Energy storage for black start services : a review

With the increasing deployment of renewable energy-based power generation plants, the power system is becoming increasingly vulnerable due to the intermittent nature of renewable energy, and a blackout can be the worst scenario. The current auxiliary generators must be upgraded to energy sources with substantially high power and storage capacity, a short response time, good profitability, and minimal environmental concern. Difficulties in the power restoration of renewable energy generators should also be addressed. The different energy storage methods can store and release electrical/thermal/mechanical energy and provide flexibility and stability to the power system. Herein, a review of the use of energy storage methods for black start services is provided, for which little has been discussed in the literature. First, the challenges that impede a stable, environmentally friendly, and cost-effective energy storage-based black start are identified. The energy storage-based black start service may lack supply resilience. Second, the typical energy storage-based black start service, including explanations on its steps and configurations, is introduced. Black start services with different energy storage technologies, including electrochemical, thermal, and electromechanical resources, are compared. Results suggest that hybridization of energy storage technologies should be developed, which mitigates the disadvantages of individual energy storage methods, considering the deployment of energy storage-based black start services

An interlaboratory comparison of aerosol inorganic ion measurements by ion chromatography : Implications for aerosol pH estimate

Water-soluble inorganic ions such as ammonium, nitrate and sulfate are major components of fine aerosols in the atmosphere and are widely used in the estimation of aerosol acidity. However, different experimental practices and instrumentation may lead to uncertainties in ion concentrations. Here, an intercomparison experiment was conducted in 10 different laboratories (labs) to investigate the consistency of inorganic ion concentrations and resultant aerosol acidity estimates using the same set of aerosol filter samples. The results mostly exhibited good agreement for major ions Cl-, SO2-4, NO-3, NHC4 and KC. However, F-, Mg2C and Ca2C were observed with more variations across the different labs. The Aerosol Chemical Speciation Monitor (ACSM) data of nonrefractory SO2-4, NO-3 and NHC4 generally correlated very well with the filter-analysis-based data in our study, but the absolute concentrations differ by up to 42 %. Cl-from the two methods are correlated, but the concentration differ by more than a factor of 3. The analyses of certified reference materials (CRMs) generally showed a good detection accuracy (DA) of all ions in all the labs, the majority of which ranged between 90 % and 110 %. The DA was also used to correct the ion concentrations to showcase the importance of using CRMs for calibration check and quality control. Better agreements were found for Cl-, SO2-4, NO-3, NHC4 and KC across the labs after their concentrations were corrected with DA; the coefficient of variation (CV) of Cl-, SO2-4, NO-3, NHC4 and KC decreased by 1.7 %, 3.4 %, 3.4 %, 1.2 % and 2.6 %, respectively, after DA correction. We found that the ratio of anion to cation equivalent concentrations (AE/CE) and ion balance (anions-cations) are not good indicators for aerosol acidity estimates, as the results in different labs did not agree well with each other. In situ aerosol pH calculated from the ISORROPIA II thermodynamic equilibrium model with measured ion and ammonia concentrations showed a similar trend and good agreement across the 10 labs. Our results indicate that although there are important uncertainties in aerosol ion concentration measurements, the estimated aerosol pH from the ISORROPIA II model is more consistent

Spatial Alignment for Unsupervised Domain Adaptive Single-Stage Object Detection

Domain adaptation methods are proposed to improve the performance of object detection in new domains without additional annotation costs. Recently, domain adaptation methods based on adversarial learning to align source and target domain image distributions are effective. However, for object detection tasks, image-level alignment enforces the alignment of non-transferable background regions, which affects the performance of important target regions. Therefore, how to balance the alignment of background and target remains a challenge. In addition, the current research with good effect is based on two-stage detectors, and there are relatively few studies on single-stage detectors. To address these issues, in this paper, we propose a selective domain adaptation framework for the spatial alignment of a single-stage detector. The framework can identify the background and target and pay different attention to them. On the premise that the single-stage detector does not generate region suggestions, it can achieve domain feature alignment and reduce the influence of the background, enabling transfer between different domains. We validate the effectiveness of our method for weather discrepancy, camera angles, synthetic to real-world, and real images to artistic images. Extensive experiments on four representative adaptation tasks show that the method effectively improves the performance of single-stage object detectors in different domains while maintaining good scalability

Effect of cytoskeleton on ice crystal growth in cells during freezing

The factors affecting intracellular ice formation (IIF) and growth is essential to the mechanistic understanding of cellular damage through freezing. In the aid of high speed and high-resolution cryo-imaging technology, the broad bean intracellular ice formation and growth processes were successfully captured during freezing. Cytochalasin B（CB）was used to solubilize the cytoskeleton. Images of IIF were compared between cells with and without cytoskeleton. The behavior of intracellular ice crystal formation in plant tissues with or without CB was evaluated using changes of cell areas, the probability of crystallization, and growing rate of intracellular ice crystal. Moreover, light intensity figures were used to determine cell damage. This study showed that the cytoskeleton was involved in ice crystal nucleation mechanism during freezing responses of the plant cells

Formation process of thermal damage in a target area of high intensity focused ultrasound and effectiveness analysis of B-ultrasound real-time monitoring

High intensity of focused ultrasound (HIFU) is an effective tumor therapy, taking advantage of the thermal effect and cavitation effect to generate thermal damage to the target tissue. However, inaccurate ultrasonic dose control may result in ineffective or excessive treatment. Thus, real-time monitoring of the thermal damage formation process is critical. To evaluate the effectiveness of real-time monitoring of B-ultrasound, ex-vivo bovine livers were irradiated by 1.155 MHz focused ultrasound with emission time T1 of 200 ms and interval time T2 of 200 ms. For orthogonal experiments, ultrasound was irradiated at sound power of 100 W, 125 W, and 150 W for 10 s, 20 s, and 40 s, respectively. B-ultrasound image sequences are collected using a 7.5 MHz linear array and compared with backscattered echo signals and thermal damage slices, respectively, to build relationships between B-mode ultrasound monitoring and thermal effect or cavitation effect. The experimental results demonstrated that the tissue ablation process caused by thermal effect cannot be effectively monitored using B-ultrasound, but the process caused by the cavitation effect can. The analysis revealed a strong temporal correlation between the appearance of bright spots in B-ultrasound images and the sudden increase of the scattered echo power spectrum, which were caused by a large number of micro-bubbles from cavitation. The damaged cavity structure of the slices and the development trend of micro-bubbles showed a strong spatial correlation. Furthermore, the sudden increase in the scattered echo signal shows the potential of early warning of cavitation, as it is 1.2–2.0 s ahead of the bright spot in the B-ultrasound image, laying the experimental basis for improving the effectiveness of B-ultrasound monitoring in clinical HIFU surgery