Effect of lateral stiffness of secondary suspensions on heavy-haul locomotives stability during braking based on simulation and experiment

This paper aimed to investigate the effect of the lateral stiffness of secondary suspensions on the stability capacity and running safety of heavy-haul locomotives during braking based on the dynamic model and the field braking tests. The dynamic model of heavy-haul locomotives included two double-unit locomotives and five coupler systems. Simulation results indicate that the increasing of the lateral stiffness of secondary suspensions can improve the stability capacity and running safety of heavy-haul locomotives. Then, the field braking experiments were conducted to validate the dynamic model. Comparing the experiment results of different locomotives, the coupler and carbody yaw angles are respectively decreased by 31.8 and 29.5%, which is consistent with the simulation results. It is worthy to be noted that lateral vibration behaviour of the carbody increases with the increasing of the lateral stiffness of secondary suspensions. For the improved locomotive, the main frequency of lateral acceleration is 1…2 Hz. However, the main frequency of lateral acceleration is 0.5…1 Hz in the original locomotive tests. Moreover, the high-frequency vibration is increased, especially in 10…12.5 Hz. According to the simulation and experiment results, the reasonable lateral stiffness of secondary suspensions is 400 kN/m for the test locomotive

Progress of nanoparticle drug delivery system for the treatment of glioma

Gliomas are typical malignant brain tumours affecting a wide population worldwide. Operation, as the common treatment for gliomas, is always accompanied by postoperative drug chemotherapy, but cannot cure patients. The main challenges are chemotherapeutic drugs have low blood-brain barrier passage rate and a lot of serious adverse effects, meanwhile, they have difficulty targeting glioma issues. Nowadays, the emergence of nanoparticles (NPs) drug delivery systems (NDDS) has provided a new promising approach for the treatment of gliomas owing to their excellent biodegradability, high stability, good biocompatibility, low toxicity, and minimal adverse effects. Herein, we reviewed the types and delivery mechanisms of NPs currently used in gliomas, including passive and active brain targeting drug delivery. In particular, we primarily focused on various hopeful types of NPs (such as liposome, chitosan, ferritin, graphene oxide, silica nanoparticle, nanogel, neutrophil, and adeno-associated virus), and discussed their advantages, disadvantages, and progress in preclinical trials. Moreover, we outlined the clinical trials of NPs applied in gliomas. According to this review, we provide an outlook of the prospects of NDDS for treating gliomas and summarise some methods that can enhance the targeting specificity and safety of NPs, like surface modification and conjugating ligands and peptides. Although there are still some limitations of these NPs, NDDS will offer the potential for curing glioma patients

Edge-Guided Parallel Network for VHR Remote Sensing Image Change Detection

Change detection (CD) is an important research topic in the remote sensing field, and it has a wide range of applications, including resource monitoring, disaster assessment, urban planning, etc. Recently, deep learning (DL) has shown its advantages in CD. However, most existing DL-based methods cannot capture the complementary information between bitemporal and difference features. This article proposes an edge-guided parallel network (EGPNet) to solve this problem. First, our EGPNet extracts bitemporal and difference features simultaneously through a parallel encoding framework. During parallel encoding, we design a supplementary mechanism to enrich the difference features with bitemporal features. Second, we fuse bitemporal and difference features at each feature level to sufficiently exploit their complementarity. Finally, the edge-aware module and edge-guidance feature module are introduced to enhance the edge representation for improving blurred edges of detection results. Benefiting from the rich change-related information in difference features and detailed information in bitemporal features, our EGPNet can detect change regions entirely and accurately. Experimental results on the LEVIR-CD, SYSU-CD, and CDD datasets demonstrate that the proposed method outperforms several state-of-the-art approaches. Especially, our EGPNet can detect more precise and sharper edges than other methods

Effects of Flue Gas Impurities on the Performance of Rare Earth Denitration Catalysts

Selective catalytic reduction (SCR) is still the most widely used process for controlling NOx gas pollution. Specifically, commercial vanadium-based catalysts have problems such as narrow operating temperature range and environmental pollution. Researchers have developed a series of cerium-based catalysts with good oxygen storage performance and excellent redox performance of CeO2. However, the anti-poisoning performance of the catalyst is the key to its application. There are many kinds of impurities in the flue gas, which has a huge impact on the catalyst. The deposition of substances, the reduction of active sites, the reduction of specific surface area, and the reduction of chemically adsorbed oxygen will affect the denitration activity of the catalyst to varying degrees, and the poisoning mechanism of different impurities on the catalyst is also different. Therefore, this review divides the impurities contained in flue gas into different types such as alkali metals, alkaline earth metals, heavy metals, and non-metals, and summarizes the effects and deactivation mechanisms of various types of impurities on the activity of rare earth catalysts. Finally, we hope that this work can provide a valuable reference for the development and application of NH3-SCR catalysts for rare earth denitration in the field of NOx control

Suitability Evaluation for Land Reclamation of Nonmetallic Mines in Xinjiang, China

The ecological environment is fragile in Xinjiang, so it is necessary to carry out land reclamation for mines to restore its ecology. The premise of mines land reclamation is to determine the direction of land reclamation, which requires the suitability evaluation for land reclamation. In this paper, the evaluation index system and suitability evaluation model for land reclamation of nonmetallic mines in Xinjiang Uygur Autonomous Region were established. This model was established by using factor analysis, cluster analysis, and discriminant analysis and tested by back-substitution. First, using 149 units of 21 nonmetallic mines as research samples, the samples were divided into 4 categories by a combination of factor and cluster analysis. Then, the samples were trained using a discriminant analysis method to establish the corresponding land reclamation suitability evaluation model. This model was verified by back-substitution with an accuracy of 98.7%, and only 2 of 149 samples were misclassified. Finally, the evaluation model was applied to the Dabancheng Toga Solo limestone mine in Urumqi. Evaluation analysis of 15 land reclamation units of this mine showed satisfactory results. The evaluation model developed here could serve as a powerful complement to the evaluation of land reclamation suitability in Xinjiang

Influence of Wheel Eccentricity on Vertical Vibration of Suspended Monorail Vehicle: Experiment and Simulation

This paper investigates the influence of wheel eccentricity on vertical vibration of suspended monorail vehicle based on experiment and simulation. Two sets of tests are conducted in the first Chinese suspended monorail, and the tested acceleration is analyzed and exhibited. A multibody dynamic model of the suspended monorail vehicle is established to simulate the vertical vibration of car body excited by wheel eccentricity. The results show that there are three factors which may cause an abnormal vibration considering the track and the vehicle system. The influence of wheel eccentricity on the car body vibration was firstly analyzed. Simulated acceleration of car body has a great accordance with test. The wheel eccentricity could excite the resonance of car body at the speed of 21 km/h, and the vertical acceleration would increase considerably. Decreasing the secondary stiffness can effectively reduce the vertical vibration caused by wheel eccentricity, especially at the resonant speed. In the secondary test, the peak of car body acceleration at speed of 20 km/h is not appearing when only renewing the wheels, and the acceleration is decreasing obviously at the domain frequency. It is further determined that the abnormal vibration is mainly caused by the wheel eccentricity

Investigation on Derailment of Empty Wagons of Long Freight Train during Dynamic Braking

The derailments of empty wagons of long freight trains frequently occurred around the world, which caused tremendous losses every year. Aiming at an actual derailment of empty wagons on straight line during dynamic braking, the field investigation was conducted to find the reasons of the accident. According to the investigation results, the large coupler yaw angle and coupler force, the special connection mode by drawbars, as well as the poor conditions of wheel treads and flanges were supposed to be responsible for the accident. The simulaiton model composed of 3 C80-type gondolas, and two RFC-type drawbars is established, the accuracy of which is validated by the field experimental test. When the wheel-rail friction coefficient is set to be 0.7 and the coupler forces are set to be 350 kN with a coupler yaw angle of 7 degrees, the simulation results are consistent with the field investigation results. Simulation results indicate that the coupler yaw angle, coupler force, and wheel-rail friction coefficient have significant influences on the derailment. The increasing coupler yaw angle and coupler force will increase the risk of derailment. For the wagon units adopting the drawbars, the riskiest wagon changes from the middle wagon to the front one as the lateral components of the coupler forces increase. A large wheel-rail friction coefficient can raise the risk of derailment. However, an overlarge friction coefficient will decrease the derailment risk. According to the field investigation and simulation results, the wheel-rail friction coefficients should be limited below 0.5 to ensure the running safety of empty wagons. Besides, the operations of the train should be optimized to avoid large coupler yaw angle and coupler force

A New Composite Slab Using Crushed Waste Tires as Fine Aggregate in Self-Compacting Lightweight Aggregate Concrete

A composite slab comprised of self-compacting rubber lightweight aggregate concrete (SCRLC) and profiled steel sheeting is a new type of structural element with a series of superior properties. This paper presents an experimental research and finite element analysis (FEA) of the flexural behavior of composite slabs consisting of SCRLC to develop a new floor system. Four composite slabs specimens with different shear spans (450 mm and 800 mm) and SCRLC (0% and 30% in rubber particles substitution ratio) are prepared, and the flexural properties including failure modes, deflection at mid-span, profiled steel sheeting, and concrete surface stain at mid-span and end slippage are investigated by four-point bending tests. The experimental results indicate that applying SCRLC30 in composites slabs will improve the anti-cracking ability under the loading of composite slabs compared with composite slabs consisting of self-compacting lightweight aggregate concrete (SCLC). FEM on the flexural properties of SCRLC composites slabs show that the yield load, ultimate load, and deflection corresponding to the yield load and the ultimate load of composite slabs drop as the rubber particles content increases in SCRLC. The variation of SCRLC strength has less impact on the flexural bearing capacity of corresponding composite slabs. Based on the traditional calculated method of the ultimate bending moment of normal concrete (NC) composite slabs, a modified calculated method for the ultimate bending moment of SCRLC composite slabs is proposed

Study on Compaction Effect and Process of Reclaimed Soil of Nonmetallic Mines in Xinjiang, China

Reclaimed soil is the key substrate for land reclamation and ecological restoration in the mine areas. The change of the density of reclaimed soil of the nonmetallic mines in Xinjiang during the land reclamation process was studied in this paper. Firstly, the in situ test method of static load was used to simulate the compaction of reclaimed soil with different thickness of overlying soil by different compaction times of mines reclamation machinery, and field in situ test compaction data were obtained. Then, the numerical simulation method was used to simulate the variation process of displacement and porosity at different depths for different thickness of the reclaimed soil under different compaction conditions. The numerical simulation and the in situ test results verified each other to acquire the compaction process and results of reclaimed soil under different compaction. The results showed that the numerical simulation results were consistent with the in situ test. The reclaimed soil thickness and compaction times were crucial factors affecting the compaction effect of the soil. The difference between the three times compaction and the uncompacted soil was obvious, and the effect of single compaction was weakened with the increase of compaction times. Under the same compaction action, the thicker the soil was, the less obvious the compaction effect would be. In the process of reclamation, the compaction effect of the surface part (at the depth of 10 cm) was visible, and the amount of compression and springback was larger. The research results can provide a reference to the land reclamation of nonmetallic mines in Xinjiang, China

Surface nanoprecipitation induced by severe plastic deformation in the Fe49.3Co23Ni23C0.85Mn1Si2.85 biphasic multicomponent alloy

Precipitation strengthening plays a vital role in enhancing the mechanical properties of metallic materials, typically achieved through heat treatment. However, deformation-induced precipitation (DIP) in multicomponent alloys (MAs) without the assistance of annealing is rarely reported, owing to their inherent high entropy and sluggish diffusion effects. This work reveals the significant formation of nanoscale and microscale precipitates in the dual-phase Fe49.3Co23Ni23C0.85Mn1Si2.85 MA triggered by surface severe plastic deformation (SSPD) through industrial shot blasting. The SSPD process leads to the formation of ultrafine gradient structures comprising nanocrystalline and submicron-crystalline zones. Submicron SiO2 precipitates emerge at the interfaces of both these zones, while various Mn5Si3 and Si nanoparticles precipitate within the nanocrystalline zone. This phenomenon can be ascribed to the high density of generated substructures, the accelerated diffusion of atoms, and the reduction in solid solubility limits in the SPD-driven non-equilibrium state