Ultrasonic Welding of Aluminum to Steel: A Review

As a solid-state bonding technology, ultrasonic welding (USW) has the characteristics of green energy saving and environmental friendliness. It is more suitable for joining dissimilar metals than other welding technologies. The aluminum-to-steel USWed joint has been widely used in the automotive and aviation industries. Currently, there is no review literature report on aluminum-to-steel USW. The main physical phenomena of the USW process include interface temperature increase, ultrasonic softening, plastic deformation, formation and growth of the IMCs, and dynamic recrystallization. Hence, the microstructures and mechanical properties of aluminum-alloy-to-low-carbon-steel, aluminum-alloy-to-stainless steel, and aluminum-alloy-to-galvanized-steel-joints by USW are reviewed. Moreover, the effect of interface temperature, interface plastic deformation, and interface macrostructure and microstructure is explored. Lastly, tensile-shear and fatigue strength of joints and numerical simulation of the USW process are also discussed. In addition, some new application types of aluminum-to-steel USW are introduced. Finally, the future trends of aluminum-to-steel USW with guidance are provided

The Effect Analysis of Water Diversion on Water Quality Improvement: A Case Study in Urban Lake, China

With the rapid progress of society and economy on a regional level, river pollution trends have risen, causing an overwhelmingly poor water quality in urban lakes. In this study, a two-dimensional coupled hydrodynamic and water quality model was employed to assess the enhancement of water quality subsequent to the implementation of water diversion measures in Lake Hou, a representative urban lake located in Wuhan. The model was established based on detailed data collection via survey analysis, model simulation, and joint analysis. The total amount of pollutants in Lake Hou before and after pollution interception and control was compared and analyzed. The observed lake water level, discharge, and water quality parameters, including total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD), were utilized to evaluate the performance of the model. The results showed that the water quality of Lake Hou improved as the recharge flow increased. When the recharge flow was 10 m3/s, TP, TN, and COD improvements were 28.94%, 24.14%, and 14.30%, respectively. When the recharge flow was 15 m3/s, TP, TN, and COD improvements were 33.14%, 27.77%, and 15.57%, respectively. When the recharge flow was 20 m3/s, TP, TN, and COD improvements were 35.74%, 30.10%, and 16.29%, respectively. However, a downward trend can be observed with increasing rates of TP, TN, and COD improvements (%), from 10 m3/s to 15 m3/s, at 4.2%, 3.56%, and 1.27%, respectively. The increasing rates of TP, TN, and COD improvements (%) from 15 m3/s to 20 m3/s were 2.6%, 2.4%, and 0.27%, respectively. This study offers a valuable technical solution for the management of urban lakes

Simulation and Experimental Study on Jet Velocity of Zr-Based Amorphous Alloy Liner

Zr-based amorphous alloy is a new energetic material that has been closely monitored and extensively studied for the design of highly effective shaped charge warheads in recent years. In order to accurately determine the motion parameters of shaped charge jets during the detonation-driven formation process of Zr-based amorphous alloy liners, we prepared conical ZrCuNiAlAg liners by vacuum die casting and supercooled liquid high-rheological-rate formation processes. Based on jet-formation numerical simulation, pulsed X-ray imaging and copper foil target velocity measuring tests were conducted to identify the variation trend of the jet velocity of Zr-based amorphous alloy liners with time. The jet velocities at typical moments in the free flight stage were verified. The research results showed that Zr-based amorphous alloy liners could produce solid jets, whose velocity was in gradient descent from the head to the tail, and that the jet’s head velocity peaked at 12 μs and then slowly decreased with time. The average velocities measured by the X-ray imaging and copper foil target tests were 6913 m/s and 7177 m/s, respectively, and both of them were in good agreement with the simulation results, verifying the accuracy of the numerical simulation model for jet formation. The formation processes of shaped charge liners were found to affect the mechanical properties of the material and thus, the jet’s formation process and motion parameters. The Zr-based amorphous alloy liner formed by the supercooled liquid-phase high-rheological-rate formation process exhibited a jet velocity 6.5% higher than that formed by the vacuum die casting process

Extra spuisluis in de Afsluitdijk: Effect op onderhoud havens

Datasets for constructing the miRNA-disease association prediction models. Four datasets such as three positive sample sets “positive_miR”, “positive_HMDD” and “positive_miRcancer” and the negative sample set “negative_expression” are stored. The three positive sample sets are retrieved from the three existing databases such as miR2Disease, HMDD v2 and miRCancer, while the negative sample set was obtained via analyzing the expression of the miRNAs.This file can also be downloaded from: https://drive.google.com/open?id=0B6lH3mKdA9CSTkg2OVBPS0ZfVnM . (XLS 947 kb

Additional file 1 of Imbalance learning for the prediction of N6-Methylation sites in mRNAs

Data set of human mature mRNA N6-Methylation. Training and testing data used in this paper is accessible in this file. For each sample, the transcript id, site position, transcript length and flanking sequence with a size of 26 nts are given. (XLSX 15155 kb

Additional file 2 of Imbalance learning for the prediction of N6-Methylation sites in mRNAs

Supplementary Tables, Algorithm and Figure. Table S1: The result of Fisher’s exact test on training data. The SNP variant states of positive and negative samples are counted respectively at all positions in window sequence. The P-value is computed with Fisher’s exact function from Python scipy package. Table S2: Complete SNP specificity ranking for all positions. Table S3: The feature distribution in HMpre feature space. Algorithm S1: SNP Specificity Identification Algorithm. Figure S1: Distribution of feature importance scores in XGBoost Classifier learning stage. (PDF 323 kb

Three-dimensional thermal weight function method for the interface crack problems in bimaterial structures under a transient thermal loading

Different from previous two-dimensional thermal weight function (TWF) method, a three-dimensional (3D) TWF method is proposed for solving elliptical interface crack problems in bimaterial structures under a transient thermal loading. The present 3D TWF method based on the Betti's reciprocal theorem is a powerful tool for dealing with the transient thermal loading due to the stress intensity factors (SIFs) of whole transient process obtained through the static finite element computation. Several representative examples demonstrate that the 3D TWF method can be used to predict the SIFs of elliptical interface crack subjected to transient thermal loading with high accuracy. Moreover, numerical results indicate that the computing efficiency can be enhanced when dealing with transient problems, especially for large amount of time instants