A multi-terminal current differential protection setting method for fully weak-infeed distribution networks based on restricted enumeration method

With the high penetration connection of inverterinterfaced distributed generators and the increasing application of large-capacity energy routers, fully weak-infeed distribution networks consisting entirely of power-electronized weak-infeed power sources are set to become one of the fundamental forms of future distribution networks. For fully weak-infeed distribution networks, multi-terminal current differential protection is considered an optional or even preferred line protection scheme. In this paper, a multi-terminal current differential protection setting method for fully weak-infeed distribution networks is proposed based on the restricted enumeration method. To address the impact of data synchronization errors and measurement errors of multi-terminal current on differential current, the problem of determining the maximum differential current superimposed with the multi-terminal current phasor errors is transformed into a high-dimensional non-convex optimization problem. The distribution law of the global optimal solution in the non-convex constraint space is deeply studied and analyzed, and a restricted enumeration method is proposed that can quickly solve the protection setting value, thereby solving the problem of multi-terminal current differential protection setting. The accuracy and rapidity of the proposed method are verified by comparing the calculation accuracy and time consumption of the restricted enumeration method and the exhaustive search. It is shown that the proposed multi-terminal differential protection setting method exhibits sufficient reliability and sensitivity in fully weak-infeed distribution networks, as verified through simulation analysis using a fully weak-infeed distribution network model built in PSCAD/EMTDC

Navigating the depths: a stratification-aware coarse-to-fine received signal strength-based localization for internet of underwater things

Underwater wireless sensor networks (UWSNs) are the primary enabling technology for the Internet of underwater things (IoUT), with which all underwater objects can interact and communicate. In UWSNs, localization is vital for military or civilized applications since data collected without location are meaningless. However, accurate localization using acoustic signals in UWSNs is challenging, especially for received signal strength (RSS)-based techniques. The adverse effect of hybrid loss (path and absorption loss) and stratified propagation may severely impact localization accuracy. Even though some schemes have been proposed in the literature, the accuracy is unsatisfactory. To this end, this study proposes a coarse-to-fine localization method (CFLM). The problem is reformed into an alternating nonnegative constrained least squares (ANCLS) framework, where a constrained ellipse adjustment (CEA) using block principal pivoting is proposed to obtain the coarse estimation. A refined step using a Taylor series expansion is then further presented, in which a corrected solution is acquired by iteration. Additionally, this study derives the Cramér-Rao lower bound (CRLB) to evaluate the proposed method. Simulation results show that the proposed CFLM improves the localization accuracy by up to 66 percent compared with weighted least squares (WLS), privacy-preserving localization (PPSL), two-step linearization localization approach (TLLA), particle swarm optimization-based (PSO) localization, and differential evolution-based (DE) localization under different scenarios

Comparison of the Dynamic Performance of Planar 3-DOF Parallel Manipulators

This paper presents a comprehensive comparison study on the dynamic performances of three planar 3-DOF parallel manipulators (PPMs): 3-RRR, 3-PRR, and 3-RPR. In this research work, the discrete time transfer matrix method (DT-TMM) is employed for developing dynamic models of the planar parallel manipulators. Numerical simulations using the virtual work principle and ADAMS 2016 software are performed to verify the DT-TMM dynamic model of PPMs. Numerous dynamic performance indices, including dynamic dexterity, the power requirement, energy transmission efficiency, and the joint force/torque margin, are proposed to compare the dynamic performance of three PPMs under the general circular and linear trajectories. The comprehensive analyses and comparisons show that: (1) the 3-RRR PPM has advantages in terms of a circular trajectory, offering the best dynamic dexterity performance, the smallest power requirement, and the second-highest energy transfer efficiency; (2) the 3-PRR PPM performs best in terms of a linear trajectory, offering the best dynamic dexterity, the smallest power requirement range, and the best drive performance; and (3) the 3-RPR PPM has the highest energy transfer efficiency and demonstrates better dynamic performance in a circular trajectory compared to a linear trajectory

Perceived urban green and residents’ health in Beijing

Green space serves urban residents in various functions including promoting health, but the roles of different types of green space are unclear. A survey titled “Healthy Neighborhood” was conducted in Beijing from May to July 2019 to examine and compare the associations between three types of perceived green space (park green, public-square green and utility green) and three aspects of residents' health (physical health, mental health and social health). Results from the multilevel modeling (MLM) analysis show that the perceived park green has a positive correlation with mental health, and all three types of perceived green space correlate with social health positively. No significant correlation of any type of green space is detected on participants’ physical health, nor any relation of public-square green or utility green to their mental health. Overall the role of urban green space is stronger on social health than physical and mental health. The findings support the complementary roles of different types of green space, and suggest that expansion in utility greens could be as effective as investing in more costly park and public-square greens, especially in their benefit in promoting social health

Degradation of Diesel with Microorganisms in Rhizosphere of Carex phacota Spr.

AbstractBecause of widespread use of petroleum, the Huangpu-Yangtze River estuary (HYRE) wetland has been polluted by accidental spills. The technology to degrade these compounds is a major goal of environmental research. This study isolated oil-degrading microorganisms from oil contaminated wetland in the HYRE. Three bacterial strains were discovered, and identified by sequencing their 16S rDNA genes. Two of them were Pseudomonas and the other one was Alcaligenes. Diesel biodegradation potential of these indigenous oil-degrading microorganisms(HPM) and HPM co-metabolize with the native plant Carex phacota Spr.(CPS) were assessed. During the 60-day experiment, soil samples were collected and analyzed periodically to determine the residual diesel content and microbial populations. The results showed that the oil-degrading microorganisms isolated from the HYRE wetland had a certain degradation effect on diesel. Within 60 days, the relative degradation rates of microorganisms were 8.05∼36.59%; and under the combined effects of microorganisms and plants, the degradation rates of diesel could reach 28.28∼52.94% at different concentration of diesel. They all play a good role on the n-alkanes within the range of C18∼C24 components of diesel. Results indicated that the oil-degrading bacteria isolated from the HYRE wetland have a certain degradation effect on diesel. The co-metabolize of plants and microbes would increase the diesel biodegradation rate. The plants and the oil-degraders in wetland could be reasonably matched to control the diesel pollution of wetland sediment

Characterization of the complete chloroplast genome of Allium tuberosum

Allium tuberosum is a popular vegetable, condiment, and even a traditional Chinese medicine. Here, the complete chloroplast genome sequence of Allium tuberosum was reported. The size of the chloroplast genome is 154,056 bp in length, including a large single copy region (LSC) of 83,068 bp, a small single copy region (SSC) of 17,958 bp, and a pair of inverted repeat (IR) regions with 26,515 bp. The Allium tuberosum chloroplast genome encodes 132 genes, including 87 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Phylogenetic tree analysis suggested that Allium tuberosum was closely related to Allium sativum

Characterization of the complete chloroplast genome of Allium mongolicum

Allium mongolicum is a kind of wild vegetable with high nutritional value and even a traditional Chinese medicine. Here, we reported the complete chloroplast genome sequence of Allium mongolicum. The size of the chloroplast genome is 153,376 bp in length, including a large single copy region (LSC) of 82,912 bp, a small single copy region (SSC) of 18,054 bp, and a pair of inverted repeated regions of 26,205 bp. The Allium mongolicum chloroplast genome encodes 115 genes, including 69 protein-coding genes, 38 tRNA genes, and eight rRNA genes. Phylogenetic tree showed that Allium mongolicum is closely related to Allium przewalskianum

Endoplasmic reticulum and mitochondrial double-targeted NIR photosensitizer synergistically promote tumor cell death

The excessive production of reactive oxygen species (ROS) can damage the mitochondrial membrane and induce apoptosis, causing endoplasmic reticulum stress and triggering immunogenic cell death. Therefore, the combination of apoptosis and immunogenic death by the dual-targeted ROS generator has great potential to address inefficient cancer treatment. A near-infrared photosensitizer was developed for efficient ROS production and dual-targeted cancer treatment. Due to the modulation of electron structure, the reduced transition energy barrier affords TCy5-I-3F the highest efficiency to produce ROS. TCy5-I-3F has excellent mitochondrial and endoplasmic reticulum targeting ability, causing cell apoptosis and stress of the endoplasmic reticulum for destroying cancer cells. In the dual-targeted mode, high expression of GRP780, activation of heat shock protein (HSP70), the outflow of high mobility group protein B1, efflux of Calreticulin, and massive efflux of adenosine triphosphate are evaluated in the pharmacological experiments. In vivo experiments, the maturation of dendritic cells (DC, CD80+, CD86+), CD8+ T cells and CD3+ T cells also highlights the effectiveness. The tumors of mice treated with TCy5-I-3F and near-infrared (NIR) light are significantly inhibited. The multifunctional targeting design and corresponding mechanisms prove a new insight for exploring efficient photodynamic therapy drugs