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An autonomous underwater vehicle (AUV) can only carry limited energy for improved flexibility, but this brings the problem of working endurance. The acquisition of environmental energy by an underwater robot is a positive way to supplement energy and increase endurance. However, the instability and difference in power output capacity of different environmental energies will lead to low utilization of environmental energy. In this study, a multi-energy acquisition model is established to manage the AUV’s energy, which includes a heart rate sampling system, a mixed-energy circuit topology, and a maximum power output algorithm of environmental energy based on power trajectory tracking. The simulating results show that the power output control strategy can effectively improve the multi-energy acquisition and utilization efficiency of underwater vehicles, which has a positive significance and could improve endurance time.

Additional file 10: Table S1. Clinicopathologic characteristics of patients.

Additional file 1. Materials and methods.

Additional file 11: Table S2. Expression patterns in HCC tissues and adjacent nontumor tissues revealed in immunohistochemistry analysis.

The structure of current collectors has significant effects on the performance of a lithium-ion battery (LIB). In this study, we use copper fiber felts made by multi-tooth cutting and high-temperature solid-phase sintering as the current collector for LIBs. An integrated porous electrode based on CuO nanoflowers/copper fiber felt is developed for the anode. Results suggest that the reversible capacity and cycle stability of this new anode are significantly improved, compared with the pristine bare-surface copper plate under the same condition of rate cycles. The new anode structure based on the copper-fiber felt with a porosity of 60% exhibits a higher performance with an initial specific capacity of 609.5 mAh g−1 and retains 486.1 mAh g−1 after 200 cycles at a current density of 0.5 C. The improved electrochemical performance of this electrode is attributed to its large surface area of CuO nanoflowers and porous structure of the copper fiber felt, due to enhanced contact between the active material of CuO nanoflowers and electrolyte. This pore-rich structure makes the electrolyte easy to permeate into the electrode, shortens the diffusion path of Li+, reduces the internal resistance and alleviates the volume expansion of the active material during the insertion and desertion processes of Li+.

The lithium-ion battery (LIB) is an efficient electrochemical energy storage device with high voltage, long life, good safety, etc. Silicon has a high theoretical specific capacity (4200 mA h g−1), due to which it is considered a promising anode material for next-generation LIBs. However, the huge volume change (400%) of the Si material during the lithiation/delithiation processes destroys its structure, which greatly reduces the initial coulombic efficiency, cycle stability and rate performance of the battery. Accordingly, constructing nanostructured Si, particularly silicon nanowires (SiNWs), can help to address the above issues. Additionally, it is important to further improve the electrochemical performance by incorporating some additives in SiNW-based electrodes. Therefore, this review focuses primarily on SiNW-based materials as anodes for LIBs from a material-based perspective. Various materials incorporated into SiNW-based anodes through doping or compositing are reported. The electrochemical effects of diverse additives, including carbon materials, metals, metal oxides, polymers, Si-based materials and other special substances, are comprehensively reviewed.

Lithium-ion batteries (LIBs) play an important role in modern society. The low capacity of graphite cannot meet the demands of LIBs calling for high power and energy densities. Silicon (Si) is one of the most promising materials instead of graphite, because of its high theoretical capacity, low discharge voltage, low cost, etc. However, Si shows low conductivity of both ions and electrons and exhibits a severe volume change during cycles. Fabricating nano-sized Si and Si-based composites is an effective method to enhance the electrochemical performance of LIB anodes. Using a small size of Si nanoparticles (SiNPs) is likely to avoid the cracking of this material. One critical issue is to disclose different types and electrochemical effects of various coupled materials in the Si-based composites for anode fabrication and optimization. Hence, this paper reviews diverse SiNP-based composites for advanced LIBs from the perspective of composition and electrochemical effects. Almost all kinds of materials that have been coupled with SiNPs for LIB applications are summarized, along with their electrochemical influences on the composites. The integrated materials, including carbon materials, metals, metal oxides, polymers, Si-based materials, transition metal nitrides, carbides, dichalcogenides, alloys, and metal-organic frameworks (MOFs), are comprehensively presented.

The Fe15−xMn40Al45+x (x = 0, 1, 2 and 3) and Fe15Mn40−yAl45+y (y = 1, 2 and 3) alloys were prepared by arc melting and annealed at 1000 °C for 7 days. The microstructure and magnetic properties are characterized by XRD and VSM. Corresponding corrosion potential and hardness are measured by electrochemical workstation and Vickers hardness tester. All samples have CsCl type Cubic structure. And for Fe15Mn40−yAl45+y alloys, with increasing Mn content, the lattice parameters increase from 2.9613 A to 2.9678 A, while the curie temperatures can be tuned from 288 K to 330 K. As for Fe15−xMn40Al45+x alloys, the curie temperatures rise from 315 K to 340 K with lattice parameters increasing from 2.9658 A to 2.9689 A. The peak values of magnetic entropy change under 5 T are −2.4 and −3.1 J·kg−1K−1 for Fe15Mn40Al45 and Fe14Mn40Al44 respectively. The values of refrigerant capacity power are 223.4 and 232.5 J·kg−1 under 5 T. The Arrott plots are also employed to investigate the magnetic phase transition, showing all samples undergo second order ferro-paramagnetic phase transition. Furthermore, these alloys have good hardness and corrosion resistance properties. The potential applications of these alloys as magnetic refrigerant will be also discussed in this paper.

The surface microstructure of the current collectors significantly affects the electrochemical performance of lithium-ion batteries (LIBs). This study shows that an effective method of orthogonal p...

In this paper, we propose an approach to handle the anomaly detection for the thermal system on ships by the sensor associated network method. A large number of sensors are placed in different positions of the thermal system. These sensors form a topological network which can represent the operation state of the thermal system. There are both linear correlation and nonlinear correlation between the operating parameters reflected by these sensors. The MAS index from MINE is utilized to represent the correlation information between sensors when the thermal system is in dynamic operation condition. Based on the MAS correlation coefficient, the sensor correlation network is constructed to represent the dynamic operation process of thermal system. Using DBSCAN clustering algorithm, the large topological network is divided into different subnetworks. When the system is running dynamically, the Manhattan distance between the sub networks can reflect the running state of the system. Based on the distance of sub networks, the similarity of sensor networks with continuous changes is calculated and the similarity correlation sequence is formed. Through the matching between the similarity correlation sequence and the historical experience sequence, we can judge whether the system dynamic condition is abnormal. By the simulation experiment data, we verify the effectiveness of the proposed method.

The magnetic anisotropy of SmCo-based permanent magnetic thin films are generally controlled by introducing buffer layer or heating substrate. However, the design for the multi-layer thin film system is complicated and the thickness of SmCo is limited due to a short range of interfacial stress/strain between the buffer layer and SmCo layer. In this work, the effects of temperature gradients, generated by RTP (rapid thermal process), on the magnetic anisotropy of the SmCo-based films were systematically investigated. The results show that the as-deposited films exhibit amorphous state. The out-of-plane coercivity of RTP-treated films is strongly correlated with the heating rate, and its optimum value (2810 Oe) is larger than that of the CTA (conventional thermal annealing) treated films (1670 Oe). For the RTP-treated films, the intensity of characteristic diffraction peaks for in-plane oriented SmCo5 (200) and Sm2Co17 (300) decreases, together with reducing the roughness. Besides, the grain size is finer and the contrast of magnetic domains becomes stronger for the RTP-treated films due to that the easy axis of SmCo5/Sm2Co17 phase gradually changes from in-plane to out-of-plane direction. It is suggested that the RTP treatment with a shorter annealing time has beneficial effects on obtaining finer microstructure and improving the out-of-plane magnetic anisotropy of the SmCo-based films. This work provides a novel way to control the magnetic anisotropy via annealing temperature gradients for permanent magnetic thin films, compared with conventional methods, to induce the magnetic anisotropy.

A conductive layer, made of multi-walled carbon nanotubes (MWCNTs), with micro-cracks and a micro/nano porous structure was fabricated between the active material layer (AML) and the current collector in this study. The coating thickness of MWCNTs-based conductive layer (MCL) varies in the range of 25-100 μm. The electrochemical tests of half-cells demonstrate that both the mesocarbon-microbeads (MCMB) anode and the LiCoO2 cathode with a micro-cracked MCL show higher capacity, lower impedance and less capacity fading. These improvements are closely due to the enhancement of adhesion strength, and also the outstanding buffer effect of the micro-cracked MCL. With the change of the coating thickness, the size and amount of the micro-cracks on the MCL varies accordingly to accommodate the active material with different particle sizes. The electrodes including a micro-cracked MCL with a coating thickness of 50 and 75 μm are more suitable for MCMB and LiCoO2 with a particle size of 10-20 μm.

The energy density and operational life of lithium-ion batteries (LIBs) depend sensitively on the properties of electrode materials. Transition metal oxide based electrodes attract much attention because of their potential to offer high energy density. In this study, we report a binder-free composite anode composed of CuO nanosheets and multi-wall carbon nanotubes for LIBs. This composite anode is fabricated by a cost-effective electrophoretic deposition process followed by facile solution immersion. When tested in a LIB, this composite anode delivers a high reversible capacity of 540 mAh g−1 and maintains its capacity retention of above 78% after 50 cycles at a current density of 100 mA g−1, which is much higher than the CuO anode without carbon nanotubes. The high capacity, enhanced rate capability, low resistance, and increased operational life are attributed to the unique architecture of the hybrid electrode. The carbon nanotubes facilitate the electron transfer, enhance the structural stability of CuO nanosheets, and improve the adhesion of the CuO nanosheets to current collector. Such highly porous cross-linked network based on CuO nanosheets and multi-wall carbon nanotubes has great potential as a binder-free anode for high-performance LIBs.

The relation between the microstructure and the magnetic properties of Fe2P-type (Mn,Fe)2(P,Si,B) based materials has been systematically investigated by changing the annealing temperature and time. X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy measurements show that the alloys contain the main Fe2P-type phase and two impurity phases of (Fe,Mn)5Si3-type and Fe2MnSi-type. Boron appears to facilitate the formation of the Fe2P-type phase during the arc-melting progress. Upon increasing the annealing temperatures from 1123 to 1423 K, the Curie temperature (TC) decreases from 302.0 to 270.5 K in the Mn1.15Fe0.85P0.55Si0.45 alloys and the magnetic-entropy change (ΔSM) increases linearly with annealing temperature. For the Mn1.15Fe0.85P0.52Si0.45B0.03 alloys annealed at 1423 K for different times, TC decreases from 263.8 and 232.8 K with increasing annealing time and ΔSM reaches a maximum value after annealing for 48 h. The differences in the annealing temperature and time influence the Si content in the Fe2P-type phase of the alloys and determine TC, the thermal hysteresis and the magneto-elastic transition.

Fe-based metallic glass has been reported to exhibit high degradation ability for azo dye due to its unique atomic structure. In this work, we show that the degradation efficiency of Fe-based alloy can be further improved via simple heat treatment. Fe82Si2.5B12P2.5C amorphous ribbons were prepared by arc melting and melt spinning and then annealed from 100 °C to 850 °C for 5 min. A crystallization process from single α-Fe at 500 °C, to α-Fe + Fe3B at 520 °C, to α-Fe + Fe3B + Fe2C at 850 °C, took place. The degradation efficiency of the heat-treated ribbons decreased monolithically when annealed at 100-600 °C, but increased dramatically at 850 °C. The underlying degradation mechanisms were analyzed, that the formation and interaction of nanocrystals after annealing were considered mainly responsible for the differences in their degradation performances.

The effects of Co on microstructure, crystallization behavior and magnetic properties of (Ni0.5Fe0.5-xCox)80B10Si2Cu1Zr7 (x = 0~0.5) alloys were investigated. The results show that, the as-spun alloys remain lower coercivity (Hc) values (5 A/m ~ 14 A/m) over the whole Co content range, owing to their amorphous structure. After being annealed for 20 min above the onset temperatures of primary crystallization (Tx1), amorphous and nanocrystallines are coexisted in the alloys, and the crystal structure of nanocrystallines changes between fcc-(Ni, Fe, Co) and bcc-(Fe, Ni, Co) with the increasing Co content. In particular, it was found that Hc of the annealed alloys changes anomalously between 40 A/m and 1529 A/m with the increasing Co content, owing to the integrated action of grain size (D), magnetocrystalline anisotropy (K1) and lattice distortion. Especially for the alloys with x = 0.2 and x = 0.3, serious lattice distortion is the dominant factor for their higher Hc value than 1000 A/m.

This study presents a hierarchical MCMB/CuO/Cu anode structure with super-hydrophilic CuO substrate and blind-hole structures (BHSs) for lithium-ion battery (LIB) application. The porous hierarchical CuO clusters with controllable morphology and super hydrophilicity are prepared and combined with the BHSs on the surface of copper plates (CPs). Results indicate that the new anode yields a considerable improvement in reversible capacity and robustness under the condition of rate cycles. Compared with the conventional pattern of MCMB/Cu, the MCMB/CuO/Cu anode with BHSs produces reversible initial discharge and charge capacities of 381.5 and 347 mAh g−1 at a constant current of 0.5 mA. After 30 cycle times, the battery retains 276.7 and 276.6 mAh g−1, which amounts to 5 times as much as that of 0.5 C rate cycles. The energy density of the battery can be also greatly promoted. The larger surface area and porosity of the new anode facilitate formation of contact interface between the active material and current collector (CC). It also helps shorten the diffusion path of Li-ions and alleviate the volume expansion during the insertion and desertion processes of Li-ions.

Developing high-performance electrode structures is of great importance for advanced lithium-ion batteries. This study reports an efficient method to fabricate hierarchical shell/core CuO nanowire/carbon fiber composites via electroless plating and thermal oxidation processes. With this method, a binder-free CuO nanowire/carbon fiber shell/core hierarchical network composite anode for lithium-ion batteries is successfully fabricated. The morphology and chemical composition of the anode are characterized, and the electrochemical performance of the anode is investigated by standard electrochemical tests. Owing to the superior properties of carbon fibers and the morphological advantages of CuO nanowires, this composite anode still retains an excellent reversible capacity of 598.2 mAh g −1 with a capacity retention rate above 86%, even after 50 cycles, which is much higher than the CuO anode without carbon fibers. Compared to the typical CuO/C electrode systems, the novel binder-free anode yields a performance close to that of the typical core/shell electrode systems and a much higher reversible capacity and capacity retention than the similar shell/core patterns as well as the anodes with binders. It is believed that this novel anode will pave the way to the development of binder-free anodes in response to the increasing demands for high-power energy storage.

In this paper, the water level control principle and fault model of SG are introduced. On the issue of parameter variation that caused by faults and disturbance, a robust fault tolerant controller is designed. Under the control of the designed robust fault tolerant controller, the closed-loop system can maintain stability and meet certain performance targets on the condition of normal operation and fault situation. The robust fault tolerant controller can suppress the influence of the uncertainty and minimizing the adverse effect of the actuator fault on the system. The feasibility, effectiveness and precision of the proposed method are simulated and analyzed. The result shows the capability of the designed controller in tracking, adapting, anti-interference and overcoming the impact of faults are evidently superior to standard robust controller.

Amorphous (FexNiyCoz)80B10Si2Cu1Zr7 (x + y + z = 1) alloys were prepared by melt spinning. By investigating the glass-forming ability, thermal behavior, crystallization and magnetic properties of alloy ribbons, detailed and integral pseudoternary diagrams of (FexNiyCoz)80B10Si2Cu1Zr7 alloys were constructed, which can make one clearly understand the effects of ferromagnetic elements (Fe, Co, Ni) on microstructure and physical properties. Results show that, all as-spun alloys show a fully amorphous structure and the coercivity (Hc) can be tuned to a lower value than 45 A/m. After being annealed, alloys with Ni content lower than 64 at.% (y

As environmentally friendly and high-energy density rechargeable energy storage devices, lithium-ion batteries (LIBs) have thriving prospects in the field of energy. The current collector, which serves as an important component of LIBs, significantly influences the electrochemical performance of the battery. Numerous efforts have been spent on the design and fabrication of high-performance negative current collectors in the field of LIBs to achieve excellent battery performances. These high-performance current collectors are mostly structuralized to achieve special functions. Hence, different types of structuralized current collectors used for LIB anodes are comprehensively discussed and summarized in this paper. The structuralized current collectors used in LIB anodes are classified into planar-plate-based special-surface current collectors and the 3D framework-based porous current collectors. Both types of the structuralized current collectors are further divided into the single-component and multicomponent current collectors. More subsections are provided and focus on providing description of the developing strategies, fabrication methods, electrochemical behaviors, in-depth reasons for high performances, and advantages and challenges for real applications of the structuralized current collectors in detail. Subsequently, the challenges and future research directions of structuralized anode current collectors are reasonably clarified. Based on an objective summary of the high-performance negative current collectors, this review provides an enlightening guide for the future development of current collectors and LIBs. The fundamental conclusions can also be extended to other energy storage devices.

Fe78Si11B9P2 metallic glass (MG) ribbons are proved to exhibit excellent comprehensive ability in azo dye treatment. The Fe78Si11B9P2 MG ribbons can degrade the azo dye effectively, which derived from high mass and electron transfer ability due to the cotton-like structure formed during the reaction. The degradation efficiency and reaction rate raise with the decrease of the initial Orange Ⅱ concentration, the increase of ribbon dosage and the proper addition of H2O2. The Fe78Si11B9P2 MG ribbons are more applicable in acidic and neutral solutions. Compared to the other reported Fe-based metallic glasses for dye degradation, the Fe78Si11B9P2 MG has a lower reaction activation energy and relatively good reusability in treating with azo dye. In addition, the achieved high COD removal indicates that the complex organic structures in azo dye can be decomposed completely by Fe78Si11B9P2 MG ribbons. This work not only provides a new effective and low-cost materials for wastewater treatment, but also promotes the practical applications of Fe-based MGs as functional materials.

The Fe0.6Mn0.4NiSi1−xAlx (x = 0, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, and 0.12) alloys were prepared by arc melting and annealed at 1073 K for 90 h. With increasing Al contents, the structure of Fe0.6Mn0.4NiSi1−xAlx changes from TiNiSi-type to Ni2In-type at room temperature, while the Curie temperature decreases from 390 K to 136 K. Although the refrigerant capacity is relatively small, about 126 J/kg, the maximum isothermal entropy change reaches a value of −ΔSmax = 52.9 J/(kg K) under 5 T for x = 0.04. At the same time, the alloys have great corrosion resistance. From x = 0 to 0.12, samples can be tuned from a second-order to a first-order and then to a second-order phase transition. It is worth noting that there is no magnetic hysteresis for all samples although they experience structural phase transition. The structural and magnetic phase diagrams of the Fe0.6Mn0.4NiSi1−xAlx system have been figured out. The results indicate that the relatively large magnetocaloric effects with no magnetic hysteresis and good corrosion resistance make these alloys a good candidate for magnetic refrigeration near room temperature.

FexOy-type iron oxides, especially α-Fe2O3 and Fe3O4, are powerful alternatives to the currently available graphitic anode materials for lithium-ion batteries (LIBs) owing to their high theoretical capacity, natural abundance, environmental benignity, non-flammability, and enhanced safety. In this context, compositional engineering is a widely used strategy to improve the electrochemical performance of electrode materials; in this method, the synergetic effects of individual components in a hybrid material are harnessed for improved performance. To improve FexOy-based materials in terms of compositional engineering, in this review, the factors affecting the electrochemical performance of pure FexOy and different kinds of additives combined with FexOy for LIB anodes via doping or compositing and their effects on the electrochemical performance of the anodes are discussed in detail. Several approaches that can enhance the performance of FexOy-based LIB anodes via compositional engineering are highlighted and the importance of a proper combination of compositional and structural engineering for achieving the desired physical/electrochemical properties in FexOy-type anodes is described. In the near future, such approaches may provide effective and efficient ways to obtain advanced rechargeable LIBs with a high energy/power density, long cycle life, and low cost.

Direct measurements of the adiabatic temperature change (ΔTad) in Gd and Mn1.15Fe0.8P0.5Si0.5C0.05 are made using a homemade adiabatic magnetocalorimeter at 260-360 K and 0-7 T. The system uses a servo motor to drive the samples into and out of the magnetic field under a vacuum environment provided by the Physical Property Measurement System (PPMS). The peak values of ΔTad for Gd and Mn1.15Fe0.8P0.5Si0.5C0.05 at 7 T are 8.71 K and 6.41 K at ambient temperatures of 303 K and 317 K, respectively. Based on the theory model, it is found that ΔTad of Gd depends on the 2/3 exponential function of magnetic field H (ΔTad ∝ H2/3), whereas the Mn1.15Fe0.8P0.5Si0.5C0.05 compound follows the power law of ΔTad ∝ H0.66-1.04 due to the first order magnetic transitions. Furthermore, using the constructed experimental instrument, the adiabatic temperature change in different magnetic materials, including materials with first/second order magnetic transition and blocks, flakes, or powders, can be directly measured under large magnetic fields and wide temperature spans.

The high-energy and low-cost lithium-sulfur (Li-S) battery is regarded as a new generation energy-storage device. However, the Li-S battery mostly suffers from low electronic conductivity and poor cycle capability. This study reports on a novel sandwich-structured cathode with optimized electrode architecture and interface design of the current collector (named as M-S-LTO) made by a facile layer-by-layer slurry coating process. The new integrated electrode is composed of a micro-cracked current collector (MCC) based on multi-wall carbon nanotubes, a middle layer of sulfur/carbon material and an upper current collector&interlayer (UCC&I) based on multi-wall carbon nanotubes and Li4Ti5O12 nanospheres. The M-S-LTO cathode produces a better electrochemical performance because of its improved internal electrical and ionic conductivity, stable structure and mitigation of shuttle effect, in contrast to the sulfur electrode with either an MCC (M-S cathode) or a smooth aluminum foil current collector (S cathode). At a current density of 0.2 C, the Li-S battery with the M-S-LTO cathode delivers a high initial capacity of 1248.6 mAh g−1 and retains a reversible capacity of 960.3 mAh g−1 after 200 cycles. Even at 1 C, its capacity can reach 773.4 mAh g−1 after 200 cycles. The battery with the M-S-LTO cathode shows a higher cycle performance than most of other reported cells based on the interlayer design with a comparable sulfur loading. With the enhanced electrochemical performance, the new cathode offers a promising avenue to fabricate high-performance Li-S batteries.

Rechargeable lithium-ion battery (LIB) is a kind of electrochemical energy storage and conversion device with both high energy and power densities. The real application of various advanced LIBs (e.g., three-dimensional (3D) LIBs, flexible, wearable or customized LIBs) and integrated manufacturing of LIBs or LIB-powered devices depend on specific fabrication processes. However, conventional commercialized manufacturing techniques with sophisticated and expensive processes are far away from the facile, cost-effective and free-form fabrication demands. Additive manufacturing, usually known as 3D printing, is an ideal solution. This technology enables practical freedom of fabricating objects with well-controlled complex geometry through a layer-by-layer deposition process, independent of any templates. Almost all kinds of materials, from nanoscale to macroscale, can be used for 3D printing. In this work, we review the application advance of 3D printing in the field of LIBs. The fundamental concepts of representative 3D printing techniques are presented first, including the operation principles, requirements for raw printing materials and manufacturing accuracy of different 3D printing techniques. Then the applications are discussed at both component and package levels. Finally, the methodology, challenges and future perspectives of exploiting 3D printing for real applications in LIBs are presented. All the applications of 3D printing discussed herein can provide us with right directions of better energy conservation and conversion.

The Fe78Si13B9 amorphous alloy ribbons and high-entropy amorphous alloy ribbons of (FeCoNi)78Si13B9 were prepared by melt spinning method. The decolorization performances of these ribbons were investigated in details. It was interesting that Orange Ⅱ solution of 40 mg/L can be degraded almost completely within 70 min and a reduction 52.4% in COD (Chemical Oxygen Demand) value using Fe78Si13B9 amorphous ribbons, indicating the prominent capacity of alloys on the degradation of azo dyes. As for amorphous ribbons (FeCoNi)78Si13B9, they just presented a physical adsorption process, with no chemical degradation of dye molecules under the same conditions. Furthermore, the Fe78Si13B9 amorphous ribbons possess a higher decolorization reaction rate (kobs = 0.071 min−1) compared to the (FeCoNi)78Si13B9 ribbons, together with converting dye molecules to harmless micromolecule inorganic substances, which is of practical significance from the perspective of environmental protection. In addition, all the degradation process in this work fit well with the pseudo-first-order kinetic model. The findings are attractive, valuable and promising for the practical applications and they have important implications in developing Fe-based high-entropy alloys for functional application materials in the field of wastewater treatment.

Mining mechanics usually refers to the movement of overburden rocks and stress redistribution induced by mining effects, especially during the evolution of abutment pressure at a mining face (Xie et al. 2011). The characteristic of the stress field at a mining face serves as an important foundation for achieving roof safety and preventing excess gas (Suchowerska et al. 2013; Yang et al. 2011a). The mining effect may cause coal rocks to fracture, causing coal methane to escape from the fractured rock into the mining face, resulting in the exceedance of safety limits for gas. This is especially relevant under intensive mining conditions (Yang et al. 2011b; Li et al. 2006; Wang et al. 2012). Therefore, the study of mining mechanics is of great importance in achieving the safe and efficient coal mining. Many specific studies have been conducted to investigate stress redistribution, strata deformation, strata failure and fluid flow of coal seams (Islam and Shinjo 2009; Yang et al. 2014). However, these studies only focused on mining mechanics induced by mining advances, and neglected local mining effects, such as coal caving processes used for top coal caving method. In this manuscript, a field test and analytical analysis were conducted. A combination of global and local mining mechanics was consequently proposed for the top coal caving. Based on the real-time pressure monitoring of single props and hydraulic supports at a top coal mining face, intensive factors of pressure were adopted to provide a quantitative description of the mining mechanics.

Roof-coal recovery rate and the performance of gas extraction are essentially controlled by the fractures within coal-rock mass. Thus, it is important to generate the accurate fracture network ahead of mining face. In this study, ten boreholes located differently from the 8212 working face of Tashan Mine in Datong coal mining group, China, were drilled. With the help of borehole video instruments, the location, orientation of each fracture and the fracture number of different intersection type on each borehole wall were mapped with the advancing of mining face. These data were analyzed using the Matlab Toolbox RJNS3D and Dips to determine structural homogeneity zone, to find the number of fracture sets that exist in the coal-rock mass, volume density frequency for each set and the probability distributions of orientation, fracture size in 3-D. Sampling biases associated with orientation, spacing were corrected during the process. The constructed fracture networks were validated by comparing the observed mean spacing along normal vector of mean orientation for each set and the predict value on similar scanlines.

Rectangular caverns are increasingly used in underground engineering projects, the failure mechanism of rectangular cavern wall rock is significantly different as a result of the cross-sectional shape and variations in wall stress distributions. However, the conventional computational method always results in a long-winded computational process and multiple displacement solutions of internal rectangular wall rock. This paper uses a Laurent series complex method to obtain a mapping function expression based on complex variable function theory and conformal transformation. This method is combined with the Schwarz-Christoffel method to calculate the mapping function coefficient and to determine the rectangular cavern wall rock deformation. With regard to the inverse mapping concept, the mapping relation between the polar coordinate system within plane ς and a corresponding unique plane coordinate point inside the cavern wall rock is discussed. The disadvantage of multiple solutions when mapping from the plane to the polar coordinate system is addressed. This theoretical formula is used to calculate wall rock boundary deformation and displacement field nephograms inside the wall rock for a given cavern height and width. A comparison with ANSYS numerical software results suggests that the theoretical solution and numerical solution exhibit identical trends, thereby demonstrating the method's validity. This method greatly improves the computing accuracy and reduces the difficulty in solving for cavern boundary and internal wall rock displacements. The proposed method provides a theoretical guide for controlling cavern wall rock deformation failure.

A rapid, high-throughput method was developed to evaluate zeaxanthin levels in Chinese wolfberry fruit, based on the official AOAC (970.64) method. The sample preparation was optimized from the AOAC method with supporting material added to disperse the sample thoroughly. An HPLC method was adopted to replace the time-consuming column separation and spectrophotometric method used previously. Dried Chinese wolfberry fruit was extracted and saponified, simultaneously, in a volumetric flask with a four-solvent blend of hexane:ethanol:acetone:toluene (10:6:7:7); and 40% methanolic potassium hydroxide in order to convert the extracted zeaxanthin dipalmitate to free zeaxanthin in a single step. The flask was placed in a 56° C water bath and shaken at 200 rpm for 20 min. A normal-phase HPLC method was developed on a silica gel column with an isocratic mobile phase of hexane and ethyl acetate (70:30, v:v). Zeaxanthin was determined to be the dominant carotenoid in Chinese wolfberry fruit. This method was found to be rapid, sensitive and cost-effective for quantitating zeaxanthin in wolfberries compared to the column separation and the spectrophotometric methods traditionally used. Using the developed method, a total of 30 Chinese wolfberry samples from different growers/locations of China were investigated as potential sources of zeaxanthin. The fruit produced in the Ningxia Hui autonomous region had the highest level of zeaxanthin at greater than 1500 mg/kg. The zeaxanthin content was not positively correlated to the size of fruit; suggesting that the low cost, smaller fruits may be an economical source for zexanthin extraction.

Estimation of the number of signal sources is a key problem in the direction of arrival (DOA) estimation algorithms. In this paper a new method, based on MUSIC algorithm, is proposed. The estimated signal source matrix is derived with an assumed source number which is larger than the true number. Then an approach is proposed to detect the source number based on the information of the estimated signal source matrix. Simulation results show the efficiency of the proposed method.