Cyber security of a power grid: State-of-the-art Sun, Chih-Che; Hahn, Adam; Liu, Chen-Ching
International journal of electrical power & energy systems,
July 2018, 2018-07-00, 2018-07-01, Letnik:
99, Številka:
C
Journal Article
Recenzirano
Odprti dostop
•A review of cyber systems in a smart grid is provided with a list of the communication standards.•Requirements for cyber security and industry practice are discussed.•The state-of-the-art cyber ...protection and cyber-physical system testbeds are summarized.•The proposed methodology for detection of coordinated cyber attacks is demonstrated.•Unsolved cyber vulnerabilities that require future research are described.
The integration of computing and communication capabilities with the power grid has led to numerous vulnerabilities in the cyber-physical system (CPS). This cyber security threat can significantly impact the physical infrastructure, economy, and society. In traditional IT environments, there are already abundant attack cases demonstrating that unauthorized users have the capability to access and manipulate sensitive data from a protected network domain. Electric power grids have also heavily adopted information technology (IT) to perform real-time control, monitoring, and maintenance tasks. In 2015, a sophisticated cyber attack targeted Ukrainian’s power grid causing wide area power outages. It highlights the importance of investment on cyber security against intruders. This paper provides a state-of-the-art survey of the most relevant cyber security studies in power systems. It reviews research that demonstrates cyber security risks and constructs solutions to enhance the security of a power grid. To achieve this goal, this paper covers: (1) a survey of the state-of-the-art smart grid technologies, (2) power industry practices and standards, (3) solutions that address cyber security issues, (4) a review of existing CPS testbeds for cyber security research, and (5) unsolved cyber security problems. Power grid cyber security research has been conducted at Washington State University (WSU) with a hardware-in-a-loop CPS testbed. A demonstration is provided to show how the proposed defense systems can be deployed to protect a power grid against cyber intruders.
Recently, multidrug resistance (MDR) has become a major clinical chemotherapeutic burden that robustly diminishes the intracellular drug levels through various mechanisms. To overcome the doxorubicin ...(Dox) resistance in tumor cells, we designed a hierarchical nanohybrid system possessing copper-substituted mesoporous silica nanoparticles (Cu-MSNs). Further, Dox was conjugated to copper metal in the Cu-MSNs framework through a pH-sensitive coordination link, which is acutely sensitive to the tumor acidic environment (pH 5.0–6.0). In the end, the nanocarrier was coated with D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS), a P-gp inhibitor-entrenched compact liposome net for obstructing the drug efflux pump. Copper ions in the framework synergize the antitumor activity of Dox by enhancing the intracellular reactive oxygen species (ROS) levels through a Fenton-like reaction-mediated conversion of hydrogen peroxide. Furthermore, intracellularly generated ROS triggered the apoptosis by reducing the cellular as well as mitochondrial membrane integrity in MDR cells, which was confirmed by the mitochondrial membrane potential (MMP) measurement. The advancement of the design and critical improvement of cytotoxic properties through free radical attack demonstrate that the proposed hierarchical design can devastate the MDR for efficient cancer treatment.
We report a new method to promote the conductivities of metal–organic frameworks (MOFs) by 5 to 7 magnitudes, thus their potential in electrochemical applications can be fully revealed. This method ...combines the polarity and porosity advantages of MOFs with the conductive feature of conductive polymers, in this case, polypyrrole (ppy), to construct ppy‐MOF compartments for the confinement of sulfur in Li–S batteries. The performances of these ppy‐S‐in‐MOF electrodes exceed those of their MOF and ppy counterparts, especially at high charge–discharge rates. For the first time, the critical role of ion diffusion to the high rate performance was elucidated by comparing ppy‐MOF compartments with different pore geometries. The ppy‐S‐in‐PCN‐224 electrode with cross‐linked pores and tunnels stood out, with a high capacity of 670 and 440 mAh g−1 at 10.0 C after 200 and 1000 cycles, respectively, representing a new benchmark for long‐cycle performance at high rate in Li–S batteries.
MOF host S: The electrical conductivity of metal–organic frameworks (MOFs) was promoted by the construction of polymer–MOF composites. Using MOF‐based sulfur hosts, the critical role of porosity at high charge–discharge rates in Li–S batteries was elucidated. MOFs with short ion transfer pathways and large pore apertures were identified as the most suitable for long‐term cycling at extremely high rates.
Summary
Background
Patients with chronic hepatitis B virus (HBV) infection are at risk of developing liver disease. Serum hepatitis B core‐related antigen (HBcrAg) is a new biomarker for intrahepatic ...templates for HBV replication.
Aim
To explore whether a high HBcrAg level is associated with increased risk of cirrhosis, especially in patients with intermediate viral load (HBV DNA 2000‐19 999 IU/mL) due to their moderate risk of disease progression.
Methods
A total of 1673 treatment‐naïve, non‐cirrhotic patients with negative hepatitis B e antigen (HBeAg) and alanine aminotransferase (ALT) level <40 U/L at baseline were enrolled. We explored the relationship between baseline levels of HBcrAg and cirrhosis development in all patients, and whether a higher HBcrAg level (<10 vs ≥10 KU/mL) was associated with an increased risk of disease progression in those with intermediate viral load.
Results
Of the 1673 patients, 104 developed cirrhosis after a mean follow‐up of 15.9 years. Higher HBcrAg levels were associated with increased incidence of cirrhosis, cirrhosis‐related complications, and liver‐related death. In 445 patients with intermediate viral load, the cirrhosis risk stratified by HBcrAg level of 10 KU/mL yielded a hazard ratio of 3.22 (95% CI: 1.61‐6.47). The risk stratification remained significant when exploring other pre‐cirrhosis endpoints, including HBeAg‐negative hepatitis, hepatitis flare, and HBV DNA >20 000 IU/mL after 3 years of follow‐up.
Conclusions
In HBeAg‐negative patients with normal ALT levels, higher HBcrAg levels are associated with increased risk of cirrhosis. Among those with intermediate viral load, HBcrAg <10 KU/mL defines a low‐risk group for disease progression.
C–H Functionalization of Aromatic Amides Zheng, Quan; Liu, Chen‐Fu; Chen, Jie ...
Advanced synthesis & catalysis,
April 8, 2020, Letnik:
362, Številka:
7
Journal Article
Recenzirano
Since the beginning of the 21st century, significant progress has been made in transition metal‐catalyzed C–H functionalization of aromatic amides. The achievements in this field have mainly focused ...on ortho (proximal) functionalization, there have been far fewer reports on remote C–H functionalization, and para‐ and meta‐selective functionalizations remain a major challenge. Interestingly, there are few related comments in this field. In a few published cases, the scope of the report is relatively narrow, either to comment on the functionalization of a specific directing group or to summarize the functionalization of a specific reaction site. Herein, for the first time, we have comprehensively summarized the C–H functionalization of aromatic amides. This review is divided into three parts: ortho‐, para‐ and meta‐C–H functionalization of aromatic amides, and is subdivided according to the type of catalyst. The directing groups, reaction types, conditions, mechanism and applications of the corresponding reactions are discussed in detail.
Enantioselective synthesis of N−N biaryl atropisomers is an emerging area but remains underexplored. The development of efficient synthesis of N−N biaryl atropisomers is in great demand. Herein, the ...construction of N−N biaryl atropisomers through iridium‐catalyzed asymmetric C−H alkylation is reported for the first time. In the presence of readily available Ir precursor and Xyl‐BINAP, a variety of axially chiral molecules based on indole‐pyrrole skeleton were obtained in good yields (up to 98 %) with excellent enantioselectivity (up to 99 % ee). In addition, N−N bispyrrole atropisomers could also be synthesized in excellent yields and enantioselectivity. This method features perfect atom economy, wide substrate scope, and multifunctionalized products allowing diverse transformations.
A highly efficient iridium‐catalyzed asymmetric C−H alkylation reaction is described. A series of structurally diverse indole‐pyrrole and pyrrole‐pyrrole N−N atropisomers were obtained in good yields (up to 98 %) with excellent enantioselectivity (up to 99 % ee). This reaction features perfect atom economy, wide substrate scope, and multifunctionalized products allowing diverse transformations.
Microgrids can be used to restore critical load after a natural disaster, enhancing resilience of a distribution network. To deal with the stochastic nature of intermittent energy resources, such as ...wind turbines (WTs) and photovoltaics (PVs), forecast information is usually required. However, some microgrids may not be equipped with power forecasting tools. To fill this gap, a risk-limiting strategy based on measurements is proposed. A Gaussian mixture model is used to represent a prior joint probability density function of power outputs of WTs and PVs over multiple periods. As time rolls forward, the probability distribution of WT/PV generation is recursively updated using the latest measurement data. The updated distribution is used as an input of the risk-limiting load restoration problem, enabling an equivalent transformation of the original chance constrained problem into a mixed integer linear programming. Simulations on a distribution system with three microgrids demonstrate the effectiveness of the proposed method. Results indicate that networked microgrids can perform better in uncertainty management relative to stand-alone microgrids.
The first copper‐catalyzed intermolecular dearomatization of indoles by an asymmetric propargylic substitution reaction was developed. This method provides a highly efficient synthesis of versatile ...furoindoline and pyrroloindoline derivatives containing a quaternary carbon stereogenic center and a terminal alkyne moiety with up to 86 % yield and 98 % ee.
New sub: The title reaction provides a highly efficient synthesis of versatile furoindoline and pyrroloindoline derivatives containing a quaternary carbon stereogenic center and a terminal alkyne moiety with up to 86 % yield and 98 % ee by an asymmetric propargylic substitution reaction.
Extending traditional deterministic economic dispatch to incorporate significant stochastic wind power is an important but challenging task in today's power system decision making. In this paper, ...this issue is formulated as a chance-constrained economic dispatch (CCED) problem. Usually, in the presence of non-Gaussian correlated random variables, both the objective function and constraints are difficult to handle. To address this issue, this paper provides a novel method dealing with non-Gaussian random variables. First, the Gaussian mixture model is adopted to represent the joint probability density function of power output for multiple wind farms. Then, analytical formulae are derived that can be used for fast computation of partial derivatives of the objective function and transformation of chance constraints into linear ones. Thereafter, the CCED can be solved as a deterministic linear convex optimization with a global optimal solution. The effectiveness and efficiency of the proposed methodology are validated via a case study with a modified IEEE 39-bus system.
A copper(I) 3,5‐diphenyltriazolate metal–organic framework (CuTz‐1) was synthesized and extensively characterized by using a multi‐technique approach. The combined results provided solid evidence ...that CuTz‐1 features an unprecedented Cu5tz6 cluster as the secondary building unit (SBU) with channels approximately 8.3 Å in diameter. This metal–organic framework (MOF) material, which is both thermally and chemically (basic and acidic) stable, exhibited semiconductivity and high photocatalytic activity towards the degradation of dyes in the presence of H2O2. Its catalytic performance was superior to that of reported MOFs and comparable to some composites, which has been attributed to its high efficiency in generating .OH, the most active species for the degradation of dyes. It is suggested that the photogenerated holes are trapped by CuI, which yields CuII, the latter of which behaves as a catalyst for a Fenton‐like reaction to produce an excess amount of .OH in addition to that formed through the scavenging of photogenerated electrons by H2O2. Furthermore, it was shown that a dye mixture (methyl orange, methyl blue, methylene blue, and rhodamine B) could be totally decolorized by using CuTz‐1 as a photocatalyst in the presence of H2O2 under the irradiation of a Xe lamp or natural sunlight.
In the frame: A thermally and chemically stable CuI–triazolate metal–organic framework (CuTz‐1) was prepared and demonstrated to exhibit high photocatalytic activity towards the degradation of dyes in the presence of H2O2 (see figure for dye decolorization). CuTz‐1 could be used as a catalyst for at least four cycles without significant change to the crystallinity and catalytic activity.
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