bluuebunny/crossref_metadata_2025 huggingface dataset:
Escherichia coli as a platform microbial host for systems metabolic engineering
Authors: Yang Dongsoo , Prabowo Cindy Pricilia Surya , Eun Hyunmin , Park Seon Young , Cho In Jin , Jiao Song , Lee Sang Yup
Published: May 2021

Bio-based production of industrially important chemicals and materials from non-edible and renewable biomass has become increasingly important to resolve the urgent worldwide issues including climate change. Also, bio-based production, instead of chemical synthesis, of food ingredients and natural products has gained ever increasing interest for health benefits. Systems metabolic engineering allows more efficient development of microbial cell factories capable of sustainable, green, and human-friendly production of diverse chemicals and materials. Escherichia coli is unarguably the most widely employed host strain for the bio-based production of chemicals and materials. In the present paper, we review the tools and strategies employed for systems metabolic engineering of E. coli. Next, representative examples and strategies for the production of chemicals including biofuels, bulk and specialty chemicals, and natural products are discussed, followed by discussion on materials including polyhydroxyalkanoates (PHAs), proteins, and nanomaterials. Lastly, future perspectives and challenges remaining for systems metabolic engineering of E. coli are discussed.
Cognitive radio based efficient video multicast in TV white space
Authors: Liu Cong , Fei Wei , Hu Sheng , Wu Minghu , Liu Meng
Published: May 2021

The wireless video multicast in TV White Space (TVWS) is a challenging task due to the characteristics of the wireless channels and the video streaming. This paper studies the optimized real‐time video multicast in TVWS, and proposes a practical and bandwidth‐efficient TVWS video multicast framework. First, a TVWS‐based efficient quasi‐static spectrum access scheme is employed to reduce the spectrum switch delay. Second, a cross‐layer optimized resource scheduling scheme is proposed to further improve the multicast performance, which considers various cross‐layer design factors, including scalable video coding, adaptive modulation‐coding, to maximize the overall received video quality. Finally, the proposed resource scheduling problem is formulated as a mixed‐integer non‐linear programming problem. Considering that the video streaming is delay‐sensitive, the problem is addressed with a proposed sub‐optimal but computational efficient algorithm. The simulation results demonstrate the effectiveness and superiority of the proposed scheme.
Enhanced contribution of photovoltaic power systems to frequency control in future power systems
Authors: Seidel Julia , Rauscher Florian , Engel Bernd
Published: May 2021

In contemporary grid infrastructure, grid frequency is still predominantly controlled by conventional power plants. However, the increasing installed power of distributed energy resources and the declining amount of synchronous generators will necessitate major participation of wind farms as well as photovoltaic systems in frequency control. From a technical point of view, PV inverters are able to provide not only manual but also automatic frequency restoration reserves as well as frequency containment reserves. However, market and regulatory conditions are not designed for them to participate yet. As power electronic‐based systems, photovoltaic inverters are able to react even faster to frequency deviations than conventional power plants. This characteristic is leveraged to analyse the contribution of photovoltaic systems to stabilise the grid frequency. Therefore, a new control reserve product, called fast frequency containment reserves is developed. It is shown that the frequency stability can be considerably improved by integrating PV systems into frequency control.
Risk assessment of heavy landing based on BWM and cloud model
Authors: Jiahui Shi , Jihui Xu , Tengfei Liu , Jing Zhang , Pu Zhu , Chunlin Yang
Published: May 2021

Aiming at the systemic, ambiguity and randomness characteristics of the aircraft's heavy landing risk, this paper starts from the system perspective and proposes a risk assessment method based on the Best- Worst method (BWM) and cloud model. Aiming at the ambiguity and randomness of the information in the risk assessment, the cloud model is used to describe the language. In view of the difference in weights, combining BWM and cloud models for weighting. Finally, an example is given to ver ify the reasonableness and effectiveness of the model.
Under the Processing of Network Data Images, the Position Recognition Technology of Mechanical Parts Based on "Mathematical Modeling" is Studied
Authors: Zhao Jiaqi
Published: May 2021

With the development of the times and the progress of society, science and technology has been developing more and more rapidly. In this regard, modern society has been composed of science and technology. Compared with the original steam engine, Jenny textile machine and other industrial era starters, now the technology has entered the era of large machines. As a result, the processing of mechanical parts is becoming more and more complex than before. Therefore, the purpose of this paper is to use the network data image processing based on mathematical modeling of mechanical parts processing location recognition technology. After consulting the relevant literature on mechanical parts processing and location recognition technology, this paper goes to the factory to observe the mechanical working principle and mechanical working process, and then uses the two-dimensional spectral peak search algorithm to design the position recognition technology in the process of mechanical parts processing to process mechanical parts based on mathematical modeling. The experimental results show that the two-dimensional spectral peak search algorithm can make the system better point out the relevant problems in the process of mechanical parts processing and solve them intelligently, and if there are problems that cannot be solved, it will be fed back to the system informer in time to check. Finally, the accuracy and correctness of mechanical parts processing are improved, and some improvements are put forward for mechanical parts processing, which is of great help to mechanical parts processing.
Research on Clothing Rental Model under Sharing Economy
Authors: Mu Xiaoyao , Li Chenggang
Published: May 2021

In recent years, the emergence of various clothing rental platforms makes the clothing rental model has been well applied. Based on the premise of the rapid development of sharing economy, this paper discusses the necessity of clothing rental model in the boom of sharing economy. Based on the analysis of the investment scale, profit growth rate, operation mode and industry structure of the garment rental mode, this paper illustrates the problems of this mode in the supply side, transaction cost, health and safety and market positioning, and then puts forward the strategies to solve these problems.
An execution time prediction model for crew information processing in new special vehicles
Authors: Guo Sinan , Liu Shuang , Liang Chaoran , Xie Fang , Zheng Sijuan
Published: May 2021

Task execution time prediction modeling is of great significance to the safety of special vehicle crew and maintenance of overall combat effectiveness. In our study, a task execution time prediction model for crew information processing task is proposed considering the characteristics of information processing task, as well as the interaction mode of man-machine system of special vehicles. In addition, a model validation experiment was conducted adopting 20 subjects facing to two kinds of representative tasks, and both of them have two levels of complexities. The result shows that there is a highly positive correlation (r = 0.999, p = 0.001) between the model prediction and the experimental results of four tasks, which indicates that the model has a good applicability. Based on the rationality of model validation, the application research of the model was conducted. The result shows that for the sub-tasks with more objects and visual searching difficulty, the speech interaction mode can reduce the operation duration to a great extent; for simple subtasks with less operation steps and strong coherence, the touch interaction mode has certain advantages.
Research on the Dilemma and Countermeasures of the Customer Service Management of International Freight Forwarders under the New Normal——Take Guangdong GW Company as an example
Authors: Zhang Ling , Zhan Yifang , Wang Zixi , Xiao Meiyan
Published: May 2021

In the context of the global epidemic that has lasted for many months, international trade has been declining, and China’s economy has entered a new normal. The global international freight forwarding industry is becoming more and more competitive. Many small and medium-sized international freight forwarding companies are facing difficulties in survival. Risk of bankruptcy. This article takes the customer service management of Guangdong GW international freight forwarder as an example, analyzes the dilemma of international freight forwarder customer service management under the new normal, and proposes corresponding solutions, explores the path to improve customer service management, and enhances the core competition in the market force. Thus, in order to improve the quality of customer service of international freight forwarders, it is necessary to carry out effective management innovation from improving the professional level of customer service personnel, improving customer service management system and improving customer service performance management. This will serve as a reference for the small and medium international freight forwarding industry to enhance the company's core competitiveness.
Research on the Improvement of Employee’s Innovation Performance Under Moral Leadership
Authors: Fang Yuping
Published: May 2021

With the rapid development of technology and economy, more and more local Chinese enterprises are gradually growing and becoming prominent in all walks of life. However, the environment is complex and changeable, and various competitors and pressures make the importance of business management more prominent. One of the main purpose of business management is to improve enterprise performance so as to obtain more profits. Therefore, enterprise managers began to take a variety of measures in order to obtain higher performance. As an effective source to improve performance, innovation has become a goal that enterprise managers are chasing. The level of innovation performance has thus become one of the standards to measure the development of enterprises. Employees are the driving force of enterprise development, many a mickle makes a muckle, so in this process, their individual innovation performance is crucial, which is directly affected by the leadership style. Leadership has always been one of the hot topics in the field of business management and it has a direct impact on the effectiveness of business management. The main purpose of our study is to explore the underlying mechanisms that how moral leadership impacts employees’ innovation performance by examining positive psychological safety’s moderating role and voice behavior’s mediating role of subordinates. We found that moral leadership is positively correlated with employee’s innovation performance and this relationship is mediated by employees’ voice behavior. Our results also demonstrate that employees’ psychological safety moderates the positive relationship between moral leadership and voice behavior. Compared with a high level of psychological safety, this relationship is stronger when it is low.
Research on the Impact of Financial Flexibility on Innovation Investment from the Perspective of Institutional Ownership
Authors: Han Dongping , Li Jing , Zhang Mengwen
Published: May 2021

Uncertainty in the business environment brings many challenges and opportunities to enterprises. This paper studies the impact of financial flexibility on innovation investment from the perspective of institutional ownership, using data of A-share high-tech enterprises from 2014 to 2018 as the empirical analysis sample. The results show that financial flexibility can promote innovation investment. Moreover, compared with state-owned enterprises, cash flexibility plays a more significant role in promoting non-stateowned enterprises, while debt flexibility only promotes innovation investment in non-state-owned enterprises. Through further research, it is found that the size of institutional investors’ shareholding has the positive moderating effect on the relationship between financial flexibility and innovation investment. In addition, non-independent institutional investors’ shareholding plays a negative role in regulating the impact of financial flexibility on innovation investment.
Applying Data Mining in Music influences analysis
Authors: Lai Siqi
Published: May 2021

Nowadays, music has become an indispensable part of our life. Studying the influence and evolution process of music will help to promote the progress of human civilization. The purpose of this paper is to understand and measure the impact of previously produced music on new music and music artists, and to develop a model for measuring the impact of music. Taking music genre as the main body, this paper constructs a directional network of music influence and a sub-network reflecting the relationship between "influencer and follower". In addition, this paper also defines the influence of music, and puts forward the "contagiousness index" to reveal a person's actual influence. Finally, using the parallel coordinate characteristics, the paper analyzes the influence of music on culture in time or environment.
Design and Implementation of Port Video Terminals Security Access Authentication System Using Blockchain Technology
Authors: Tang Chunming , Ma Yuyu , Yu Xiang
Published: May 2021

In the face of the increasing scale of port video surveillance systems, edge computing is gradually used to improve the real-time processing efficiency of surveillance systems and reduce the load on the cloud with the advantages of distributed computing. In order to improve the security factor of terminal access in the edge computing environment, this paper proposes a decentralized terminal security access authentication system based on blockchain, which realizes the identity registration, revocation and mutual authentication of two interfaces between terminal devices and edge computing through the smart contract technology of blockchain, and establishes a trusted channel for data transmission between terminals and edge nodes. Through the functional test of the system and the security analysis of the system on the Hyperledger Fabric platform, it shows that the system has more security attributes and higher security.
Service innovation roadmaps and responsible entities learning
Authors: Spohrer Jim
Published: May 2021

Service-Dominant Logic (S-D Logic) and service science provide a way for innovators and learners to look at the world differently and thereby improve quality-of-life for people over time. The continued development of service science as an emerging transdiscipline will depend on developing better measurements and tools for understanding the past and future identities, reputations, values, goals, and strategies of entities interacting to achieve outcomes. For example, Service Innovation Roadmaps (SIRs) can be thought of as an attempt to make explicit the “learning investment strategy” of responsible entities (people, businesses, regional governments) to change and become “better future version of themselves” in terms of value co-creating service interactions. In short, SIRs can help with the challenge of upskilling people in an age of accelerating technology and policy changes. All service systems, as responsible entities learning, invest in three types of activities, herein termed Run- Transform-Innovate activities. This short paper provides context for a research direction to develop further the notions of SIRs and embrace complexity economics as a tool for advancing service science.
Build to think, build to learn: What can fabrication and creativity bring to rethink (higher) education?
Authors: Morin Jean-Henry , Moccozet Laurent
Published: May 2021

With the global digital transition, we are witnessing, it is clear that learning is no longer done in isolation and without the use of many digital resources. However, the teaching approaches that are still dominant in higher education are largely marked by old paradigms. Without saying they are wrong; however, one can only witness that they no longer fully correspond to the world we live in and should consequently be adapted. In this paper we propose to introduce the Design Thinking and akin approaches found in FabLabs in order to define a learning space complementary to the traditional teaching experience of higher education, which are rather organised in silos: faculties, departments, degrees. Such a place, which we call a FacLab and which can be described as a physical space extended by a virtual digital space, can be seen as a FabLab embedded in the academic environment. It would favour transversality, encounters, co-construction, collaboration, serendipity and most importantly the putting into practice of transverse skills around the mainly digital factory of the tangible and the intangible, supported and sustained by the methodologies resulting from Design Thinking and related creativity approaches. Here we present our approach and the first developments we have implemented.
Digital innovation process in the academic sector - The case of the University of Geneva
Authors: Serugendo Giovanna Di Marzo , Friha Lamia
Published: May 2021

In this paper, we describe an innovative process towards digital transformation in the high-educational field, developed at the University of Geneva since 2016. It aims to provide novel services identified proactively as of high value for improving student and university members experience. This approach is made possible through our Digital Innovation Hub and its different tools. One of these tools is the “Accelerator of digital science and services”, born from the original combined effort of two main digital actors of the university: The Information Systems Division (DISTIC) entity, providing professional expertise in developing and deploying digital services, and the Computer Science Center (CUI), providing research-led innovations. Through the Accelerator, we experiment and incrementally build new innovative services to be scaled up and deployed. This paper reports on our experience gathered throughout the establishment of this innovative process and its impact on governance and structure.
Oxidation and hot corrosion behavior of a directionally solidified W richen cobalt-based superalloy
Authors: Zhou Yuebo , Mo Chenggang , Wang Hong
Published: May 2021

In this study, isothermal and hot corrosion in molten 75 mass% Na2SO4+25 mass% NaCl at 900 °C was carried out on an W richen Co-based directionally solidified Co-27.53Cr-9.85W-10.29Ni-0.75Al superalloy. For comparison, K38G with composition of 16.34Cr-4Al-1.77Mo-3.81Ti-2.66W-8.38Co were also conducted under same condition. Isothermal oxidation indicates that Co-based superalloy forms a Co-oxide dispersion chromia scale. However, K38G forms a purer chromia scale due to higher weight percentage ratio of Cr to Al. Under molten Na2SO4-NaCl salts, the defects in Ni/Co oxide dispersion chromia layer make it feasible that the molten salt can penetrates along grain boundaries into the internal interface to form internal sulfides, which causes the spallation of scales and significantly decreases its hot corrosion resistance.
Telerehabilitation bei unspezifischen Rückenschmerzen
Authors: Hacker Volker , Bauer Natascha
Published: May 2021

In Zeiten der Corona-Pandemie steht die Physiotherapie vor besonderen Herausforderungen. Nicht zuletzt wegen des deswegen verhängten Lockdowns hat die Telerehabilitation erheblich an Bedeutung gewonnen. Anhand eines Fallbeispiels stellen die Autoren eine Möglichkeit vor, wie Befunderhebung und Therapie eines Patienten mit unspezifischen Rückenschmerzen online erfolgen und wie der Weg zurück zum Kraftsport gestaltet werden kann.
Association Between Serum Irisin and Diabetic Nephropathy in Patients with Type 2 Diabetes Mellitus: A Meta-Analysis
Authors: Wang Rui , Liu Hongyan
Published: May 2021

Irisin, an emerging adipokine, has been involved in the pathogenesis of type 2 diabetes mellitus (T2DM). However, previous studies evaluating the association between irisin and diabetic nephropathy (DN) showed inconsistent results. We performed a meta-analysis to evaluate the above association. Matched case-control studies evaluating the difference of serum irisin between T2DM patients with and without DN were identified via systematic search of PubMed, Embase, Cochranes’ Library, China National Knowledge Infrastructure, and WanFang databases from inception to December 5, 2020. A random-effects model or a fixed-effects model was used to pool the results according to the heterogeneity. Overall, thirteen matched case-control studies including 1735 T2DM patients were included. Results of meta-analysis showed that compared to T2DM patients with normoalbuminuria, those with microalbuminuria [10 studies, standard mean difference (SMD): 1.12, 95% confidence interval (CI): 0.48–1.77, p<0.001; I2=94%] and macroalbuminuria (10 studies, SMD: 1.86, 95% CI: 0.93–2.79, p<0.001; I2=97%) had significantly lower serum irisin. Besides, the serum level of irisin was significantly lower in T2DM patients with macroalbuminuria than those with microalbuminuria (10 studies, SMD: 0.91, 95% CI: 0.44–1.38, p<0.001; I2=90%). In addition, patients with estimated glomerular infiltration rate (eGFR)<60 ml/min 1.73 m2 had lower serum irisin compared to those with eGFR≥60 ml/min 1.73 m2 (4 studies, SMD: 0.89, 95% CI: 0.32–1.46, p=0.002; I2=91%). In conclusion, serum irisin may be associated with albuminuria and reduced eGFR in T2DM patients.
Contralateral Masking in the Measurement of Auditory Brainstem Responses with Air-Conducted Tone Burst Stimuli in Individuals with Unilateral Hearing Loss
Authors: Silva Bárbara Cristiane Sordi , Jacob-Corteletti Lilian Cássia Bórnia , Sassi Tyuana Sandim da Silveira , Chaves Juliana Nogueira , Araújo Eliene Silva , Alvarenga Kátia de Freitas
Published: May 2021

Abstract Background Contralateral noise masking is an important aspect of auditory brainstem response (ABR) measurements. Purpose The primary aim of this study is to determine how contralateral white noise (WN) masking influences the amplitude
and the latency of V wave generated during ABR measurements, using tone burst (TB), in adult ears with normal hearing (NH). The secondary aim of this study is to ascertain the need of contralateral masking in ABR measurements with the TB stimuli using a 3A insertion earphone, and to propose
the applicability of WN masking in unilateral sensorineural hearing loss (USNHL). Research Design It is a cross-sectional observational and descriptive study. Study Sample Experiment 1: Thirty individuals, without any otologic, psychological, or neurological
dysfunction, were selected. Experiment 2: Fifteen individuals with previous audiological diagnoses of severe and profound USNHL were considered. Intervention The study involves ABR TB at specific frequencies of 0.5, 1, 2, and 4 kHz. Data Collection and Analysis Experiment
1: The evaluation was performed at the fixed intensity of 80 dB nHL (decibel normalized hearing level) on the tested ear, followed by the application of simultaneous masking to the nontested ear, intensity ranged from 0 to 80 dB. Experiment 2: ABR threshold measurements were
first performed on the ear with hearing loss (HL) at the frequencies of 1, 2, and 4 kHz. The results were subsequently confirmed using contralateral masking. Results Experiment 1: At any given frequency, there were no statistically significant differences in the amplitude
and latency of V wave with increase in the intensities of WN masking. Experiment 2: Cross-hearing was observed at least once in all frequencies analyzed through the occurrence of V wave. Conclusion In conclusion, the contralateral WN masking at the maximum intensity of 80 dB
does not affect the amplitude and latency of V wave of the ABR TB at 1, 2, and 4 kHz. Contralateral masking for the ABR TB presented using 3A insertion earphones is necessary at 1, 2, and 4 kHz in individuals with severe or profound degrees of USNHL and at intensities of 15,
20, and 10 dB above the ABR threshold of the nontested ear.
Giant Calcified Cavernous Hemangioma Managed with Modified Double Concentric Craniotomy
Authors: Jha Vikas Chandra , Abhijit Vishal , Jha Neera , Rewatkar Sudhanshu , Sinha Vivek Sharan , Alam Mohammad Shahnawaz
Published: May 2021

Giant calcified cavernous hemangioma is uncommon, and calvarial invasion with intracranial extension and dural breach is rare. Radiological resemblance to lesions like meningioma is unreported. Surgical excision of such lesions is technically challenging. A 35-year-old female presented with recurrent generalized tonic-clonic seizures for 2 years. Imaging suggested a highly vascular lesion arising from the skull, mimicking intraosseous meningioma, sarcoma, metastases, and so on. Double concentric craniotomy was done with lifting of bones separately around sinuses with radial cuts of dura to visualize tumor-cortical interface to safeguard neurovascular structures, and complete excision was achieved. Histopathology was suggestive of calcified cavernous hemangioma. The patient was asymptomatic at 1 year of follow-up.Differentiating angiomatous and intraosseous meningioma from calcifying giant hemangioma and other mimicking lesions may be difficult on imaging. Modified double concentric craniotomy, although used uncommonly, can be a useful technique safeguarding the neurovascular structures in its proximity.
Systematic Review of Radiation-Based Therapies for Hepatocellular Carcinoma
Authors: Mathew Namita E. , Elsayed Mohammad , Nezami Nariman , Majdalany Bill S. , Gandhi Ripal , Haber Michael , Bercu Zachary L. , Kokabi Nima
Published: May 2021

Aim Despite the increasing trend to utilize radiation therapies for the treatment of hepatocellular carcinoma (HCC), there is limited analysis comparing treatment outcomes of various radiation-based therapies including selective internal radiation therapy (SIRT) to stereotactic body radiation therapy (SBRT) and proton beam therapy (PBT). This study aims to examine the heterogeneity of designs and outcomes in existing radiation therapy studies for the treatment of HCC.

Methods A systematic review was performed to compare the radiation therapies for HCC including SBRT, PBT, and yttrium-90 (Y90) SIRT by searching through PubMed, EMBASE, Medline, and Cochrane library databases. The main outcomes analyzed were overall survival rates, median overall survival, and progression-free survival with additional analysis of baseline patient characteristics, including Barcelona Clinic Liver Cancer stage, Child–Pugh class, and tumor size.

Results Eighty-seven studies comprising 7,462 patients were included. The pooled 1-year overall survival rates for the Y90 SIRT, SBRT, and PBT groups were 57.8, 83.1, and 78.7%, respectively. The rates of Barcelona Clinic Liver Cancer A, B, and C patients were 22.9, 32.2, and 42.5% in Y90 SIRT; 52.5, 20.2, and 25.1% in SBRT; and 36.3, 33.4, and 28.2% in PBT groups, respectively. The baseline intergroup differences were statistically significant (p < 0.0001). The median tumor sizes were 5.8, 3.1, and 4.5 cm in the Y90 SIRT, SBRT, and PBT groups, respectively.

Conclusion In the management of HCC, there is substantial heterogeneity in studies investigating Y90 SIRT, SBRT, and PBT, with Y90 SIRT patients having worse Barcelona Clinic Liver Cancer and tumor burden at baseline, which likely contributes to the observed lower survival outcome.
Using biofabricated tissue-engineered vascular systems to study cardiovascular disease
Authors: McConnon Aili
Published: May 2021

Tissue-engineered vascular systems that are biofabricated using novel materials can serve to model certain heart diseases, such as atherosclerosis, and to test drug therapies for these diseases.
Double field theory algebroid and curved L
∞-algebras
Authors: Grewcoe Clay James , Jonke Larisa
Published: May 2021

A double field theory algebroid (DFT algebroid) is a special case of the metric (or Vaisman) algebroid, shown to be relevant in understanding the symmetries of double field theory. In particular, a DFT algebroid is a structure defined on a vector bundle over doubled spacetime equipped with the C-bracket of double field theory. In this paper, we give the definition of a DFT algebroid as a curved L∞-algebra and show how implementation of the strong constraint of double field theory can be formulated as an L∞-algebra morphism. Our results provide a useful step toward coordinate invariant descriptions of double field theory and the construction of the corresponding sigma-model.
Mixing enhancement in T-junction microchannel with acoustic streaming induced by triangular structure
Authors: Endaylalu Sintayehu Assefa , Tien Wei-Hsin
Published: May 2021

The T-shaped microchannel system is used to mix similar or different fluids, and the laminar flow nature makes the mixing at the entrance junction region a challenging task. Acoustic streaming is a steady vortical flow phenomenon that can be produced in the microchannel by oscillating acoustic transducer around the sharp edge tip structure. In this study, the acoustic streaming is produced using a triangular structure with tip angles of 22.62°, 33.4°, and 61.91°, which is placed at the entrance junction region and mixes the inlets flow from two directions. The acoustic streaming flow patterns were investigated using micro-particle image velocimetry (μPIV) in various tip edge angles, flow rate, oscillation frequency, and amplitude. The velocity and vorticity profiles show that a pair of counter-rotating streaming vortices were created around the sharp triangle structure and raised the Z vorticity up to 10 times more than the case without acoustic streaming. The mixing experiments were performed by using fluorescent green dye solution and de-ionized water and evaluated its performance with the degree of mixing (M) at different amplitudes, flow rates, frequencies, and tip edge angles using the grayscale value of pixel intensity. The degree of mixing characterized was found significantly improved to 0.769 with acoustic streaming from 0.4017 without acoustic streaming, in the case of 0.008 μl/min flow rate and 38 V oscillation amplitude at y = 2.15 mm. The results suggested that the creation of acoustic streaming around the entrance junction region promotes the mixing of two fluids inside the microchannel, which is restricted by the laminar flow conditions.
Principles and Key Applications: Principles and Applications of Synthetic Solar Irradiance
Authors: Boland John , Grantham Adrian
Published: May 2021

In this chapter we first describe the basic concepts of synthetic generation of time series data. We examine several of the realms where it is needed. One area is downscaling from a coarse temporal resolution to a higher frequency. For example, when estimating the performance of solar cells, one-minute data is more useful than hourly, but it may not be available. Also, infilling missing data is crucial if one is forecasting output from a solar farm. On the other hand, generating any number of years of data from a limited number of measured years—known as bootstrapping—is useful for estimating risk for farms and other solar installations. In energy markets, there is scope for generating possible future trajectories for either solar radiation time series or financial instruments that depend on them. In describing these situations and others, we briefly explain the mechanisms for these computations. We end by describing in detail some specific example applications of synthetic solar irradiance tools.
Established Mathematical Approaches for Synthetic Solar Irradiance Data Generation
Authors: Munkhammar Joakim , Widén Joakim
Published: May 2021

This chapter gives an overview of established state-of-the-art mathematical approaches for generating synthetic solar irradiance data. The most important scientific studies from the last half-century are identified and discussed, and the general development of the field is characterized. The mathematical methods used for modeling both deterministic and stochastic components of solar irradiance are categorized and explained, along with examples of their application to synthetic irradiance modeling. The mathematical approaches described include methods to achieve stationarity, probability distribution models, autoregressive processes, Markov chain models, multivariate distribution modeling, and copulas. Synthesis of time series data with resolutions ranging from days to minutes is covered, including both purely temporal as well as more recent spatiotemporal approaches.
Industrial Application of Synthetic Irradiance: Case Study of Solar Yield
Authors: Larrañeta Miguel , Fernández-Peruchena Carlos , Silva Pérez Manuel A.
Published: May 2021

Industrial activity concerned with the profitability and safety of investments can be supported and promoted by research through the creation of new mathematical modeling approaches, and the quantification and mitigation of uncertainties. In recent years there has been increasing interest in the adoption of probabilistic approaches to assess sources of uncertainty in solar energy systems to estimate their feasibility, considering yield estimates, investments, operation and maintenance costs, and solar resource. In this context, the synthetic solar irradiance data set approach emerges as a promising tool to emulate the variability inherent to the solar resource in confident designs and feasibility analyses of these systems. Chapter 5 deals with the requirements of the industry with respect to synthetic solar data, and how such requirements are currently addressed during the main stages of development of solar projects. We recap methods for benchmarking the success of generated synthetic irradiance, reviewing statistical indicators for that purpose. We discuss and compare the use of single annual and multiple synthetic annual data sets of solar irradiance in the first stages of solar projects, and present their uses in a case study application in a Concentrating Solar Power (CSP) plant with a similar configuration to a well-known operational Parabolic Trough (PT) plant located in Spain.
The Future of Synthetic Solar Irradiance
Authors: Bright Jamie M. , Frimane Âzeddine , Munkhammar Joakim , Widén Joakim
Published: May 2021

This chapter starts by reflecting on the learning outcomes from the book. The rest of the chapter is dedicated to the possible next steps for the field of synthetic solar irradiance. Previous applications of synthetic solar irradiance are discussed highlighting areas for improvement. Future potential applications are suggested, as well as defining what would be the best implementation of any new synthetic solar irradiance model. Next, the gaps in the existing synthetic solar irradiance methodologies are explored, focusing on whether there is a need for new techniques and if there are promising new approaches, as well as commenting on any scientific questions that remain unanswered. Last, we describe what the future of synthetic solar irradiance validation might look like. We investigate why we validate, and under what terms the structure of a synthetic solar irradiance validation should take. The ideal validation measurement setup is discussed as well as commenting on potential disadvantages that can skew a validation.
Comparative Study of Wind Farm Stabilization using DFIG and STATCOM under grid requirements
Authors: Okedu Kenneth
Published: May 2021

Grid codes require taking into account the reactive power of the wind farm in order to contribute to the network stability, thus operating the wind farm as active compensator devices. This chapter presents a comparative study of stabilizing a wind farm using DFIGs or using a static synchronous compensator (STATCOM) during wind speed change and grid fault. Simulation results show that the wind farm could be effectively stabilized with both systems, but at a lower cost with the DFIGs system, because it can provide reactive power through its frequency converters without an external reactive power compensation unit like the STATCOM system, and at the same time generate power to the grid.
Effect of ECS low pass filter timing on grid frequency dynamics of a power network affected by wind energy penetration
Authors: Okedu Kenneth
Published: May 2021

This chapter investigates the effect of wind energy penetration on the frequency response of a multi-machine power network, with different time constants of a low pass filter (LPF) in the DC chopper of an energy capacitor system (ECS). The power network is made up of wind farms composed of fixed-speed induction generators interconnected to steam and hydro synchronous power plants. Heavy and light loads were connected in the system. The ECS is connected at the terminal of the wind turbine. The LPF time constant parameter was varied for different cases, using the same wind speed for the wind turbine. Scenarios with and without the synergy of a series dynamic braking resistor (SDBR) connected to the stator of the wind turbine and the ECS were investigated. The results obtained were compared to a case where no frequency control was employed in the power network. Simulations were carried out in Power System Computer Aided Design and Electromagnetic Transient Including DC. The results show that a higher time constant of the LPF effectively damps the oscillations of the grid variables and quickly restores the system during network disturbance. The SDBR was used to further enhance the performance of the ECS.
Assessing Grid Frequency Performance Using Flywheel-Based Variable-Speed Drive and Energy Capacitor Systems
Authors: Okedu Kenneth
Published: May 2021

The penetration of renewable energy into modern grid networks is on the rise. Consequently, power networks become increasingly subjected to grid disturbances due to the stochastic nature of wind energy. Grid connected wind turbines must be operated based on the stipulated grid codes, with minimum frequency deviation during grid dynamics. In this chapter, a comparative study of grid frequency stability using two topologies of frequency control is presented. The first scheme uses a flywheel-based doubly fed induction generator (DFIG) variable-speed wind turbine, while the second scheme uses an energy capacitor system (ECS)-based induction generator fixed-speed wind turbine (FSWT). The DFIG coordinated maximum point power tracking system employed in the first scheme is presented, based on the reference power control to achieve smoothing of the fluctuated wind power. The ECS control strategy used to achieve smoothing of the fluctuated wind power output during dynamic periods in the FSWT, for the second scheme, is also presented. The wind farm is connected to a traditional grid system containing steam and hydro turbines. Simulations were run in PSCAD/EMTDC for both schemes, using the same natural wind speed for effective comparison of results.
Wind Energy and its Application in Hydrogen Production
Authors: Okedu Kenneth
Published: May 2021

Wind energy is the fastest-growing form of renewable energy in the world. Hydrogen is very useful as fuel. This chapter presents a simulation model of producing hydrogen from wind energy, using the Power System Computer Aided Design and Electromagnetic Transient Including DC (PSCAD/EMTDC) platform. Some optimization techniques for storing hydrogen are also discussed. The importance of the integration of hydrogen to wind energy plants in relation to electricity generation is also highlighted.

This chapter also presents the use of an energy capacitor system (ECS) connected to a wind farm with an electrolyzer system to produce hydrogen gas. Voltage and frequency control of the network was achieved. The simulation results display the effect the energy capacitor system has in the smoothing of the output power of the wind farm, through the provision of active and reactive power from its electronic voltage source converter (VSC) unit to the grid system.
The effects of prompt types on L2 learners’ textual emotionality and lexical complexity
Authors: Abdi Tabari Mahmoud , Wang Yizhou
Published: May 2021

This study investigated the role of prompt types in the emotion and lexical complexity level in L2 writing performance using fine-grained automatic textual analyzing tools and indices. Fifty-three ESL advanced-mid students wrote essays on pandemic (esp. COVID-19) and non-pandemic prompts. A textual Sentiment Analysis was carried out to detect both positive and negative emotions expressed in the students’ writing. A set of six lexical complexity indices was calculated to examine further the rarity, fluency, sophistication, and diversity levels in writing. The results revealed that the prompt types affect the emotional and lexical complexity of L2 writing. These results also showed that emotionality and lexical complexity have intricate and significant interactions, providing evidence for an emotion-lexicon link in L2 writing. Our results indicated that emotion has a substantial role in L2 writing beyond the traditional cognition-centered perspective, echoing the call of an ‘affective turn’ in second language acquisition (SLA) research.
MyD88 oligomer size functions as a physical threshold to trigger IL1R Myddosome signaling
Authors: Deliz-Aguirre Rafael , Cao Fakun , Gerpott Fenja H.U. , Auevechanichkul Nichanok , Chupanova Mariam , Mun YeVin , Ziska Elke , Taylor Marcus J.
Published: May 2021

A recurring feature of innate immune receptor signaling is the self-assembly of signaling proteins into oligomeric complexes. The Myddosome is an oligomeric complex that is required to transmit inflammatory signals from TLR/IL1Rs and consists of MyD88 and IRAK family kinases. However, the molecular basis for how Myddosome proteins self-assemble and regulate intracellular signaling remains poorly understood. Here, we developed a novel assay to analyze the spatiotemporal dynamics of IL1R and Myddosome signaling in live cells. We found that MyD88 oligomerization is inducible and initially reversible. Moreover, the formation of larger, stable oligomers consisting of more than four MyD88s triggers the sequential recruitment of IRAK4 and IRAK1. Notably, genetic knockout of IRAK4 enhanced MyD88 oligomerization, indicating that IRAK4 controls MyD88 oligomer size and growth. MyD88 oligomer size thus functions as a physical threshold to trigger downstream signaling. These results provide a mechanistic basis for how protein oligomerization might function in cell signaling pathways.
Unconventional voltage sensing in an inwardly rectifying potassium channel
Authors: Kurata Harley T.
Published: May 2021

Inwardly rectifying potassium channels are generally thought to achieve their physiological voltage dependence via an “extrinsic” mechanism involving voltage-dependent block by polyamines. A surprising finding of polyamine-independent gating of Kir4.1/Kir5.1 heteromeric channels suggests a mechanism of voltage dependence arising from interactions with permeating ions.
Ehrenfest’s scheme and microstructure for regular-AdS black hole in the extended phase space
Authors: Guo Sen , Liang En-Wei
Published: May 2021

The regular (Bardeen)–anti-de Sitter (AdS) (BAdS) black hole (BH) in the extended phase space is taken as an example for investigating the BH phase transition grade from both macroscopic and microscopic points of view. The equation of state and thermodynamic quantities of this BH are obtained. It is found that the BAdS BH phase space in the extended phase space should be a second-order phase transition near the critical point by verifying the Ehrenfest’s equation, and the possibility of its first-order phase transition can be ruled out by the entropy continuity and the heat capacity mutation. The critical exponents from the microscopic structure are analytically and numerically presented with the Landau continuous phase transition theory by introducing a microscopic order-parameter.
Fuzzy and discrete black hole models*
Authors: Argota-Quiroz J N , Majid S
Published: May 2021

Using quantum Riemannian geometry, we solve for a Ricci = 0 static spherically-symmetric solution in 4D, with the S
2 at each t, r a noncommutative fuzzy sphere, finding a dimension jump with solutions having the time and radial form of a classical 5D Tangherlini black hole. Thus, even a small amount of angular noncommutativity leads to radically different radial behaviour, modifying the Laplacian and the weak gravity limit. We likewise provide a version of a 3D black hole with the S
1 at each t, r now a discrete circle

Z

n

, with the time and radial form of the inside of a classical 4D Schwarzschild black hole far from the horizon. We study the Laplacian and the classical limit

Z

n

→

S

1

. We also study the 3D FLRW model on

R
×

S

2

with S
2 an expanding fuzzy sphere and find that the Friedmann equation for the expansion is the classical 4D one for a closed

R
×

S

3

Universe.
Test of global monopole based alternative dark matter model from gravitational lensing studies
Authors: Sarkar Kabita , Ghosh Samrat , Bhadra Arunava , Mukhopadhyay Amitabha
Published: May 2021

Non-minimally coupled global monopole or a Schwarzschild black hole that swallowed a global monopole at the center of a galaxy can correctly describe the observed flat rotation curve of galaxies without the need of dark matter. To become a viable alternative to dark matter the global monopole based model also needs to explain the other observations hinting for the existence of dark matter. Here we have studied weak gravitational lensing due to Schwarzchild space time with global monopole and compare with the findings of galaxy-galaxy weak lensing and also the lensing observations of the rich galaxy cluster Abell 370. We find that global monopole based model cannot describe the mentioned lensing observations without the presence of dark matter.
On the axisymmetric metric generated by a rotating perfect fluid with the vacuum boundary
Authors: Makino Tetu
Published: May 2021

We consider the equations for the coefficients of stationary rotating axisymmetric metrics governed by the Einstein–Euler equations, that is, the Einstein equations together with the energy–momentum tensor of a barotropic perfect fluid. Although the reduced system of equations for the potentials in the co-rotating co-ordinate system is known, we derive the system of equations for potentials in the so called zero angular momentum observer co-ordinate system. We newly give a proof of the equivalence between the reduced system and the full system of Einstein equations. It is done under the assumption that the angular velocity is constant on the support of the density. Also the consistency of the equations of the system is analyzed. On this basic theory we construct on the whole space the stationary asymptotically flat metric generated by a slowly rotating compactly supported perfect fluid with vacuum boundary.
Classical and quantum exact solutions for a FRW in chiral like cosmology
Authors: Socorro J , Pérez-Payán Sinuhé , Hernández-Jiménez Rafael , Espinoza-García Abraham , Díaz-Barrón Luis Rey
Published: May 2021

In this work, first, we study a flat Friedmann–Robertson–Walker Universe with two scalar fields but only one potential term, which can be thought as a simple quintessence plus a K-essence model. Employing the Hamiltonian formalism we are able to obtain the classical and quantum solutions. The second model studied, is also a flat Friedmann–Robertson–Walker Universe with two scalar fields, with the difference that the two potentials are considered as well as the standard kinetic energy and the mixed term (chiral field approach). Regarding this second model, it is shown that setting to zero the coefficient accompanying the mixed momenta term, two possible cases can be studied: a quintom like case (

m

+

12

) and a quintessence like case (

m

−

12

). For both scenarios classical and quantum solutions are presented.