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Energy storage materials are vital to the use of clean energy such as hydrogen and electrochemical energy. This paper reviews the recent progress on the application of dielectric barrier discharge plasma-assisted milling (P-milling), a new material synthesis method developed by ourselves, in preparing energy storage materials including Mg-based hydrogen storage materials and anode materials for lithium-ion batteries. We discuss in particular the advantages of this novel milling technique on preparing those materials and improving their energy storage performances. For Mg-based hydrogen storage materials, P-milling can realize the simultaneous rapid formation of a Mg-based solid solution and the in - situ induced catalyst MgF 2 , thus realizing the dual tuning of thermodynamic and kinetic properties. For anode materials of lithium-ion batteries, core-shell structures are easily formed by P-milling, and those prepared materials show higher capacities and cycling stability in comparison to those prepared by conventional ball milling (C-milling). P-milling offers a simple, cost effective and pollution-free way for preparing nano-materials or accelerating mechanochemical reactions, paving the way for large scale production of energy storage materials in the future.

In-situ soil properties exhibit natural spatial variability. In this study, the Karhunen-Loeve (K-L) expansion method and the Coupled Eulerian-Lagrangian (CEL) method are integrated to simulate large deformation behavior of slopes with spatially varied shear strengths. The impact on pipelines induced by spatially varied landslides is investigated. The mean value of the maximum impact force is significantly larger than the deterministic value obtained for a homogeneous slope. The proportion of the maximum impact force from stochastic analysis that exceeds the deterministic value is much greater than 50%. This result shows that the deterministic study can significantly underestimate the damage of pipeline by a landslide if the spatial variability is not considered. The uncertainty of the impact force increases with the coefficient of variation (COV) of the undrained shear strength and decreases with the reduction of horizontal correlation length. By considering buckling failure and plastic yielding failure of pipelines, the failure probabilities are assessed and a pipeline design based on stochastic analysis for spatially varied slope is presented.

(Ti0.85Zr0.15)1.1Cr1−xMnFex (x = 0, 0.05, 0.075, 0.1, 0.15) alloys with a C14-type Laves structure have been investigated for potential application in hybrid high-pressure metal hydride tanks used for fuel cell vehicles. The effects of the partial substitution of Cr with Fe on the hydrogen storage properties of (Ti0.85Zr0.15)1.1CrMn have been systematically investigated. Results show that the desorption plateau pressure increases with increasing the Fe content in (Ti0.85Zr0.15)1.1Cr1−xMnFex alloys, whereas the hydrogen capacity decreases. Among these alloys, (Ti0.85Zr0.15)1.1Cr0.925MnFe0.075 has the best overall properties, with a hydrogen desorption pressure of 10.6 atm and a reversible capacity of 1.54 wt% at 0 °C under the pressure range between 0.1 atm and 120 atm.

Ti–Cr–Mn-based alloys with a C14-type Laves structure have been investigated for potential application in hybrid high-pressure metal hydride tanks for fuel cell vehicles. The effects of partial substitution of Ti by Zr, and of Cr by Mo and W, on the hydrogen storage properties of Ti–Cr–Mn-based alloys have been systematically investigated. Among these alloys, (Ti 0.85 Zr 0.15 ) 1.1 Cr 0.9 Mo 0.1 Mn shows the best overall properties, with a hydrogen desorption pressure and capacity of 9.54 atm and 1.78 wt% at 0 °C. The kinetics and cycling stability are also discussed for on-board hybrid high-pressure metal hydride tank applications. According to calculations, the volumetric H 2 density of the hybrid system can reach the Department of Energy (DOE) 2017 target, while its gravimetric density remains at a high value of 2.72 wt% when 28% of the inner volume in a hybrid hydrogen metal hydride tank is filled with this alloy.

The dehydrogenation enthalpy change of MgH2 by reversibly forming an Mg0.95In0.05 solid solution offers a new method for tuning the thermodynamics of Mg-based alloys. In order to further lower the stability of MgH2, Al has been introduced into Mg(In) solid solution. At the same time, to solve the problem of sluggish kinetic properties of Mg–In solid–solution systems and to lower the dehydrogenation activation energy, Ti has also been added. It has been demonstrated that the Mg85In5Al5Ti5 alloy synthesized by plasma milling (P-milling) shows both enhanced dehydriding thermodynamics and kinetics. This technique could be used to synthesize Mg(In, Al) ternary solid solution incorporating the Ti catalyst in only one step, making it much more efficient than the two-step method. Compared with Mg-based solid solutions, the addition of Ti and in-situ synthesized MgF2 improved the kinetics and the introduction of In as well as Al imparted enhanced thermodynamics to the Mg85In5Al5Ti5 system. The dehydrogenation enthalpy change and activation energy were lowered to 65.2 kJ/(mol H2) and 125.2 kJ/mol, respectively, for the Mg85In5Al5Ti5 alloy.

A high-Sm, Pr/Nd-free, and low-Co La 0.95 Sm 0.66 Mg 0.40 Ni 6.25 Al 0.42 Co 0.32 alloy is reported as an A 2 B 7 -type electrode for Ni/MH batteries. The structural characteristics and electrochemical properties of this alloy have been investigated. La 0.95 Sm 0.66 Mg 0.40 Ni 6.25 Al 0.42 Co 0.32 is composed of La 2 Ni 7 and LaNi 5 phases, and shows high discharge capacity and excellent cyclic property. The discharge capacity can reach 311.8 mAh/g and 227.0 mAh/g at large discharge currents of 2C and 5C, respectively, and 80% of the capacity is retained after 239 cycles at 1C.

Hydrolysis of sodium borohydride (NaBH4) is one of the most attractive methods for energy generation of mobile systems used as hydrogen source because of the high gravimetric density and controllable hydrogen generation of NaBH4. However, regeneration of NaBH4 is a key issue that remains to be solved, and the energy efficiency of NaBH4 is unknown. In the present study, the energy efficiency of NaBH4 hydrolysis and the entire process of sodium metaborate (NaBO2) regeneration via reaction with magnesium hydride (MgH2) is determined through thermodynamics calculations. The maximum energy efficiency is 49.91%, indicating that NaBH4 generation by reaction between MgH2 and NaBO2 during ball milling is feasible. An inexpensive high-energy ball milling method is employed to regenerate NaBH4 by reaction of NaBO2 with magnesium–lanthanum hydrides (H–Mg3La). Products after ball milling are characterized through Fourier transform infrared spectroscopy and X-ray diffraction measurements. In the reaction of NaBO2 with H–Mg3La, MgH2 reacts with NaBO2 and then lanthanum hydride (LaH3) reacts with NaBO2 to produce NaBH4.

In order to improve the high-rate discharge properties of La 11.3 Mg 6.0 Sm 7.4 Ni 61.0 Co 7.2 Al 7.1 (AB 3.0 ) alloy electrodes, the effects of plasma milling (PM) and graphene addition on their electrochemical properties and kinetics have been investigated. It was found that the discharge capacity of AB 3.0 at a high discharge current density was significantly improved after the addition of graphene followed by PM for only 10 min. Moreover, the high-rate dischargeability (HRD) and the exchange current density I 0 of the alloy electrodes were also increased. The PM technique exhibits obvious advantages for improving the high-rate discharge properties of hydrogen-storage alloys.

The hydrogenation/dehydrogenation characteristics and hydrogen storage properties of nominal Mg3Ag and Mg3Y alloys prepared by induction melting were investigated. The as-melted Mg3Ag alloy was composed of Mg54Ag17 phase, while Mg3Y consisted of Mg24Y5 and Mg2Y phases. Mg54Ag17 transformed into MgAg and MgH2 during the first hydrogenation, and the phase transition of the following hy/dehydrogenation cycles was Mg3Ag + 2H2 ↔ MgAg + 2MgH2. Both Mg24Y5 and Mg2Y undertook disproportion reactions and decomposed into MgH2 and YH3. Experimental and calculated results demonstrated that there was no necessary relation between the thermodynamic stabilities and the size interstices in these alloys. The dehydrogenation enthalpy change (ΔH) and entropy change (ΔS) of Mg3Ag were calculated and compared with that of pure Mg, which indicated that the increase of ΔS could counteract the stabilization effect of ΔH, which offered a method for tuning the thermodynamic properties of Mg-based alloys.

The reversible formation of Mg(In) solid solution provides a new way to tune the dehydriding thermodynamics of MgH2. However, the preparation of this solid solution is quite difficult and its dehydriding kinetics is rather sluggish. This work offers a novel technique, plasma milling (P-milling), to solve the two problems simultaneously. The efficiency of the synthesis of Mg(In) solid solution, with a hydrogen capacity of up to 5.16 wt.%, is improved significantly. Meanwhile, the kinetics is also modified by the catalyzing effect of in situ synthesized MgF2.

Mg2In0.1Ni solid solution with an Mg2Ni-type structure has been synthesized and its hydrogen storage properties have been investigated. The results showed that the introduction of In into Mg2Ni not only significantly improved the dehydrogenation kinetics but also greatly lowered the thermodynamic stability. The dehydrogenation activation energy (Ea) and enthalpy change (ΔH) decreased from 80 kJ/mol and 64.5 kJ/mol H2 to 28.9 kJ/mol and 38.4 kJ/mol H2, respectively. The obtained results point to a method for improving not only the thermodynamic but also the kinetic properties of hydrogen storage materials.

We developed a saturated iron-core type 35 kV/90 MVA superconductive fault current limiter and installed the device in a transmission network at Puji substation of China Southern Power Grid for live-grid operation. Innovative design in the iron-core configuration ensures that the device has low impedance in normal power transmission and sufficiently high impedance for a fault current limiting action. A magnetization control circuit allows the iron-core to be saturated or de-saturated depending upon the functional requirements. An energy release and voltage-surge protection unit can promptly discharge the magnetic energy accumulated in the iron-core and suppress the induced and surge voltages of the dc circuit in a current limiting event. This device has been designed to reduce the magnitude of a fault current by about 50%, which will prevent the breaking capacity of the existing circuit breakers in the transmission network from being exceeded in the predictable future. This article presents structural and functional specifications and reports up-to-date live-grid operation data of the device.

A superconductive coil with 141,000 ampere-turns designed magnetizing power, made of 17,600 meters of BSCCO 2223 HTS tapes, was fabricated and tested. This coil was built for a 35 kV/90 MVA saturated iron-core fault current limiter. Computer simulations on the performance of the coil were carried out using ANSYS. The critical current of the superconducting coil and the dc resistance of the coil, including the non-superconducting joints, were investigated. Spatial distribution of the magnetic field was measured and compared with the simulation results. In this paper, we will report the configuration and the key parameters of the coil as well as the experimental and simulation results.

A scatter model is proposed for parallel-, fan-, and cone-beam SPECT imaging. In this model, a photon is allowed to be scattered only once, and the probability of scatter for given angle and energy is computed by using the Klein-Nishina formula. The detector is assumed to have perfect energy resolution. The scatter counts are computed for every projection bin. From the scatter counts, the scatter line source response function and scatter-to-primary ratio (SPR) are obtained. They agree well with those from Monte Carlo (MC) simulation including only single scattering, but deviate from those from full MC simulation including both single and multiple scattering. The deviation depends on the source depth within the medium. For a source depth of 6 cm, the difference of the scatter-to-primary ratio between the model and full MC simulation is less than 7%, while for a 21.6 cm source depth, the difference goes up to 27% for parallel-beam geometry and 32% for cone-beam geometry. Since scatter accounts for 20-40% of the total counts in most clinical studies, the scatter model yields a SPR accuracy that ranges from 3% to 12%. The scatter model provides an effective means to estimate the scatter response with reasonable accuracy, and can be used in developing scatter compensation techniques in parallel- and converging-beam SPECT. >

To optimize both spatial resolution and detection efficiency in brain SPECT (single photon emission computed tomography) imaging using a rectangular camera, an asymmetric double-focal cone-beam collimator is proposed with the focal points located near the base of the patient's head. To fit the entire head into the field-of-view of the detector (50 cm*40 cm) for a radius-of-rotation of 15 cm, the focal lengths of the collimator are 55 and 70 cm, respectively, in the transverse and axial directions. With this geometry, the artifacts in the reconstructed image become more severe due to the larger vertex angle between the top of the head and the central plane compared to that in a symmetric cone-beam geometry. To improve the reconstructed image quality, a fully 3-D reconstruction algorithm which involves a nonstationary 2-D filtering and a reprojection technique for estimation of the missing data caused by a single-orbit cone-beam geometry are implemented. The results from simulation studies with the 3-D Defrise slab phantom demonstrated that, by using the full 3-D algorithm and the reprojection technique, the reconstructed image quality was significantly improved in terms of reduced slice-to-slice cross talks and shape elongation compared to that produced by the conventional Feldkamp algorithm. >

Conventional single-orbit cone beam tomography suffers from incomplete sampling and an inadequate three-dimensional (3D) reconstruction algorithm. The commonly used Feldkamp reconstruction algorithm simply extends the two-dimensional (2D) fan beam algorithm to 3D cone beam geometry. A truly 3D reconstruction formulation based on the 3D Fourier slice theorem is derived for a single-orbit cone beam SPECT. In the formulation, a nonstationary filter which depends on the distance from the central plane of the cone beam is derived and applied to the 2D projection data in directions along and normal to the axis of rotation. This algorithm was evaluated using both computer simulation and experimental measurements. Significant improvement in image quality was demonstrated in terms of decreased artifacts and distortions in cone beam reconstructed images. However, compared with the Feldkamp algorithm, a fivefold increase in processing time is required. >

The reconstruction methods currently available for use in quantitative brain SPECT (single photon emission computed tomography) imaging were studied. The conventional reconstruction methods are based on the filtered backprojection algorithm. Assuming uniform attenuation, the Chang algorithm is effective in attenuation compensation. The collimator response can be compensated for by a restoration filter with an average collimator response function. Scatter compensation can be achieved by the dual window subtraction method or by incorporating an average scatter response function in the restoration filter. The dual window subtraction method is an approximate but efficient means of providing projection data which are compensated for scatter. The iteration reconstruction method can be applied to these data for addition compensation for attenuation and the spatially variant collimator response. The latter is accomplished by incorporating the exact model of attenuation and detector response function in the projector/backprojector of the iterative algorithm. A 3-D brain phantom was used in the evaluation study. The images obtained from various reconstruction methods were compared for quantitative accuracy with respect to the known 3-D phantom activity distribution. >

This paper develops a package of EXCEL worksheets and functions/Add-In to implement an advanced Monte Carlo method called Subset Simulation in the EXCEL spreadsheet and applies it to reliability analysis of slope stability. The deterministic slope stability analysis and uncertainty modeling and propagation are deliberately decoupled so that they can proceed separately by personnel with different expertise and in a parallel fashion. An illustrative example demonstrates application of the EXCEL package to a slope with uncertainty on undrained shear strength and highlights computational efficiency of Subset Simulation for the slope stability problem.

Multifocal cone-beam collimation has been proposed for cardiac SPECT (single photon emission computed tomography) imaging to increase sensitivity over the heart without truncation of activity distribution in the chest. An accurate and efficient algorithm has been derived for multifocal fan-beam SPECT reconstruction and has been extended to multifocal cone-beam SPECT reconstruction. In the multifocal fan-beam algorithm, the projection data were weighted and filtered for every discrete distance from the detector plane, and then the filtered data were interpolated for a given image point in the backprojection. Thus, the backprojection was carried out only once at a projection view. The multifocal cone-beam algorithm was evaluated using the simulated 3-D Defrise slab phantom and the 3-D Shepp-Logan head phantom. In addition, a preliminary study to evaluate the multifocal cone-beam collimator was performed, in which effects of the focal length distribution and the radius-of-rotation (ROR) on the reconstructed image quality were examined. The image quality was improved with decreased ROR. >

A truly 3-D reconstruction formulation is derived for the single-orbit cone beam SPECT (single photon emission computed tomography) based on the 3-D Fourier slice theorem. In the formulation, a nonstationary filter is derived which depends on the distance from the central plane of the cone beam. This filter is applied to the 2-D projection data in directions along and normal to the axis of rotation. The nonstationary filtering technique was evaluated using both computer simulation and phantom measurements. Significant improvement in image quality was demonstrated in terms of decreased artifacts along the axis of rotation at the cost of a fivefold increase in processing time. The quality of the reconstructed image from the 3-D algorithm is superior to that from the Feldkamp algorithm, especially near the ends of the image along the axis of rotation. >