Electric vehicles (EVs) are promising to provide frequency regulation services due to their fast regulating characteristics. However, when EVs participate in supplementary frequency regulation, it is ...challenging to simultaneously achieve the dispatch of the control center and the expected state of charge (SOC) levels of EV batteries. To solve this problem, in this paper we propose a vehicle-to-grid (V2G) control strategy, in which an uncertain dispatch is implemented in the control center without detailed EV charging/discharging information. The regulation from the control center is achieved by allocating the regulation task within the frequency regulation capacity of EVs. The expected SOC levels of EV batteries are guaranteed by a real-time correction of their scheduled V2G power in EV charging stations. Simulations on an interconnected two-area power system validate the effectiveness of the proposed V2G control in achieving both the frequency regulation and the expected SOC levels of EVs.
Small-Signal Stability Constrained Optimal Power Flow (SSSC-OPF) can provide additional stability measures and control strategies to guarantee the system to be small-signal stable. However, due to ...the nonsmooth property of the spectral abscissa function, existing algorithms solving SSSC-OPF cannot guarantee convergence. To tackle this computational challenge of SSSC-OPF, we propose a Sequential Quadratic Programming (SQP) method combined with gradient sampling for SSSC-OPF. At each iteration of the proposed SQP, the gradient of the spectral abscissa function is randomly sampled at the current iterate and additional nearby points to make the search direction computation effective in nonsmooth regions. The method can guarantee SSSC-OPF is globally and efficiently convergent to stationary points with probability one. The effectiveness of the proposed method is tested and validated on WSCC 3-machine 9-bus system, New England 10-machine 39-bus system, and IEEE 54-machine 118-bus system.
In this study, graphene-oxide (GO)-reinforced Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium-alloy-matrix composites were fabricated by powder metallurgy. The mixed powders with well-dispersed GO ...sheets were obtained by temperature-controlled solution mixing, in which GO sheets adsorb on the surface of titanium alloy particles. Vacuum deoxygenating was applied to remove the oxygen-containing groups in GO, in order to reduce the introduction of oxygen. The compact composites with refined equiaxed and lamellar α phase structures were prepared by hot isostatic pressing (HIP). The results show that in-situ TiC layers form on the surface of GO and GO promotes the precipitation of hexagonal (TiZr)6Si3 particles. The composites exhibit significant improvement in strength and microhardness. The room-temperature tensile strength, yield strength and microhardness of the composite added with 0.3 wt% GO are 9%, 15% and 27% higher than the matrix titanium alloy without GO, respectively, and the tensile strength and yield strength at 600 °C are 3% and 21% higher than the matrix alloy. The quantitative analysis indicates that the main strengthening mechanisms are load transfer strengthening, grain refinement and (TiZr)6Si3 second phase strengthening, which accounted for 48%, 30% and 16% of the improvement of room-temperature yield strength, respectively.
System on Wafer (SoW) based on chiplets may be implanted with hardware Trojans (HTs) by untrustworthy third-party chiplet vendors. However, traditional HTs protection techniques cannot guarantee ...complete protection against HTs, which poses a great challenge to the hardware security of SoW. In this paper, we propose a computing architecture based on endogenous security theory—dynamic heterogeneous redundant computing architecture (DHRCA) that can tolerate and detect HTs at runtime. The security of our approach is analyzed by building a generalized stochastic coloring petri net (GSCPN) model of DHRCA. The simulation results based on the GSCPN model show that our method can improve the system security probability to 0.8690 and the system availability probability to 0.9750 in the steady state compared with typical triple-mode redundancy and runtime monitoring methods. Furthermore, the impact of different attack and defense strategies on system security of different methods is simulated and analyzed in this paper.
The essence of traditional power system’s small signal stability analysis model using the eigenvalue analysis method is to analyze the time-invariant system obtained after the approximate ...linearization of the system, because it only considers the equilibrium state and therefore cannot consider the power system nonlinearity. In contrast, time-domain simulation can fully consider the system nonlinearity from the whole small signal dynamic period, because it considers not only the equilibrium state but also the state after the equilibrium point. On the basis of the time-domain simulation idea, this paper proposes an SSSC-OPF (small signal stability constrained-optimal power flow) based on optimizing the rotor angle trajectory. The objective function and the SSS constraint (small signal stability constraint) of the model are extracted from rotor angle curves of each generator, and the system stability is ensured by both in concert. Compared with the general SSSC-OPF model using the SSS constraint based on the eigenvalues, the proposed model can consider nonlinearity while avoiding the errors caused by the approximate linearization in the general SSSC-OPF model, and has a higher degree of generalizability. Finally, this paper performs the simulations in three test systems, the IEEE 9-bus test system, the IEEE 39-bus test system, and the IEEE 118-bus test system, and verifies the proposed model’s effectiveness by comparing the simulation results.
Background
Hepatocellular carcinoma (HCC) remains a worldwide burden. However, the mechanisms behind the malignant biological behavior of HCC remain unclear. The homeobox (HOX) family could act as ...either promoters or suppressors in different kinds of malignancies. Our study discovered the role of HOXB5 in regulating HCC progression.
Methods
The HOXB5 expression was assessed by RT-PCR analysis in human HCC samples and cell lines. HOXB5 transcriptional regulation of the EGFR was verified by the luciferase reporter assay and chromatin immunoprecipitation experiment. The oncogenic role of HOXB5 in HCC progression was analyzed by CCK8, colony-forming, and transwell assays.
Results
Upregulation of HOXB5 was found in human HCC, and was strongly correlated with HCC tumor size, tumor-nodule metastasis, TNM stage, and relatively unfavorable OS and DFS. Ectopic expression of HOXB5 promoted the capacity of cell growth and clonogenicity, while the inhibition of HOXB5 decreased the proliferation and clonogenicity potential
in vitro
by CCK8 and colony-forming assays. In addition, HOXB5 also promoted cell migration by transwell experiment. Mechanism studies elucidated that HOXB5 triggers HCC progression
via
direct transcriptional activation of EGFR. The upregulation of HOXB5 is regulated by miR-200a-3p and miR-181-5p. Transfection of miR-200a-3p and miR-181-5p mimics blocked the cell proliferation and migration regulated by HOXB5, while overexpression of the 3′-UTR mutant HOXB5 abolished the suppressive effect of miR-200a-3p and miR-181-5p, but not the wild-type HOXB5.
Conclusion
HOXB5 is a promising prognostic factor in human HCC. Targeting miR-200a-3p and the miR-181-5p/HOXB5/EGFR signaling pathway may provide new options for the treatment strategies of HCC.
Cardiovascular aging has been reported to accelerate in spaceflights, which is a great potential risk to astronauts’ health and performance. However, current exercise routines are not sufficient to ...reverse the adverse effects of microgravity exposure. Recently, salidroside (SAL), a valuable medicinal herb, has been demonstrated to display an important role for prevention and treatment in cardiovascular and other diseases. In the present work, Sprague–Dawley rats with four-week tail-suspension hindlimb-unloading were used to simulate microgravity effects on the cardiovascular system. We found that intragastrical administration of SAL not only significantly decreased the expressions of senescence biomarkers, such as P65 and P16, but also obviously increased the expressions of BK-dependent apoptotic genes, including the large-conductance calcium-activated K+ channel (BK), Bax, Bcl-2, and cleaved caspase-3, in vascular smooth muscle cells (VSMCs) in vivo and in vitro. In addition, relative non-coding RNAs were screened, and a luciferase assay identified that SAL increased apoptosis by activating LncRNA-FLORPAR, inhibiting miR-193, and then triggering the activity of the BK-α subunit. Our work indicated that SAL is a novel non-coding RNA modulator for regulating the LncRNA-FLORPAR sponging miR-193 pathway, which significantly promoted BK-dependent apoptosis and delayed cerebrovascular aging-like remodeling during simulated microgravity exposure. Our findings may provide a new approach to prevent cardiovascular aging in future spaceflights.
Forming complex geometries using the casting process is a big challenge for bulk metallic glasses (BMGs), because of a lack of time of the window for shaping under the required high cooling rate. In ...this work, we open an approach named the "entire process vacuum high pressure die casting" (EPV-HPDC), which delivers the ability to fill die with molten metal in milliseconds, and create solidification under high pressure. Based on this process, various Zr-based BMGs were prepared by using industrial grade raw material. The results indicate that the EPV-HPDC process is feasible to produce a glassy structure for most Zr-based BMGs, with a size of 3 mm × 10 mm and with a high strength. In addition, it has been found that EPV-HPDC process allows complex industrial BMG parts, some of which are hard to be formed by any other metal processes, to be net shaped precisely. The BMG components prepared by the EVP-HPDC process possess the advantages of dimensional accuracy, efficiency, and cost compared with the ones formed by other methods. The EVP-HPDC process paves the way for the large-scale application of BMGs.
Power system outages/blackouts, especially weather related, are becoming more and more frequent, incurring significant economic and social costs. The ability to restore power services quickly after a ...blackout is crucial for power system resilience. Power system restoration is an extremely complicated process, involving multiple steps, highly combinatorial operational decisions, and highly nonlinear technical constraints, which make restoration planning an exceptionally challenging task. This paper will first introduce the restoration process and operations, examine important issues in restoration, and survey the state of the art in the research and practice of power system restoration planning. Then, we will focus on the commonly used buildup restoration planning strategy, in which the system is sectionalized into smaller subsystems with initial power sources, and then the subsystems are restored in parallel. Due to the complexity, existing approaches treat the sectionalization and restoration separately, leading to a suboptimal restoration plan. We will introduce an integrated restoration planning approach to improve the quality of restoration plans globally (such as shorter overall restoration time) by using mathematical programming and simulation in an interactive and iterative way. Case studies will be provided to illustrate the effectiveness of the proposed approach.
The non-isothermal oxidation behaviors of TiAl and Ti3Al alloys at 1450-1570 ℃ in a pure oxygen atmosphere were studied by using TGA/DSC simultaneous thermal analysis, SEM and EPMA characterizations ...and theoretical calculation. The results show that a continuous dense Al2O3 barrier layer is formed on the melt surface of TiAl alloy, when the oxidation temperature is higher than the melting point of TiAl alloy. The Gibbs free energy of Al reacting with O in the melt is 50-150 kJ∙mol-1 lower than that of Ti, Cr and Nb. The diffusion coefficient(D) of Al atom in the melt of TiAl alloy is about 1.7 times that of Ti atom. The Al atoms continue to diffuse to the melt surface and preferentially react with O to form a continuous and dense Al2O3 layer. The Al2O3 barrier layer effectively hinders the diffusion of oxygen and metal ions inside and outside the matrix. TiAl alloy melts and absorbs heat to reduce the matrix temperature and slows down the oxidation rate, resulting in the non-isothermal oxidation resistance of
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