bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidatively induced reactivity in Rh(iii)-catalyzed 7-azaindole synthesis: insights into the role of the silver additive
Authors: Ryu Ho , Pudasaini Bimal , Cho Dasol , Hong Sungwoo , Baik Mu-Hyun
Published: August 2022

The Ag+ cations oxidize and promote the activity of Rh-intermediates in the coupling of 2-aminopyridine and alkyne to form 7-azaindole.
Assembling diuranium complexes in different states of charge with a bridging redox-active ligand
Authors: Modder Dieuwertje K. , Batov Mikhail S. , Rajeshkumar Thayalan , Sienkiewicz Andrzej , Zivkovic Ivica , Scopelliti Rosario , Maron Laurent , Mazzanti Marinella
Published: August 2022

Convenient routes to dinuclear complexes of uranium where two uranium centers are bridged by the redox-active ligand bpym were identified resulting in unique and stable radical-bridged dimetallic complexes of U(iii) and U(iv) showing SMM behaviour.
Pushing the limits of the hydrogen bond enhanced halogen bond—the case of the C–H hydrogen bond
Authors: Decato Daniel A. , Sun Jiyu , Boller Madeleine R. , Berryman Orion B.
Published: August 2022

C–H hydrogen bonds to iodine halogen bond donors are shown to improve halogen bonding and molecular preorganization.
Ag2Se/nylon self-supporting composite films for wearable photo-thermoelectric generators with high output characteristics
Authors: Yang Zhen-yu , Jin Xin-zheng , Wang Wen-yan , Huang Chen-hui , Lei Yan-zhou , Wang Yong
Published: August 2022

High performance flexible Ag2Se/nylon self-supporting thermoelectric composite films were obtained. The photothermal effect of Ag2Se was introduced into the field of thermoelectricity for the first time to construct photo-thermoelectric generators.
The complex genetic basis of fibromuscular dysplasia, a systemic arteriopathy associated with multiple forms of cardiovascular disease
Authors: Georges Adrien , Bouatia-Naji Nabila
Published: August 2022

Artery stenosis is a common cause of hypertension and stroke and can be due to atherosclerosis accumulation in the majority of cases and in a small fraction of patients to arterial fibromuscular dysplasia (FMD). Artery stenosis due to atherosclerosis is widely studied with known risk factors (e.g. increasing age, male gender, and dyslipidemia) to influence its etiology, including genetic factors. However, the causes of noninflammatory and nonatherosclerotic stenosis in FMD are less understood. FMD occurs predominantly in early middle-age women, a fraction of the population where cardiovascular risk is different and understudied. FMD arteriopathies are often diagnosed in the context of hypertension and stroke and co-occur mainly with spontaneous coronary artery dissection, an atypical cause of acute myocardial infarction. In this review, we provide a comprehensive overview of the recent advances in the understanding of molecular origins of FMD. Data were obtained from genetic studies using complementary methodological approaches applied to familial, syndromic, and sporadic forms of this intriguing arteriopathy. Rare variation analyses point toward mechanisms related to impaired prostacyclin signaling and defaults in fibrillar collagens. The study of common variation, mainly through a recent genome-wide association study, describes a shared genetic link with blood pressure, in addition to point at potential risk genes involved in actin cytoskeleton and intracellular calcium homeostasis supporting impaired vascular contraction as a key mechanism. We conclude this review with future strategies and approaches needed to fully understand the genetic and molecular mechanisms related to FMD.
Estimating Early Language Input in Deaf and Hard of Hearing Children With the Language Access Profile Tool
Authors: Hall Matthew L. , De Anda Stephanie
Published: August 2022

Purpose:

The purpose of this study was to describe the Language Access Profile Tool (LAPT) and its psychometric properties with the aim of evaluating its suitability as an alternative to the deaf or hard of hearing (DHH) Language Exposure Assessment Tool (D-LEAT) in clinical practice with DHH children age 12 years and younger.

Method:

We administered both the LAPT and D-LEAT to the caregivers of 105 DHH children 12 years old and younger from across the United States, 40% of whom were interviewed again after a delay of at least 1 month. Each interview resulted in a child-specific estimate of their cumulative experience with language input, expressed as a proportion divided across eight categories.

Results:

Participants in the sample reported experience with all eight input categories, but four categories were common and four were rare. Estimates for all input categories were consistent at both initial and follow-up interviews. Estimates for each input category were also strongly correlated with the corresponding estimates from the D-LEAT, although correlations for the rare categories should be interpreted cautiously.

Conclusions:

The LAPT demonstrates sufficient test–retest reliability and convergent validity to be a useful and more user-friendly alternative to the D-LEAT. We provide recommendations for how the LAPT and the D-LEAT can be best used in their current form.

Supplemental Material:

https://doi.org/10.23641/asha.20669001
Which Videofluoroscopy Parameters Are Susceptible to the Influence of Differences in Barium Product and Concentration?
Authors: Steele Catriona M. , Barrett Emily , Peladeau-Pigeon Melanie
Published: August 2022

Purpose:

Prior studies suggest there may be differences in videofluoroscopic measures of swallowing across different barium concentrations. Whether different barium products of identical concentration result in similar swallowing physiology remains unknown. This is important, as barium intended for videofluoroscopy (i.e., Bracco Varibar) is not available globally. Our aim was to identify differences in healthy swallowing across five different barium stimuli.

Method:

Twenty healthy adults (10 women), aged 22–54 years, underwent videofluoroscopy including comfortable sips of thin liquid barium: two sips of 20% weight-to-volume (w/v) barium prepared with E-Z-HD powder, and two sips each of 20%w/v and 40%w/v barium prepared with Liquid Polibar Plus and E-Z-Paque powder. Recordings were analyzed according to the Analysis of Swallowing Physiology: Events, Kinematics and Timing Method. Measures of timing, kinematics and residue were obtained. Chi-square, Friedman's, and Wilcoxon signed-ranks test were used to identify differences across stimuli.

Results:

Significant differences were seen across barium stimuli for upper esophageal sphincter (UES) opening duration, UES diameter, pharyngeal area at maximum constriction, and residue. In all cases, smaller values were seen with the 20%w/v E-Z-HD stimulus; however, this stimulus had questionable opacity for visualization. Patterns of residue severity were not explained by barium concentration.

Conclusions:

This study confirms that some measures of swallowing are influenced by barium product and/or concentration. Measures are not necessarily similar across different barium products at the same concentration. This study illustrates the importance of using standard and appropriate stimuli in videofluoroscopy, and for clinicians to report not only the product but also the concentration of stimuli used.

Supplemental Material:

https://doi.org/10.23641/asha.20669712
Black Children With Developmental Disabilities Receive Less Augmentative and Alternative Communication Intervention Than Their White Peers: Preliminary Evidence of Racial Disparities From a Secondary Data Analysis
Authors: Pope Lauramarie , Light Janice , Franklin Amber
Published: August 2022

Purpose:

Ensuring equitable access to augmentative and alternative communication (AAC) intervention services for children with complex communication needs (CCN) is crucial. Evidence suggests that racial disparities exist in access to communication interventions, disadvantaging Black children. However, no research has investigated specifically the evidence for racial disparities in AAC services for children with developmental disabilities and CCN.

Method:

The current study applied post hoc data analysis methods within a preexisting, open-access data set to explore preliminary evidence of racial disparities in AAC intervention. Amount of AAC intervention was compared for Black versus white

1

preschool students at study initiation (
M
age
= 3;8 [years;months]) and 2 years later at study completion (
M
age
= 5;10).

Results:

Black preschool students were reported to receive significantly less AAC intervention per week as compared to their white peers, both at study initiation and 2 years later. By study end, 75% of the Black children were receiving less than 60 min of AAC intervention per week, an inadequate amount to achieve meaningful gains given their significant disabilities.

Conclusions:

It is unclear what mechanisms may contribute to the observed disparities; however, it is critical that concrete steps are taken by individual speech-language pathologists, school districts, preservice preparation programs, and researchers to identify inequities in AAC services and take actions to rectify them. Future research is essential to investigate the potential factors contributing to inequalities and determine effective interventions to address them.
Sparse channel estimation algorithms for OTFS system
Authors: Ouchikh Rabah , Aïssa‐El‐Bey Abdeldjalil , Chonavel Thierry , Djeddou Mustapha
Published: August 2022

Orthogonal time‐frequency space (OTFS) modulation, which has recently been proposed in the literature, is one of the promising techniques designed in the 2D Delay‐Doppler domain adapted to combat high Doppler fading channels. However, channel estimation in high Doppler scenarios in advanced mobile‐communication systems is still a challenging task. In this paper, the problem of channel estimation in the Delay‐Doppler domain of the OTFS is focused on. First, a simple adaptation of the generalized orthogonal matching pursuit procedure, which will serve as a baseline method in this work, is proposed. Then, iterative algorithms are derived beneficiating from the sparsity of the channel. The unknown channel vector is separated into an unknown sparse support vector corresponding to the delay and Doppler taps, and an unknown vector of channel gains. These algorithms involve ℓ1‐norm minimization and a two‐stage iterative procedure to recover alternatively the channel support and its coefficients. The estimation problem is also addressed from a Bayesian point of view. The sparse representation is reformulated as a specific marginalization of the maximum a posteriori problem on the support of the channel. To deal with the intractability of this problem, two existing techniques are adapted to this context, namely: The Monte Carlo Markov chain with the Gibbs sampler and variational mean‐field approximation with the variational Bayesian expectation‐maximization procedure. Finally, to assess the performance of the proposed algorithms, their complexity and performance are compared against existing methods. Experimental tests, conducted in high‐mobility scenarios and low‐latency applications, show that the proposed schemes are slightly more expensive in terms of complexity load but perform significantly better in terms of normalized mean square error and bit error rate.
Distributed MPC algorithm with row‐stochastic weight matrix over non‐ideal time‐varying directed communication
Authors: Zhao Duqiao , Liu Ding , Liu Linxiong
Published: August 2022

Distributed model predictive control (DMPC) approaches have achieved remarkable results in complex multiple subsystems network applications, such as unmanned aerial vehicle and sensor control networks. However, most of the existing DMPC algorithms require that the communication network of subsystems is time‐invariant or undirected with local constraints, by ignoring the cooperation of multiple subsystems with global constraint in the non‐ideal communication network, which greatly limits the applicability of the algorithms. To this end, the authors develop a fully DMPC algorithm of linear system with global constraint over time‐varying unbalanced directed communication. Considering the uncertainty of communication network, this algorithm can handle the non‐ideal communication network (e.g. communication noise, communication delay). Specifically, the row‐stochastic weight matrix is adopted to improve the independent controllability of subsystems. Under reasonable assumptions, it is proved that the algorithm can converge to the optimal solution while guaranteeing the recursive feasibility and exponential stability of closed‐loop system. Finally, the simulation experiments are shown to substantiate the convergence and robustness of the proposed algorithm.
An event knowledge graph system for the operation and maintenance of power equipment
Authors: Tian Jiapeng , Song Hui , Sheng Gehao , Jiang Xiuchen
Published: August 2022

Power equipment operation and maintenance (O&M) requires plenty of domain knowledge to improve equipment security and power grid reliability. However, most knowledge is implicitly represented by the semantic text, which is hard to be comprehended by algorithms and restricts the intelligence level of equipment O&M. Therefore, this article proposes an event knowledge graph system to automatically extract event knowledge from O&M reports and represent the knowledge by an event knowledge graph (KG). First, a bidirectional long short‐term memory network (BiLSTM) combined with conditional random field (CRF) is employed to recognize the entities. Next, an attention‐based sequence‐to‐sequence model is proposed to detect multiple events and extract document‐level representation vectors. Then, a tree‐based table filling strategy is utilized to complete the artificially designed event tables. Finally, the proposed system renders the event tables into an event KG. Verified by the experiments, the proposed system outperforms the baselines with the F‐measure of 83.5% for event extraction and 94.2% for event detection. When dealing with coexisting events and scattering arguments, the F‐measure of the proposed system achieves 74.8% and 79.0%, respectively. Moreover, the proposed system has positive effects on intelligent retrieval, fault diagnosis, and condition assessment, verifying its potential value for equipment O&M.
Moving target detection method based on CUR‐RPCA for missing array elements
Authors: Shi Jianli , Guo Yifan , Qi Hua , Wang Yingmin , Cheng Siyuan
Published: August 2022

Moving target detection performance is seriously affected by missing array elements for multichannel synthetic aperture radar (Multi‐SAR) systems. Meanwhile, there is a contradiction between the accuracy of data recovery and the computational burden in traditional methods. To solve the problems, a moving target detection method based on CUR‐RPCA for missing array elements is proposed in this paper. First, key nodes of the echo data are extracted and rearranged into a low‐rank matrix. Then we uses the low‐rank characteristic to complete key nodes of data. Subsequently, complete echo data is constructed by utilising recovered key nodes of data and CUR decomposition. Therefore using the ideas of CUR and RPCA, a novel optimization problem is constructed to achieve separation of moving targets and clutter while recovering data. In addition, only key nodes of the data is completed to achieve the performance of all data recovery, so that the disadvantage of low computational efficiency has been overcome for traditional matrix completion methods. Finally, the superior clutter suppression performance of the proposed method is verified by several numerical simulations and comparative studies.
Magnetised winds in transition discs
Authors: Martel Étienne , Lesur Geoffroy
Published: August 2022

Context. Protoplanetary discs are cold, dense, and weakly ionised environments that witness planetary formation. Among these discs, transition discs (TDs) are characterised by a wide cavity (up to tens of au) in the dust and gas distribution. Despite this lack of material, a considerable fraction of TDs are still strongly accreting onto their central star, possibly indicating that a mechanism is driving fast accretion in TD cavities.

Aims. The presence of radially extended ‘dead zones’ in protoplanetary discs has recently revived interest in magnetised disc winds (MDWs), where accretion is driven by a large magnetic field extracting angular momentum from the disc. We propose that TDs could be subject to similar disc winds, and that these could naturally explain the fast-accreting and long-lived cavities inferred in TDs.

Methods. We present the results of the first 2.5D global numerical simulations of TDs harbouring MDWs using the PLUTO code. We imposed a cavity in the gas distribution with various density contrasts, and considered a power-law distribution for the large-scale magnetic field strength. We assume the disc is weakly ionised and is therefore subject to ambipolar diffusion, as expected in this range of densities and temperatures.

Results. We find that our simulated TDs always reach a steady state with an inner cavity and an outer ‘standard’ disc. These models also maintain an approximately constant accretion rate through the entire structure, reaching 10−7 M⊚ yr−1 for typical surface density values. The MDW launched from the cavity is more magnetised and has a significantly larger lever arm (up to 10) than the MDW launched from the outer disc. The material in the cavity is accreted at sonic velocities, and the cavity itself is rotating at 70% of the Keplerian velocity due to the efficient magnetic braking imposed by the MDW. Overall, our cavity matches the dynamical properties of an inner jet emitting disc (JED) and of magnetically arrested discs (MADs) in black-hole physics. Finally, we observe that the cavity is subject to recurring accretion bursts that may be driven by a magnetic Rayleigh-Taylor instability of the cavity edge.

Conclusions. Some strongly accreting TDs could be the result of magnetised wind sculpting protoplanetary discs. Kinematic diagnostics of the disc or the wind (orbital velocity, wind speeds, accretion velocities) could disentangle classic photo-evaporation from MDW models.
A decade-long magnetic monitoring of Vega
Authors: Petit P. , Böhm T. , Folsom C. P. , Lignières F. , Cang T.
Published: August 2022

Aims. The very weak magnetic field detected at the surface of Vega hints at a widespread population of weakly magnetic stars of A and B spectral types. We contribute here to gather more clues about the origin of this magnetism by investigating the long-term stability of the field geometry of this prototypical star.

Methods. We use spectropolarimetric data collected as part of a long-term campaign, with more than 2000 observations spread between 2008 and 2018. Using various sub-sets extracted from the whole time series, we reconstruct several maps of the large-scale surface magnetic field.

Results. We confirm that the polarimetric signal is modulated according to a ~0.68 d period, which we interpret as the stellar rotation period. The surface magnetic field is organized in a complex geometry. We confirm the existence of a very localized, polar magnetic spot previously reported for Vega, with a radial field strength of about −5 G. We show that the surface of the star is also covered by a dipole, with a polar strength close to 9 G and a dipole obliquity close to 90°. Both magnetic structures are remarkably stable over one decade. The available data suggest that smaller-scale magnetic spots may not be limited to the polar region, although the poor reliability of their reconstruction does not allow us to firmly conclude about their temporal evolution.
Evolution of coronal hole solar wind in the inner heliosphere: Combined observations by Solar Orbiter and Parker Solar Probe
Authors: Perrone D. , Perri S. , Bruno R. , Stansby D. , D’Amicis R. , Jagarlamudi V. K. , Laker R. , Toledo-Redondo S. , Stawarz J. E. , Telloni D. , De Marco R. , Owen C. J. , Raines J. M. , Settino A. , Lavraud B. , Maksimovic M. , Vaivads A. , Phan T. D. , Fargette N. , Louarn P. , Zouganelis I.
Published: August 2022

We study the radial evolution, from 0.1 AU to the Earth, of a homogeneous recurrent fast wind, coming from the same source on the Sun, by means of new measurements by both Solar Orbiter and Parker Solar Probe. With respect to previous radial studies, we extend, for the first time, the analysis of a recurrent fast stream at distances never reached prior to the Parker Solar Probe mission. Confirming previous findings, the observations show: (i) a decrease in the radial trend of the proton density that is slower than the one expected for a radially expanding plasma, due to the possible presence of a secondary beam in the velocity distribution function; (ii) a deviation for the magnetic field from the Parker prediction, supported by the strong Alfvénicity of the stream at all distances; and (iii) a slower decrease in the proton temperature with respect to the adiabatic prediction, suggesting the local presence of external heating mechanisms. Focusing on the radial evolution of the turbulence, from the inertial to the kinetic range along the turbulent cascade, we find that the slopes, in both frequency ranges, strongly depend on the different turbulence observed by the two spacecraft, namely a mostly parallel turbulence in the Parker Solar Probe data and a mostly perpendicular turbulence in the Solar Orbiter intervals. Moreover, we observe a decrease in the level of intermittency for the magnetic field during the expansion of the stream. Furthermore, we perform, for the first time, a statistical analysis of coherent structures around proton scales at 0.1 AU and we study how some of their statistical properties change from the Sun to the Earth. As expected, we find a higher occurrence of events in the Parker Solar Probe measurements than in the Solar Orbiter data, considering the ratio between the intervals length and the proton characteristic scales at the two radial distances. Finally, we complement this statistical analysis with two case studies of current sheets and vortex-like structures detected at the two radial distances, and we find that structures that belong to the same family have similar characteristics at different radial distances. This work provides an insight into the radial evolution of the turbulent character of solar wind plasma coming from coronal holes.
Candidate cosmic filament in the GJ526 field, mapped with the NIKA2 camera
Authors: Lestrade J.-F. , Désert F.-X. , Lagache G. , Adam R. , Ade P. , Ajeddig H. , André P. , Artis E. , Aussel H. , Beelen A. , Benoît A. , Berta S. , Béthermin M. , Bing L. , Bourrion O. , Calvo M. , Catalano A. , Coulais A. , De Petris M. , Doyle S. , Driessen E. F. C. , Gomez A. , Goupy J. , Kéruzoré F. , Kramer C. , Ladjelate B. , Leclercq S. , Macías-Pérez J. F. , Maury A. , Mauskopf P. , Mayet F. , Monfardini A. , Muñoz-Echeverría M. , Perotto L. , Pisano G. , Ponthieu N. , Revéret V. , Rigby A. J. , Ritacco A. , Romero C. , Roussel H. , Ruppin F. , Schuster K. , Shu S. , Sievers A. , Tucker C. , Zylka R.
Published: August 2022

Distinctive large-scale structures have been identified in the spatial distribution of optical galaxies up to redshift z ∼ 1. In the more distant universe, the relationship between the dust-obscured population of star-forming galaxies observed at millimetre wavelengths and the network of cosmic filaments of dark matter apparent in all cosmological hydrodynamical simulations is still under study. Using the NIKA2 dual-band millimetre camera, we mapped a field of ∼90 arcmin2 in the direction of the star GJ526 simultaneously in its 1.15-mm and 2.0-mm continuum wavebands to investigate the nature of the quasi-alignment of five sources found ten years earlier with the MAMBO camera at 1.2 mm. We find that these sources are not clumps of a circumstellar debris disc around this star as initially hypothesized. Rather, they must be dust-obscured star-forming galaxies, or sub-millimetre galaxies (SMGs), in the distant background. The new NIKA2 map at 1.15 mm reveals a total of seven SMGs distributed in projection on the sky along a filament-like structure crossing the whole observed field. Furthermore, we show that the NIKA2 and supplemental Herschel photometric data are compatible with a model of the spectral energy distributions (SEDs) of these sources when a common redshift of 2.5 and typical values of the dust parameters for SMGs are adopted. Hence, we speculate that these SMGs might be located in a filament of the distant ‘cosmic web’. The length of this candidate cosmic filament crossing the whole map is at least 4 cMpc (comoving), and the separations between sources are between 0.25 cMpc and 1.25 cMpc at this redshift, in line with expectations from cosmological simulations. Nonetheless, further observations to determine the precise spectroscopic redshifts of these sources are required to definitively support this hypothesis of SMGs embedded in a cosmic filament of dark matter.
Cosmic voids and the kinetic analysis
Authors: Gurzadyan V. G. , Fimin N. N. , Chechetkin V. M.
Published: August 2022

The kinetic approach to the formation of the filaments in the large-scale matter distribution in the Universe is considered within the Vlasov formalism. The structures arise due to the self-consistent dynamics, along with the repulsive term in the modified Newtonian gravity which includes the cosmological constant. That modified gravity enables one to describe the Hubble tension as a result of two flows, the local and global ones. The criteria for formation of non–stationary semi-periodic structures in a system of gravitating particles described by Vlasov–Poisson equations are obtained in the case of that repulsive term. The obtained dispersion relations for the Vlasov equation in the vicinity of the singular point of the modified gravitational potential demonstrate the possibility of the emergence of filaments as coherent complex states of relative equilibrium in non–stationary systems as structures of low dimensions (walls), and voids between them, of scales (diameters) defined by the balance between the gravity and repulsive term of the cosmological constant.
Energy-efficient retrofitting with incomplete building information: a data-driven approach
Authors: Feng Kailun , Lu Weizhuo , Reddy Penaka Santhan , Eklund Erik , Andersson Staffan , Olofsson Thomas
Published: August 2022

The high-performance insulations and energy-efficient HVAC have been widely employed as energy-efficient retrofitting for building renovation. Building performance simulation (BPS) based on physical models is a popular method to estimate expected energy savings for building retrofitting. However, many buildings, especially the older building constructed several decades ago, do not have full access to complete information for a BPS method. To address this challenge, this paper proposes a data-driven approach to support the decision-making of building retrofitting under incomplete information. The data-driven approach is constructed by integrating backpropagation neural networks (BRBNN), fuzzy C-means clustering (FCM), principal component analysis (PCA), and trimmed scores regression (TSR). It is motivated by the available big data sources from real-life building performance datasets to directly model the retrofitting performances without generally missing information, and simultaneously impute the case-specific incomplete information. This empirical study is conducted on real-life buildings in Sweden. The result indicates that the approach can model the performance ranges of energy-efficient retrofitting for family houses with more than 90% confidence. The developed approach provides a tool to predict the performance of individual buildings from different retrofitting measures, enabling supportive decision-making for building owners with inaccessible complete building information, to compare alternative retrofitting measures.
Configurations and exergy analysis of district heating substations based mainly on renewable energy
Authors: Gao Y.J. , Wang S.G. , Jiang S. , Wu X.Z. , Wang J.H. , Zhang T.F. , Ma Z.J.
Published: August 2022

The energy in the district heating system is transforming into a clean, low-carbon and integrated production and consumption mode to reduce greenhouse gas emissions and dependence on fossil energy. The district heating system has developed to the fifth generation currently, and the water temperature is continuously reduced, and thus the heating efficiency is improved. The proportion of renewable energy sources such as solar, wind, and geothermal energy in substations will continue to increase. In this paper, substation configurations of the fifth-generation district heating system are firstly reviewed, and the exergy analysis is applied to the thermodynamic simulation of the district substations. Thermal simulation models of several types of substations mainly based on solar water heating, water source- and air source- heat pumps or combined forms are developed, the conventional heat exchanger substation is also modeled to compare their performance. The optimization algorithm in Matlab/Simulink is used to solve the thermodynamic numerical model, and performance indicators such as exergy and efficiency are selected to evaluate the performance of these systems.
Case analysis of thermal defect detection of near-zero energy building envelope based on infrared thermography
Authors: Li Huanyu , Feng Guohui , Pu Yi , Wang Han
Published: August 2022

The thermal performance of the envelope structure is one of the important components of the performance design of near-zero energy buildings. Minimizing envelope heat loss is the key to improving building energy efficiency. A necessary first step in the building envelope optimization process is the assessment of its actual thermal performance. This paper summarizes the application status of infrared thermography in thermal defect detection of building envelopes and common forms of thermal defects in near-zero energy buildings. Taking a near zero energy building in Shenyang area as the target object, an efficient and non-destructive infrared thermal image measurement method is applied to determine the thermal defect rating of the building from both qualitative and quantitative aspects. The results show that the building has high thermal performance. The temperature field distribution of the building envelope could be quickly obtained by using the infrared thermal imaging instrument. In this way, it can accurately identify the location of thermal bridges and air tightness defects, and provide an efficient and accurate detection method for building energy-saving diagnosis and evaluation.
A case study on airflow characteristics in greenhouses with adaptive wall-based attachment ventilation
Authors: Han Ou , Li Angui , Li Jiaxing
Published: August 2022

Modern greenhouses require not only heat preservation in winter but also temperature control in summer to provide a suitable growth environment. The efficiency and homogeneity of ventilation and cooling systems for greenhouses have always been challenges for facility agriculture engineering. This paper proposes the application of adaptive wall-based attachment ventilation (AWAV) in greenhouses. The case study on airflow characteristics and thermal environment of a typical greenhouse under AWAV mode are investigated numerically with the standard k-ε turbulent model, a solar ray tracing algorithm, and a surface-to-surface (S2S) radiation model. The ventilation performance of AWAV for greenhouses is examined and evaluated by air velocity and temperature distribution, non-uniformity coefficient, and ventilation efficiency. The results show that AWAV mode presents a more uniform airflow distribution (Ku=0.31, Kt=0.10) in the plant growth region, with relatively low temperature and an excellent cooling effect (ET =1.39). In addition, another advantage of AWAV mode is that the height of the deflector can be adjusted as the plant grows to meet the required air environment of greenhouses.
A study on the influence of different blowing systems on indoor thermal environment and air quality in underfloor air conditioning system
Authors: Arao Yuki , Kuwahara Ryoichi
Published: August 2022

The purpose of this study is to investigate the most effective blowing method of underfloor air conditioning system from the viewpoint of comfort and ventilation performance using CFD simulation. In this study, we simulated three types of air blowing systems: floor radiation, floor-supply displacement air-conditioning, and floor chamber. Then, comfort was evaluated from thermal environment and PMV, and ventilation performance was evaluated from air age. As a result, the floor radiation system was able to maintain comfort. However, it was found that the floor-supply displacement air-conditioning system and the floor chamber system caused a great deal of discomfort because the temperature difference between the top and bottom was easily observed. In terms of ventilation performance, it was confirmed that ventilation was efficient in all methods. Of these, the floor-supply displacement air-conditioning system was found to be the most efficient.
Case study of a multiple confluents jets system in a virtual chamber
Authors: Conceição Eusébio , Conceição Mª Inês , Lúcio Mª Manuela , Gomes João , Awbi Hazim
Published: August 2022

This article presents a case study of a multiple confluents jets system in a virtual chamber. In this study, it is obtained the behavior of the airflow in an office, simulated by a virtual camera, whose ventilation system is of the horizontal confluent jets type. The ventilation system has an inlet system consisting of four vertical ducts mounted in the corners of the compartment. Each duct has four groups of 32 nozzles, aligned and equally spaced, positioned from the base of the duct close to the floor. Each two groups of nozzles are directed towards each of the walls adjacent to the duct The exhaust system consists of a quadrangular vertical duct mounted close to the ceiling and positioned in the center of the compartment. The study uses a numerical differential model in order to simulate the Computational Fluids Dynamics. Ventilation by horizontal confluent jets creates a horizontal air velocity close to the wall surface as well as the floor surface. With the increase in the exit velocity of the jets, the interactive effect of the confluence of the jets, coming from opposite ducts, in the central area of the wall becomes more evident. The airflow resulting from the interactions of the jets has an upward characteristic towards the exhaust system.
Column-Attached Airflow Fields Created by Multi-slot in Single Ring
Authors: Wang Tianqi , Han Ou , Li Angui , Yin Haiguo
Published: August 2022

Researchers have shown increasing interest in attachment ventilation due to its high ventilation efficiency and good thermal comfort. To meet the ventilation performance and engineering design challenges of Circular Column Attached Ventilation (CCAV) mode due to low ventilation rates, large-diameter cylinders, and installation too high at the top of large spaces. This paper proposes a novel ventilation mode known as Column-attached ventilation with Multi-slot in Single Ring (MCAV). Through measurement of air velocity and computational fluid dynamics simulation, the air distribution characteristics of the MCAV were studied. The findings show that MCAV and CCAV have similar trends of maximum velocity decay in the vertical attachment region. The MCAV has a 10.48% higher average value of dimensionless axial velocity in the horizontal air reservoir region than the CCAV. Besides, the flow pattern envelope surface and the velocity non-uniform coefficient were introduced to verify ventilation performance. The current study helps understand a new air distribution and is used as a reference for Attachment Ventilation design.
Experimental and numerical study on the cooling performance of a new earth-air heat exchanger(EAHE) system with a supply air static pressure chamber
Authors: Yang Qizhi , Hu Zhiru , Zhou Zhuo , Zhang Yuxin , Wang Bin , Wang Yong
Published: August 2022

Earth-air heat exchanger (EAHE) is a low-carbon device that use renewable energy to improve the thermal environment of buildings by heating/cooling the air with the help of the thermal inertia of the soil. However, the traditional earth-air heat exchanger has the problem of large fluctuations in air temperature with the outdoor air temperature fluctuations. A system that combines an air supply chamber with an EAHE is proposed to address this problem. The outdoor air first enters the underground air supply static pressure chamber for initial cooling, and then enters the EAHE treatment. To investigate the effect of this air supply static pressure chamber on the cooling performance of EAHE, a three-dimensional numerical model was developed in ANSYS Fluent and validated with field measurement data. Then comparative studies of the EAHE system with a supply air static pressure chamber and the traditionnal EAHE system were conducted under summer conditions in Chongqing (China). The results show that the air supply static pressure chamber can reduce the EAHE outlet air temperature fluctuation by 31.98% at the maximum under the continuous operation of different air volume systems for 7 days. At the same time, the cooling capacity can be increased by 19.89% at maximum compared with the conventional EAHE cooling capacity.
A pilot study of occupant centric control stratum ventilation based on computer vision
Authors: Liu Yihang , Yang Bin , Lin Zhang
Published: August 2022

Indoor occupant information has an obvious influence on operating parameters of heating ventilation and air conditioning (HVAC) system, which further affects occupants’ thermal comfort and energy consumption. This pilot study proposes an occupant centric control (OCC) strategy for stratum ventilation (SV) to achieve demand control ventilation (DCV). Firstly, the computer vision sensing system and deep learning algorithm are used to detect the number of occupants in real time, and the accuracy of the number of occupants in the office environment was evaluated. Then, the occupant centric stratum ventilation control strategy is designed by the dynamic changes of cooling load. Finally, the thermal comfort and air quality of the thermal environment created by the OCC strategy were evaluated through subject experiment, and the energy consumption of the HVAC system was calculated in combination with the energy consumption simulation software. This study adjusts system setting values according to actual needs, so that the HVAC system responds to the dynamic changes of the indoor cooling load in real time, creating a comfortable and healthy indoor environment in an energy efficient manner.
Performance Analysis of a Passive Mixing Strategy assisted Heat-Pump-driven Liquid-Desiccant Air-Conditioning System
Authors: Lee Jae-Hee , Cheon Seong-Yong , Kim Minseong , Park Hyo-Lim , Jeong Jae-Weon
Published: August 2022

In liquid desiccant systems, an operating strategy of mixing small fractions of weak and strong solutions integrated with a closed-loop operating strategy has drawn attention for its ability to improve the system energy performance. This study proposed a passive mixing strategy integrated with the closed-loop strategy for a heat-pump-driven liquid-desiccant (HPLD) air-conditioning system and experimentally analysed its operating performances. Based on the density difference between the weak solution in the absorber sump after dehumidification process and the strong solution in the regenerator sump after regeneration process, the proposed passive mixing strategy can practically mix them without moving parts. The results showed that the passive mixing strategy was found to be feasible to properly maintain the solution temperatures and concentrations of both absorber and regenerator within the target range in the operation of the system. Therefore, the converged dehumidification rate was shown to be 4.3 g/kg and the converged cooling capacity was shown to be 5.4 kW, which satisfied the target performance. Consequently, the closed-loop and the proposed passive mixing strategy can be concluded to be applicable to the HPLD air-conditioning system.
Analysis on influencing factors and energy saving potential of photovoltaic curtain wall preheating fresh air system in severe cold area
Authors: Lv Xue , Huang Kailiang , Feng Guohui , Xu Jintian , Zhangs Dongxu
Published: August 2022

In the general building air conditioning load, the fresh air load accounts for more than 30%, especially in the severe cold areas in the north, with long winter and large indoor and outdoor temperature difference, the fresh air heat load will account for a larger proportion in the air conditioning system load. Making full use of renewable energy can effectively reduce building energy consumption. In this paper, the air flow field distribution in the ventilation duct of photovoltaic curtain wall is numerically simulated by fluent simulation software, and the air distribution form and temperature field distribution in the system cavity under different ambient temperature, cavity thickness and tuyere position are analyzed and compared, so as to obtain the influence of different influencing factors on the performance of the fresh air preheating system, and combine the photovoltaic curtain wall preheating fresh air system and electric heating system to explore its energy-saving potential. The results show that when the cavity thickness is greater than 400mm, the reduction range of photovoltaic curtain wall temperature becomes smaller, and the overall temperature distribution of the cavity tends to be uniform. When the ambient temperature is different, with the increase of ambient temperature, after the fresh air passes through the photovoltaic curtain wall preheating system, the temperature difference at the inlet and outlet of the air flow channel decreases, and the maximum temperature difference decreases from 4.6k to 3.4K.The combination of photovoltaic curtain wall and electric heating is used to preheat the fresh air. Compared with the traditional method, the same fresh air load is treated, and the energy-saving rate is 60% ∼ 70%. It shows that using photovoltaic curtain wall to preheat the fresh air can achieve better results, which provides guidance for putting forward more appropriate, economic and energy-saving design schemes in the project.
Classification and Analysis of User Behavior based on Action Duration in Residential Split-type Air Conditioners
Authors: Gu Xiaobei , Liu Meng
Published: August 2022

In residential buildings, split-type air conditioners (ACs) are important indoor thermal environment control equipment. This study focused on ACs in China’s hot summer and cold winter zone. The valid data included 196 million real-time operation log records of more than 5,000 ACs in one year. The goal of this study is to classify action duration in a quantitative and interpretable way and analysis the user behavior based on the classification of action duration. Through the human intervention by indicators and multiple-Jenks algorithm, user behaviors based on action duration were divided into 6 categories and 12 types. The comparison of these action types in mode, wind speed and setting temperature were discussed as well. It reveals that some action durations are need to be focused in different conditions.
Research on air-conditioning usage behaviour in offices with different occupancy
Authors: Zeng Fei , Pan Yiqun , Deng Huiyan , Huang Zhizhong
Published: August 2022

Occupant behaviours in the buildings are not only random and uncertain but also related to each occupant’s habitual preference. This leads to the performance gap between actual and expected energy consumption in buildings. Therefore, accurate information and modelling with regard to occupant behaviour are important for reliable energy simulation and energy-saving optimization design. Existing studies on occupant behaviour models in office space usually focus on single-person offices or full-floor buildings, without considering the behavioural differences among offices with different occupancy. Therefore, this study established the air-conditioning usage behaviour models in offices with different occupancy based on questionnaires and measured data. The results show that occupant compromise and clustering effect will increase with the increase of occupancy. Using the established models as input, this study compared the simulation results with that under the standard schedule. The difference rate is as high as 32.19% in winter and 13.07% in the whole year. And for areas with high energy consumption in winter, the gap may be bigger.
Analysis of energy-saving effect of fresh air heat recovery system for residential buildings in severe cold area
Authors: Hao Yuxiang , Huang Kailiang , Feng Guohui , Hou Xu
Published: August 2022

In recent years, the tightness of residential buildings has been continuously enhanced, causing the problem of indoor air quality degradation. Therefore, it is necessary to introduce fresh air that meets the air quality requirements from the outside, and the outdoor air temperature in the severe cold area is low, which increases the fresh air load of the building. To save energy consumption, regularly use air heat recovery equipment to recover heat energy. In order to verify the energy-saving effect of the fresh air heat recovery system in residential buildings in severe cold areas, taking an experimental building in Shenyang as an example, the operating performance curve of an air source heat pump equipped with a fresh air heat recovery system was measured, and TRANSYS software was used to simulate and compare two kinds of heat recovery mode, namely the exhaust mixture of outdoor air and pure out door air low temperature heat source. The results show that when the exhaust air is mixed with outdoor air as the low-temperature side heat source, the average COP value reaches 3.24 and increases by 17%, which can save 7.6% of the energy consumption of the air source heat pump throughout the entire heating season.
Performance evaluation of intermittent air supply system: a case study in Xi’an
Authors: Jin Dacheng , Yang Bin
Published: August 2022

Intermittent air jet strategy (IAJS) has been proven to provide a satisfactory indoor thermal climate with high energy efficiency in spaces with high occupancy density. Compared with traditional ventilation strategy, IAJS system creates heterogeneous conditions around the occupants, which complicates the relationship between thermal sensation and thermal comfort. The effect of different intermittent cycles on the thermal comfort of occupants needs to be further discussed. In addition, it is necessary to investigate whether IAJS system can play a better role in hot and humid summer conditions in China. Experiments were conducted in a chamber with two rows of seated occupants. Twelve cases were designed, including different combinations of room air temperatures (24°C, 26°C and 28°C) and intermittent period (start 90 s stop 90 s, start 3 min stop 1.5 min, start 1.5 min stop 3 min and start 3 min stop 3 min). Twelve subjects were recruited for subjective investigations. The subjects performed sedentary work and wore summer clothing. Subjective responses to the thermal environments were collected. Wind speed, temperature and CO2 concentration in the occupied area were measured. The results show that IAJS has a potential to be used as a primary ventilation system primary ventilation system such as classrooms in China. When the indoor air was set between 24°C and 26°C, IAJS could create a thermal climate that made the occupants thermally neutral. Additionally, IAJS created an indoor thermal environment acceptable to most occupants, even at a setting temperature of 28 °C.