This paper reviews optical injection locking (OIL) of semiconductor lasers and its application in optical communications and signal processing. Despite complex OIL dynamics, we attempt to explain the ...operational principle and main features of the OIL in an intuitive way, aiming at a wide understanding of the OIL phenomenon and its associated techniques in the optic and photonic communities. We review and compare different control techniques that enable robust OIL in practical systems. The applications are reviewed with a focus on new developments in the past decade, under the categories of `High Speed Directly Modulated Lasers' and `Optical Carrier Recovery'. Finally, we draw our vision for future research directions.
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•The influence of spatio-temporal factors on human comfort was quantified.•Seasonal change is the main factor affecting physical ...comfort.•Theartificialimpermeablematrixincreasesthesurfacethermalfieldtemperature.•Natural factors can always effectively reduce the surface temperature.•Human comfort can be improved to a certain extent through human intervention.
In recent decades, urbanization and the dramatic increase in urban populations have exacerbated the urban heat island effect. At present, much attention has been paid to the causes and patterns of the urban heat island effect. However, there are few quantitative studies on the impact of the urban heat island effect. By extracting post-world climate data, DEM data, and land use data for 20 years between 2001 and 2020, this paper first studies the variation pattern and spatial distribution characteristics of urban heat islands in New York State, summarizes the seasonal distribution characteristics of temperature, and then uses Giles formula to calculate Tom's discomfort index and evaluate human thermal comfort, and evaluates the effect of heat island effect on human sensory thermal comfort. The results show that on the time scale, the surface temperature in the study area generally showed a slow upward trend over the past 20 years. For example, in July, the maximum and minimum temperatures increased by 3.2 °C and 4.1 °C, respectively. At the spatial scale, most of the heat island areas in the study area were distributed in the New York City agglomeration, especially from May to October, when the heat island effect was particularly obvious. The temperature map showed obvious high temperatures. Compared with 2001, the human discomfort index (DI) increased between June and August 2020. The land use map shows that as the city expands, people's DI index also increases, and the proportion of people who feel uncomfortable with heat increases to 50%. Except for the New York City cluster, other areas were mostly athermic-free. This result shows that excessive urban development concentration seriously affects residents' quality of life. We should pay attention to the superimposed impact of climate change and urban heat islands on the human discomfort index, and adjust the local high temperature and thermal field area through reasonable planning, strengthening greening, and using building technology to make cities more livable.
From the beginning of 2002 and 2012, severe respiratory syndrome coronavirus (SARS‐CoV) and Middle East respiratory syndrome coronavirus (MERS‐CoV) crossed the species barriers to infect humans, ...causing thousands of infections and hundreds of deaths, respectively. Currently, a novel coronavirus (SARS‐CoV‐2), which has become the cause of the outbreak of Coronavirus Disease 2019 (COVID‐19), was discovered. Until 18 February 2020, there were 72 533 confirmed COVID‐19 cases (including 10 644 severe cases) and 1872 deaths in China. SARS‐CoV‐2 is spreading among the public and causing substantial burden due to its human‐to‐human transmission. However, the intermediate host of SARS‐CoV‐2 is still unclear. Finding the possible intermediate host of SARS‐CoV‐2 is imperative to prevent further spread of the epidemic. In this study, we used systematic comparison and analysis to predict the interaction between the receptor‐binding domain (RBD) of coronavirus spike protein and the host receptor, angiotensin‐converting enzyme 2 (ACE2). The interaction between the key amino acids of S protein RBD and ACE2 indicated that, other than pangolins and snakes, as previously suggested, turtles (Chrysemys picta bellii, Chelonia mydas, and Pelodiscus sinensis) may act as the potential intermediate hosts transmitting SARS‐CoV‐2 to humans.
Highlights
The critical residues of S protein RBD binding with ACE2 indicated the potential intermediate hosts transmitting SARS‐CoV‐2 to humans.
This paper investigates the consensus problem of a three dimensional (3D) version of the widely studied Vicsek model, where each member moves in 3D Euclidean space with a constant speed with headings ...updated according to the average direction of neighbors. In comparison with the original Vicsek model, each agent’s heading is determined by two angle sequences interacting with each other, one of which evolves according to a “linear” non-homogeneous equation, which makes the theoretical analysis quite complicated. By analyzing the underlying structure of the system and relying on estimation of some characteristics concerning the initial states, we will establish consensus results for 3D Vicsek model under random framework without resorting to any a priori connectivity assumption.
This paper presents an active disturbance rejection position control scheme for a magnetic rodless cylinder in servo systems without pressure states. It is very hard to achieve precise position ...control of magnetic rodless cylinders due to nonlinearity from large friction force and hysteresis. In this paper, the overshoot, which has a negative influence on position control, is effectively reduced by using a tracking differentiator. Furthermore, the nonlinearity is estimated by a designed extended-state observer. In addition, the self-stable region theory is used to prove the convergence of the extended-state observer. Finally, both control precision and response speed are guaranteed via a nonlinear error feedback controller in the pneumatic system. Experimental results show that the steady-state error within 0.05 mm is achieved for a step signal.
IoT-based services benefit from cloud which offers a virtually unlimited capabilities, such as storage, processing, and communication. However, the challenges are still open for mobile users to ...receive computation from the cloud with satisfied quality-of-service (QoS) provisioning. In this paper, we study computation offloading by using edge computing, which is a new paradigm to deliver computation to the edge of pervasive networks nearby mobile users. Without strong incentive in place, however, local edge servers may be reluctant to help offload computation. To stimulate cloud service operator and local edge server owners to participate in computation offloading, we formulate the interactions among cloud service operator and edge server owners as a Stackelberg game to maximize the utilities of cloud service operator and edge server owners by obtaining the optimal payment and computation offloading strategies. Through theoretical analysis, we show that the game is guaranteed to reach a unique Nash equilibrium. We then design two computation offloading algorithms that can quantify their efficiencies in terms of low delay and reduced complexity. Additionally, we extend our work by considering that edge server owners dynamically join or leave computation offloading. Numerical results show that our proposed algorithms perform well in computation offloading and efficiently stimulate edge server owners to make contribution to computation offloading.
Metal-enhanced photocatalysis has recently received increasing interest, mainly due to the ability of metal to directly or indirectly degrade pollutants. In this review, we briefly review the recent ...breakthroughs in metal-enhanced photocatalysis. We discussed the recent progress of surface plasmon resonance (SPR) effect and small size effect of metal nanoparticles on photocatalysis; in particular, we focus on elucidating the mechanism of energy transfer and hot electron injection/transfer effect of metal nanoparticles and clusters while as photocatalysts or as cophotocatalysts. Finally, we discuss the potential applications of metal-enhanced photocatalysis, and we also offer some perspectives for further investigations.
Blockchain, as a new force for transforming the Internet, will bring about tremendous changes in information resource sharing activities and information service organizations. Information resource ...sharing activities and information services are the main content of the research in the field of library and information. Therefore, the article attempts to explore the application of blockchain in the field of library and information, and guides blockchain technology to better carry out information services. Firstly, this paper analyzes the time distribution and research hotspots of blockchain research by means of bibliometrics and content analysis, expounds the research content, significance, challenges and directions of breakthroughs in the field of library and information. Finally, using the empirical research method, combined with the characteristics of the blockchain, the application of blockchain technology in the future intelligence field is prospected from the specific application scenarios such as copyrigh
The aim of the systematic review was to determine the effectiveness of organizational-level person-centered care for people living with dementia in relation to their quality of life, mood, ...neuropsychiatric symptoms and function. ALOIS, the Cochrane Dementia and Cognitive Improvement Group Specialised Register databases, were searched up to June 2018 using the terms dementia OR cognitive impairment OR Alzheimer AND non-pharmacological AND personhood OR person-centered care. Reviewed studies included randomized controlled trials (RCTs), cluster-randomized trials (CRTs) and quasi-experimental studies that compared outcomes of person-centered care and usual (non-person-centered) care, for people with a diagnosis of dementia. The search yielded 12 eligible studies with a total of 2599 people living with dementia in long-term care homes, 600 receiving hospital care and 293 living in extra-care community housing. Random-effects models were used to pool adjusted risk ratios and standard mean differences from all studies; the findings were assessed followed the PRISMA guidelines and GRADE criteria. Statistical heterogeneity was assessed using the I2 method and Chi2 P value; studies with low statistical heterogeneity were analyzed using a random-effects model with restricted maximum likelihood estimation in R. Analyses of pre/post data within 12 months identified: a significant effect for quality of life (standardized mean difference (SMD) 0.16 and 95% CI 0.03 to 0.28; studies = 6; I2 = 22%); non-significant effects for neuropsychiatric symptoms (SMD 0.06, 95% CI -0.08 to 0.19; studies = 4; I2 = 0%) and well-being (SMD 0.15, 95% CI -0.15 to 0.45; studies = 4; I2 = 77%); and no effects for agitation (SMD -0.05 (95% CI -0.17 to -0.07; studies 5; I2 = 0%) and depression (SMD -0.06 and 95% CI -0.27 to 0.15, studies = 5; I2 = 53%). The evidence from this review recommends implementation of person-centered care at the organizational-level to support the quality of life of people with living with dementia.
The investment in hydrogen-refueling stations (HRS) is key to the development of a hydrogen economy. This paper focuses on the decision-making for potential investors faced with the thought-provoking ...question of when the optimal timing to invest in HRS is. To fill the gap that exists due to the fact that few studies explain why HRS investment timing is critical, we expound that earlier investment in HRS could induce the first mover advantages of the technology diffusion theory. Additionally, differently from the previous research that only considered that HRS investment is just made by one individual firm, we innovatively examine the HRS co-investment made by two different firms. Accordingly, we compare these two optional investment modes and determine which is better considering either independent investment or co-operative investment. We then explore how the optimal HRS investment timing could be figured out under conditions of uncertainty with the real options approach. Given the Chinese HRS case under the condition of demand uncertainty, the hydrogen demand required for triggering investment is viewed as the proxy for investment timing. Based on analytical and numerical results, we conclude that one-firm independent investment is better than two-firm cooperative investment to develop HRS, not only in terms of the earlier investment timing but also in terms of the attribute for dealing with the uncertainty. Finally, we offer recommendations including stabilizing the hydrogen demand for decreasing uncertainty, and accelerating firms’ innovation from both technological and strategic perspectives in order to ensure firms can make HRS investments on their own.
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