Improving Big Data Box-Cox Transformation on Spark

This study investigates improving Spark computation with Box-Cox Information Array when it is used to implement the linear regression models. In order to find the best linear regression model that fit the data, traditional methods have to read whole data many times, which is really time-consuming. Apache Spark can train linear regression model efficiently with distributed clusters because it processes all the data in memory. However, if the data size is huge or there are a lot of temporary data during the computation, it has to spill the data to disk and read it back later. These frequent I/O operations will affect the Spark computation. With the method proposed by Zhang and Yang (2017), information needed for linear regression can be stored in memory with small matrix called Box-Cox Information Array. This information array requires raw data to be scanned one time only. With this information array, the best linear regression model could be obtained at once. This study applies the Box-Cox Information Array method in Spark to understand how it affects the Spark computation performance. The experiment proves that when training forty-one models, the Box-Cox Information Array method is about 8 times faster than the existing API provided in Apache Spark when training 41 models, and it has better performance of prediction

Predictive Analysis and Correction Control of <i>CCT</i> for a Power System Based on a Broad Learning System

Transient stability is an important factor for the stability of a power system. With improvements in voltage levels, and the expansion of power network scales, the problem of transient stability is particularly prominent. When a power system circuit fails, if the operation time of the relay protection device is higher than the critical clearing time (CCT), the relay protection device cannot cut the fault line in a timely manner. It is essential to forecast and adjust the CCT to improve the stability of the system; therefore, a method is proposed in this paper to predict and evaluate the critical clearing time using the broad learning system (BLS). The sensitivity of the critical clearing time can be easily calculated based on the prediction results of the critical clearing time using BLS. Moreover, the critical clearing time can be modified using the BLS correction control model. The proposed method was verified using a 4-machine 11-node system and a 10-machine 39-node system. According to the experimental results, the proposed model can predict, evaluate, and correct the CCT very well

Impedance-frequency characteristic analysis of bypass damping filter in suppressing AC–DC system’s subsynchronous resonance

Recently, subsynchronous resonance (SSR) in HVDC transmission is considered to be related to electronic converter equipment and complex control systems. Aiming at the subsynchronous resonance problem caused by frequent topology changes of AC–DC systems, this paper firstly proposes an impedance-frequency characteristic analysis method based on Thevenin Equivalent and Fast Fourier Transform (FFT) algorithm. This method is used to analyze the impedance frequency characteristics of AC–DC systems after the bypass damping filter (BDF) is configured. Firstly, based on the IEEE first benchmark model, the mechanism of BDF in suppressing subsynchronous resonance is explained by quantitative analysis, and the BDF parameter setting method is proposed. Then, the time domain simulation model of a single-machine HVDC system with BDF is established in PSCAD/EMTDC. Finally, according to Thevenin’s theorem, the equivalent structure of each subsystem is simplified, and the FFT algorithm is used to solve the harmonic equivalent impedance of each subsystem. After BDF is configured, the mechanical resonance frequency ”transfers” from 16Hz to 10Hz, and the minimum electrical damping changes from -0.9637 to -0.4581. The results show that the BDF configuration can change the impedance-frequency characteristics of the system, thereby improving the electrical damping in the torsional vibration mode in a targeted manner, and has a certain effect on suppressing the subsynchronous resonance of AC–DC systems

The Expression Pattern of Insulin-Like Growth Factor Subtype 3 (igf3) in the Orange-Spotted Grouper Epinephelus coioides and Its Function on Ovary Maturation

A new insulin-like growth factor (Igf) subtype 3 (igf3) has recently been found in the bony fish orange-spotted grouper (Epinephelus coioides). However, the role of igf3 in the maturation of the ovary and sex differentiation in E. coioides is currently unknown. We examined the ovarian localization and receptor binding of the novel ortholog Igf3 using qRT-PCR, and Western blotting, combined with in situ hybridization and immunohistochemistry methods. Results demonstrated the presence of igf3 mRNA and protein in mature oocytes. Furthermore, Igf3 protein expression was not detected in testis, brain, kidney and liver homogenates. The calculated molecular weight of Igf3 was 22 kDa, which was consistent with the deduced amino acid sequence from the full-length open reading frame. The immunoreactivity showed that Igf3 was strongly present in the follicle staining fully-grown stage. The igf3 mRNA expression level was significantly positively correlated with ovarian follicular maturation. Meanwhile, Igf3 increased germinal-vesicle breakdown in a time- and dose-dependent manner. In vitro, treatment of primary ovarian cells with Igf3 up-regulated significantly the mRNA expression level of genes related to sex determination and reproduction such as forkhead boxl2 (foxl2), dosage-sensitive sex reversal adrenal hypoplasia critical region on chromosome x gene 1 (dax1), cytochrome P450 family 19 subfamily member 1 a (cyp19a1a), cytochrome P450 family 11 subfamily a member 1 a (cyp11a1a) and luteinizing hormone receptor 1 (lhr1). Overall, our results demonstrated that igf3 promotes the maturation of the ovary and plays an important role in sex differentiation in E. coioides

Prophylactic Effect of Lactobacillus plantarum YS4 on Oxazolone-Induced Colitis in BALB/c Mice

In the present research, the effects of Lactobacillus plantarum YS4 (LP-YS4) on colitis were tested in an oxazolone-induced mouse model. BALB/c mice were induced by oxazolone and then treated with LP-YS4. The serum levels of mice were analyzed using commercial kits and the protein and mRNA expression levels of mouse colon tissue were detected by Western blotting and qPCR assay, respectively. The results demonstrated that LP-YS4 significantly (P<0.05) increased the colon length and ratio of colon weight/length in mice with colitis and attenuated the negative effects of colitis. The results also showed that treatment with LP-YS4 significantly reduced the serum concentrations of ET-1, SP, and IL-10 while significantly increasing those of SS, VIP, and IL-2 in colitis mice (P<0.05). In addition, LP-YS4 significantly increased the activities of GSH and SOD while decreasing those of MPO and MDA in the colon tissue of colitis mice (P<0.05). LP-YS4 also significantly upregulated the mRNA and protein expression of c-Kit, eNOS, nNOSe, and SCF in colitis mice while significantly downregulating the relative expression of iNOS. In summary, LP-YS4 could reduce the negative effects of colitis, and such effects were better than those of the common probiotic Lactobacillus bulgaricus

Reactivity and Mechanism Studies of Hydrogen Evolution Catalyzed by Copper Corroles

Several copper corrole complexes were synthesized, and their catalytic activities for hydrogen (H₂) evolution were examined. Our results showed that substituents at the <i>meso</i> positions of corrole macrocycles played significant roles in regulating the redox and thus the catalytic properties of copper corrole complexes: strong electron-withdrawing substituents can improve the catalysis for hydrogen evolution, while electron-donating substituents are not favored in this system. The copper complex of 5,15-pentafluorophenyl-10-(4-nitrophenyl)­corrole (<b>1</b>) was shown to have the best electrocatalytic performance among copper corroles examined. Complex <b>1</b> can electrocatalyze H₂ evolution using trifluoroacetic acid (TFA) as the proton source in acetonitrile. In cyclic voltammetry, the value of <i>i</i>_cat/<i>i</i>_p = 303 (<i>i</i>_cat is the catalytic current, <i>i</i>_p is the one-electron peak current of <b>1</b> in the absence of acid) at a scan rate of 100 mV s^–1 and 20 °C is remarkable. Electrochemical and spectroscopic measurements revealed that <b>1</b> has the desired stability in concentrated TFA acid solution and is unchanged by functioning as an electrocatalyst. Stopped-flow, spectroelectrochemistry, and theoretical studies provided valuable insights into the mechanism of hydrogen evolution mediated by <b>1</b>. Doubly reduced <b>1</b> is the catalytic active species that reacts with a proton to give the hydride intermediate for subsequent generation of H₂

The Mechanism of E–H (E = N, O) Bond Activation by a Germanium Corrole Complex: A Combined Experimental and Computational Study

(TPFC)­Ge­(TEMPO) (<b>1</b>, TPFC = tris­(pentafluorophenyl)­corrole, TEMPO^• = (2,2,6,6-tetramethylpiperidin-1-yl)­oxyl) shows high reactivity toward E–H (E = N, O) bond cleavage in R₁R₂NH (R₁R₂ = HH, ^<i>n</i>PrH, ^<i>i</i>Pr₂, Et₂, PhH) and ROH (R = H, CH₃) under visible light irradiation. Electron paramagnetic resonance (EPR) analyses together with the density functional theory (DFT) calculations reveal the E–H bond activation by [(TPFC)­Ge]⁰(<b>2</b>)/TEMPO^• radical pair, generated by photocleavage of the labile Ge–O bond in compound <b>1</b>, involving two sequential steps: (i) coordination of substrates to [(TPFC)­Ge]⁰ and (ii) E–H bond cleavage induced by TEMPO^• through proton coupled electron transfer (PCET)

Reactivity and Mechanism Studies of Hydrogen Evolution Catalyzed by Copper Corroles

Several copper corrole complexes were synthesized, and their catalytic activities for hydrogen (H₂) evolution were examined. Our results showed that substituents at the <i>meso</i> positions of corrole macrocycles played significant roles in regulating the redox and thus the catalytic properties of copper corrole complexes: strong electron-withdrawing substituents can improve the catalysis for hydrogen evolution, while electron-donating substituents are not favored in this system. The copper complex of 5,15-pentafluorophenyl-10-(4-nitrophenyl)­corrole (<b>1</b>) was shown to have the best electrocatalytic performance among copper corroles examined. Complex <b>1</b> can electrocatalyze H₂ evolution using trifluoroacetic acid (TFA) as the proton source in acetonitrile. In cyclic voltammetry, the value of <i>i</i>_cat/<i>i</i>_p = 303 (<i>i</i>_cat is the catalytic current, <i>i</i>_p is the one-electron peak current of <b>1</b> in the absence of acid) at a scan rate of 100 mV s^–1 and 20 °C is remarkable. Electrochemical and spectroscopic measurements revealed that <b>1</b> has the desired stability in concentrated TFA acid solution and is unchanged by functioning as an electrocatalyst. Stopped-flow, spectroelectrochemistry, and theoretical studies provided valuable insights into the mechanism of hydrogen evolution mediated by <b>1</b>. Doubly reduced <b>1</b> is the catalytic active species that reacts with a proton to give the hydride intermediate for subsequent generation of H₂

Production of Formamides from CO and Amines Induced by Porphyrin Rhodium(II) Metalloradical

It is of fundamental importance to transform carbon monoxide (CO) to petrochemical feedstocks and fine chemicals. Many strategies built on the activation of CO bond by π-back bonding from the transition metal center were developed during the past decades. Herein, a new CO activation method, in which the CO was converted to the active acyl-like metalloradical, [(por)­Rh­(CO)]^• (por = porphyrin), was reported. The reactivity of [(por)­Rh­(CO)]^• and other rhodium porphyrin compounds, such as (por)­RhCHO and (por)­RhC­(O)­NH^<i>n</i>Pr, and corresponding mechanism studies were conducted experimentally and computationally and inspired the design of a new conversion system featuring 100% atom economy that promotes carbonylation of amines to formamides using porphyrin rhodium­(II) metalloradical. Following this radical based pathway, the carbonylations of a series of primary and secondary aliphatic amines were examined, and turnover numbers up to 224 were obtained