Optimal Pattern Synthesis of Linear Array and Broadband Design of Whip Antenna Using Grasshopper Optimization Algorithm

Antenna arrays with high directivity, low side-lobe level, and null control in desired direction and whip antenna with wider bandwidth both need to be optimized to meet different needs of communication systems. A new natural heuristic algorithm simulating social behavior of grasshoppers, grasshopper optimization algorithm (GOA), is applied to electromagnetic field as a new effective technology to solve the antenna optimization problem for the first time. Its algorithm is simple and has no gradient mechanism, can effectively avoid falling into local optimum, and is suitable for single-objective and multiobjective optimization problems. GOA is used to optimize the side lobe suppression, null depth, and notch control of arbitrary linear array and then used to optimize the loading and matching network of 10-meter HF broadband whip antenna compared with other algorithms. The results show that GOA has more advantages in side-lobe suppression, null depth, and notch control of linear array than other algorithms and has better broadband optimization performance for HF whip antenna. The pattern synthesis and antenna broadband optimization based on GOA provide a new and effective method for antenna performance optimization

Numerical simulation of working characteristics of energy pile group under thermo-mechanical coupling

In order to study the working characteristics of energy pile groups, based on the Abaqus finite element simulation, assigns the average temperature of the heat transfer stable stage to the pile body for steady-state thermo-mechanical coupling calculation, and proposes a simplified analysis method for the bearing characteristics of energy pile groups.The reliability of this research method is verified through the comparative analysis with field data.Combined with an example, this method is used to analyze the bearing characteristics of energy group piles under the action of pure mechanical load and thermal coupling.The results show that the non-uniform settlement of the distributed symmetrical arrangement of energy piles in the pile group foundation is significantly less than that of the centralized arrangement, and the layout has a great influence on the response characteristics of the pile foundation structure.Under the condition of equal stiffness of pile foundation, the control effect of pile group tilt is better by increasing pile diameter and decreasing pile spacing.The research results of this paper can provide some reference value for the engineering application of energy pile group

The Unsteady-State Response of Tires to Slip Angle and Vertical Load Variations

The tire is the only part that connects the vehicle and the road surface. Many important properties of vehicles are related to the mechanical properties of tires, such as handling stability, braking safety, vertical vibration characteristics, and so on. Although a great deal of research on tire dynamics has been completed, mainly focusing on steady-state tire force and moment characteristics, as well as linear unsteady force characteristics, less research has been conducted on nonlinear unsteady characteristics, especially when the vertical load changes dynamically. Therefore, the main purpose of this paper is to improve the tire unsteady-state model and verify it by experiment. To achieve this goal, we first study the nonlinear unsteady tire cornering theoretical model and obtain clear force and torque frequency response functions. Then, based on the results of the theoretical model, a high-precision and high-efficiency semi-physical model is developed. Finally, model identification and accuracy verification are carried out based on the bench test data. The model developed in this paper has high accuracy, and it significantly improves the expression of the aligning torque, which helps to improve the virtual simulation of transient conditions, such as vehicle handling and dynamic load conditions

A Calculation Method of Available Transmission Capacity for Medium and Long-term Electricity Trading

In view of the fact that China’s power dispatching agencies and trading centers are relatively independent, but the medium and long-term power transactions need physical execution, which leads to higher requirements for transaction security boundary, this paper proposes a calculation method of available transmission capacity for medium and long-term power transactions, which calculates the available transmission capacity of transmission channels through probabilistic method to improve the enforceability of transaction results. Numerical simulation results also verify the effectiveness of the algorithm

Multi-Peak Double-Dwell GPS Weak Signal Acquisition Method and VLSI Implementation for Energy-Constrained Applications

Power consumption of Global Positioning System (GPS) acquisition is a great challenge for energy-constrained applications. In this work, a metric named acquisition mean computation overhead is proposed to measure the energy cost. A novel multi-peak double-dwell (MP/DD) acquisition method for GPS weak signal is proposed. It adopts multi-peak correlation results as candidates in the first acquisition dwell and selects the largest one as the final acquisition result in the second acquisition dwell. Theoretical analysis and numerical simulation are presented in detail. Meanwhile, the very-large-scale integration (VLSI) implementation of coarse- and fine-grained acquisition engines applied to the proposed method is done. The detection probability and acquisition mean computation overhead are simulated using the Monte-Carlo method, and its mean acquisition power is tested with an actual chip. We fabricated the GPS signal acquisition engine with a 40 nm complementary metal oxide semiconductor (CMOS) process. The simulation results demonstrate that detection probability is promoted from 18% to 67% when signal power is equal to 23 dB/Hz. The acquisition mean computation overhead is reduced greatly by 64%. Measurement results show that the energy consumption of this design is only 21.5% of the conventional double-dwell/maximum (DD/MAX) method

Mining footprint of the underground longwall caving extraction method: a case study of a typical industrial coal area in China

Longwall caving mining (LCM) can lead to many environmental problems that have drawn worldwide attention. A previous survey found that most scholars tend to analyze the two issues separately, that is, coal mining-induced subsidence and heavy metal pollution sources in the soil of the mining regions. Based on field monitoring as well as the collection and analysis of soil samples, a previous study estimated ground settlement and analyzed the surface subsidence law and spatial distribution characteristics of heavy metals in soils. Moreover, a geographic information system was combined with multivariate statistical analysis methods to analyze the heavy metal pollution sources in soils. At the same time, the mechanism of heavy metal accumulation in the subsidence area was analyzed. The study found that the most active subsidence of settlement was 137.5 m behind the workface and moved forward with the workface. LCM has already caused significant disturbance to the soils in the Hengyuan Mine. Moreover, the distribution pattern of eight heavy metals was consistent with the surface subsidence law. The sources of heavy metal pollution in the soils were also identified; namely, coal mining-induced subsidence (64.1%) and mixed transportation and wind-mediated spread (35.9%), offering a reinterpretation of the LCM’s footprint.The authors gratefully acknowledge the support by the Open Fund Project of Key Laboratory of Coal Resources and Mineral Resources, China National Administration of Coal Geology, China [grant number KFKT-2020–1], China National Administration of Coal Geology Funded Research Project, China [grant number ZMKJ-2020-J04–4], Postgraduate Research & Practice Innovation Program of Jiangsu Province, China [grant number KYCX21_2370], and the first author is supported by the China Scholarship Council, China [grant number 202006420032]. The authors would like to extend their thanks to the providers of the materials used in this study, and their appreciation to those who offered support for this study, including the Hengyuan Mine and CUMT. The authors would like to acknowledge the editor and six anonymous reviewers for their valuable comments for the improvement of this paper. Finally, we would like to thank all scholars in the citations for their inspiration, especially Hou Deyi.Peer ReviewedPostprint (author's final draft

Mechanistic insights into Fe3O4-modified biochar relieving inhibition from erythromycin on anaerobic digestion

Anaerobic digestion (AD) of antibiotic manufacturing wastewater to degrade residual antibiotics and produce mixture of combustible gases has been investigated actively in the past decades. However, detrimental effect of residual antibiotic to microbial activities is commonly faced in AD process, leading to the reduction of treatment efficiency and energy recovery. Herein, the present study systematically evaluated the detoxification effect and mechanism of Fe3O4-modified biochar in AD of erythromycin manufacturing wastewater. Results showed that Fe3O4-modified biochar had stimulatory effect on AD at 0.5 g/L erythromycin existence. A maximum methane yield of 327.7 ± 8.0 mL/g COD was achieved at 3.0 g/L Fe3O4-modified biochar, leading to the increase of 55.7% compared to control group. Mechanistic investigation demonstrated that different levels of Fe3O4-modified biochar could improve methane yield via different metabolic pathways involved in specific bacteria and archaea. Low levels of Fe3O4-modified biochar (i.e., 0.5–1.0 g/L) led to the enrichment of Methanothermobacter sp., strengthening the hydrogenotrophic pathway. On the contrary, high levels of Fe3O4-modified biochar (2.0–3.0 g/L) favored the proliferation of acetogens (e.g., Lentimicrobium sp.) and methanogen (Methanosarcina sp.) and their syntrophic relations played vital role on the simulated AD performance at erythromycin stress. Additionally, the addition of Fe3O4-modified biochar significantly decreased the abundance of representative antibiotic resistant genes (ARGs), benefiting the reduction of environmental risk. The results of this study verified that the application of Fe3O4-modified biochar could be an efficient approach to detoxify erythromycin on AD system, which brings high impacts and positive implications for biological antibiotic wastewater treatment.</p

Utilization of mine waste heat in phase change rechargeable battery

Mine geothermal energy has been recognized as “heat hazard”, which is harmful to the health of miners and causes disasters. In order to realize the transformation of mine geothermal energy and waste heat from “hazard/waste” into “treasure”, this paper analyzes the distribution characteristics and genesis of mine geothermal energy with the field geothermal temperature monitoring data, evaluates geothermal reserves, and reveals the mutual influencing mechanism of stratified exploitation of two-layer geothermal reservoir and the law of thermal energy conduction and evolution in the stope of geothermal-coal synergetic mining (GE-COSM), using numerical models verified by experiments. In the end, the improvement effect of mine waste heat on the development potential of geothermal-coal mine (G-CM) was analyzed. The result shows that: The present geothermal field distribution characteristics of Anju Mine are high in the north and low in the south, high in the east and low in the west. There are two layers of zoned reservoir, with the temperatures of 43 °C and 54 °C respectively, the average heat flow value 70.1 mW/m2 and 80.9 mW/m2 respectively, and the geothermal water type SO42--Na+·Ca2+. The simultaneous exploitation of the two geothermal reservoirs will form a Coal-Austria geothermal reservoir joint influence area(C-Area) with lower temperature, which reduces the harm of “heat hazard” to miners. But the phase change heat storage function of functional cemented paste backfill material for phase change heat storage (F-CBM) is not fully utilized in the late stage of geothermal exploitation. The mine generates 4.6 × 1011 J of waste heat per day, and according to the type of heat source of mine waste heat can be continuously “heat charging” for a conventional backfill working face. Moreover, under the action of high temperature surrounding rock, the thermal energy recovery rate is greater than 1, and under the action of “heat charging”, the average maximum value of solid phase ratio is greater than 70 %. Therefore, the phase change rechargeable battery mode creatively proposed by this paper is significantly better than the traditional rock layer heat storage mode and is worth vigorously popularizing.The authors gratefully acknowledge the support by the Open Fund Project of Key Laboratory of Mineral Resource in Coal Measures, China National Administration of Coal Geology, China [grant number KFKT-2020-1], China National Administration of Coal Geology Funded Research Project, China [grant number ZMKJ-2020-J04-4], the Postgraduate Research & Practice Innovation Program of Jiangsu Province, China [grant number KYCX21_2370], the National Natural Science Foundation of China [grant number 52104151], and the first author is supported by the China Scholarship Council, China [grant number 202006420032]. The authors would like to acknowledge the editor and reviewers for their valuable comments for the improvement of this paper. Finally, we would like to thank all scholars in the citations for their inspiration.Peer ReviewedObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (author's final draft