In this letter, an enhanced step-up five-level inverter is proposed for photovoltaic systems. Compared with conventional five-level inverters, the proposed topology can realize the multilevel ...inversion with high step-up output voltage, simple structure, and reduced number of power switches. The operating principle of the proposed inverter has been analyzed and the output voltage expression has been derived. In addition, the comparison with existing topologies of single-phase five-level inverters is presented. Finally, experimental results validate the performance of the proposed topology.
Little research has investigated the relations of emotional states and passage of time judgments over a long period and explored the mechanisms underlying the relations. In this research, we ...conducted three studies (N = 2010 in total) in the three time points throughout a year including the end of 2020, the beginning and middle of 2021. In each study, we measured participants' negative emotional states that arise in daily life (including loneliness, anxiety, and depression), feelings of how easy/hard to recall the things having done in the last year, and yearly passage of time judgments. The results from the three studies consistently showed that individuals' feelings of ease-of-retrieval mediated the relations of negative emotional states and yearly passage of time judgments. The stronger the negative emotional states, the harder people feel to recall the things from the last year, and the faster people perceive time passing last year. This research provides novel insights for understanding the relations of negative emotional states and passage of time judgments, and importantly, individuals' feelings of ease-of-retrieval plays a significant role on explaining the relations.
•Individuals experiencing stronger negative emotions tend to perceive time passing more quickly on a yearly basis.•The ease of retrieval of memories mediates the relationship between negative emotions and yearly passage of time judgments.•Stronger negative emotions make it harder to recall events from the past year, inducing a perception of time passing faster.
This study examines the relationships among intrinsic motivation, critical variables related to technology adoption, and students’ behavioral intention in mobile-assisted language learning (MALL). To ...test the hypothesized model through a path analysis, 169 survey responses were collected from undergraduate students who were foreign language learners of English in a Chinese research university. The results indicated that although intrinsic motivation did not have a direct influence on students’ behavioral intention in MALL, it had a positive influence on students’ behavioral intention through the two intervening variables, perceived usefulness and task technology fit. Perceived ease of use, however, was not associated with students’ behavioral intention directly, nor was it predicted by intrinsic motivation. The findings suggested proper instructional design that is aligned with and supports the language learning task was important to increase students’ behavioral intention to adopt mobile devices for language learning.
The chemical diversity and structural flexibility of lead halide perovskites (LHPs) offer tremendous opportunities to tune their optical properties through internal molecular engineering and external ...stimuli. Herein, we report the wide‐range and ultrapure photoluminescence emissions in a family of homologous 2D LHPs, MeOPEA2PbBr4−4xI4x (MeOPEA=4‐methoxyphenethylammonium; x=0, 0.2, 0.425, 0.575, 1) enabled through internal chemical pressure and external hydrostatic pressure. The chemical pressure, induced by the C−H⋅⋅⋅π interactions and halogen doping/substitution strengthens the structural rigidity to give sustained narrow emissions, and regulates the emission energy, respectively. Further manipulation of physical pressure leads to wide‐range emission tuning from 412 to 647 nm in a continuous and reversible manner. This work could open up new pathways for developing 2D LHP emitters with ultra‐wide color gamut and high color purity which are highly useful for pressure sensing.
Wide‐range and ultrapure emissions are achieved in 2D lead halide perovskites (LHPs) by combined chemical pressure from halogen doping/substitution and physical pressure from hydrostatic compression. This work demonstrates precise emission tuning and effective color regulation of 2D LHPs by pressure engineering, which would open a new pathway for developing ultrapure emitters and highly sensitive pressure sensors.
Abstract
In the past several decades, the car-following model has attracted many experts and scholars from the fields of traffic engineering, computational physics, psychology and so on, these ...experts and scholars have carried on the thorough research and the exploration to it, causes the model analysis essential factor from simple to rich, from simple to complex. With the continuous improvement of the model, the improved car-following model is more and more in line with the actual traffic conditions. With the development of traffic technology, driver’s car-following behavior will change greatly, which is realized by developing and establishing ITS, driver information guidance system and vehicle automatic intelligent cruise system. Therefore, a lot of car-following models for specific problems have emerged, which is of great practical significance to the further study of car-following theory. In this paper, the research background and significance of car-following model are deeply discussed, the current research status and conclusions are comprehensively analyzed, and the future research direction in this field is prospected.
The structural reconstruction at the crystal layer edges of 2D lead halide perovskites (LHPs) leads to unique edge states (ES), which are manifested by prolonged carrier lifetime and reduced emission ...energy. These special ES can effectively enhance the optoelectronic performance of devices, but their intrinsic origin and working mechanism remain elusive. Here it is demonstrated that the ES of a family of 2D Ruddlesden–Popper LHPs BA2CsPb2Br7, BA2MAPb2Br7, and BA2MA2Pb3Br10 (BA = butylammonium; MA = methylammonium) arise from the rotational symmetry elevation of the PbBr6 octahedra dangling at the crystal layer edges. These dangling octahedra give rise to localized electronic states that enable an effective transport of electrons from the interior to layer edges, and the population of electrons in both the interior states and the ES can be manipulated via controlling the external fields. Moreover, the abundant phonons, activated by the dangling octahedra, can interact with electrons to facilitate radiative recombination, counterintuitive to the suppressive role commonly observed in conventional semiconductors. This work unveils the intrinsic atomistic and electronic origins of ES in 2D LHPs, which can stimulate the exploration of ES‐based exotic optoelectronic properties and the corresponding design of high‐performance devices for these emergent low‐dimensional semiconductors.
The low‐energy and long‐lived edge states of 2D lead halide perovskites arise from the rotational symmetry elevation at the crystal layer edges, which are enabled by dangling PbBr6 octahedra at the lattice terminals. These dangling octahedra with enhanced atomic vibrations can give rise to localized electronic states that enable an effective electron transport from the interior to layer edges.
We map out the QCD phase structure at finite temperature and chemical potential for 2-flavour and 2+1-flavour QCD. This is done within a generalised functional approach to QCD put forward in 1. ...Specifically we compute the quark propagator and the finite-temperature and density fluctuations of the gluon propagator and the quark-gluon vertex on the basis of precision data for vacuum correlation functions. The novel ingredient is the direct self-consistent computation of the DSEs for the three dominant dressings of the quark-gluon vertex, in contrast to the common use of STI-inspired vertices.
For small densities the results for the chiral order parameter agree with the respective lattice and functional renormalisation group results, for large densities the present results are in a quantitative agreement with the latter, including the location of the critical end point.
Many important biological facts have been found as single-cell RNA sequencing (scRNA-seq) technology has advanced. With the use of this technology, it is now possible to investigate the connections ...among individual cells, genes, and illnesses. For the analysis of single-cell data, clustering is frequently used. Nevertheless, biological data usually contain a large amount of noise data, and traditional clustering methods are sensitive to noise. However, acquiring higher-order spatial information from the data alone is insufficient. As a result, getting trustworthy clustering findings is challenging. We propose the Cauchy hyper-graph Laplacian non-negative matrix factorization (CHLNMF) as a unique approach to address these issues. In CHLNMF, we replace the measurement based on Euclidean distance in the conventional non-negative matrix factorization (NMF), which can lessen the influence of noise, with the Cauchy loss function (CLF). The model also incorporates the hyper-graph constraint, which takes into account the high-order link among the samples. The CHLNMF model's best solution is then discovered using a half-quadratic optimization approach. Finally, using seven scRNA-seq datasets, we contrast the CHLNMF technique with the other nine top methods. The validity of our technique was established by analysis of the experimental outcomes.
This paper studies how retailers can effectively deliver online and offline information to omnichannel consumers who strategically choose whether to gather information online or offline and whether ...to buy products online or offline. Information resolves two types of uncertainty: product value uncertainty (i.e., consumers realize valuations when they inspect the product in store, but may end up returning the product when they purchase online) and availability uncertainty (i.e., store visits are futile when consumers encounter stockouts). We consider three information mechanisms:
physical showrooms
allow consumers to learn valuations anytime they visit the store, even during stockouts;
virtual showrooms
give consumers online access to an imperfect signal of their valuations;
availability information
provides real-time information about whether the store has a product in stock. Our main results follow. First, physical showrooms may prompt retailers to reduce store inventory, which increases availability risk and discourages store patronage. Second, virtual showrooms may increase online returns and hurt profits, if they induce excessive customer migration from store to online channels. Third, availability information may be redundant when availability risk is low and may render physical showrooms ineffective when implemented jointly. Finally, when customers are homogeneous, these mechanisms may not exhibit significant complementarities and the optimal information structure may involve choosing only one of the three.
Pressure‐induced emission enhancement (PIEE) is a novel phenomenon in contrast to conventional pressure‐induced emission quenching, and has attracted considerable attention owing to the potential ...application of materials with this effect as optical pressure‐sensing devices. The urgent need and significant significance lie in the design and exploration of systems that possess high‐efficiency PIEE. Here, a large PIEE in a novel zero‐dimensional (0D) hybrid manganese bromide is realized, (BPPH)2MnBr4·1.5CH3CN BPPH+ = bis(triphenylphosphine)iminium. The experimental and theoretical results demonstrate that such emission enhancement is primarily attributed to the pressure‐induced reconfiguration of electronic band alignment and resultant redistribution of band‐edge excitons. Under compression, the electronic bandgap of (MnBr4)2− experiences a more rapid reduction compared to that of the organic cations. Consequently, this leads to the gradual closure of the charge transfer pathway from (MnBr4)2− to BPPH+. This progression results in a higher retention of excitons on (MnBr4)2−, amplifying the efficiency of Mn2+ d–d transitions, and leading to a substantial enhancement in emission. This study not only offers fresh insights into the behavior of carrier dynamics induced by pressure in hybrid manganese halides but also presents a promising avenue for the advancement of PIEE systems.
Significant emission enhancement is achieved in a hybrid manganese bromide via pressure‐induced band‐edge carrier reconfiguration. This study not only offers fresh insights into the behavior of carrier dynamics induced by pressure in hybrid manganese halides but also presents a promising avenue for the advancement of pressure‐induced emission enhancement systems.
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