cooperative mechanism between nodes further increases the network lifetime by 17% to 44%. Our proposed scheme effectively extends the network lifetime while ensuring quality of service, avoiding frequent battery resets for users, and effectively improving the user experience quality.

Differential Energy Criterion for Brittle Fracture: Conceptualization and Application to the Analysis of Axial and Lateral Deformation in Uniaxial Compression of Rocks.

This paper discusses modeling the behavior and prediction of fracture of brittle materials. Numerous publications show that progress in this area is characterized by the emergence of a number of new models that meet the requirements of the mining industry, construction and other engineering practices. The authors focus only on one class of models, paying special attention to the compromise between simplicity of solution and versatility of the model. A new version of the model is proposed, taking into account the advantages of previous models. We present a differential energy criterion for brittle fracture substantiated, according to which, fracture occurs at a certain ratio of dissipated and stored (elastic) energy. Fracture is considered as the end of the deformation process with a virtual transformation of the initial material almost without cracks into a real material with cracks. The highest and lowest elastic moduli are analytically determined, respectively, on the ascending and descending branches of the stress-strain curve. A graphical version of the algorithm for determining the brittle fracture point on the post-peak branch of the stress-strain curve is proposed. The modeling results are consistent with the experimental data known from the literature.

Heterogeneous Graph Neural Network for identifying hadronically decayed tau leptons at the High Luminosity LHC

We present a new algorithm that identifies reconstructed jets originating from hadronic decays of tau leptons against those from quarks or gluons. No tau lepton reconstruction algorithm is used. Instead, the algorithm represents jets as heterogeneous graphs with tracks and energy clusters as nodes and trains a Graph Neural Network to identify tau jets from other jets. Different attributed graph representations and different GNN architectures are explored. We propose to use differential track and energy cluster information as node features and a heterogeneous sequentially-biased encoding for the inputs to final graph-level classification.

Cosmic Rays Self-arising Turbulence with Universal Spectrum −8/3

In the inertial subrange of scales, an exact compressible turbulence universal spectrum law −8/3 for the density fluctuations of cosmic rays (CRs) in the frame of the known two-fluid model of CR dynamics is obtained. It is shown that the origin of this scaling law may be due to the arising of shocks at the breaking of the nonlinear simple waves of CRs near the scale of their Larmor’s radii, as it is well known for the solar wind with the same turbulent spectrum law −8/3. The consistency of the turbulence spectrum −8/3 of CRs with the observed nonthermal differential energy distribution of CRs with a similar index −8/3 due to the possibility of self-reacceleration of the CRs on the self-arising shocks is stated. The turbulent diffusion mechanism for the observed CRs energy spectrum breaks is considered.

Alprazolam modulates persistence energy during emotion processing in first-degree relatives of individuals with schizophrenia: a network control study

Schizophrenia is marked by deficits in facial affect processing associated with abnormalities in GABAergic circuitry, deficits also found in first-degree relatives. Facial affect processing involves a distributed network of brain regions including limbic regions like amygdala and visual processing areas like fusiform cortex. Pharmacological modulation of GABAergic circuitry using benzodiazepines like alprazolam can be useful for studying this facial affect processing network and associated GABAergic abnormalities in schizophrenia. Here, we use pharmacological modulation and computational modeling to study the contribution of GABAergic abnormalities toward emotion processing deficits in schizophrenia. Specifically, we apply principles from network control theory to model persistence energy – the control energy required to maintain brain activation states – during emotion identification and recall tasks, with and without administration of alprazolam, in a sample of first-degree relatives and healthy controls. Here, persistence energy quantifies the magnitude of theoretical external inputs during the task. We find that alprazolam increases persistence energy in relatives but not in controls during threatening face processing, suggesting a compensatory mechanism given the relative absence of behavioral abnormalities in this sample of unaffected relatives. Further, we demonstrate that regions in the fusiform and occipital cortices are important for facilitating state transitions during facial affect processing. Finally, we uncover spatial relationships (i) between regional variation in differential control energy (alprazolam versus placebo) and (ii) both serotonin and dopamine neurotransmitter systems, indicating that alprazolam may exert its effects by altering neuromodulatory systems. Together, these findings provide a new perspective on the distributed emotion processing network and the effect of GABAergic modulation on this network, in addition to identifying an association between schizophrenia risk and abnormal GABAergic effects on persistence energy during threat processing.

A Novel High Impedance Fault Detection Strategy for Microgrid Based on Differential Energy Signal of Current Signatures and Entropy Estimation

The non-linearly deterministic fault current characteristics with low current magnitude of high impedance fault (HIF) have thrown an inevitable challenge to the microgrid protection system. Moreover, differentiating HIF from non-fault events is also a challenging task under different operating scenarios of the microgrid. In order to address this, a simple and fast protection algorithm, based on Empirical Mode Decomposition (EMD) in conjugation with Teager-Kaiser Energy Operator (TKEO) is proposed in this article. This scheme process the current signals retrieved from both ends of the line through EMD, and subsequently, the current signal energy is extracted by TKEO. The incidence of a fault is affirmed by measuring the energy difference signal and estimation of entropy. By employing the second layer algorithm using entropy analysis, the non-fault disturbances, such as capacitor and load switching, temporary overloading, and DG outage, have been effectively distinguished from HIFs. The proposed technique is tested for grid-tied and autonomous microgrid operation modes with several HIF and non-fault cases. It is inferred that the proposed technique can detect and differentiate HIFs from other system perturbations seamlessly in less time. Compared to other methods, this scheme has procured excellent accuracy and reliability, and is also not affected by the dynamic current behavior of the microgrid. The PSCAD-EMTDC software is used to build and simulate the test system, and the MATLAB programming interface is utilized to develop and test the suggested method.

Microscopic investigation of crack and strain of LiCoO2 cathode cycled under high voltage

The structural stability of LiCoO2 at high voltages is especially important when enhancing the cutoff voltage used as an effective method to boost the energy density. we trace the origin of different crack formation mechanisms during fast and slow charging rates using a combination of qualitative atomic-scale differential phase-contrast scanning transmission electron microscope (STEM) images and electron energy loss spectroscopy (EELS) analysis of LiCoO2 (LCO). We demonstrate that fast charging induces large heterogenous Li flux insertion into the cathode, resulting in large strain and big crack formation; in contrast, low cycling rates trigger phase transformations that only induce micro-cracks. To clarify the mechanisms, we mapped out local strain analysis for the LCO particles and detailed phase transition routes. The comprehensive characterization results are meaningful for researchers to understand the failure mechanisms under high voltage and inspire innovative solutions to capture higher capacity out of LCO.

Noise Reduction Method of Pipeline Infrasonic Leakage Signal Based on Improved Prony Algorithm and Difference Energy Model

To solve the difficult problem of low-frequency noise processing in pipeline infrasonic leakage detection signals, a pipeline infrasonic leakage signal denoising method based on improved Prony algorithm and differential energy model was proposed to reduce the low-frequency interference noise in the signal and to improve the signal denoising effect. First, the frequency window of the effective signal is obtained according to the spectrogram of the infrasound signal. Aiming at the problem that the Prony algorithm is affected by noise, a difference energy model is proposed. The difference energy model is used to filter out the part of the frequency domain signal with large energy fluctuation, and a relatively stable preprocessing signal is obtained. In view of the instability of the traditional Prony algorithm, a Hankel matrix is established in the operation process. The stability is improved by extracting the extremum and residue of the signal instead of directly solving the sampling data points, and the extremum and residue of the effective signal are selected by combining the frequency window of the active ingredient. Finally, the effective signal is reconstructed to obtain a relatively stable infrasound leakage noise reduction signal. Experimental results show that the noise reduction technology based on the improved Prony algorithm and differential energy model can effectively reduce the noise of pipeline leakage signals. Compared with the traditional Prony algorithm, the noise reduction effect of the proposed method is up to 38.01% higher. Compared with the empirical mode decomposition method, the noise reduction effect of this method is improved by 9.25% at least, which opens up a new idea for pipeline leakage signal noise reduction.

Mapping of operating windows for methane and ethane pyrolysis in the pulsed compression reactor by experiments and modelling

By modelling and experiments optimal operating conditions for methane (between 1000 and 3000 K, 300 bar) and ethane pyrolysis (between 800 and 3200 K, 400 bar) in the pulsed compression reactor (PCR) were evaluated. The PCR is a free piston reactor that can compress a gas from atmospheric pressure up to 600 bar in a single pulse. A differential internal energy balance was used for solving the temperature and pressure during the compression. The GERG-2008 equation of state was used to account for non-idealities. To predict the reaction products, both chemical equilibrium (EQ) and kinetic models available from literature were evaluated. The kinetic models (GRI-mech, Holmen et al., 1995 etc.) did not predict part of the experiments well. The EQ model predicts trends well. Therefore, the EQ model was used to map the operating domains. The aim is to reach a maximum concentration of products (olefins and aromatics) in the product gas and a conversion of 20% or more. For methane pyrolysis at 1600 K and 320 bar with nitrogen as diluent and an initial gas temperature of 588 K, the model analysis led to an experimentally observed factor 5.2 increase in ethylene in the outlet (1.4%mol) compared to a previous optimum point (Slotboom et al., 2021). With ethane pyrolysis 9% of ethylene was obtained at a conversion of 66% with an ethylene selectivity of 61% around 1480 K and 400 bar. Further analysis with the EQ model showed that for the thermal coupling of methane with an initial gas temperature of 773 K, conversion is possible without diluting with nitrogen. For ethane decomposition nitrogen is always needed as a diluent up to 773 K.

Differential energy expenditure is involved in the difference in activity levels between the Djungarian hamster (Phodopus sungorus) and the Roborovskii hamster (P. roborovskii)

The Djungarian hamster (Phodopus sungorus) shows calm behavior, while the Roborovskii hamster (P. roborovskii) exhibits hyperactivity. Even though they belong to the same genus, Phodopus, these two species are quite different. The current study investigated the relationship between energy expenditure and the markedly different levels of activity shown by these hamsters. Roborovskii hamsters showed significantly higher energy expenditure than Djungarian hamsters under both feeding and fasting conditions during darkness. Roborovskii hamsters showed a repeated increase and decrease in energy expenditure under the feeding condition; however, this changed under the fasting condition, during which the repeated increase and decrease in energy expenditure corresponded to the repeated active and sleeping conditions. Djungarian hamsters had a tendency to keep their energy expenditure constant during the fasting condition, while Roborovskii hamsters moved around a lot to find food. The respiratory quotient (RQ) values in Djungarian hamsters were relatively constant. However, Roborovskii hamsters showed a wide variation in RQ. In particular, the RQ value declined immediately before a dark phase commenced, indicating a switchover from the utilization of glucose to that of lipids as a substrate for energy production. In conclusion, Djungarian hamsters and Roborovskii hamsters showed different behavioral patterns that were related to differences in energy metabolism.

The difference in the cellular uptake of tocopherol and tocotrienol is influenced by their affinities to albumin

Vitamin E is classified into tocopherol (Toc) and tocotrienol (T3) based on its side chains. T3 generally has higher cellular uptake than Toc, though the responsible mechanism remains unclear. To elucidate this mechanism, we hypothesized and investigated whether serum albumin is a factor that induces such a difference in the cellular uptake of Toc and T3. Adding bovine serum albumin (BSA) to serum-depleted media increased the cellular uptake of T3 and decreased that of Toc, with varying degrees among α-, β-, γ-, and δ-analogs. Such enhanced uptake of α-T3 was not observed when cells were incubated under low temperature (the uptake of α-Toc was also reduced), suggesting that Toc and T3 bind to albumin to form a complex that results in differential cellular uptake of vitamin E. Fluorescence quenching study confirmed that vitamin E certainly bound to BSA, and that T3 showed a higher affinity than Toc. Molecular docking further indicated that the differential binding energy of Toc or T3 to BSA is due to the Van der Waals interactions via their side chain. Overall, these results suggested that the affinity of Toc and T3 to albumin differs due to their side chains, causing the difference in their albumin-mediated cellular uptake. Our results give a better mechanistic insight into the physiological action of vitamin E.

Effects of viscous dissipation, internal heat source/sink and Prandtl number on flow and heat transfer in a moving fluid over a moving flat surface with an applied magnetic field

The goal of this study is to see how heat sources and sinks, as well as viscous dissipation, affect natural convection magneto hydrodynamic flow of an incompressible moving fluid across a moving flat surface. Using partial differential equation similarity finding, additional momentum and energy equations were altered into non-linear ordinary differential equations. Keller box technique is a finite difference system that produces the desired results. The influences of movement, internal heat source/sink, Prandtl number, Eckert number and MHD parameter are clearly seen on the velocity and temperature outlines. The thermal boundary layer thickness is influenced by heat source/sink, Prandtl number and viscous dissipation.

Limits of Performance of Polyurethane Blowing Agents

A MATLAB program was developed to simulate urethane-forming reactions by solving over a dozen differential equations, energy balance, mass balance, and constitutive equations simultaneously. The simulation program was developed for half a decade to simulate the basic kinetics of polyurethane reactions and more complex phenomena that cannot be obtained in laboratories. In the current investigation, the simulation is applied to determine the limits of the performance of polyurethane foam formation. n-pentane, cyclohexane, and methyl formate were used as physical blowing agents, and water was used as a chemical blowing agent. The simulation code increases the accuracy of the results and makes the foam performance process less time- and money-consuming. Specifically, the MATLAB code was developed to study the impact of physical and chemical blowing agents at different loadings on the performance of rigid polyurethane foams. Experimental data were used to validate the simulation results, including temperature profiles, height profiles, and the tack-free time of urethane foam reactions. The simulation results provide a window for the proper type and the optimum amount range of different physical and chemical blowing agents.

An improved differential bond energy algorithm with fuzzy merging method to improve the document clustering for information mining

AbstractThe vast and diversified text materials on the internet in recent years have drastically increased the importance of information mining. By organizing documents into cohesive groupings, a document clustering method is a suitable tool for dealing with massive amounts of documents. Text documents, on the other hand, include sparse and uninformative features like noise, unrelated, and unneeded features, which reduce the efficiency of the document clustering methods. For noise removal, this work employs the hyperclique pattern‐based data cleaner pre‐processing approach. Then, differential bond energy algorithm (DBEA) is combined with a fuzzy merging approach and termed improved differential bond energy algorithm with fuzzy merging (IDBEFM) to handle the issues present in text document clustering. It seeks to discover and display natural variable clusters among large amounts of data. IDBEFM clusters are documented in three steps: in the first step, a cluster similarity matrix is instantiated by applying the DBEA. The second step develops an innovative technique for automatically dividing the cluster matrix into compact cohesive clusters, and in the third step, a fuzzy merging approach is used for combining identical clusters by the correlations and interrelationships between the resultant clusters. The test findings demonstrated that the accomplishment of the proposed technique is much superior to standard clustering algorithms.

Recognizing boiled bone-remains from the Boca de Lega archaeological site in Argentina through mechanical spectroscopy studies

A study in thermo-altered bone-remains recovered from the Boca de Lega archaeological site (Santa Fe, Argentina) is performed with the aim of distinguishing among the whole group of seven investigated bone-remains which ones were boiled during culinary activities. In fact, for the boiled-bone-remains, the damping spectra exhibited the appearance of the damping peaks related to the loss of free water, the loss of the crystallization water, and the peak related to the viscous movement of collagen fibrils, after the triple helix to random coil transition; at around 370 K, 420 K and 510 K, respectively. In addition, the dynamic modulus behaviour in boiled samples exhibited the peaked shape behaviour as a function of temperature, i.e., an increase from around 370 K up to around 450 K, which was already reported for experimental bones. The results from mechanical spectroscopy were corroborated through scanning electron microscopy studies at high resolution. Besides, differential thermal analysis, thermogravimetry, and energy dispersive spectroscopy, are used also as instrumental techniques and their obtained results are discussed in the present work too.

Oxygen-defects evolution to stimulate continuous capacity increase in Co-free Li-rich layered oxides

Though oxygen defects are associated with deteriorated structures and aggravated cycling performance in traditional layered cathodes, the role of oxygen defects is still ambiguous in Li-rich layered oxides due to the involvement of oxygen redox. Herein, a Co-free Li-rich layered oxide Li1.286Ni0.071Mn0.643O2 has been prepared by a co-precipitation method to systematically investigate the undefined effects of the oxygen defects. A significant O2 release and the propagation of oxygen vacancies were detected by operando differential electrochemical mass spectroscopy (DEMS) and electron energy loss spectroscopy (EELS), respectively. Scanning transmission electron microscopy-high angle annular dark field (STEM-HAADF) reveals the oxygen vacancies fusing to nanovoids and monitors a stepwise electrochemical activation process of the large Li2MnO3 domain upon cycling. Combined with the quantitative analysis conducted by the energy dispersive spectrometer (EDS), existed nano-scale oxygen defects actually expose more surface to the electrolyte for facilitating the electrochemical activation and subsequently increasing available capacity. Overall, this work persuasively elucidates the function of oxygen defects on oxygen redox in Co-free Li-rich layered oxides.

Research on internal flow characteristics of the labyrinth disc regulating valve

As a new type of multi-stage high-performance regulating valve, the labyrinth disc regulating valve takes advantage of the labyrinth channel on the sleeve disc to dissipate the high-pressure differential energy into the multi-stage throttling flow resistance. It can effectively prevent the failure problems such as erosion, cavitation, and noise caused by extreme working conditions such as the high-pressure differential, high-speed flow, and high temperature. In order to study the flow characteristics of the fluid inside a new type of labyrinth disc-type regulating valve in the thermal power process, an experiment on the pressure reduction characteristics of a double-entrance labyrinth flow channel was carried out. Firstly, an experimental device was designed and built, and then the pressure drop values of each horizontal flow channel were measured and compared with the numerical simulation results to verify the accuracy of the numerical model. Aiming at the actual working conditions of the labyrinth disc regulating valve in thermal power generation applications, the Realizable k-- turbulence model and the mixture multiphase flow model are combined with the Zwart-Gerber-Belamri cavitation model to clarify the flow characteristics and cavitation of the incompressible medium water in the labyrinth flow channel inside the labyrinth disc regulating valve and the flow characteristics of a double-entrance labyrinth flow channel under different opening degrees.