Fast projection onto the ordered weighted ℓ1 norm ball

In this paper,we provide a finitely terminated yet efficient approach to compute the Euclidean projection onto the ordered weighted?₁(OWL1)norm ball.In particular,an efficient semismooth Newton method is proposed for solving the dual of a reformulation of the original projection problem.Global and local quadratic convergence results,as well as the finite termination property,of the algorithm are proved.Numerical comparisons with the two best-known methods demonstrate the efficiency of our method.In addition,we derive the generalized Jacobian of the studied projector which,we believe,is crucial for the future designing of fast second-order nonsmooth methods for solving general OWL1 norm constrained problems.     

Rhombicuboctahedral Ag100: Four-Layered Octahedral Silver Nanocluster Adopting the Russian Nesting Doll Model

Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size-evolution principles. Reported here is the largest known FCC-based (FCC=face centered cubic) silver nanocluster, [Ag₁₀₀(SC₆H₃^3,4F₂)₄₈(PPh₃)₈]⁻: the first all-octahedral symmetric nesting Ag nanocluster with a four-layered Ag₆@Ag₃₈@Ag₄₈S₂₄@Ag₈S₂₄P₈ structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC-based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC-based Russian nesting doll model constitutes a new platform for the study of the size-evolution principles of Ag NCs.     

Rhombicuboctahedral Ag100: Four‐Layered Octahedral Silver Nanocluster Adopting the Russian Nesting Doll Model

Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size‐evolution principles. Reported here is the largest known FCC‐based (FCC=face centered cubic) silver nanocluster, [Ag₁₀₀(SC₆H₃^3,4F₂)₄₈(PPh₃)₈]^?: the first all‐octahedral symmetric nesting Ag nanocluster with a four‐layered Ag₆@Ag₃₈@Ag₄₈S₂₄@Ag₈S₂₄P₈ structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC‐based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC‐based Russian nesting doll model constitutes a new platform for the study of the size‐evolution principles of Ag NCs.     

High-resolution bone microstructure imaging based on ultrasonic frequency-domain full-waveform inversion

The main challenge in bone ultrasound imaging is the large acoustic impedance contrast and sound velocity differences between the bone and surrounding soft tissue. It is difficult for conventional pulse-echo modalities to give accurate ultrasound images for irregular bone boundaries and microstructures using uniform sound velocity assumption rather than getting a prior knowledge of sound speed. To overcome these limitations, this paper proposed a frequency-domain fullwaveform inversion(FDFWI) algorithm for bone quantitative imaging utilizing ultrasonic computed tomography(USCT).The forward model was calculated in the frequency domain by solving the full-wave equation. The inverse problem was solved iteratively from low to high discrete frequency components via minimizing a cost function between the modeled and measured data. A quasi-Newton method called the limited-memory Broyden–Fletcher–Goldfarb–Shanno algorithm(L-BFGS) was utilized in the optimization process. Then, bone images were obtained based on the estimation of the velocity and density. The performance of the proposed method was verified by numerical examples, from tubular bone phantom to single distal fibula model, and finally with a distal tibia-fibula pair model. Compared with the high-resolution peripheral quantitative computed tomography(HR-p QCT), the proposed FDFWI can also clearly and accurately presented the wavelength scaled pores and trabeculae in bone images. The results proved that the FDFWI is capable of reconstructing high-resolution ultrasound bone images with sub-millimeter resolution. The parametric bone images may have the potential for the diagnosis of bone disease.     

Preparation and characterization of pavement materials with phase-change temperature modulation

A kind of pavement crack repairing material with temperature regulation property was successfully prepared through one-step method, in which the paraffin was incorporated into the polyurethane/epoxy resin-interpenetrating polymer networks. Differential scanning calorimeter results indicated that the phase-change latent heat of sample A was 14.4 kJ kg^?1, and the phase transition temperature was ??0.3 °C. FTIR and thermogravimetry measurements verified that the paraffin was successfully incorporated into the interpenetrating polymer network without leakage and reacted with the carrier, which exhibited high thermal stability above 300 °C. After 1 year of road test, there was no breakage for the repairing pavement with paraffin–polyurethane/epoxy resin-interpenetrating polymer networks, and there was almost no change for the accumulated attenuation of phase-change latent heat. Therefore, the materials of paraffin–polyurethane/epoxy resin-interpenetrating polymer networks have good chemical stability and thermal stability.

     

Fundamentals and Environmental Applications of Non-thermal Plasmas: Multi-pollutants Emission Control from Coal-Fired Flue Gas

Simultaneous control of multi-pollutants emission from coal-fired flue gas is essential for environmental quality. Non-thermal plasma (NTP) technologies have made numerous successful applications of combined removal for sulfur dioxide (SO₂), nitrous oxide, particulate matter and mercury. Nitric oxide, elemental mercury can be oxidized in the gas phase, while fine particle gets agglomeration in the same NTP device. SO₂ gets absorbed after heterogeneous oxidation by discharge. All the gaseous pollutants and aerosols generated will be further oxidized and captured in wet NTP device. Applications of NTP and typical configurations are also summarized.     

An investigation on the unsatisfactory rate capability of spherical LiNi<Subscript>1/3</Subscript>Co<Subscript>1/3</Subscript>Mn<Subscript>1/3</Subscript>O<Subscript>2</Subscript> particles prepared by using Na<Subscript>2</Subscript>CO<Subscript>3</Subscript> as a precipitant

Spherical LiNi_1/3Co_1/3Mn_1/3O₂ particles were successfully synthesized using Na₂CO₃ as a precipitant. Electrochemical measurements indicate that the as-synthesized spherical particles deliver a high reversible capacity of above 180 mAh g^?1 at 0.1 C in the voltage range of 2.8–4.4 V and display an excellent cyclic performance at 0.5 C. However, unsatisfactory rate capability was detected for the as-prepared spherical particles. The reason for the unsatisfactory rate capability was investigated through a comparison of the properties of the as-synthesized spherical particles versus the ball-milled samples via a combination of specific surface areas test, electronic conductivity measurement, and electrochemical impedance spectroscopy. The results show that both the rate capabilities of cathode materials and the electronic conductivities of the mixtures of active material, conductive additive, and binder are highly improved when the secondary spherical particles were broken, indicating that the poor electronic conductivity of electrode caused by the large secondary spherical particles with a great amount of nano-pores is a significant factor for the unsatisfactory rate capability.