MLatom 3: Platform for machine learning-enhanced computational chemistry simulations and workflows

Machine learning (ML) is increasingly becoming a common tool in computational chemistry. At the same time, the rapid development of ML methods requires a flexible software framework for designing custom workflows. MLatom 3 is a program package designed to leverage the power of ML to enhance typical computational chemistry simulations and to create complex workflows. This open-source package provides plenty of choice to the users who can run simulations with the command line options, input files, or with scripts using MLatom as a Python package, both on their computers and on the online XACS cloud computing at XACScloud.com. Computational chemists can calculate energies and thermochemical properties, optimize geometries, run molecular and quantum dynamics, and simulate (ro)vibrational, one-photon UV/vis absorption, and two-photon absorption spectra with ML, quantum mechanical, and combined models. The users can choose from an extensive library of methods containing pre-trained ML models and quantum mechanical approximations such as AIQM1 approaching coupled-cluster accuracy. The developers can build their own models using various ML algorithms. The great flexibility of MLatom is largely due to the extensive use of the interfaces to many state-of-the-art software packages and libraries

Diversity and evolution analysis of glycoprotein GP85 from avianleukosis virus subgroup J isolates from chickens of differentgenetic backgrounds during 1989?2016: Coexistence of fiveextremely different clusters

Abstract: ALV-J has caused the most serious losses tothe poultry industry in China. The gp85-coding sequenceof ALV-J is known to be prone to mutation, but any associationbetween the gp85 gene and breed of chicken remainsunclear. A comprehensive and systematic study of theevolutionary process of ALV-J in China is needed. In thisstudy, we compared and analyzed gp85 gene sequencesfrom 198 ALV-J isolates, originating from China, USA,UK and France during 1989-2016. These were sorted intofive clusters. Cluster 1, 2, 3, 4 and 5 included isolates fromchicken types of different genetic backgrounds, e.g. whitefeatherbroiler, Guangxi indigenous chicken breeds, Yellowchickens and layer chickens respectively. A correlationcomparison of amino acid sequence similarities in the gp85protein among the five clusters showed significant differences(P 0.05). Results of entropyanalysis of the gp85 sequences revealed that cluster 3 hadthe largest variation and cluster 1 had the least variation. TheN-glycosylation sites in the majority of isolates numbered14, 16, 17, 16 and 16, respectively, with regards to clusters1-5. In addition, 5 isolates from cluster 3 had one more glycosylationsite than the other isolates from cluster 3. Ourstudy provides evidence that there were five extremely differentALV-J clusters during 1989-2016 and that the gp85genes isolated from indigenous chicken breed isolates hadthe largest variation

Application of new type pre-classification hydrocyclone with centrifugal volute in grinding process

Hydrocyclone is widely used in closed-circuit grinding process. But in the first classification operation of coarse particles with high pulp density, the shortcomings of traditional cyclone are that the grinding cycle load is much high, the apex of cyclone is easily to be blocked and classification efficiency is less. Specifically, the problems of traditional cyclone used in grinding process are as follows: (1) Mill utilization factor is low and its handling capacity is small; (2) Coarse particles mixing in cyclone overflow affects the following separation process and fine particles mixing in underflow causes over-grinding, which affects the total recovery rate of valuable minerals; (3) High grinding cycle load leads to large amount of high density slurry pumping, which causes high energy consumption and severe wear of cyclones, pipelines and pumps. The applications of new type pre-classification hydrocyclone with centrifugal volute in the first classification process of Iron Mine Mill are introduced in the paper. Pulp particles fed in the centrifugal volute were arranged in advance, so that coarse particles can be far away from the overflow pipe, which can reduce the short circuit current to avoid coarse particles entering overflow and improve classification efficiency and accuracy of cyclone. The strong points of the new cyclone in the coarse classification operation are as follows: (1) finer overflow and less fine particles mixing in underflow improves classification efficiency more than 10%; (2) lower ball mill load cycle improves ball capacity more than 10%; (3) grinding energy consumption reduces by more than 20% and cyclone feed pump reduces energy consumption by more than 12%. In short, new type pre-classification cyclone with centrifugal volute solves the problems of fine particles mixing in underflow, high grinding cycle load and less classification efficiency in the coarse classification operation. Therefore, it has broad application prospects in ferrous metal and non-ferrous metal ore dressing plant

Optimal Shut-Down Policy for Air Separation Units in Integrated Steel Enterprises during a Blast Furnace Blow-Down

Optimal shut-down policy for air separation units (ASUs) in the oxygen distribution system is studied for the integrated steel enterprises with a captive oxygen plant during a blast furnace blow-down. A multiperiod mixed-integer linear programming (MILP) model was proposed, which includes the minimum time constraints for ASU shut-down and start-up and the zero vent constraint of gaseous oxygen. When the decision variables are scheduled simultaneously, such as the on/off states of the fixed-load compressors and ASUs, the rate of the variable-load compressors, and the rate of liquefaction units, the model can easily offer the on-site manager a solution to operate the facilities in the oxygen distribution system while avoiding oxygen venting and minimizing the pressure levels of the high-pressure network in the buffer system, thereby reducing the overall energy consumption for oxygen production. The applicability of the model was demonstrated and justified using a real-world case study

Stock Price Prediction Based on XGBoost and LightGBM

Stock trading, as a kind of high frequency trading, generally seeks profits in extremely short market changes. And effective stock price forecasting can help investors obtain higher returns. Based on the data set provided by Jane Street, this paper makes use of XGBoost model and LightGBM model to realize the prediction of stock price. Since the given training set has a large amount of data and includes abnormal data such as missing value, we first carry out feature engineering processing on the original data and take the mean value of the missing value, so as to obtain the preprocessed data that can be used in modeling. The experimental results show that the combined model of XGBoost and LightGBM has better prediction performance than the single model and neural network

The interactions of Li3FeN2 with H-2 and NH3

Li3FeN2 was synthesized by calcinating equivalent Li3N and Fe under N-2 atmosphere and 700 degrees C. The interactions of Li3FeN2 with H-2 and NH3 were studied by using XRD, Mossbauer spectroscopy, temperature-programmed reaction and isothermal (de)hydrogenation. Our results show that the hydrogenation of Li3FeN2 gives rise to Fe metal rather than FeN following the reaction of Li3FeN2 + 2.5H(2) = 2LiNH(2) LiH + Fe. Whereas heating the mixture of 2LiNH(2)/LiH./Fe results in a two-step dehydrogenation that partially regenerates Li3FeN2. Furthermore, Li3FeN2 can react easily with ammonia at room temperature, forming LiNH2 and an amorphous FeN-containing compound. At higher temperatures Li3FeN2 outperforms Fe2N in catalyzing ammonia decomposition. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Dynamic speckle multiplexing scheme in volume holographic data storage and its realization

Abstract: Dynamic speckle multiplexing scheme in volume holographic data storage is proposed, since it offers a novel multiplexing geometry, and could be combined with other schemes to make the full use of the dynamic ranges. In this scheme, a random diffuser is added in the original reference path of the classical 90º setup. In this paper, we analyzed the propagation of the speckle field in the holographic system and established the related theoretical model based on the dynamic speckle auto-correlation function and diffraction theory. We successfully realized the dynamic speckle multiplexing in our experimental system and reached a storage density of 4.6 Gigapixels/cm 3 based on the DPL laser source. Spectroscopy 65, 392-395 (1988). 12. Peikun zhang, Qingsheng He, Guofan Jin, "A novel speckle angular-shift multiplexing for high-density holographic storage," Proceedings of SPIE 4081, 236-241 (2000) 2003 Optical Society of Americ