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To expand the application scope of prestressed carbon fiber-reinforced polymer (CFRP) cables in civil engineering, the ultimate tensile strength of these cables was tested and evaluated under bending conditions. First, the study analyzed the tensile failure mechanism of CFRP cables under bending conditions based on elastic bending analysis theory. Thereafter, the ultimate stress state of individual tendons and cables was derived and a calculation model for the tensile strength of bent CFRP cables was established. Second, 14 sets of test conditions were created for CFRP cables under bending angles of 20–40° and bending radii of 1.5–3 m. Then, bending tensile tests were conducted to evaluate the effects of the above factors on the ultimate tensile strength, and the correctness of the computational model was verified using experiments. Finally, the ultimate performance of CFRP cables was theoretically predicted using the established model. The results showed that the cable bending tensile strength was associated with the radius r, tensile strength f, and elastic modulus E of the reinforced material and the bending radius R, but was not correlated with the interface buffer material or the bending angle of the steering system. Moreover, the flexural tensile residual strength was only affected by R/r and E/f. When E/f involved conventional material parameters, the residual strength increased nonlinearly with increased R/r. When R/r ≥ 600, the residual strength reached more than 80%. Therefore, R/r at 600 could be used as the design basis for a safe critical radius. [ABSTRACT FROM AUTHOR]

PP/EPDM (TPV) is a common thermoplastic elastomer with excellent performance and a wide range of uses. Polyhedral oligomeric silsesquioxane (POSS) with its own functional organic group (OV-POSS) was used to improve the combustion performance of TPV systems. 1 wt%, 3 wt% and 5wt% OV-POSS were added to TPV respectively, and their mechanical properties and thermal stability were tested. The results showed that the TPV mechanics performance of OV-POSS was slightly reduced, but the thermal stability was improved. Cone test results showed a 53% reduction in the heat release rate of TPV containing 5wt% OV-POSS compared with TPV without adding OV-POSS. The release of CO and CO2 also decreased significantly, and the amount of carbon formation increased from 1.1% to 14.8%. As can be seen from TG-IR analysis, the addition of OV-POSS slows down the thermal decomposition process of hydrocarbons. OV-POSS was added to improve flame-retardant properties and reduces fire risk of TPV. [ABSTRACT FROM AUTHOR]

Summary: With the increasing amount and type of connected microgrids in the near‐term future power networks, how to optimize the operation of multimicrogrids efficiently and reliably has become essential for taking full advantage of the complex systems. In this paper, a multitimescale coordinated optimization strategy for hybrid three‐phase/single‐phase multimicrogrids is proposed. The multitimescale strategy is implemented for day‐ahead economic optimization on a long‐time scale and real‐time tracking optimization on a short‐time scale. With the consideration of the economy of microgrids and three‐phase unbalance constraints in multimicrogrids, a strategy of collecting‐distributing fuzzy modified adaptive particle swarm economic optimization is introduced. In this day‐ahead strategy, a bilayer rolling optimizing structure is designed, where the lower layer conducts economic optimization at all time slots and the upper layer balances the tie‐line power at each time slot based on the results obtained from the lower layer. On this basis, by taking a day‐ahead optimized tie‐line power as baseline values, the real‐time power of energy storage systems is obtained by adopting an improved nondominated sorting genetic algorithm, which achieves distributed real‐time optimization for the multimicrogrid. Simulation results verify that the proposed strategy is feasible. [ABSTRACT FROM AUTHOR]

With the microgrids large-scale interconnect to the power grid, a number of neighboring microgrids in a certain region will form a multi-microgrids (MMGs) system. In the development from microgrid to smart grid, the MMGs will be a new research hotspot after microgrid. The paper analyses the basic structure of the MMGs from many aspects such as voltage grade classification, AC/DC constitutional forms, and phase-sequence constitutional forms. Next the remote-area type, residential-area type, office-building type, industrial-park type and research-study type MMGs are analyzed according to the typical application scenarios. Lastly, based on the research of the four aspects of the planning and design, mode switching, optimal operation and control devices, the key technology of the MMGs is discussed and explored. [ABSTRACT FROM AUTHOR]

With the fast proliferation of microgrids integrated into the power grid, several nearby microgrids with common benefit have been coupled to be multi‐microgrids (MMGs), which is a significant stage for developing the smart grid. A suitable control structure and corresponding control device need to be proposed for the MMGs operating efficiently. However, mostly micrgrid control devices are still restricted to the single microgrid and have limited application without the common design. The authors develop control devices with a prodigious popularisation value for the MMGs based on the hierarchical control structure. According to the proposed four‐layer control architecture (scheduling layer, central control layer, integrated terminal layer and bottom layer), the hardware and software design suitable for the MMGs control devices and its multi‐time scale communication architecture has been presented. Furthermore, the appearance design and interface exploitation were introduced as well. Experimental results are provided to demonstrate the validity of the proposed MMGs control structure and devices, which could contribute to the large‐scale application of MMGs control devices and provide a reference for other MMGs projects. [ABSTRACT FROM AUTHOR]

The high flammability of vinyl ester resin (VE) significantly limits its widespread application in the fields of electronics and aerospace. A new phosphorus-based flame retardant 6,6'-(1-phenylethane-1,2 diyl) bis (dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (PBDOO), was synthesized using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and acetophenone. The synthesized PBDOO was further incorporated with VE to form the VE/PBDOO composites, which displayed an improved flame retardancy with higher thermal stability. The structure of PBDOO was investigated using Fourier transformed infrared spectrometry (FTIR) and nuclear magnetic resonances (NMR). The thermal stability and flame retardancy of VE/PBDOO composites were investigated by thermogravimetric analysis (TGA), vertical burn test (UL-94), limiting oxygen index (LOI), and cone calorimetry. The impacts of PBDOO weight percentage (wt%) on the flame-retardant properties of the formed VE/PBDOO composites were also examined. When applying 15 wt% PBDOO, the formed VE composites can meet the UL-94 V-0 rating with a high LOI value of 31.5%. The peak heat release rate (PHRR) and the total heat release (THR) of VE loaded 15 wt% of PBDOO decreased by 76.71% and 40.63%, respectively, compared with that of untreated VE. In addition, the flame-retardant mechanism of PBDOO was proposed by analyzing pyrolysis behavior and residual carbon of VE/PBDOO composites. This work is expected to provide an efficient method to enhance the fire safety of VE. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have a wide range of applications in many aspects due to their unique properties. Here we carry out a detailed structural search and design of the BP2 using the first principles method, and find a new PMM2 sheet. The analysis of the phonon dispersive curves shows that the 2D PMM2 is dynamic stable. The study of molecular dynamics shows that the 2D PMM2 can be stable under high temperature, even at 600 K. Most importantly, when a suitable strain is applied, the structure can exhibit other electronic properties such as direct band gap semiconductor. In addition, the small strain can tune the band gap value of the PMM2 structure to around 1.4 eV, which is very close to the ideal band gap of solar materials. Therefore, the 2D PMM2 may have potential applications in the field of photovoltaic materials. [ABSTRACT FROM AUTHOR]

The new coronavirus pneumonia (COVID-19) epidemic spread rapidly throughout the world. Considering the strong infectivity and clustering of COVID-19, early detection of infectious cases is of great significance to control the epidemic. Nucleic acid testing (NAT) plays an important role in rapid laboratory diagnosis, treatment assessment, epidemic prevention and control of COVID-19. However, since COVID-19 is caused by a new emerging virus and NAT for COVID-19 has not been clinically applied before, false negative results inconsistent with clinical diagnosis have appeared in clinical practice. Therefore, it is urgent to improve the sensitivity of NAT for COVID-19. This study aimed to summarize the current situation and prospect of NAT based on the latest findings on COVID-19 infection. Also, the quality control of sample collection was discussed. Hopefully, this study could help to improve the effectiveness of NAT for COVID-19. • The entry of SARS-CoV-2 into host cells requires S protein and ACE2 on cell membrane. • Most COVID-19 NAT kits can detect three or two gene fragments (ORF1ab and core-shell protein gene N fragment). • RT-PCR is a major clinically diagnostic method for COVID-19. • Standardizing specimen preparation, test operation, and results interpretation can ensure the test accuracy and reliability. [ABSTRACT FROM AUTHOR]

Wireless sensor networks have been attracting research attention for the past decade and will continue to be a hot topic due to the emerging trend of Internet-of-Things (IoT). Edge computing for IoT (Edge-IoT) is a promising framework that can help low-powered sensor networks to conduct complex computational tasks. Different from the existing works that focus on cooperative task execution for edge and sensor networks, in this paper, we investigate the problem of reliable data transmission in edge-aided sensor networks. Firstly, we discuss how edge servers can help to improve the data transmission of sensor networks. Secondly, we propose a forwarding scheme for edge nodes to forward packets according to coverage and corresponding interference. Thirdly, we propose an edge-based error recovery approach. By employing edge servers for data transmission and error recovery, the efficiency and reliability of data transmissions can be largely improved. [ABSTRACT FROM AUTHOR]

Background: We aimed to develop a nomogram that can be combined with point-of-care gastric ultrasound and utilised to predict postoperative nausea and vomiting (PONV) in adult patients after emergency surgery. Methods: Imaging and clinical data of 236 adult patients undergoing emergency surgery in a university hospital between April 2022 and February 2023 were prospectively collected. Patients were divided into a training cohort (n = 177) and a verification cohort (n = 59) in a ratio of 3:1, according to a random number table. After univariate analysis and multivariate logistic regression analysis of the training cohort, independent risk factors for PONV were screened to develop the nomogram model. The receiver operating characteristic curve, calibration curve, decision curve analysis (DCA) and clinical impact curve (CIC) were used to evaluate the prediction efficiency, accuracy, and clinical practicability of the model. Results: Univariate analysis and multivariate logistic regression analysis showed that female sex, history of PONV, history of migraine and gastric cross-sectional area were independent risk factors for PONV. These four independent risk factors were utilised to construct the nomogram model, which achieved significant concordance indices of 0.832 (95% confidence interval [CI], 0.771–0.893) and 0.827 (95% CI, 0.722–0.932) for predicting PONV in the training and validation cohorts, respectively. The nomogram also had well-fitted calibration curves. DCA and CIC indicated that the nomogram had great clinical practicability. Conclusions: This study demonstrated the prediction efficacy, differentiation, and clinical practicability of a nomogram for predicting PONV. This nomogram may serve as an intuitive and visual guide for rapid risk assessment in patients with PONV before emergency surgery. [ABSTRACT FROM AUTHOR]

With the proliferation of distributed generation in distribution networks, quickly and smoothly converting to a state of regional autonomy in the case of distribution network failure is one of the main challenges for the stable operation of a multimicrogrid (MMG). To address the aforementioned problem, this paper proposes coordinated control of the passive transition from grid-connected to islanded operation for a three/single-phase hybrid MMG. Under the premise of fully considering the constraints on the tie-line transfer power undertaken by the master power supply (MPS), the following two scenarios regarding safety and emergency are formulated: 1) when the output power of the MPS is in the safe range, the proposed strategy coordinates the energy storage (ES) in each submicrogrid (SMG) to achieve power balance; 2) when the output power is in the emergency range, this paper proposes a three-phase balance method based on a bubble sort to realize the combination optimization of the single-phase source-load-storage (SLS) and a fast power regulation method based on implicit enumeration for the SLS to reduce the tie-line transfer power, which could prevent failure of the mode transition from power overload. The test results verify the effectiveness and feasibility of the proposed coordination strategy. [ABSTRACT FROM AUTHOR]

The aim of the work described here was to investigate the value of point-of-care ultrasound (POCUS) in the early assessment of the severity of pulmonary edema in rabbits. A rabbit oleic acid (OA)-induced pulmonary edema model was used. Thirty-two New Zealand rabbits were randomly divided into four groups: a control group and three pulmonary edema groups (mild, moderate and severe). Features of transthoracic B-line artifacts (BLA), blood pH, PaO2 and PaCO2, serum inflammatory factors, lung coefficient (LC), lung wet-to-dry weight ratio (W/D) and lung histopathology were assessed. BLA features and severity of pulmonary edema were semiquantitatively scored. Correlations between the number of BLA and PaO2, PaCO2, serum inflammatory factors, LC and W/D were analyzed. An additional 8 rabbits with severe pulmonary edema were used as the verified group, in which the lung was divided into ex vivo BLA (BLA-ev)-free (BLA-ev-free) and BLA-ev-clustered subregions depending on the features of BLA-ev recorded by ex vivo lung ultrasound. Lung specimens from each subregion were collected for histopathological examination. Relationships between features of BLA-ev and lung histopathological abnormalities were analyzed. With increasing doses of OA, number of BLA, W/D and levels of serum inflammatory factors decreased. Meanwhile, lung pathologic abnormalities were aggravated. In addition, time of appearance of BLA, blood pH and PaO2, and PaCO2 decreased dose dependently on OA (p < 0.05). Number of BLA was linear positively correlated with severity of pulmonary edema (r = 0.953, p < 0.05). Consistently, the features of BLA-ev reflected the severity of lung histopathological abnormalities (r = 0.936, p < 0.05). Thus, POCUS is useful in the early quantitative assessment of the severity of pulmonary edema. [ABSTRACT FROM AUTHOR]

In this paper, a novel type of voltage control strategy based on internal model robust and compound control is proposed for three/single-phase hybrid multimicrogrid, which is composed of two parts, feedforward control and internal model robust feedback control. Feedforward control is mainly used to improve the dynamic response and reduce the steady-state error of the system. The objective of the internal model robust feedback control system is to achieve the optimization of control performance, robustness, and the ability to suppress disturbances of the whole system. In order to achieve the goal, the design of the internal model robust feedback controller is transformed into solving a convex optimization problem with linear matrix inequality constraints and linear objective functions. The proposed voltage control strategy is verified by a variety of experimental tests. The experimental results show that the controller can get better voltage output characteristics and robustness in dealing with micro-source output power fluctuations, loads abrupt change or nonlinear loads and unbalanced loads. [ABSTRACT FROM PUBLISHER]

In this paper, an islanded medium-voltage (MV) microgrid placed in Dongao Island is presented, which integrates renewable-energy-based distributed generations (DGs), energy storage system (ESS), and local loads. In an isolated microgrid without connection to the main grid to support the frequency, it is more complex to control and manage. Thus, in order to maintain the frequency stability in multiple time scales, a hierarchical control strategy is proposed. The proposed control architecture divides the system frequency in three zones: (A) stable zone, (B) precautionary zone, and (C) emergency zone. In this way, dynamic stability control that copes with disturbances in short-time scale is implemented by microgrid central controller within Zone B and Zone C. Meanwhile, steady-state stability control to solve the peaks and valleys problem of loads and DGs in long-time scale is executed by the microgrid energy management system within Zone A. Furthermore, based on the developed complete small-signal state-space model, sensitivity analysis of the eigenvalues is conducted in order to reveal the dynamic stability margin of the MV microgrid, and to identify the proper range of the control parameters of Zone B. Theoretical analysis, time-domain simulation, and field test results under various conditions and scenarios in the Dongao Island microgrid are presented to prove the validity of the introduced control strategy. [ABSTRACT FROM AUTHOR]