bluuebunny/crossref_metadata_2025 huggingface dataset:
Meta-heuristic optimization methods applied to renewable distributed generation planning: A review
Authors: Tarraq Ali , Elmariami Faissal , Belfqih Aziz , Haidi Touria
Published: February 2021

Due to its proven efficiency and computational speed, the most recent developed meta-heuristic optimization methods are widely used to better integrate renewable distributed generation (RDG) into the electricity grid. The main objective of this paper is to obtain a better knowledge of current trends in meta-heuristics applied to optimally integrate RDGs to the distribution network. This is a review of well known meta-heuristic approaches, used to solve the problem of optimal renewable distributed generation allocation planning (ORDGAP). In this context, some research gaps were mentioned, and recommendations were proposed to expand the scope of research in this field.
The environmental knowledge and pro-environmental behavior of future engineers in Morocco
Authors: Ait taleb Zakaria , El Farouki Mounia , El Mejdoub Mehdi
Published: February 2021

During the recent decades, raising the level of environmental awareness has become one of the main social goals, which has reached a level of social and political consensus never seen before. Education can be the catalyst that changes people’s behavior regarding the environment (Zsóka et al., 2013; Schultz, 2014). Many studies have demonstrated a positive link between education level and pro-environmental behavior (Fernandez-Manzanal et al., 2007; Levine and Strube, 2012; Meyer, 2015; Monier et al., 2009). In Morocco, as in many countries of the world, human behavior towards the environment has been defective. However, the country has been taking a number of steps to protect the environment. There have been few researchers investigating the role of universities as agents contributing to environmental awareness, especially engineering schools. Engineering work has a significant effect on the world. The advent of engineers, engineering work, and engineering schooling is closely related to countries development (Downey and Lucena 2004, Downey and Lucena 2005). This paper aims to analyze the relationship between 3 factors: the sources of environmental issues, the acquired knowledge and the pro-environmental behavior to protect the environment. In order to do that, a survey of 141 engineering students has been assessed in 5 different engineering schools and the results have then shown that the sources of information is the internet and this source doesn’t lead to accountability of the individuals. Furthermore, the taken actions for the environment rarely include trash sorting, paper and meat consumption.
Distributed Encirclement Points Deployment of Autonomous Mobile Multi-Agents Based on Finite-Time Consensus
Authors: Yan Pengpeng , Fan Yonghua , Chen Yuanlin , Wang Mingang
Published: February 2021

In the many-to-one pursuit-evasion game, autonomous mobile multi-agents can effectively improve the probability of successful hunting by achieving the cooperative encirclement to the target from multiple directions. To solve the encirclement points deployment, a distributed control protocol is proposed based on finite-time consensus. Firstly, the encirclement points deployment is formulated as the coverage control problem on a circle. The presented distributed control protocol can realize uniform coverage on the circle, i.e., optimal encirclement around the target. Secondly, by introducing the strategy of time-varying feedback gain, the convergence rate of closed-loop system turns into finite-time consensus from asymptotical consensus, such that the efficiency of the deployment is improved greatly. Finally, numerical simulations are carried out to verify the effectiveness of the presented distributed control protocols.
Identification Algorithm Based on Key-Point Detection Network for Vital Parts of Infrared Aerial Target
Authors: Zhang Kai , Liu Hao , Yang Xi , Li Shaoyi , Wang Xiaotian
Published: February 2021

The precision strike capability of an infrared-guided air-to-air missile to target the vital parts of a fighter is key to precision-guidance weapons. The traditional image processing algorithms select features and designs classifiers according to human prior knowledge, but this has some limitations. Therefore we propose an algorithm for identifying the vital parts of an infrared aerial target based on key-point detection networks. The algorithm uses the end-to-end deep learning network architecture and combines illumination with texture. The data set is augmented and enhanced in terms of lighting, texture and deformation. The entire image information is preprocessed simply as input, and a loss function with constraints is constructed and iterated with an optimization algorithm. Compared with the conventional algorithms with the same training, the average recognition rate of the trained network model increases by 10%. The vital parts of the infrared aerial target are identified at the speed of ≤ 10 ms/frame. The accuracy of recognition of the 4 vital parts proposed by us is more than 80%.
A Space-Time Adaptive Processing Method Based on Sparse Reconstruction of Reverberation Interference
Authors: Kou Siwei , Feng Xi'an , Huang Hui , Bi Yang
Published: February 2021

Aiming at the problem of how to obtain reverberation samples and estimate their covariance matrix in the space-time adaptive processing(STAP) of sonar system, a new space-time adaptive processing method is proposed based on sparse reconstruction of reverberation in this paper. Firstly, according to the space-time distribution characteristics of reverberation received by moving platform sonar, a space-time steering dictionary for sparse reconstruction of reverberation is designed along the relation curve between Doppler frequency shift and incident cone angle cosine of the reverberation unit. Then, a reverberation sample in the rangecell under test (RUT) is reconstructed with high precision by sparse decomposition of signals obtained from the sonar array in the space-time steering dictionary. Finally, based on the prior information of reverberation probability distribution model, a sufficient number of reverberation samples are generated to meet the requirement of performance loss index on reverberation sample size in the space-time adaptive processing, so as to correctly obtain estimation of the covariance matrix of reverberation. This method can reconstruct the reverberation samples and estimate the reverberation covariance matrix directly from the data in RUT without relying on the auxiliary data from units adjacent to the RUT. Therefore, it is not only suitable for the environment with constant reverberation statistical characteristics, but also suitable for the environment with varying statistical characteristics. Simulation results of sonar forward-looking array and side-looking array indicate that the improvement factor of the proposed method is about 10dB lower than the traditional space-time adaptive processing method. So this new STAP method has good anti-reverberation performance.
Fettabsaugungen im ambulanten Setting
Authors: Güven Asim , Schaffartzik Walter , Allert Sixtus
Published: February 2021

Hintergrund Fettabsaugungen gehören weltweit zu den häufigsten plastisch-chirurgischen Eingriffen. Sie werden sowohl im ambulanten als auch im stationären Rahmen durchgeführt. Im ambulanten Setting wird zumeist Tumeszenzlösung unterschiedlicher Zusammensetzung eingesetzt. Vielfach besteht Unklarheit darüber, bis zu welcher Absaugmenge noch ambulant abgesaugt werden kann bzw. ab wann ein stationäres Setting geeigneter wäre. Zudem ist es unklar, welche Parameter in der Nachbeobachtungsphase eines ambulanten Eingriffes über welche Dauer überwacht werden sollen, um für die Patienten eine größtmögliche Sicherheit zu gewährleisten.

Material und Methoden Es wurde eine systematische Literaturrecherche mit Hilfe der Datenbank MEDLINE der U.S.-amerikanischen National Library of Medicine (NLM) sowie der bibliografischen Suchmaschine Google Scholar (https://scholar.google.com) des Unternehmens Google LLC durchgeführt. Dabei wurden die Schlagwörter „Liposuction Anesthesia“ und „Liposuction Guidelines“ verwendet. Es wurden alle aus der Suche resultierenden Arbeiten anhand des Titels und des Abstracts auf thematische Übereinstimmung geprüft. Die Arbeiten wurden gewichtet nach Evidenzgrad, Aussagekraft und Verfügbarkeit analysiert und entsprechend der Fachrichtung der Autoren in die Gruppe Chirurgie oder Anästhesie aufgeteilt.

Ergebnisse Nach der Literaturrecherche und Überprüfung wurden insgesamt 197 Arbeiten identifiziert und analysiert. Es konnten die Empfehlungen aus der internationalen und deutschsprachigen Literatur systematisch zusammengefasst werden.

Schlussfolgerung Die Tumeszenzlokalanästhesie im ambulanten Rahmen bietet diverse Vorteile für Behandler und Patienten, unter anderem eine Kostenreduktion und das Vermeiden der Risiken einer Intubationsnarkose. Das Verfahren zeigt allerdings Limitationen in Bezug auf die Liposuktionsmengen, die sicher entfernt werden können. Je größer die Absaugmenge, umso größer die verabreichte Lokalanästhetikadosis und damit umso länger die notwendige postoperative Beobachtungzeit. Aus unserer Sicht sollte die Tumeszenzlokalanästhesie für kleine und lokalisierte Liposuktionen vorbehalten werden. Die Liposuktion in Narkose bietet mehr Vorteile, vor allem bei steigendem Absaugvolumen.
Effect of the COVID-19 Pandemic in German Trauma Centres and Geriatric Trauma Centres DGU
Authors: Schoeneberg Carsten , Eschbach Daphne-Asimenia , Friess Thomas , Lendemans Sven , Hoefer Christine , Ruchholtz Steffen
Published: February 2021

Background The COVID 19 pandemic is a major challenge to all social systems, particularly the healthcare system. Within an international study, German Trauma Centres DGU and Geriatric Trauma Centres DGU have been questioned about their situation.

Method The questionnaire was translated from English into German and sent to all contacts. The evaluation was performed descriptively.

Results 71 of 692 centres participated in this study. Government instructions to avoid elective treatments have been adhered to by 68% of the hospitals, and the remaining performed only urgent elective treatments. There was also a decline in the number of traumatological patients. In more than 90% of the hospitals, only 0 – 4% of all patients treated for proximal femur fracture were tested positive for COVID-19. It appears that 84% of these hospitals have or will have financial deficits. Almost all hospitals were organised and ready to fight the pandemic with their personal and/or infrastructural resources they possess.

Conclusion Our questionnaire shows that the pandemic had an enormous effect on Trauma Centres DGU and Geriatric Trauma Centres DGU. The hospitals expect financial losses. Almost all the hospitals have provided personal and infrastructural resources to be used in the fight against the pandemic with a better outcome in Germany in comparison with international standards.
Technical trick in suture-button suspensionplasty for the treatment of thumb carpometacarpal arthritis
Authors: Cavit Ali , Civan Osman , Özcanli Haluk
Published: February 2021

Suture-button suspensionplasty has been popularized in the treatment of thumb carpometacarpal (CMC) arthritis in recent years. The surgical technique of this method was well defined previously. The most challenging and important part of this technique is the tensioning of the suture-button system to preserve first metacarpal height after trapeziectomy. In present study, we would like to present a technical trick about adjusting the tension while performing suspensionplasty using suture-button device in thumb CMC joint osteoarthritis. In the original technique, trapeziectomy is performed prior to fixation and tensioning of suture-button system. However, it is quite difficult to recreate the original trapezial space, since first metacarpal subsides after trapeziectomy. The trick in our technique is that trapezium remains in its anatomic position up to the end of the operation. Thus, we do not need to make effort to adjust the thumb ray height and use fluoroscopic imaging to ensure its position. In conclusion, we believe that our technique simplifies the most challenging part of the operation, shortens the operation time, preserves the original first ray height and diminishes the exposure of ionizing radiation as it reduces the need for fluoroscopy.
Percutaneous Tracheostomy in COVID-19 Critically Ill Patients: Experience from 30 Consecutive Procedures
Authors: Bertini Pietro , Forfori Francesco , Bruschini Luca , Corradi Francesco , Ribechini Alessandro , Brogi Etrusca , Guarracino Fabio
Published: February 2021

Introduction Percutaneous tracheostomy (PT) in the intensive care unit (ICU) is a well-established practice that shows a reduced risk of wound infection compared with surgical tracheostomy, thus facilitating mechanical ventilation, nursing procedures, reduction in sedation and early mobilization.

Objective This is an observational case-control study that compares the results of PT in ICU patients with coronavirus disease 2019 (COVID-19) prospectively enrolled to a similar group of subjects, retrospectively recruited, without COVID-19.

Methods Ninety-eight consecutive COVID-19 patients admitted to the ICU at Pisa Azienda Ospedaliero Universitaria Pisana between March 11th and May 20th, 2020 were prospectively studied. Thirty of them underwent PT using different techniques. Another 30 non-COVID-19 ICU patients were used as a control-group. The main outcome was to evaluate the safety and feasibility of PT in COVID-19 patients. We measured the rate of complications.

Results Percutaneous tracheostomy was performed with different techniques in 30 of the 98 COVID-19 ICU patients admitted to the ICU. Tracheostomy was performed on day 10 (mean 10 ± 3.3) from the time of intubation. Major tracheal complications occurred in 5 patients during the procedure. In the control group of 30 ICU patients, no differences were found with regards to the timing of the tracheostomy, whereas a statistically significant difference was observed regarding complications with only one tracheal ring rupture reported.

Conclusion Percutaneous tracheostomy in COVID-19 patients showed a higher rate of complications compared with controls even though the same precautions and the same expertise were applied. Larger studies are needed to understand whether the coronavirus disease itself carries an increased risk of tracheal damage.
Association between Receipt of Intrapartum Magnesium Sulfate and Postpartum Hemorrhage
Authors: Miller Emily M.S. , Sakowicz Allie , Leger Elise , Lange Elizabeth , Yee Lynn M.
Published: February 2021

Objective The aim of the study is to investigate the association between intrapartum administration of magnesium sulfate in women with hypertensive disorders of pregnancy and postpartum hemorrhage.

Study Design This was a retrospective cohort study of women diagnosed with a hypertensive disorder of pregnancy who delivered singleton gestations >32 weeks at a single, large volume tertiary care center between January 2006 and February 2015. Women who received intrapartum magnesium sulfate for seizure prophylaxis were compared with women who did not receive intrapartum magnesium sulfate. The primary outcome was frequency of postpartum hemorrhage. Secondary outcomes included estimated blood loss, uterine atony, and transfusion of packed red blood cells. Bivariable analyses were used to compare the frequencies of each outcome. Multivariable logistic regression models examined the independent associations of magnesium sulfate with outcomes.

Results Of 2,970 women who met inclusion criteria, 1,072 (36%) received intrapartum magnesium sulfate. Women who received magnesium sulfate were more likely to be nulliparous, publicly insured, of minority race or ethnicity, earlier gestational age at delivery, and undergo labor induction. The frequency of postpartum hemorrhage was significantly higher among women who received magnesium sulfate compared with those who did not (12.4 vs. 9.3%, p = 0.008), which persisted after controlling for potential confounders. Of secondary outcomes, there was no difference in estimated blood loss between women who did and did not receive magnesium sulfate (250 mL [interquartile range 250–750] vs. 250 mL [interquartile range 250–750], p = 0.446). However, compared with women who did not receive magnesium sulfate, women who received magnesium sulfate had a greater frequency of uterine atony (8.9 vs 4.9%, p < 0.001) and transfusion of packed red blood cells (2.0 vs. 0.8%, p = 0.008). These differences persisted after controlling for potential confounders.

Conclusion Intrapartum magnesium sulfate administration to women with hypertensive disorders of pregnancy is associated with increased odds of postpartum hemorrhage, uterine atony, and red blood cell transfusion.
Successful Reimplantation of Spinal Cord Stimulator One Year after Device Removal Due to Infection
Authors: Schwartz Ruben H. , Southerland Warren , Urits Ivan , Kaye Alan D. , Viswanath Omar , Yazdi Cyrus
Published: February 2021

Spinal cord stimulation is an effective treatment modality for patients with numerous pain conditions. Although proven to be highly successful, device implantation does come with some inherent risks. One of the most challenging complications is perioperative infection. For most patients, a simple trial of oral antibiotics and in-office drainage of any superficial infectious material may be sufficient. Deeper infections with wound dehiscence necessitate device removal and intravenous antibiotic therapy. The question remains, if the device was previously providing pain relief for the patient, when is the appropriate time to reimplant the device after the infection has cleared? We describe the case of explantation of an infected device and successful reimplantation after 1 year.
The Deviated Nasal Tip: A Personal Technique for Correction Using Monolateral Crural Overlay and Monolateral Dome Truncation
Authors: Marianetti Tito M. , Vellone Valentino , Ramieri Valerio , De Angelis Francesca
Published: February 2021

This study aimed to present a novel approach to correct nasal tip deviation with monolateral crural overlay or monolateral dome truncation, presenting as an isolated deformity or in complex nose deviations. Nasal tip deviation can be congenital or posttraumatic, due to a dislocated septum or cartilaginous septal or lower lateral cartilage malformations. Although some treatment strategies have been introduced, appropriate treatment remains a challenge because of the complexity and variability of such deformities. It had been assumed that in most nasal tip deviations, a lower lateral cartilage was longer than the contralateral one. The authors analyzed 158 patients from January 2015 to October 2019 with nasal tip deviation and corrected the deviated tip by using a monolateral interruptive technique (lateral crural overlay or monolateral dome truncation) on the lower lateral cartilage. Photographic comparison between preoperative and at least 1-year follow-up for nasal axis deviation variable was analyzed and a self-assessment questionnaire was administrated to the patients at 1-year follow-up. The mean nasal deviation was 6.59° (±3.1°) preoperatively and 1.56° (±0.26°) postoperatively (p < 0.05). The range of differences between pre and postoperative deviations was 2.7° to 15.1°, and the mean difference was 6.1° (±3.21°). Of the 84 patients, 47 (55.95%) were very satisfied, 33 (39.28%) were satisfied, and 4 (4.76%) were unsatisfied with surgical the results and required revision surgery. In authors' hands, monolateral interruptive techniques (lateral crural overlay or monolateral dome truncation) are a viable and feasible option to restore nasal tip symmetry. These techniques achieved high satisfaction rates among patients and resulted in reliable and reproducible symmetry immediately visible after surgery and stable over time (1-year postsurgery controls).
Facial Protection to Prevent Facial Trauma and Allow for Optimal Protection after Facial Fracture Repair
Authors: Kim Roderick , Shokri Tom , Wang Weitao , Ducic Yadranko
Published: February 2021

Facial skeletal fractures continue to affect humankind, and many methods to alleviate and prevent the injuries outright have been sought after. Prevention is desired, but the implementation and general compliance may contribute to missed opportunities to decrease the burden of facial skeletal trauma. In this article, we explore the preventative as well as postoperative options for the protection of the facial skeleton.
GVC transformation and a new investment landscape in the 2020s: Driving forces, directions, and a forward-looking research and policy agenda
Authors: Zhan James X.
Published: February 2021

Global value chains (GVCs) will undergo substantive transformation in the decade ahead, reshaping the global trade and investment landscape. The change will be driven by five major forces: economic governance realignment, the new industrial revolution, the sustainability endeavor, corporate accountability, and resilience-oriented restructuring. All of this will present challenges and opportunities for firms and states alike, leading to an investment-development paradigm shift. This article discusses the five driving forces for the GVC transformation, projects ten broad trends in the evolution of the global trade and investment landscape, and also presents a forward-looking agenda for multi-dimensional research and policy in the decade ahead. It aims at providing a framework for future research that encourages cross-disciplinary collaboration as well as a structured dialogue between academia and policymakers.
A new set of analytical formulae for the computation of the bootstrap current and the neoclassical conductivity in tokamaks
Authors: Redl A. , Angioni C. , Belli E. , Sauter O. ,   ASDEX Upgrade Team,   EUROfusion MST1 Team
Published: February 2021

A new set of analytical formulae for calculating the bootstrap current and the neoclassical conductivity in tokamak experiments is presented. Previous works comparing the widely used Sauter model with results of recently developed numerical neoclassical solvers have shown the Sauter model to be inaccurate at higher collisionalities typical of tokamak edge pedestals and in the presence of impurities. Thus, its applicability, particularly for the analysis of the highly interesting and highly complex plasma edge, is limited. For a revised set of analytical formulae, the procedure to determine the analytical formulae described by Sauter is repeated with the more accurate and more reliable numerical code NEO [E. Belli, Plasma Phys. Controlled Fusion 54, 015015 (2012)]. For the determination of the respective bootstrap current coefficient, the linearity of neoclassical transport is exploited. This new set of analytical formulae consists of the same analytical structure as the original set of analytical formulae published by Sauter [Phys. Plasmas 6, 2834 (1999); ibid. 9, 5140 (2002)] and also continues to use only three neoclassical key parameters: the fraction of trapped particles ftrap, the collisionality νσ*, and the effective charge number Zeff.
Frequency domain analysis of 3ω-scanning thermal microscope probe—Application to tip/surface thermal interface measurements in vacuum environment
Authors: Pernot G. , Metjari A. , Chaynes H. , Weber M. , Isaiev M. , Lacroix D.
Published: February 2021

The characterization of material thermal properties at nanoscales remains a challenge even if progress was achieved in developing outstanding characterization techniques like scanning thermal microscopy (SThM). In the present work, we propose a detailed procedure based on the combined use of a SThM probe characterization and its Finite Element Method (FEM) modeling to recover in operando 3ω measurements achieved under high vacuum. This approach is based on a two-step methodology: (i) a fine description of the probe's electrical and frequency behaviors in “out of contact” mode to determine the intrinsic parameters of the SThM tip and (ii) a minimization of the free parameter of our model, i.e., the contact thermal resistance, by comparing 3ω measurements with the simulations of the probe operating “in contact mode.” Such an approach allows us to measure thermal interface resistances between the tip and the surface. We applied our methodology to three different materials with known thermal properties: Si, SiO2 bulk materials, and a gold thin film. In addition, the FEM modeling provides insights into SThM thermal probes sensitivity, as a function of probe/sample interface resistance and the contact area to measure material thermal conductivity paving the way to quantitative SThM measurements.
Influence of Al/Er ratio on the optical properties and structures of Er3+/ Al3+ co-doped silica glasses
Authors: Jiao Yan , Guo Mengting , Wang Renle , Shao Chongyun , Hu Lili
Published: February 2021

In this study, Er3+/Al3+ co-doped silica glasses with various Al/Er ratios ranging from 0 to 200 and a constant Er2O3 amount were prepared using the sol-gel method combined with high-temperature vacuum sintering. The absorption, emission spectra, and fluorescence lifetime of Er3+ ions were recorded and the absorption and emission cross sections were calculated. Using Raman, 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS-NMR), 27Al triple-quantum (TQ)-MAS-NMR, and electron paramagnetic resonance (EPR) spectroscopies, the physical and optical properties were correlated with the glass structural modifications due to the Al/Er ratio change. With the increase in the Al/Er ratio, the content of Al3+ ions around the Er3+ ions gradually increased. Meanwhile, the AlO5 and AlO6 polyhedrons increased at the expense of the AlO4 and SiO4 tetrahedrons, which resulted in an improved symmetry and better ionic Er–O bonds. These structural changes led to the site-to-site variations in the Er3+ local environment and the changes in the ligand field strength of the Er–O bonds. This, in turn, resulted in the inhomogeneous broadening of the absorption and emission spectra, with a blue shift of both absorption and emission peaks and a decrease in both absorption and emission at 1.53 μm. With the increase in Al/Er ratio, the full width at half maximum (FWHM) of the emission increased from 27.2 to 54.3 nm. The FWHM × emission cross section (σemi) parameter for evaluating broadband amplification behavior was 30.1 × 10−20 cm2 · nm. This work reveals the close relationship between the glass structure and the spectroscopic properties of Er3+ ions and provides an important reference for the design of broadband amplifier materials in the field of optical communication.
Bilayer artificial spin ice: Magnetic force switching and basic thermodynamics
Authors: Nascimento Fabio S. , Pereira Afranio R. , Moura-Melo Winder A.
Published: February 2021

We study an artificial spin ice system consisting of two identical layers separated by a height offset h. For a small separation, the layers are shown to attract each other provided the whole system is in the ground state. Such an attraction comes about by means of a power-law force that we compare to van der Waals forces. When magnetic monopoles occur in one (or both) layers, the scenario becomes even more interesting, and these layers may also repel each other. By tuning parameters like h and monopole distance, switching between attraction and repulsion may be accomplished in a feasible way. Regarding its thermodynamics, the specific heat peak shifts to lower temperature as h increases.
Stability of generalized ecological-network models
Authors: Awender Stefan , Wackerbauer Renate , Breed Greg A.
Published: February 2021

The stability of ecological networks of varying topologies and predator–prey relationships is explored by applying the concept of generalized modeling. The effects of omnivory, complexity, enrichment, number of top predators, and predatory response are discussed. The degree of omnivory plays a large role in governing web stability at steady state. Complexity as measured from connectance and network size is not a perfect indicator of stability; large, highly connected webs can be just as stable as smaller, less connected ones. Learning behavior as expressed in Holling’s type III predatory response is stabilizing for food webs and provides exceptions to the paradox of enrichment for some topologies.
An optimal operation method of cascade hydro-PV-pumped storage generation system based on multi-objective stochastic numerical P systems
Authors: Huang Xing , Wang Jun , Huang Tao , Peng Hong , Song Xiaoxiao , Cheng Sixiong
Published: February 2021

To take full advantage of the complementary characteristics of various renewable energy sources, hybrid generation systems (HGSs) are used to accommodate the increased variability and uncertainty. In southwest China, there are many small cascade hydropower stations (CHSs) and PV power stations, which have spatial and temporal correlation characteristics and complementary characteristics. Pumped-storage units are considered as ideal large-scale energy storage elements for HGSs due to their fast response and long life. The purpose of this study is to increase the system reliability and water power utilization rate and maximize the economic benefits of a cascade hydro-PV-pumped storage (CH-PV-PS) generation system. Considering the reliability, economy, and water power utilization rate of the system, the CH-PV-PS system model with multiple objectives and multiple constraints is established. Then, a multi-objective stochastic numerical P system (MOSNP) is proposed. The external storage set and correction method in the MOSNP algorithm are introduced to ensure the diversity of the solution and improve the efficiency of the algorithm. The CH-PV-PS system is introduced in Sichuan Province, Southwest China. The simulation results show that (1) the MOSNP method can obtain robust and effective optimization results for the hybrid system; (2) the use of pumped storage units has increased the daily economy by 1018 CNY, and the total fluctuation of CHSs has been reduced by 29.3%, which makes the hybrid system safer and more economical; and (3) the uncertainty of PV and runoff will lead to frequent dispatching of CHSs, thus reducing the economic benefits of the system.
How a supercooled liquid borrows structure from the crystal
Authors: Pedersen Ulf R. , Douglass Ian , Harrowell Peter
Published: February 2021

Using computer simulations, we establish that the structure of a supercooled binary atomic liquid mixture consists of common neighbor structures similar to those found in the equilibrium crystal phase, a Laves structure. Despite the large accumulation of the crystal-like structure, we establish that the supercooled liquid represents a true metastable liquid and that liquid can “borrow” the crystal structure without being destabilized. We consider whether this feature might be the origin of all instances of liquids with a strongly favored local structure.
An interaction potential for zinc selenide: A molecular dynamics study
Authors: Costa-Prado Sandra Cristina , Rino José Pedro
Published: February 2021

The structural, thermodynamic, and dynamical properties of zinc selenide, as well as the structural phase transformation induced by pressure, based on a many-body interatomic potential that considers two- and three-body interactions, were studied using molecular dynamics simulations. The potential was able to describe the energetics of the zinc-blende, wurtzite, and rock-salt structures of ZnSe. The effective interatomic potential was parameterized using experimental values of the bulk modulus and cohesive energy at an experimental density. Other properties, not used in the parameterization of the potential, such as the vibrational density of states, were correctly described. Cooling from the liquid, an amorphous phase or a re-crystallized material could be obtained. Pair distribution function, coordination number, volume change, and bond angle distributions are presented and compared with available experimental data. The structural phase transition from zinc-blend to rock-salt induced by hydrostatic pressure was obtained at ∼21 GPa for monocrystals and ∼16 GPa for polycrystals.
Sampling efficiency of the counting method for permeability calculations estimated with the inhomogeneous solubility–diffusion model
Authors: Davoudi Samaneh , Ghysels An
Published: February 2021

Permeability is a key property in various fields such as membrane technology for chemical separation and transport of substances through cell membranes. At the molecular scale, the counting method uses the number of membrane crossings in a conventional unbiased molecular dynamics simulation to predict the permeability. This contribution investigates under which conditions the counting method has insufficient statistics. An equation is derived for a compartmental model based on the inhomogeneous solubility–diffusion (Smoluchowski) model, giving insight into how the flux correlates with the solubility of permeants. This equation shows that a membrane crossing is a rare event not only when the membrane forms a large free energy barrier but also when the membrane forms a deep free energy well that traps permeants. Such a permeant trap has a high permeability; yet, the counting method suffers from poor statistics. To illustrate this, coarse-grained MD was run for 16 systems of dipalmitoylphosphatidylcholine bilayer membranes with different permeant types. The composition rule for permeability is shown to also hold for fluxes, and it is highlighted that the considered thickness of the membrane causes uncertainty in the permeability calculation of highly permeable membranes. In conclusion, a high permeability in itself is not an effective indicator of the sampling efficiency of the counting method, and caution should be taken for permeants whose solubility varies greatly over the simulation box. A practical consequence relevant in, e.g., drug design is that a drug with high membrane permeability might get trapped by membranes thus reducing its efficacy.
Coexistence of different magnetic ordering in thin films of SrMnO3 studied by spin transport
Authors: Das A. , Phanindra V. Eswara , Watson A. J. , Banerjee T.
Published: February 2021

The ability to tune magnetic ordering in complex oxide based correlated antiferromagnetic insulators, due to the coupling between the charge, spin, lattice, and orbital degrees of freedom, opens a vast playground in spintronics. Here, we study a tensile strain induced coexistence of a wide range of magnetic ordering, as established from the temperature dependence of the spin Hall magnetoresistance (SMR) and spin Seebeck effect (SSE) studies and complemented by structural and bulk magnetization measurements. The temperature dependence of the SMR, SSE, and bulk magnetization studies fingerprints the competition between different magnetic domains across the manganite film thickness. Our work demonstrates that strain induced spatial variation of magnetization in such nominal antiferromagnetic manganite, SrMnO3, can be tuned by orbital ordering and opens research opportunities in antiferromagnetic spintronics.
Comparison of carrier-recombination in Ga(As,Bi)/Ga(N,As)-type-II quantum wells and W-type heterostructures
Authors: Veletas Julian , Hepp Thilo , Dobener Florian , Volz Kerstin , Chatterjee Sangam
Published: February 2021

The realization of efficient semiconductor lasers on GaAs substrates operating at 1.55 μm and beyond remains a technological challenge. As a potential solution, epitaxial heterostructures with type-II band alignment are currently discussed as an active region. Each individual layer in such heterostructures features a comparably large bandgap energy; therefore, spurious effects in laser operation such as reabsorption, multi-photon absorption, or Auger scattering are expected to be suppressed. The actual laser operation occurs across the internal interfaces as the electron and hole wave functions have their extrema in adjacent layers. Hence, a large wave-function overlap is key for efficient recombination. A direct comparison of symmetric and asymmetric Ga(N,As)/Ga(As,Bi) type-II quantum well heterostructures reveals that the symmetry of the layer arrangement drastically influences the charge-carrier recombination: disorder in the Ga(As,Bi) layer has more prominent effects for the asymmetric configuration compared to the symmetric one. The temperature dependence of the emission energy is mainly influenced by the Ga(N,As)-electron layers, while the temperature dependence of the full width at half maximum and the excitation dependence of the emission energy are dominated by the Ga(As,Bi)-hole layers. Photoluminescence excitation spectroscopy reveals the corresponding carrier-relaxation paths to the type-II transition.
Spin–orbit torque rectifier for weak RF energy harvesting
Authors: Sayed Shehrin , Salahuddin Sayeef , Yablonovitch Eli
Published: February 2021

We propose a rectifier concept, simultaneously utilizing the Hall effect and the spin–orbit-torque, that is well matched to the low impedance of antennas. This rectifier is promising for general radio detection and, particularly, for harvesting ambient weak radio signals, where conventional rectification fails to operate. The Hall effect and spin–orbit-torque are both proportional to current density, which improves inversely with the device cross-sectional area, providing a large signal at the nanoscale. A single device made using existing materials can provide 200 μV DC from 500 nW of radio frequency (RF) power. A series array of such devices can efficiently enhance the DC voltage to 300 mV while matching the receiver antenna impedance. Such magnetic devices can convert weak RF power into DC power with substantial efficiency at low voltage and low impedance where conventional semiconductor rectifiers fail.
Laser-induced vaporization of a stretching sheet of liquid tin
Authors: Liu Bo , Meijer Randy A. , Hernandez-Rueda Javier , Kurilovich Dmitry , Mazzotta Zeudi , Witte Stefan , Versolato Oscar O.
Published: February 2021

We experimentally study the mass distribution of a sheet of liquid tin formed by the impact of a ns-laser pulse on a spherical microdroplet. The mass distribution is obtained using a low-intensity, second ns-laser pulse, which induces vaporization of the stretching thin tin sheet. This careful vaporization enables the investigation of the thickness profile of the sheet, and its mass, at early times after laser pulse impact on a droplet, which have remained inaccessible by the methods used in recent work [B. Liu et al., Phys. Rev. Appl. 13, 024035 (2020)]. The vaporization method, moreover, allows the visualization of the thick rim that bounds the thin sheet. Our results unambiguously demonstrate that increasing the energy of the ns-laser pulse incident on the droplet, which enables reaching a predetermined target radius more quickly, results in a larger mass fraction remaining in the sheet. Specifically, our studies show a doubling of the sheet mass fraction by reducing the required expansion time. As a corollary, less tin will end up in other channels of the mass distribution, such as fragments surrounding the sheet. Accordingly, more mass would be available in the target sheet for interaction with the more energetic, main laser pulse that is used in the industry to produce a hot and dense plasma from tin sheet targets in order to create extreme ultraviolet light for nanolithography.
Re-evaluation of ortho-para-dependence of self pressure-broadening in the

ν

1 +

ν

3 band of acetylene
Authors: Gross Eisen C. , Tsang Kimberly A. , Sears Trevor J.
Published: February 2021

Optical frequency comb-referenced measurements of self pressure-broadened line profiles of the R(8) to R(13) lines in the ν1 + ν3 combination band of acetylene near 1.52 µm are reported. The analysis of the data found no evidence for a previously reported [Iwakuni et al., Phys. Rev. Lett. 117(14), 143902 (2016)] systematic alternation in self pressure-broadened line widths with the nuclear spin state of the molecule. The present work brought out the need for the use of an accurate line profile model and careful accounting for weak background absorptions due to hot band and lower abundance isotopomer lines. The data were adequately fit using the quadratic speed-dependent Voigt profile model, neglecting the small speed-dependent shift. Parameters describing the most probable and speed-dependent pressure-broadening, most probable shift, and the line strength were determined for each line. Detailed modeling of the results of Iwakuni et al. showed that their neglect of collisional narrowing due to the speed-dependent broadening term combined with the strongly absorbing data recorded and analyzed in transmission mode were the reasons for their results.
A field programmable gate array based high speed real-time weak periodic signal detection technique
Authors: Hu Jiadong , Shen Zhongtao , Liu Shubin , An Qi
Published: February 2021

The detection of a high repetition rate weak signal is studied in this paper. Owing to the characteristics of the signal of interest, both high speed analog-to-digital converter (ADC) and low computational complexity data processing techniques are required for high speed real-time weak signal detection. In this paper, a novel field programmable gate array (FPGA) based high speed real-time periodic weak signal detection technique is presented. Cascaded comparators outside the FPGA and cascaded flip flops in the FPGA are used to implement a one-bit ADC, which performs quantization first followed by sampling. Based on this novel design, a time-interleaved structure with several sub-channels is further proposed to significantly improve the sampling rate of the one-bit ADC, which does not require calibration for offset, gain, and sample-time mismatches between sub-channels. Each sub-channel has a long-time coherent integration structure to coherently integrate the sampled one-bit data. A full layer clearance mechanism that only operates on specific bits of the integrated sums is proposed to overcome the influence of a noise baseline drift on the weak signal detection. Compared with the traditional adaptive threshold, this mechanism has a significantly lower computational complexity. A prototype with three sub-channels performing 1.5 Gs/s sampling is implemented to verify the proposed technique. The results obtained confirm its high sampling rate and noise baseline drift tolerance in weak signal detection.
First principles design of Ohmic spin diodes based on quaternary Heusler compounds
Authors: Aull T. , Şaşıoğlu E. , Mertig I.
Published: February 2021

The Ohmic spin diode (OSD) is a recent concept in spintronics, which is based on half-metallic magnets and spin-gapless semiconductors (SGSs). Quaternary Heusler compounds offer a unique platform to realize the OSD for room temperature applications as these materials possess very high Curie temperatures as well as half-metallic and spin-gapless semiconducting behavior within the same family. Using state-of-the-art first-principles calculations combined with the nonequilibrium Green's function method, we design four different OSDs based on half-metallic and spin-gapless semiconducting quaternary Heusler compounds. All four OSDs exhibit linear current–voltage (I–V) characteristics with zero threshold voltage VT. We show that these OSDs possess a small leakage current, which stems from the overlap of the conduction and valence band edges of opposite spin channels around the Fermi level in the SGS electrodes. The obtained on/off current ratios vary between 30 and 105. Our results can pave the way for the experimental fabrication of the OSDs within the family of ordered quaternary Heusler compounds.
A quantum optics approach to photoinduced electron transfer in cavities
Authors: Wellnitz D. , Pupillo G. , Schachenmayer J.
Published: February 2021

We study a simple model for photoinduced electron transfer reactions for the case of many donor–acceptor pairs that are collectively and homogeneously coupled to a photon mode of a cavity. We describe both coherent and dissipative collective effects resulting from this coupling within the framework of a quantum optics Lindblad master equation. We introduce a method to derive an effective rate equation for electron transfer by adiabatically eliminating donor and acceptor states and the cavity mode. The resulting rate equation is valid for both weak and strong coupling to the cavity mode and describes electronic transfer through both the cavity-coupled bright states and the uncoupled dark states. We derive an analytic expression for the instantaneous electron transfer rate that depends non-trivially on the time-varying number of pairs in the ground state. We find that under proper resonance conditions, and in the presence of an incoherent drive, reaction rates can be enhanced by the cavity. This enhancement persists, and can even be largest, in the weak light–matter coupling regime. We discuss how the cavity effect is relevant for realistic experiments.
Probing the phonon mean free paths in dislocation core by molecular dynamics simulation
Authors: Sun Yandong , Zhou Yanguang , Hu Ming , Jeffrey Snyder G. , Xu Ben , Liu Wei
Published: February 2021

Thermal management is extremely important for designing high-performance devices. The lattice thermal conductivity of materials is strongly dependent on detailed structural defects at different length scales, particularly point defects like vacancies, line defects like dislocations, and planar defects such as grain boundaries. Traditionally, the McKelvey–Shockley phonon Boltzmann’s transport equation (BTE) method, combined with molecular dynamics simulations, has been widely used to evaluate the phonon mean free paths (MFPs) in defective systems. However, this method can only provide the aggregate MFPs of the whole sample, as it is challenging to extract the MFPs in different regions with varying thermal conductivities. In this study, the 1D McKelvey–Shockley phonon BTE method was extended to model inhomogeneous materials, where the contributions of defects to the phonon MFPs are explicitly obtained. Then, the method was used to study the phonon scattering with the core structure of an edge dislocation. The phonon MFPs in the dislocation core were obtained and were found to be consistent with the analytical model in a way that high frequency phonons are likely to be scattered in this area. This method not only advances the knowledge of phonon–dislocation scattering but also shows the potential to investigate phonon transport behaviors in more complicated materials.
Design of highly ordered hierarchical catalytic nanostructures as high-flexibility counter electrodes for fiber-shaped dye-sensitized solar cells
Authors: Gu Xiu Yun , Chen En Zi , Wei Kun , Chen Lu Lu , Zhang Chao Yue , Sun Guo Wen , Tan Jun Ren , Bi Hua-Sheng , Xie Hang , Sun Geng Zhi , Gao Xia , Pan Xiao Jun , Zhou Jin Yuan
Published: February 2021

Ordered array structures will greatly reduce the stress formation in wearable electric devices during dynamic bending operation. In this work, highly flexible TiN-based fiber counter electrodes (FCEs) were designed via a post-ammonization treatment on the hydrothermally grown TiO2 nanowire arrays. Results show that the obtained TiN nanorod arrays (NRAs) are well aligned with a diameter of 200–320 nm and a length of several hundred nanometers to ∼1 μm. Moreover, fiber-shaped dye-sensitized solar cells assembled using TiN FCEs showed the maximum photoelectric conversion efficiency (PCE) of 5.69%, which is 16.3% higher than that of the ones based on Pt FCEs. Analysis indicated that this enhancement in PCE could be mainly due to the better electrochemical catalytic activity of TiN NRAs. Furthermore, the optimizations of the nanoscale morphologies of TiN NRAs suggest that both small diameters and large lengths can benefit the PCE and the dynamic bending stability, while the diameters show a major influence on them. The optimal FCEs show an ultralow decay rate of 0.017‰ per bending cycle.