bluuebunny/crossref_metadata_2025 huggingface dataset:
On site measurement and hygrothermal modelling of degraded ETICS facade with EPS and mineral wool fire breaks
Authors: Talvik M , Klõšeiko P , Kalamees T , Liisma E , Ilomets S
Published: December 2023

External Thermal Insulation Composite System (ETICS) facades are widespread and cost-effective building solutions in many climates. However, they are frequently found to deteriorate prematurely. In addition to other possible defects, several buildings were found with horizontal cracks on the facade between every floor level. Because of the fire safety requirements of multi-storey buildings, EPS insulation has been divided by mineral wool fire breaks at each floor level. The service life of the system usually ends up with horizontal cracks appearing at the lower level of the wool belt. This study aimed to determine the damage mechanism. One deteriorated facade was opened to explore possible construction technology errors and specimen were analysed in the laboratory. Temperature and RH were measured in situ inside the walls at different positions. It turned out that built in moisture of concrete was still drying out after three and a half years. Moisture content of concrete was found to be between 0.046 to 0.063 m3/m3 behind EPS insulation and 0.047 to 0.074 m3/m3 behind MW insulation - slightly higher than hygrothemal model was predicting. A possible solution was proposed to alleviate the similar problem in the future with application of waterproofing membrane behind mineral wool.
A chronological development of a framework for emission free construction sites in Norway
Authors: Wiik Marianne Kjendseth , Fufa Selamawit Mamo , Homaei Shabnam , Fjellheim Kristin
Published: December 2023

The building and construction sector is responsible for 3.4% of total GHG emissions in Norway. Around 95% of these emissions arise from the combustion of fossil fuels for the operation of construction machinery and transport. This highlights the importance of transitioning to renewable energy sources for the operation of construction sites. To facilitate this transition, a new concept is emerging in Norway, called emission free construction sites. To fully implement this concept, a clear and consistent definition of emission free construction sites and a commonly agreed stepwise approach to decarbonisation of construction activities is required. This paper presents a chronology of the development of emission free construction sites in Norway to further develop a framework. First, a review of experiences from different research and on-going national activities are presented as a background. The results from applying this framework on construction sites in Norway are presented and issues around harmonisation of definitions, standards, and system boundaries are discussed. The results of this paper are relevant for actors within the construction industry that are interested in reducing GHG emissions from construction works. In conclusion, this paper presents the first steps towards the decarbonisation of construction sites in Norway and demonstrates how Norway has become a testbed for the electrification of construction machinery on construction sites.
The IEQ Occupant Manikin: a holistic indoor environmental quality assessment tool
Authors: Rohde Lasse , Johra Hicham , Jensen Rasmus Lund , Michalak Paulina , Fabian Martin , Wielgolewski Marcin
Published: December 2023

Indoor environmental quality (IEQ) measurement is a fundamental part of quantifying the performance of any space. Performing measurements and interpreting the results require expensive equipment and specialist knowledge for each parameter. Since holistic IEQ assessment requires investigation of multiple parameters across atmospheric, thermal, acoustic, and visual indoor environment, this is a comprehensive and expensive task. The IEQ Occupant Manikin concept presents an operational holistic IEQ assessment based on measurements of various parameters. The paper presents the development of a prototype manikin equipped with various sensors strategically positioned to best represent the exposure occupants would experience. Since the manikin also physically mimics an occupant in the space, the term occupant-centric measurements is used. In addition, the paper presents a preliminary methodology for the assessment, weighting, and aggregation of individual IEQ parameters towards an overall holistic IEQ assessment. Practical implementation of the work is discussed, including the potential implications for standards on IEQ measurement. The paper reflects upon the future perspectives on using machine learning for a black box modelling approach to tackle the complex issues with the interaction effects between IEQ parameters and relative IEQ parameter weights for holistic assessment. Finally, the paper presents suggestions for future work on the IEQ Occupant Manikin concept.
Validation of decomposition models for solar irradiance at high latitudes: A preliminary study
Authors: Manni M , Nocente A , Skeie K , Bellmann M , Lobaccaro G
Published: December 2023

The accurate estimation of buildings’ solar potential contributes to boost the exploitation of solar energy at high latitudes. The decomposition of global irradiation into the direct and diffuse fractions is a fundamental step of the solar irradiance model chain. Diffuse and direct irradiation are, in fact, rarely measured. Previous works recommended Yang4 as the decomposition model with the best overall performance. However, in geographically limited applications, quasi-universal decomposition models such as Yang4 and Engerer4 can be outperformed by local models (i.e., models parametrized with climate-specific data) such as Skartveit3 and Starke3. This makes necessary to perform local validation studies to verify the findings from worldwide validation studies. In this study, the four decomposition models are implemented in Python and experimentally validated against one-minute solar irradiance data (i.e., direct and diffuse irradiance) of Trondheim (Lat. 63°26’ N, Norway). Two months representative of clear sky (August) and overcast (October) conditions are considered. The study confirms that the Yang4 model performed the best for high-latitude application: the nMBE ranged from -0.54% (August) to 0.65% (October), the nRMSE from 17.18% (August) to 22.29% (October), and the R2 from 0.96 (August) to 0.97 (October). However, Skartveit3 combines a level of performance close to Yang4 with the lower number of input parameters.
Research on Confidence Analysis Method of Lightning Strike Accidents on Distribution Lines
Authors: Huang Weixiang , Chen Qianyi , Zhang Wei , Lin Xiuqing , Hu Gang , Feng Bo , Zhou Yangjun , Ling Ying
Published: December 2023

Currently, lightning is the main cause of power system faults. Due to insufficient equipment and technology, low insulation level, the distribution network being the main part of power outages, and the complex causes of distribution network faults, it is difficult to determine whether each fault in the distribution network is caused by lightning strikes. In this paper, the concept of lightning strike confidence, i.e., the possibility of a line lightning strike fault caused by falling lightning, is proposed, and a lightning strike confidence analysis is performed for a 10 kV distribution line in the mountainous region of South China to determine the possibility of a line lightning strike fault caused by falling lightning based on the lightning locating system data of the distribution line at the moment of the fault. First, the calculation method of the lightning strike confidence is derived; then the distribution law of the distribution line lightning strike confidence, the influence of the ground tilt direction, and ground tilt angle on the distribution line lightning strike confidence are analyzed; finally, the distribution line lightning strike confidence is analyzed by an example.
Wind power access site selection method based on scenario probability
Authors: Li Tao , Lv Xuetao , Zhang Yiyang , Liao Yiliang , Wang Mingli , Wang Bo , Zhao Jie
Published: December 2023

The fluctuation of new energy output makes the power system operation more complex, and the traditional power system tide calculation is no longer fully applicable. Therefore, the determination of wind farm output and site selection is important and fundamental research at present. Based on this, a combination of wind farm output scenario and probability is proposed. The site selection model with the minimum network loss of the distribution network as the optimization objective is proposed. First, the wind farm output is clustered into several typical scenarios by K-Means, and the output time series model and the probability of each typical scenario are obtained. The probabilities of each scenario are multiplied by the network losses under that scenario. Then, the network losses obtained for all individual scenarios are summed up and used as the minimum objective function. The model is solved by a genetic algorithm with tidal current constraint and node voltage constraint to derive the optimal wind farm access point. With the IEEE33 node, simulations are performed to derive the minimum value of the daily average network loss, which verifies the rationality and feasibility of the optimized model.
The Calculation Method of the Floating Conductor Potential in the Ion Flow Field
Authors: Liu Lei , Liao Minchuan , Jia Lei , Li Bin , Wan Wenxin
Published: December 2023

For bipolar DC transmission projects, when one pole conductor is charged and running normally, and the other pole conductor is in a standby state (including cold standby and hot standby), if the standby pole conductor is not grounded, a high charging potential will appear on the surface. On the one hand, it will affect the insulation coordination and protection setting of the DC system. On the other hand, it will also affect the ion current and synthetic electric field on the ground. This article studies the calculation method of the potential of suspended conductors in the presence of floating conductors in the ion flow field, establishes a calculation model based on the minimum absolute value of the space charge density on the surface of the conductor, and calculates and analyzes the distribution of ionizing current and synthetic electric field below the ground of high-voltage DC lines in the presence of suspended conductors. The distribution laws of ground field strength and ion current in single-circuit bipolar DC transmission lines are studied when one pole is suspended, the other is operated, and when one circuit is operated. One circuit is shut down in double-circuit DC transmission lines on the same tower. For practical engineering, on the one hand, it is possible to predict the potential of suspended conductors in the ion flow field and propose adjustment plans for protection settings, insulation coordination, etc., in advance. On the other hand, when considering abnormal operating conditions, the impact of ion flow fields on the ground electromagnetic environment can be reduced by changing the geometric architecture and line selection.
Research on the output voltage control of the Dual active bridge converter
Authors: Song Zhuo , Zhang Haiyan
Published: December 2023

in order to make the dual active bridge DC / DC converter output voltage stability, for the single shift phase control mode load disturbance, the input voltage disturbance affect the output voltage, puts forward a closed loop based on MATLAB self-regulation control, the control for a certain range of disturbance to maintain the output voltage stability effect is particularly obvious. This paper mainly introduces the working principle of DAB converter under single-shift phase modulation (SPS) and analyzes the topological structure of the circuit. Finally, the simulation model of the converter closed-loop control system is built on the simulink platform in Matlab, and the PID parameters are determined by using the self-regulation function to realize the pressure stabilizing output.
A Flexible DC Ranging Scheme Based on Variational Mode Decomposition and Teager Energy Operator
Authors: Wang Lingbai , Wang Sihua , Gao Chang
Published: December 2023

In this paper, a new Cable fault location scheme is proposed for the existing flexible DC Cable fault location methods, in which the fault signal is mixed with noise and the traveling wave speed is affected by line parameters. This scheme is based on the propagation characteristics of fault line mode voltage traveling waves in flexible DC transmission. Firstly, the fault voltage is effectively decomposed using Variational Mode Decomposition (VMD). Then, the decomposed intrinsic mode functions (IMF) are reconstructed to obtain the high-frequency components of the recorded fault information. Finally, the traveling wave head is calibrated using the Teager Energy Operator (TEO). A dual terminal ranging algorithm that is not affected by wave velocity has been proposed, which can effectively avoid the impact of fault traveling wave velocity uncertainty on the ranging results. A dual ended flexible DC power grid model was built in PSCAD/EMTDC, and a large number of simulation results show that the algorithm proposed in this paper can accurately calibrate the fault traveling wave head, has little interference from transition resistance, strong noise resistance, and can obtain high-precision fault location results in different fault locations.
Simulation of Thermal Dissipation and Fatigue Properties of a Pressing Sealed Insulated Gate Bipolar Transistor Device
Authors: Huang Tianyi , Chen Yuxiang
Published: December 2023

Insulated gate bipolar transistor (IGBT) is widely needed in many applications, such as motors, inverters, express railways, and automobiles. As the integrity level of IGBT increases, thermal management becomes a more significant issue, especially when third-generation semiconductor chips made with SiC or GaN come into application. Here, a press packaging SiC IGBT module is designed, which involves silver sintering. Firstly, we make a thermal analysis using the finite element method (FEM). Then, a heat dissipation plane is optimized. Groups of heat sink materials and airflow velocities are investigated, and an optimized one is chosen as the basis of further fatigue analysis. In the simulated working condition, the maximum temperature can reach 100°C, which could further induce serious problems in fatigue performance. We have analyzed 4 models with different silver layer edge shapes. The best one shows a 27% higher expected fatigue life than the standard one, which shows that the fatigue performance is very sensitive to the edge shape of the silver layer. This research can help further optimization and designing of advanced IGBT devices.
Research on Operational Status Monitoring Technology of the Secondary Circuit of Intelligent Substation Based on Virtual Circuit Visualization
Authors: Zhang Yue , Chen Hengxiang , Xu Jingran , Yu Yue , Zhu Zhenwei , Zeng Jingjing
Published: December 2023

With the promotion and construction of intelligent substations, how to reliably monitor the operation status of the intelligent components and related circuits of the secondary circuit equipment has become a difficult problem to which needs to be paid attention in the optimization operation and relay protection of the power system. This article proposes an intelligent substation secondary circuit operation status monitoring technology, which visualizes the design of SCD files. At the same time, the entropy weight method and grey correlation analysis method are introduced into the monitoring system to improve the work efficiency of on-site operation and maintenance personnel and promote the development of substation intelligence.
Complementary Ensemble Empirical Mode Decomposition and Maximum Correlated Kurtosis Deconvolution for Wind Turbine Bearing Fault Feature Extraction
Authors: Fu Dong , Lu Qifu , Tang Longhua , Ran Wang , Shi Quan , Fu Ming , You Dehua
Published: December 2023

Wind turbine bearing fault signals exhibit characteristics such as nonlinearity, non-stationarity, and susceptibility to external noise interference, making it challenging to extract fault features and identify them accurately. In light of these issues, this paper proposes a fault signal feature extraction method that combines complementary ensemble empirical mode decomposition (CEEMD) and maximum correlated kurtosis deconvolution (MCKD). CEEMD is utilized to decompose the signals, reducing mode mixing and eliminating residual auxiliary noise in the decomposition process, thereby obtaining linear and stationary signals that enhance the significance of the features. MCKD is employed to increase the kurtosis value of the fault signals, facilitating the extraction of continuous transient impacts from weak fault signals. Finally, a Convolutional Neural Network (CNN) is employed to validate that the method enhances fault characteristics and improves the accuracy of fault signal recognition.
The intelligent monitoring method of main distribution microgrid operation panorama considering the high percentage of new energy sources
Authors: Chen Xinbin , Huang Honghui , Xie Cheng , Zhang Pengfei
Published: December 2023

In the context of new power system construction, the proportion of new energy generation connected to the power system is increasing year by year. However, due to the strong randomness and volatility of new energy generation, a large number of accesses may threaten the safety of power system operations. Therefore, it is one of the important aspects in the construction of new power systems to improve the grid operation monitoring technology. This paper proposes a panoramic intelligent monitoring method for the operation of the main distribution microgrid considering the high percentage of new energy sources, in order to protect the safe operation of the new power system.
Two-stage AGC Control Method for Wind Farm Considering Power Forecast and Theoretical Power Error
Authors: Yan Quanchun , Gu Wen , Ji Jie , Mei Rui , Huang Jiaxing
Published: December 2023

With the large-scale wind farm connected to the power system, the uncertainty and fluctuation of its output bring challenges to the power grid dispatching and operation, especially in the automatic generation control. The problem of inaccurate theoretical power upper limit and power forecast has always been prominent. Therefore, this paper proposes a two-stage AGC control method for wind farms. In the first stage, the power control target value of the wind turbine group is determined by comprehensively considering the grid connection point of the station, the power consumption of the station, the loss in the station, and the theoretical power error. In the second stage, the power control of the wind turbine group is divided according to the proportion of the maximum power generation capacity and sent to the wind turbine, to realize the closed-loop control. Based on the measured data of a typical wind farm in Jiangsu province, the calculation results show that the control strategy proposed in this paper is effective and can greatly improve the response speed and accuracy of wind farm AGC.
Optimal Dispatch of Integrated Energy Systems Considering Advanced Adiabatic Compressed Air Energy Storage with a High Percentage of Fluctuating Energy Consumption
Authors: Wang Xia , Ma Guocai , Chen Xiaotao
Published: December 2023

Aiming at the integrated energy system (IES) of the region with a multi-energy coupling of cold, heat, and power (CHP), this research establishes the IES model with the advanced adiabatic compressed air energy storage (AA-CAES) as the energy hub. Further, to increasingly improve the system’s consumption ratio of fluctuating energy sources such as wind power, this paper designs the AA-CAES wide operating condition operation scheme based on the compressor adjustable inlet guide vanes (VIGVs) regulation technology. Finally, it is validated with a real application Case. Simulation results indicate that the operating costs of the newly modeled IES can be decreased by 20% compared to a regular integrated energy system, which demonstrates the effectiveness of AA-CAES-wide operating conditions in promoting the economic operation of integrated energy systems (IES).
Study of the Relationship Between Temperature Change and Energy Transfer in Thermodynamic Processes in Buildings
Authors: Zhou Junjie , Yao Jiangxiu , Wang Ruyi
Published: December 2023

In this paper, the relationship between room temperature and outside temperature, wall temperature, system operation, and energy consumption is investigated through mathematical modeling and simulation experiments. The thermodynamic parameters of a typical room are used in the study, and the characteristics of the heating and cooling system are considered. 1. This paper analyses the variation of room temperature, wall temperature, switching state, and heating power with time. The results show that the room and wall temperatures are influenced by the external temperature and system operation, while the switching state and heating power are regulated by the room temperature. The correlation between temperature and heating power is quantified by calculating the correlation coefficient matrix. The results show that there is a positive correlation between room temperature and heating power, while there is a negative correlation between wall temperature and room temperature and heating power. 2. This paper investigates the effect of external temperature on room temperature and wall temperature. The results show that an increase in external temperature leads to a decrease in room temperature and wall temperature. In addition, it is found that the indoor temperature is more sensitive to changes in external temperature within the range of changes in external temperature. 3. It is based on the steady-state solution curves between temperature and external temperature, as well as thermodynamic plots of system operation and energy consumption. The visual presentation of the effect of external temperature on the system provides a reference for optimizing building energy use and designing efficient heating and cooling systems. This study provides insight into the relationship between temperature change and energy transfer in building thermodynamic processes, guiding for achieving sustainable energy utilization and reducing environmental impacts. It is of great significance for optimizing the design of building energy systems and improving the efficiency of energy use.
Influence of Cell Pore Configuration on Dynamic Mechanical Properties of Honeycomb Structures
Authors: Li Jiaxing , Zhong Weizhou , Li Jian , Liu Yuan , Zhang Zexiong
Published: December 2023

With the rapid development of advanced manufacturing technologies such as additive manufacturing, which provides an effective means for processing and preparing a variety of structures with more complex geometrical configurations, the design and study of honeycomb structures have played an important role in promoting the design and study of honeycomb structures. At present, the study of such structures is mainly limited to hexagonal honeycombs, and relatively few studies have been conducted on other cell geometries. In this study, by using the finite element method, we have simulated and investigated the mechanical properties of typical honeycomb structures, in which these structures have different cellular pore configurations and arrangements that are subjected to in-plane low-velocity impact loading. We compared their dynamic load-carrying capacity and deformation patterns with the relative density and impact velocity which is kept constant. Our results show that different cell pore configurations lead to different cell wall stress states during the compression of the honeycomb structure, which affects the macroscopic mechanical properties of the overall structure. Honeycombs with predominantly cell-edge bending have lower stiffness, compressive strength and smoother platform stresses. Honeycombs with deformation modes dominated by cell-wall plastic buckling have the opposite properties. The design of protective structures through further combinatorial optimization of honeycomb structures provides more options to enhance their overall behavior and energy absorption properties.
Investigation of Small Strain Dynamics in Modified Aeolian Sand under Vibration Triaxial Conditions
Authors: Zhao Xiping , Sun Xiao , Liu Wanle , Tian Zhenghong
Published: December 2023

By utilizing vibration triaxial tests, this study analyzed the effects of various factors, such as confining pressure, consolidation ratio, and silt content on the elastic modulus and damping ratio of silt-modified aeolian sand under conditions of minor deformation. The results indicate that with increasing confining pressure and consolidation ratio, the dynamic elastic modulus of improved aeolian sand gradually increases, while the damping ratio decreases progressively. The dynamic elastic modulus growth rate of untreated aeolian sand demonstrates a positive correlation with confining pressure, while the corresponding rate for the modified aeolian sand by adding cement and silt exhibits an inverse correlation with confining pressure. As dynamic strain increases, the dynamic elastic modulus decreases and approaches a stable value. The damping ratio rises at a diminishing rate and eventually stabilizes as dynamic strain continues to increase. The dynamic stress-strain backbone curve of the modified aeolian sand follows a theoretical hyperbolic model, while the small strain dynamic behavior is consistent with the Hardin-Drnevich model.
The Effects of the Addition of Ca, Gd, La, and Y on Mechanical Properties and Microstructure of Pure Magnesium
Authors: Lin Biao-Zhi , Xu Yuan-Hao , Hou Jie , Huang Xin-Ting , Jiang Bing-Chun
Published: December 2023

The effects of different elements on the mechanical properties and microstructure of pure Mg were studied by XRD, SEM, and tensile tests. The results show that with the addition of 1wt% Ca, Gd, La, and Y elements alone, different second-phase particles appear in the microstructure of Mg-1X. The addition of Gd and Y elements generates a small amount of Mg5Gd and Mg24Y5 particles, respectively. In contrast, the addition of the Ca element generates a large number of coarse Mg2Ca particles, and the addition of the La element generates a large number of fine and evenly distributed Mg12La particles. After extrusion, the extruded Mg-1X magnesium alloy shows a fine equiaxed recrystallization structure. All four alloys show bimodal texture distribution with deflection along the ED direction, and the texture deflected along the TD direction appears in Mg-1La alloy. The tensile test shows that the yield strength of MG-1La alloy is the highest when it is drawn along the ED direction. The yield strength of Mg-1La alloy is the lowest when it is drawn along TD.
A mechanical analysis based on pterosaur flight
Authors: Liu Yangting
Published: December 2023

Pterosaurs are the earliest vertebrates known to have evolved powered flight and are one of the heaviest flying animals. The reason why pterosaurs can fly has puzzled scientists. This article conducts a mechanical analysis of the cause of pterosaur flight. First, based on the theory of hydrodynamics and aerodynamics, the energy conservation and N-S equations are established to simulate the whole process of pterosaur flight (takeoff-glide-landing). Then, based on Newton’s second law, energy equation, and differential motion equation, the power during pterosaur flight is analyzed, and the U-shaped curve is obtained. Next, based on the leaf element-momentum theory, we chose Wellnhopterus brevirostris as our analysis object, and the average velocity and flutter frequency of pterosaur during flight were analyzed[1].
Super-resolution Localization Problem Based on the Mobile Scenario
Authors: Zhu Ying Hao , Wei Xi Chuan , Jiang Xin Yu
Published: December 2023

Target positioning has always been a hot research topic in the field of sensors. In recent years, radar detection technology has become increasingly mature, resulting in a large number of radar sensors have begun to be used in traffic, security, medical and other fields for target detection. This paper mainly studies the super-resolution localization problem of FMCW FMCW in moving scenes. It analyzes the echo data by mathematical modeling to obtain the distance and angle information of the object to find the place of the object. To restore the motion trajectory of objects more realistically and achieve super-resolution positioning, a super-resolution radar positioning model based on Kriging interpolation based on the Fourier spectrum is established. By constructing a frame of intermediate frequency data Fourier spectrum tensor space, Fourier spectrum analysis is used to obtain the spectral characteristics of spatiotemporal changes when objects move. The Fourier spectrum surface is reasonably predicted through the statistical method - kriging interpolation. More Fourier spectrum information of objects in the time dimension can be obtained, and then more object points can be restored to achieve super-resolution positioning. This is widely used in the automotive field, which develops autonomous driving systems to help drivers better control the vehicle and reduce the probability of car accidents.
Transmission section search method based on variable scale nearest neighbor propagation clustering
Authors: Wang Zhen , Tang Jun , Mao Xun , Wang Jingjing , Peng Wei , Xia Junli , Zhang Dabo
Published: December 2023

Transmission sections have great significance in modern power systems. Given the phenomenon of frequent power outages caused by the chain tripping of transmission sections, a method for transmission section search based on the variable-scale affinity propagation clustering algorithm is proposed. Considering only the connection relationship, the power system model can be simplified to a topological map in graph theory for analysis. So firstly the algorithm considers the importance of each line from the perspectives of the structure of the graph and the actual operation of the power flow and then uses the variable-scale affinity propagation clustering algorithm for the network based on this value with the change of the number of cluster centers. The network will be partitioned at different scales, then find out the partition contact line at different scales, and judge whether it is a transmission cross-section by the power flow direction and the number of contact lines. This method can search out as many potential transmission sections of the power network as possible to provide more monitored objects for the staff and reduce the probability of large power outages. Finally, simulation in the IEEE-118-bus system and the IEEE-39-bus system verifies the effectiveness of the proposed method.
Distribution Network Optimization Dispatch Method Based on Renewable Energy Scenario Reduction
Authors: Huang Xinghua , Zhang Gonglin , Fan Yuanliang , Wu Han , Li Lingfei , Lin Jianli , Chen Shichuan , Chen Feixiong , Wang Hailong , Shao Zhenguo
Published: December 2023

The scenario analysis method is an important method to adapt to the optimal dispatch of power systems with a high percentage of new energy sources. As a hot research topic in scenario analysis methods, the significance of scenario reduction is to describe many complex scenarios that feature a small number of representative scenarios to achieve the purpose of reducing computational complexity. In this paper, a distribution network optimization dispatch method based on the hierarchical clustering algorithm for scenario reduction is proposed considering wind power output and photovoltaic output. Firstly, the original scenes are quickly categorized because of the hierarchical clustering algorithm to derive typical scenarios. Secondly, an optimal dispatch model of the distribution network containing renewable energy is established. Finally, the arithmetic example is verified by using the IEEE33 distribution network, and the experimental results validate the validity and superiority of the proposed scenario reduction method.
Power supply restoration strategy of distribution system considering load demand response
Authors: Wang Dawei , Liu Yan , Yan Xinxu , Wu Juan
Published: December 2023

The fluctuation of new energy output decreases distribution system reliability and increases the risk of a power outage. Based on this, considering the participation of new energy sources, the influence of load participation demand response on the distribution system is analyzed, the load demand response model is established, and the corresponding unit capacity compensation cost model is proposed. Considering the recovery income, operation cost, demand response compensation cost, and risk, a bi-level optimization model is established to solve the maximum recovery net income of the system. The upper layer aims at maximizing the expected net recovery income of the entire distribution system and proposes a distribution system partition scheme that takes into account the participation of new energy sources and mobile sources. The lower layer aims at maximizing the net recovery income of each partition and solves the recovery time and recovery amount of the load in each partition or the response time and response amount of the load participating in demand response under the condition of limited resources. Finally, the effectiveness of the power supply recovery optimization strategy of the distribution system proposed in this paper is verified by an example.
A fast simulation method of ground clutter for airborne wideband radar based on measured SAR image
Authors: Xu Yong , Zhu Yongfeng , Song Zhiyong
Published: December 2023

Ground clutter simulation is a key factor in the design and development of air-to-ground wideband radar. In this paper, the ground clutter simulation technology of stepped frequency airborne wideband radar is studied, and a fast simulation method of ground clutter based on SAR image is proposed. Firstly, the segmented area of high-resolution SAR image according to the radar illumination region is used as the input of the ground scattering coefficient to improve the fidelity of clutter simulation. Then, the antenna pattern is constructed by the uniform plane phased array, by which the power gain of the clutter point is modulated. Thirdly, the clutter echo of stepped-frequency radar is calculated according to the equidistant circle principle which improves the efficiency of computation. Finally, the proposed method is verified via computer simulation. The results show that the method can simulate ground clutter of radial space-variation effect induced by narrow antenna beam, verifying the effectiveness of the method. This method is applicable to various scenarios.
A Bi-directional Attention Based End to End Mispronunciation Detection and Diagnosis of Mandarin
Authors: Liu Qingqing , Wumaier Aishan , Shen Yunfei
Published: December 2023

An increasing number of individuals are acquiring proficiency in Mandarin, signifying the growing significance of employing computer-assisted pronunciation training systems for Mandarin learners. One pivotal component within these systems is the technique for identifying and addressing mispronunciations, known as Mispronunciation Detection and Diagnosis (MDD). Recently, certain end-to-end techniques have tried to fuse features of prompt text and acoustic features into the model for training and have shown good results. However, previous approaches have fused acoustic features with prompt text features by a simple attention mechanism. In this paper, we posit that the impact of text features varies significantly when mapped to distinct acoustic characteristics. Furthermore, we propose that the prompt text can lead the model towards achieving an integrated text-audio representation, thereby enhancing the inference quality. Hence, this article presents a model aimed at detecting and diagnosing mispronunciations. The model utilizes a bidirectional attention mechanism to integrate acoustic and prompt text features. Good results were achieved by conducting experiments on a self-built dataset of short Mandarin read-aloud texts.
Equipment consumption prediction based on improved HOLT exponential smoothing method
Authors: Gao Yu , Yao Kelei , Xiao Longbin , Gao Shuo
Published: December 2023

In response to the prediction of equipment consumption, the Markov chain was used to improve the Holt index smooth method. The results show that the improved Holt exponential smoothing method makes the average relative error drop significantly, and the prediction accuracy of the model is improved significantly, providing a scientific decision basis for equipment demand in equipment maintenance and guarantee work.
Security of quantum key distribution with imperfect phase randomisation
Authors: Currás-Lorenzo Guillermo , Nahar Shlok , Lütkenhaus Norbert , Tamaki Kiyoshi , Curty Marcos
Published: December 2023

The performance of quantum key distribution (QKD) is severely limited by multiphoton emissions, due to the photon-number-splitting attack. The most efficient solution, the decoy-state method, requires that the phases of all transmitted pulses are independent and uniformly random. In practice, however, these phases are often correlated, especially in high-speed systems, which opens a security loophole. Here, we address this pressing problem by providing a security proof for decoy-state QKD with correlated phases that offers key rates close to the ideal scenario. Our work paves the way towards high-performance secure QKD with practical laser sources, and may have applications beyond QKD.
Effects of fiber type, content, orientation, and surface treatments on the mechanical properties of PAFRP composite
Authors: Singh Siddhant Pratap , Sharma Amit , Singh Vivekanand , Mishra Sanjay
Published: December 2023

In present scenario, natural fibers are the preferred choice of manufactures to fabricate the sustainable polymer matrix composites. These composites may be a good substitute for synthetic materials after achieving the comparable strength with some treatments. Pineapple leaf fiber (PALF) contains high cellulose with low micro fibrillar angle which leads to decent inherent fiber strength. It is used for reinforcement in the proposed work to fabricate the epoxy matrix composite using hand layup method. During testing of composite, the effects of fiber content, type, and orientations on mechanical properties have been examined. Samples were prepared by varying the fiber type (short and long fiber), fiber orientations (at 0°, 90°, and 45°) and fiber contents by weight % (i.e., 5, 10, 15 and 25). The results of mechanical characterization reveal that the tensile and flexural strength for short fiber composite is found maximum at 25% of fiber content (20.85 MPa and 42.70 MPa, respectively). However, long fiber reinforced composite with 5% of fiber content exhibits maximum tensile and flexural strength as: 35.72 MPa and 56.19 MPa. The maximum flexural strength and impact strength of composite were found as 52.98 MPa and 25.30 J m−2, respectively when the fibers are oriented at 0°. The maximum values of water absorption in composite were found as: 1.74% for short fiber and 1.25% for long fiber reinforced composites. The Fourier transform infrared radiation (FTIR) spectroscopy confirms the removal of non-cellulose contents within the composite. Finally, the morphological analysis was carried out to find the debonding, splitting and pull-out of fibers within the composites which are the major reasons of composite failure.
High-dimensional reinforcement learning for optimization and control of ultracold quantum gases
Authors: Milson N , Tashchilina A , Ooi T , Czarnecka A , Ahmad Z F , LeBlanc L J
Published: December 2023

Machine-learning (ML) techniques are emerging as a valuable tool in experimental physics, and among them, reinforcement learning (RL) offers the potential to control high-dimensional, multistage processes in the presence of fluctuating environments. In this experimental work, we apply RL to the preparation of an ultracold quantum gas to realize a consistent and large number of atoms at microkelvin temperatures. This RL agent determines an optimal set of 30 control parameters in a dynamically changing environment that is characterized by 30 sensed parameters. By comparing this method to that of training supervised-learning regression models, as well as to human-driven control schemes, we find that both ML approaches accurately predict the number of cooled atoms and both result in occasional superhuman control schemes. However, only the RL method achieves consistent outcomes, even in the presence of a dynamic environment.
Improvement of adult female acne with a novel weekly oestradiol-loaded peel-off mask: a split-face placebo-controlled study
Authors: EL-Komy Mohamed H M , Youssef Dina Khaled Ahmed , Shamma Rehab Nabil , Bedair Nermeen Ibrahim
Published: December 2023

Background

Adult female acne (AFA) is characterized by a relapsing eruption of acne in women aged ≥ 25 years. It can be slower to respond to traditional adolescent acne treatments. Usually, androgens promote acne by stimulating sebum production, while oestrogens have the ­opposite effect by reducing sebum output when present in adequate quantities. Oestradiol is a female sex hormone that has its highest absolute serum levels and highest oestrogenic activity during the reproductive years. Peel-off facial masks have been suggested to intensify the effect of added active ingredients by forming an occlusive film after drying.

Objectives

To study the safety and efficacy of weekly topical oestradiol 0.05% in the treatment of AFA.

Methods

Twenty women with AFA were subjected to once-weekly application of an oestradiol 0.05% mask or placebo mask to either side of their face for 8 weeks. An acne lesion count was performed at baseline, at each visit and 8 weeks post-treatment.

Results

At the end of the treatment period, the treated side showed significant improvement in comedones, papules and pustules. Although lesion counts increased 2 months post-treatment, they remained significantly less common on the oestradiol-treated side compared with the side of the face treated with placebo. No side-effects were reported. Limitations included the small number of patients studied and the short follow-up period. The oestradiol effect was not studied at the cellular or molecular levels.

Conclusions

Topical oestradiol peel-off masks may be a promising convenient, safe and effective treatment for AFA.
Comment on ‘Development of chilblain lesions during the COVID-19 pandemic is strongly associated with cold weather: a retrospective analysis of patients from a single centre in the USA’
Authors: Potestio Luca , Martora Fabrizio , Megna Matteo , Villani Alessia , Cacciapuoti Sara
Published: December 2023

We read with great interest a retrospective cohort study recently published in Clinical and Experimental Dermatology exploring the association between chilblain lesion development and the COVID-19 pandemic and infection. Data on the role of COVID-19 infection on chilblain development are conflicting. Moreover, chilblains have also been reported following COVID-19 vaccination.
Recalcitrant skin ulcers in a patient with Papillon–Lefèvre syndrome: an unusual novel presentation
Authors: Malhi Kittu , Singh Sukhdeep , Mustari Akash P , Bishnoi Anuradha , Machhua Sanghamitra , Jindal Ankur Kumar
Published: December 2023

We discuss an unusual presentation of Papillon–Lefèvre syndrome (PLS) in a 23-year-old man featuring recalcitrant pyoderma gangrenosum-like ulcers, a symptom not previously associated with PLS. Genetic testing identified a novel homozygous pathogenic variant in CTSC responsible for PLS, highlighting the importance of considering this diagnosis in patients with treatment-resistant skin ulcers. This case broadens our understanding of PLS and its diverse clinical manifestations.
Transitioning to sustainable energy by incumbent utilities: insights from M&As, alliances, and divestments
Authors: Niesten Eva , Pereira Guillermo , Pinkse Jonatan
Published: December 2023

Energy utilities play an important role in transitioning to a sustainable energy industry. Data on 8967 transactions by 19 European energy utilities from 1990 to 2019 illustrate when and how utilities invest in sustainable resources and divest traditional resources such as fossil-fuel plants. Utilities transitioning to sustainable energy have greater financial resources and experience with sustainability, are publicly owned, and access sustainable resources of international and inter-industry partners. Utilities adopt a diversified strategy of balancing sustainable and traditional resources.
Viral Load Dynamics in Plasma and Semen When Antiretroviral Therapy Is Initiated During Early HIV-1 Infection
Authors: Gilada Trupti , Ulrich Angela K , Wang Yixin , Lama Javier R , Alfaro Ricardo , Harb Socorro , Daza Glenda , Holte Sarah , Pasalar Siavash , Rios Jessica , Ganoza Carmela , Dasgupta Sayan , Coombs Robert W , Duerr Ann
Published: December 2023

We assessed human immunodeficiency virus (HIV) load in plasma and semen during primary HIV infection using serial samples of semen and plasma during the first 24 weeks after diagnosis in untreated participants and those who started antiretroviral therapy (ART) immediately at diagnosis. In the absence of treatment, semen viral load was >1000 copies/mL in almost all specimens (83%) collected 2–10 weeks after the estimated date of HIV acquisition and remained >1000 copies/mL in 35% of untreated participants at the last observed time point. Thus, in the absence of ART, semen viral load remained at a level consistent with transmissibility throughout primary infection.
The association between bacteriuria and adverse pregnancy outcomes: a systematic review and meta-analysis of observational studies
Authors: Piazzolla Hans R W , Modin Frederikke , Halkjær Sofie I , Petersen Andreas M , Calum Henrik , Holm Anne
Published: December 2023

Background

Antibiotics for bacteriuria and urinary tract infection are commonly prescribed during pregnancy to avoid adverse pregnancy outcomes. The aim of this study was to evaluate the association between significant bacteriuria in pregnancy and any of the four pregnancy outcomes: preterm delivery; low birth weight; small for gestational age; and preterm labour.

Methods

Systematic review with meta-analysis of observational studies. We searched PubMed, EMBASE, the Cochrane CENTRAL library, and Web of Science for observational studies published before 1 March 2022. The risk of bias was assessed using the Newcastle–Ottawa scale. Study identification, data extraction and risk-of-bias assessment was performed by two independent authors. We combined the included studies in meta-analyses and expressed results as ORs with 95% CIs (Prospero CRD42016053485).

Results

We identified 58 studies involving 421 657 women. The quality of the studies was mainly poor or fair. The pooled, unadjusted OR for the association between any significant bacteriuria and: (i) preterm delivery was 1.62 (95% CI: 1.30–2.01; 27 studies; I2 = 61%); (ii) low birth weight was 1.50 (95% CI: 1.30–1.72; 47 studies; I2 = 74%); (iii) preterm labour was 2.29 (95% CI: 1.53–3.43; 3 studies; I2 = 0%); and (iv) small for gestational age was 1.33 (95% CI: 0.88–2.02; 7 studies; I2 = 54%). Four studies provided an adjusted OR, but were too diverse to combine in meta-analysis.

Conclusions

This systematic review identified an association between significant bacteriuria in pregnancy and the three complications: preterm delivery; low birth weight; and preterm labour. However, the quality of the available evidence is insufficient to conclude whether this association is merely due to confounding factors. There is a lack of high-quality evidence to support active identification and treatment of bacteriuria in pregnancy.