Uncertainty and Explainable Analysis of Machine Learning Model for Reconstruction of Sonic Slowness Logs

Logs are valuable information for oil and gas fields as they help to determine the lithology of the formations surrounding the borehole and the location and reserves of subsurface oil and gas reservoirs. However, important logs are often missing in horizontal or old wells, which poses a challenge in field applications. In this paper, we utilize data from the 2020 machine learning competition of the SPWLA, which aims to predict the missing compressional wave slowness and shear wave slowness logs using other logs in the same borehole. We employ the NGBoost algorithm to construct an Ensemble Learning model that can predicate the results as well as their uncertainty. Furthermore, we combine the SHAP method to investigate the interpretability of the machine learning model. We compare the performance of the NGBosst model with four other commonly used Ensemble Learning methods, including Random Forest, GBDT, XGBoost, LightGBM. The results show that the NGBoost model performs well in the testing set and can provide a probability distribution for the prediction results. In addition, the variance of the probability distribution of the predicted log can be used to justify the quality of the constructed log. Using the SHAP explainable machine learning model, we calculate the importance of each input log to the predicted results as well as the coupling relationship among input logs. Our findings reveal that the NGBoost model tends to provide greater slowness prediction results when the neutron porosity and gamma ray are large, which is consistent with the cognition of petrophysical models. Furthermore, the machine learning model can capture the influence of the changing borehole caliper on slowness, where the influence of borehole caliper on slowness is complex and not easy to establish a direct relationship. These findings are in line with the physical principle of borehole acoustics

Experimental Quantum Communication Overcomes the Rate-loss Limit without Global Phase Tracking

Secure key rate (SKR) of point-point quantum key distribution (QKD) is fundamentally bounded by the rate-loss limit. Recent breakthrough of twin-field (TF) QKD can overcome this limit and enables long distance quantum communication, but its implementation necessitates complex global phase tracking and requires strong phase references which not only add to noise but also reduce the duty cycle for quantum transmission. Here, we resolve these shortcomings, and importantly achieve even higher SKRs than TF-QKD, via implementing an innovative but simpler measurement-device-independent QKD which realizes repeater-like communication through asynchronous coincidence pairing. Over 413 and 508 km optical fibers, we achieve finite-size SKRs of 590.61 and 42.64 bit/s, which are respectively 1.80 and 4.08 times of their corresponding absolute rate limits. Significantly, the SKR at 306 km exceeds 5 kbit/s and meets the bitrate requirement for live one-time-pad encryption of voice communication. Our work will bring forward economical and efficient intercity quantum-secure networks.Comment: 29 pages, 10 figures, 3 table

Involvement of C4 Protein of Beet Severe Curly Top Virus (Family Geminiviridae) in Virus Movement

Background: Beet severe curly top virus (BSCTV) is a leafhopper transmitted geminivirus with a monopartite genome. C4 proteins encoded by geminivirus play an important role in virus/plant interaction. Methods and Findings: To understand the function of C4 encoded by BSCTV, two BSCTV mutants were constructed by introducing termination codons in ORF C4 without affecting the amino acids encoded by overlapping ORF Rep. BSCTV mutants containing disrupted ORF C4 retained the ability to replicate in Arabidopsis protoplasts and in the agro-inoculated leaf discs of N. benthamiana, suggesting C4 is not required for virus DNA replication. However, both mutants did not accumulate viral DNA in newly emerged leaves of inoculated N. benthamiana and Arabidopsis, and the inoculated plants were asymptomatic. We also showed that C4 expression in plant could help C4 deficient BSCTV mutants to move systemically. C4 was localized in the cytosol and the nucleus in both Arabidopsis protoplasts and N. benthamiana leaves and the protein appeared to bind viral DNA and ds/ssDNA nonspecifically, displaying novel DNA binding properties. Conclusions: Our results suggest that C4 protein in BSCTV is involved in symptom production and may facilitate virus movement instead of virus replication

Finite Element Dynamic Analysis on Residual Stress Distribution of Titanium Alloy and Titanium Matrix Composite after Shot Peening Treatment

The residual stress distribution introduced by shot peening (SP) in the deformed surface layer of Ti-6Al-4V and (TiB+TiC)/Ti-6Al-4V were simulated and studied via the three-dimensional (3D) finite element dynamic analysis and the experimental validation. The program of ANSYS/LS-DYNA was utilized, and the 3D homogeneous and inhomogeneous models were set up. The homogeneous model was established for simulating SP process on Ti-6Al-4V. The influence of three important parameters, the shot balls’ size, shot velocity and coverage rate on residual stress distribution were investigated. Numerical simulation results showed that these parameters contributed different effects on SP treatment. Using a simplified method, an inhomogeneous model for simulating SP process on (TiB+TiC)/Ti-6Al-4V was set up. The max tensile and compressive residual stress (CRS) was +1155 and −1511 MPa, respectively. Based on this stress distribution, the beneficial effect of reinforcements was indicated during deformation, retarding the damage to the matrix and keeping the adverse tensile stresses in the reinforcements. In order to verify the results of simulation, the residual stress distribution along depth was measured by X-ray diffraction (XRD) method. The residual stress distribution by experiments was agreed with the simulated results, which verified the availability of 3D finite element dynamic analysis

Grain boundary and texture evolution of TiB/Ti–2Al–6Sn titanium matrix composite under electroshocking treatment

This work used electroshocking treatment (EST) plus external loading to regulate the microstructure of titanium matrix composites (TMCs). The external loading was 0.3 MPa. After EST plus external loading with 0.3 MPa, the was reduced to 2.53 m in size. The percentage of high angle grain boundaries (HAGBs) in increased first and then decreased. The percent of HAGBs in TiB decreased, mainly due to the introduction of abundant dislocations in the TiB/matrix interface after EST. After EST, the maximum texture strength of TiB decreased from 13.09 to 12.97, and that of decreased from 3.11 to 1.58. After EST under external loading with 0.3 MPa, the maximum texture strength of TiB decreased to 8.10. The orientation of TiB experienced significant variation. TEM results showed that TiB and formed a distorted interface after EST under external loading with 0.3 MPa. The interplanar spacing of TiB and was varied. All results show that the texture of TMCs can be relieved by EST plus external loading with 0.3 MPa. It is mainly attributed to the thermal and athermal effects and the imposed external loads with EST. EST plus external loading provides a new method for manipulating the microstructure of TMCs

Single underwater image enhancement based on adaptive correction of channel differential and fusion

Clear underwater images are necessary in many underwater applications, while absorption, scattering, and different water conditions will lead to blurring and different color deviations. In order to overcome the limitations of the available color correction and deblurring algorithms, this paper proposed a fusion-based image enhancement method for various water areas. We proposed two novel image processing methods, namely, an adaptive channel deblurring method and a color correction method, by limiting the histogram mapping interval. Subsequently, using these two methods, we took two images from a single underwater image as inputs of the fusion framework. Finally, we obtained a satisfactory underwater image. To validate the effectiveness of the experiment, we tested our method using public datasets. The results showed that the proposed method can adaptively correct color casts and significantly enhance the details and quality of attenuated underwater images

All-Trans Retinoic Acid Treatment Is Associated with Prohibitin Expression in Renal Interstitial Fibrosis Rats

This study was performed to investigate the association of prohibitin with renal interstitial fibrosis (RIF) lesion and to explore the association of all-trans retinoic acid (ATRA) treatment with prohibitin expression in RIF rats. Rats were divided into three groups: the sham operation group (SHO), the model group subjected to unilateral ureteral obstruction (UUO), and the model group treated with ATRA (GA). Renal tissues were collected at 14 and 28 days after surgery, and the relevant indicators were detected. In comparison with the SHO group, the RIF index in the UUO group was markedly elevated (p < 0.01), and the RIF index in the GA group was alleviated compared with that in the UUO group (p < 0.01). Compared with the SHO group, the expression of prohibitin (protein or mRNA) in the UUO group was significantly reduced (each p < 0.01). Prohibitin expression in the GA group was markedly increased when compared with that in the UUO (p < 0.01). The expression of TGF-β1 (protein and mRNA), protein expressions of Col-IV, fibronectin, α-SMA and cleaved Caspase-3, ROS generation and cell apoptosis index in the UUO group were markedly higher than those in the SHO group (all p < 0.01), and their expressions in the GA group were markedly down-regulated compared to those in the UUO group (all p < 0.01, respectively). The protein expression of prohibitin was negatively correlated with the RIF index, protein expression of TGF-β1, Col-IV, fibronectin, α-SMA or cleaved Caspase-3, ROS generation and the cell apoptosis index (each p < 0.01). In conclusion, lower expression of prohibitin is associated with the RIF, and ATRA treatment is associated with increased prohibitin, which can prevent the progression of RIF

Palmitoylation and Membrane Association of the Stress Axis Regulated Insert (STREX) Controls BK Channel Regulation by Protein Kinase C

Large-conductance, calcium- and voltage-gated potassium (BK) channels play an important role in cellular excitability by controlling membrane potential and calcium influx. The stress axis regulated exon (STREX) at splice site 2 inverts BK channel regulation by protein kinase A (PKA) from stimulatory to inhibitory. Here we show that palmitoylation of STREX controls BK channel regulation also by protein kinase C (PKC). In contrast to the 50% decrease of maximal channel activity by PKC in the insertless (ZERO) splice variant, STREX channels were completely resistant to PKC. STREX channel mutants in which Ser(700), located between the two regulatory domains of K(+) conductance (RCK) immediately downstream of the STREX insert, was replaced by the phosphomimetic amino acid glutamate (S700E) showed a ∼50% decrease in maximal channel activity, whereas the S700A mutant retained its normal activity. BK channel inhibition by PKC, however, was effectively established when the palmitoylation-mediated membrane-anchor of the STREX insert was removed by either pharmacological inhibition of palmitoyl transferases or site-directed mutagenesis. These findings suggest that STREX confers a conformation on BK channels where PKC fails to phosphorylate and to inhibit channel activity. Importantly, PKA which inhibits channel activity by disassembling the STREX insert from the plasma membrane, allows PKC to further suppress the channel gating independent from voltage and calcium. Our results present an important example for the cross-talk between ion channel palmitoylation and phosphorylation in regulation of cellular excitability