Ling Zeng

Bio: Ling Zeng is an academic researcher from Changsha University of Science and Technology. The author has contributed to research in topics: Geotechnical engineering & Water content. The author has an hindex of 10, co-authored 35 publications receiving 333 citations. Previous affiliations of Ling Zeng include University of Lorraine.

Carbonaceous mudstone and lignin-derived activated carbon and its application for supercapacitor electrode

Abstract: To solve the major issues that most carbon materials used as supercapacitors electrode should be prepared from complex chemical products with high cost and side effects to the environment. In this report, a novel kind of low-cost, abundant reserves and environmental friendly carbon materials derived from carbonaceous mudstone and lignin mixture have been prepared and the electrochemical performances have been investigated. By activation treatment with HNO3, the activated carbonaceous mudstone and lignin-derived carbons (ASLDC) has been successfully synthesized. The physical and electrochemical studies exhibit that the ASLDC electrode possesses porous structures and wonderful electrochemical behaviors, a high specific capacitance of 155.6 F g−1 can be achieved when first served as electrodes for supercapacitors, which is three times than that of the untreated carbon electrode. Meanwhile, the charge/discharge measurement further indicates that the ASLDC electrode possess the excellent supercapacitive characteristics. The results demonstrate that the as-prepared low-cost, renewable and environmental friendly carbon electrode materials can be a promising electrode material for high-performance supercapacitors. Furthermore, such abundant reserves materials would be useful for other energy storage and conversion devices.

Rapid estimation of resilient modulus of subgrade soils using performance-related soil properties

Abstract: This study aims at developing an efficient and accurate methodology to estimate the resilient modulus of subgrade soils. First, a new resilient modulus model incorporating stress dependence and moi...

Effect of the characteristics of surface cracks on the transient saturated zones in colluvial soil slopes during rainfall

Abstract: The presence of surface cracks has a great influence on the formation of transient saturated zones, which are one of the main factors affecting the stability of colluvial soil slopes during rainfall. This paper aims to examine how the distribution characteristics, such as depth (h), angle (θ), and location of surface cracks, influence the development of transient saturated zones. For this reason, a series of numerical simulations involving colluvial soil slopes is performed. The results show that the development of transient saturated zones in a slope with a crack and that in an intact slope are quite different. In a cracked slope, rainwater infiltrates into the slope along the crack and forms a transient saturated zone at the crack tip. It is found that the smaller the crack depth is, the easier it is for the transient saturated zone at the crack tip to connect with that in the shallow layer, leading to an increase in the area of the transient saturated zone in the shallow layer. Moreover, the larger the crack angle is, the more easily the transient saturated zone at the crack tip connects with both the transient saturated zone in the shallow layer and the groundwater, forming a transient saturated zone that penetrates the entire colluvium. In addition, the lower the location of the crack along the slope surface is, the shorter the time is for the formation of a transient saturated zone at the crack tip, and the larger the area of the transient saturated zone.

A promising SPEEK/MCM composite membrane for highly efficient vanadium redox flow battery

Abstract: A novel composite membrane blended the sulfonated poly (ether ether ketone) (SPEEK) with modified carbonaceous mudstone (SPEEK/MCM) has been developed for vanadium redox flow battery (VRB). Using a strong acidification treatment, a large amount of hydrophilic oxygen functional groups was introduced on the modified carbonaceous mudstone (MCM) particles, which has been evidenced to enhance the proton conductivity. It is found that the MCM particles help to retard the permeation of vanadium ions through the membrane. With these merits, the VRB single cell based on our novel SPEEK/MCM membrane exhibits outstanding device performance. Notably, the coulombic efficiency (CE) of the cell is as high as more than 99% and the per-cycle capacity loss is only 0.15% under a high current density of 120 mA cm−2. Our work provides a simple method to prepare low cost and high-performance membranes for VRB. More importantly, the SPEEK/MCM membrane has promising potential in other battery applications.

Numerical simulation of the moisture migration of unsaturated clay embankments in southern China considering stress state

Abstract: To determine the moisture contents of unsaturated clay embankments in southern China considering the stress state, 753 moisture data of three existing embankments for about 20 years were measured, and six frequency domain reflectometry sensors were installed in a widened embankment in southern China to monitor the moisture content. The soil water characteristic curve (SWCC) and stress-dependent soil water characteristic curves (SDSWCCs) were determined in the laboratory using a pressure plate apparatus and a stress-dependent parametric equation was established. The finite element model of a typical unsaturated clay embankment in southern China considering the SWCC and SDSWCCs was created. Then, the variation of the moisture contents of the clay embankment was simulated. The results show that the vertical stress has an obvious effect on the moisture distribution in embankments, especially the positions inside embankments where the vertical stress is large and cannot be neglected. The finite element model considering the SDSWCCs, therefore, should be selected when analyzing the moisture filed of embankments in southern China. For the existing clay embankments in southern China, their moisture contents gradually increase from the optimum moisture content to equilibrium values, which is close to the plastic limit and increases by 99% of the optimum moisture content. In addition, the resilient modulus values at different locations of the embankment and that of the whole embankment are reduced by 55 to 62%. And the safety factor of the slope obviously decreases, and its reduction is greater than 60%.

On the Nature of the Function Expressive of the Law of Human Mortality

Abstract: We omit Gompertz’ method of fitting, which the reader will find in Makeham, below. Also omitted are Gompertz’ mortality tables, and his discussion of life expectancy and annuities under his Law. The hyperbolic logarithms in Art. 5 are the natural logs; we are not able to follow completely his integration, which is by Newton's method of fluxions.

Ultrathin NiCo-MOF Nanosheets for High-Performance Supercapacitor Electrodes

Abstract: Metal–organic frameworks (MOFs) have attracted intensive attention for high-performance supercapacitors owing to their large specific surface area and tunable pore structure. Herein, ultrathin NiCo-MOF nanosheets are fabricated by a facile ultrasonication at room temperature and employed as a supercapacitor electrode material. The unique nanosheet-like structure of NiCo-MOF provides more electroactive sites and a shorter pathway for electron transfer and electrolyte diffusion, resulting in excellent electrochemical performance with a high specific capacitance of 1202.1 F g–1 at 1 A g–1. In addition, an asymmetric supercapacitor of NiCo-MOF//activated carbon was assembled in 2 M KOH electrolyte. It delivers an energy density of 49.4 W h kg–1 at a power density of 562.5 W h kg–1 in a voltage window of 1.5 V. The results demonstrate a new method to fabricate ultrathin MOF nanosheets for high-performance supercapacitor electrode materials.