Engineering topics
Song, Jie
Publications and source records attributed to Song, Jie.
An integrated two-dimensional modeling method for predicting ductility of thin-walled die cast magnesium
In this paper, a two-dimensional (2D) microstructure-based modeling method is developed in order to predict the ductility of a thin-walled high pressure die cast magnesium (Mg) by considering the three-dimensional (3D) thru-thickness pore distributions. For this purpose, a series of 3D synthetic microstructure-based finite element models and the corresponding 2D models are first generated with various pore volume fractions, pore size distributions and pore shapes. The input material properties for the 2D models are determined based on the 3D cubic model with a spherical pore and the generalized Neuber’s rule. Based on the resulting ductility of the 3D and 2D models, a 3D/2D ductility correlation curve is developed as a function of the characteristics/shape of the input fracture strain curve used in the 3D model. The validity of the ductility correlation curve is examined with casting samples with actual microstructures. Here, the results show that the suggested 2D modeling methodology can be used together with the ductility correlation curve in predicting the ductility of thin-walled Mg castings.
Effects of corrosion-inhibiting surface treatments on irradiated microstructure development in Ni-base alloy 718
Not Available
High fidelity Dicke-state generation with Lyapunov control in circuit QED system
In this paper, we propose a scheme to generate highly entangled Dicke-state in circuit quantum electrodynamics (QED) system, where the quantum tunneling between local potential wells is manipulated by using Lyapunov control. We employ two different types of control Hamiltonians to generate Dicke-state: one is the local Hamiltonian that requires to individually modulate control fields; the other is the global Hamiltonian (global control) where the control fields can be modulated uniformly. Furthermore, the target Dicke-state can be obtained with arbitrary initial states when applying the average-value-based Lyapunov control. Numerical simulations demonstrate that the generation of Dicke-state is remarkably accelerated by using bang–bang Lyapunov control, and the multipartite Dicke-state is implemented at nanoseconds without accurately controlling the evolution time in ultrastrong coupling regime. In addition, the scheme is robust against some kinds of uncertainties and perturbations.
In vitro single-cell dissection revealing the interior structure of cable bacteria
Filamentous Desulfobulbaceae bacteria were recently discovered as long-range transporters of electrons from sulphide to oxygen in marine sediments. The long-range electron transfer through these “cable bacteria” has created considerable interests, but it has also raised many questions, such as what structural basis will be required to enable micrometer-sized cells to build into centimeter-long continuous filaments? Here we dissected cable bacteria cells in vitro by atomic force microscopy and further explored the interior, which is normally hidden behind the outer membrane (OM). Using nanoscale topographical and mechanical maps, different types of bacterial cell-cell junctions and strings along the cable length were identified. More importantly: these strings were found to be continuous along the bacterial cells passing through the cell-cell junctions. This indicates that the strings serve an important function in maintaining integrity of individual cable bacteria cells as a united filament. Furthermore, ridges in the OM are found to envelop the individual strings at cell-cell junctions, and they are proposed to strengthen the cell-cell junctions. Finally, we propose a model for the division and growth of the cable bacteria, which illustrate the possible structural requirements for the formation of centimeter length filaments in the recently discovered cable bacteria.
Hydro-mechanically coupled finite-element analysis of the stability of a fractured-rock slope using the equivalent continuum approach: a case study of planned reservoir banks in Blaubeuren, Germany
Construction works associated with the building of reservoirs in mountain areas can damage the stability of adjacent valley slopes. Seepage processes caused by the filling and drawdown operations of reservoirs also affect the stability of the reservoir banks over time. The presented study investigates the stability of a fractured-rock slope subjected to seepage forces in the lower basin of a planned pumped-storage hydropower (PSH) plant in Blaubeuren, Germany. The investigation uses a hydro-mechanically coupled finite-element analyses. For this purpose, an equivalent continuum model is developed by using a representative elementary volume (REV) approach. To determine the minimum required REV size, a large number of discrete fracture networks are generated using Monte Carlo simulations. These analyses give a REV size of 28 × 28 m, which is sufficient to represent the equivalent hydraulic and mechanical properties of the investigated fractured-rock mass. The hydro-mechanically coupled analyses performed using this REV size show that the reservoir operations in the examined PSH plant have negligible effect on the adjacent valley slope.
The Scale‐up and Commercialization of Nonaqueous Na‐Ion Battery Technologies
Abstract This report provides an overview of development activities that enable the scale‐up and thereby a pathway toward the commercialization of sodium‐ion battery technologies for the energy storage market. The electrochemical performance of active materials and full cell performance of batteries developed by two startup companies, Novasis Energies, Inc. and Faradion Limited, are discussed in detail. Both companies offer low‐cost sodium‐ion battery chemistries with uniquely developed active materials that afford high rate capability and cycling stability. Their technologies are highly scalable due to the implementation of abundant and predominantly nontoxic elements and the ability to utilize common battery fabrication and manufacturing equipment. Both companies utilize active materials that are cost competitive compared to low‐cost lithium‐ion battery materials while exhibiting very similar specific capacity. In addition, improved safety characteristics with respect to operation and transportation distinguish the described sodium‐ion batteries from their incumbent lithium‐ion counterparts. The featured technology is particularly attractive for large‐scale energy storage applications.
Modification of Transition-Metal Redox by Interstitial Water in Hexacyanometalate Electrodes for Sodium-Ion Batteries
A sodium-ion battery (SIB) solution is attractive for grid-scale electrical energy storage. Low-cost hexacyanometalate is a promising electrode material for SIBs because of its easy synthesis and open framework. Most hexacyanometalate-based SIBs work with aqueous electrolyte, and interstitial water in the material has been found to strongly affect the electrochemical profile, but the mechanism remains elusive. Here we provide a comparative study of the transition-metal redox in hexacyanometalate electrodes with and without interstitial water based on soft X-ray absorption spectroscopy and theoretical calculations. We found distinct transition-metal redox sequences in hydrated and anhydrated Na x MnFe(CN) 6 ·zH 2 O. The Fe and Mn redox in hydrated electrodes are separated and are at different potentials, leading to two voltage plateaus. On the contrary, mixed Fe and Mn redox in the same potential range is found in the anhydrated system. This work reveals for the first time how transition-metal redox in batteries is strongly affected by interstitial molecules that are seemingly spectators. The results suggest a fundamental mechanism based on three competing factors that determine the transition-metal redox potentials. Finally, because most hexacyanometalate electrodes contain water, this work directly reveals the mechanism of how interstitial molecules could define the electrochemical profile, especially for electrodes based on transition-metal redox with well-defined spin states.
Perfect quantum state engineering by the combination of the counterdiabatic driving and the reverse-engineering technique
We propose a method to design shortcuts to adiabaticity for implementing perfect quantum state engineering by the combination of the counterdiabatic driving and the reverse engineering technique. Based on the method, we can design simple schemes to realize the intended dynamics. For the sake of clearness, we apply this method to several examples including two-level, three-level and four-level system. We show that fast quantum state engineering can be realized by utilizing simply-designed auxiliary Hamiltonian. Furthermore, a suitable choice of the control parameters can eliminate the additional couplings in the introduced auxiliary Hamiltonian. Numerical simulation reveals that the constructed scheme is reliable and robust against various dissipation effects and the fluctuations of control parameters in current technology. - Highlights: • Fast and feasible quantum state engineering can be realized by using the method. • The method allows one to control accurately the evolution of the system. • The scheme is fast and robust against dissipation effects and parameter errors. • The scheme can be generalized to realize N-dimensional quantum state engineering.
Metal cyanometallate synthesis method
A method is provided for synthesizing metal cyanometallate (MCM). The method provides a solution of AXM1Y(CN)Z; where “A” is selected from a first group of metals and M1 is selected from a second group of metals. The method adds a material including M2 to the solution to form a liquid phase material that may be either a suspension or a solution. M2 is selected from the second group of metals. The method adds acid to the liquid phase material. The addition of acid to the liquid phase material decomposes the M2 material into M2-ions. Simultaneous with the addition of the acid, a precipitate of ANM1PM2Q(CN)R.FH2O is formed, where N is in a range of 1 to 2. A variation of the above-described synthesis method is also provided.
Photocatalytic polyoxometalate compositions of tungstovanadates and uses as water oxidation catalysts
This disclosure relates to photocatalytic polyoxometalate compositions of tungstovanadates and uses as water oxidation catalysts. In certain embodiments, the disclosure relates to compositions comprising water, a complex of a tetra-metal oxide cluster and VW.sub.9O.sub.34 ligands, and a photosensitizer. Typically, the metal oxide cluster is Co. In certain embodiments, the disclosure relates to electrodes and other devices comprising water oxidation catalysts disclosed herein and uses in generating fuels and electrical power from solar energy.
Large-area, laterally-grown epitaxial semiconductor layers
Structures and methods for confined lateral-guided growth of a large-area semiconductor layer on an insulating layer are described. The semiconductor layer may be formed by heteroepitaxial growth from a selective growth area in a vertically-confined, lateral-growth guiding structure. Lateral-growth guiding structures may be formed in arrays over a region of a substrate, so as to cover a majority of the substrate region with laterally-grown epitaxial semiconductor tiles. Quality regions of low-defect, stress-free GaN may be grown on silicon.
Alkali-ion battery with enhanced transition metal cyanometallate electrode structure
An alkali-ion battery is provided with a transition metal cyanometallate (TMCM) sheet cathode and a non-alkaline metal anode. The fabrication method mixes TMCM powders, conductive additives, and a polytetrafluoroethylene binder with a solution containing water, forming a wet paste. The wet paste is formed into a free-standing sheet of cathode active material, which is laminated to a cathode current collector, forming a cathode electrode. The free-standing sheet of cathode active material has a thickness typically in the range of 100 microns to 2 millimeters. The cathode electrode is assembled with a non-alkaline metal anode electrode and an ion-permeable membrane interposed between the cathode electrode and anode electrode, forming an assembly. The assembly is dried at a temperature of greater than 100 degrees C. The dried assembly is then inserted into a container (case) and electrolyte is added. Thick anodes made from free-standing sheets of active material can be similarly formed.
Cation Translocation around Single Polyoxometalate-Organic Hybrid Cluster Regulated by Electrostatic and Cation-π Interactions
We report herein an interesting dynamic translocation process of countercations around one polyoxometalate(POM)–organic hybrid anionic cluster at various concentrations and temperatures. It was found that both electrostatic interactions and cation–π interactions regulate the position of small countercations around single clusters. The dynamic geometry and the symmetry of the hybrid macroions are largely affected by the type of counterions, as shown by nuclear magnetic resonance (NMR) spectroscopy studies and all–atom molecular dynamics simulation. It is also shown that electrostatic interactions dominate over cation–π interactions in determining the locations of the counterions in the current system.
Cation Translocation around Single Polyoxometalate-Organic Hybrid Cluster Regulated by Electrostatic and Cation-π Interactions
We report herein an interesting dynamic translocation process of countercations around one polyoxometalate(POM)–organic hybrid anionic cluster at various concentrations and temperatures. It was found that both electrostatic interactions and cation–π interactions regulate the position of small countercations around single clusters. The dynamic geometry and the symmetry of the hybrid macroions are largely affected by the type of counterions, as shown by nuclear magnetic resonance (NMR) spectroscopy studies and all-atom molecular dynamics simulation. It is also shown that electrostatic interactions dominate over cation–π interactions in determining the locations of the counterions in the current system.
Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water
Maintaining adequate or enhancing mechanical properties of shape memory polymers (SMPs) after shape recovery in an aqueous environment are greatly desired for biomedical applications of SMPs as self-fitting tissue scaffolds or minimally invasive surgical implants. Here we report stable temporary shape fixing and facile shape recovery of biodegradable triblock amphiphilic SMPs containing a poly(ethylene glycol) (PEG) center block and flanking poly(lactic acid) or poly(lactic-co-glycolic acid) blocks in warm water, accompanied with concomitant enhanced mechanical strengths. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WXRD) and small-angle X-ray scattering (SAXS) analyses revealed that the unique stiffening of the amphiphilic SMPs upon hydration was due to hydration-driven microphase separation and PEG crystallization. We further demonstrated that the chemical composition of degradable blocks in these SMPs could be tailored to affect the persistence of hydration-induced stiffening upon subsequent dehydration. These properties combined open new horizons for these amphiphilic SMPs for smart weight-bearing in vivo applications (e.g. as self-fitting intervertebral discs). In conclusion, this study also provides a new material design strategy to strengthen polymers in aqueous environment in general.
Impact of Chinese Urbanization and Aerosol Emissions on the East Asian Summer Monsoon
Effects of urbanization and anthropogenic aerosols in China on the East Asian summer monsoon (EASM) are examined using version 5.1 of the Community Atmosphere Model (CAM5.1) by comparing simulations with and without incorporating urban land cover and/or anthropogenic aerosol emissions. Findings show that the increase of urban land cover causes large surface warming and an urban frictional drag, both leading to a northeasterly wind anomaly in the lower troposphere over eastern China (EC). This weakens the southerly winds associated with the EASM and causes a convergence anomaly in southern China (SC) with increased ascent, latent heating, and cloudiness. The enhanced latent heating reinforces surface convergence and upper-level divergence over SC, leading to more northward advection in the upper level into northern China (NC) and descending between 30° and 50°N over East Asia. Cloudiness reduction, adiabatic heating, and warm advection over NC all enhance the urban heating there, together causing anomalous tropospheric warming at those latitudes over East Asia. Anthropogenic aerosols cause widespread cooling at the surface and in the troposphere over EC, which decreases the summer land–ocean thermal contrast, leading to a weakened EASM circulation with reduced moisture transport to NC. This results in wetter and drier conditions over SC and NC, respectively. When both the urbanization and anthropogenic aerosols are included in the model, aerosols’ cooling is partially offset by the urban heating, and their joint effect on the circulation is dominated by the aerosols’ effect with a reduced magnitude. Here, in the combined experiment, surface and tropospheric temperatures are also altered by the decrease (increase) in cloudiness over NC (SC) with most of the cooling confined to SC, which further weakens the EASM circulation.