| 1. |
- Li, Zheng, et al.
(författare)
-
A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures
- 2022
-
Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 13:8
-
Forskningsöversikt (refereegranskat)abstract
- Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes more severe in the fabrication of large-sized parts during the multi-laser L-PBF process. Therefore, investigations of spatter generation and countermeasures have become more urgent. Although much research has provided insights into the melt pool, microstructure, and mechanical property, reviews of spatter in L-PBF are still limited. This work reviews the literature on the in situ detection, generation, effects, and countermeasures of spatter in L-PBF. It is expected to pave the way towards a novel generation of highly efficient and intelligent L-PBF systems.
|
|
| 2. |
- Pei, Xilong, et al.
(författare)
-
RIS-Aided Wireless Communications : Prototyping, Adaptive Beamforming, and Indoor/Outdoor Field Trials
- 2021
-
Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 69:12, s. 8627-8640
-
Tidskriftsartikel (refereegranskat)abstract
- The prospects of using a Reconfigurable Intelligent Surface (RIS) to aid wireless communication systems have recently received much attention from academia and industry. Most papers make theoretical studies based on elementary models, while the prototyping of RIS-aided wireless communication and real-world field trials are scarce. In this paper, we describe a new RIS prototype consisting of 1100 controllable elements working at 5.8 GHz band. We propose an efficient algorithm for configuring the RIS over the air by exploiting the geometrical array properties and a practical receiver-RIS feedback link. In our indoor test, where the transmitter and receiver are separated by a 30 cm thick concrete wall, our RIS prototype provides a 26 dB power gain compared to the baseline case where the RIS is replaced by a copper plate. A 27 dB power gain was observed in the short-distance outdoor measurement. We also carried out long-distance measurements and successfully transmitted a 32 Mbps data stream over 500 m. A 1080p video was live-streamed and it only played smoothly when the RIS was utilized. The power consumption of the RIS is around 1 W. Our paper is vivid proof that the RIS is a very promising technology for future wireless communications.
|
|
| 3. |
- Chumakov, A., et al.
(författare)
-
Sprayed Nanometer-Thick Hard-Magnetic Coatings with Strong Perpendicular Anisotropy for Data Storage Applications
- 2022
-
Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 5:7, s. 8741-8754
-
Tidskriftsartikel (refereegranskat)abstract
- The rapid growth of digital information in the world necessitates a big leap in improving the existing technologies for magnetic recording. For the best modern perpendicular recording, the highest coercivity materials with minimal volume are required. We present a study of a facile technology for establishing mono- and multilayer surfaces from various single-domain flat magnetic nanoparticles that exhibit a strong perpendicular-oriented magnetic moment on solid and flexible substrates. Surfactant-free, hard ferromagnetic, and single-domain anisotropic strontium hexaferrite SrFe12O19nanoparticles with a perpendicular magnetic moment orientation and two different aspect ratios are self-ordered into magnetic thin nanofilms, exploiting the templating effect of cellulose nanofibrils and magnetic fields. Uniform magnetic coatings obtained by the scalable layer-by-layer spray deposition from a monolayer coverage up to thicknesses of a few tens of nanometers show a preferred in-plane orientation of the hard-magnetic nanoparticles. High coercivities of the films of up to 5 kOe and a high perpendicular anisotropy of Mr⊥/Ms> 80% are found. The application of the magnetic field during film deposition ensures additional improvement in perpendicular magnetic anisotropy and the appearance of residual magnetization in the film of up to 0.6Ms. For low-aspect-ratio nanoparticles stacked in periodic planar structures, the signs of the photonic band gap are revealed. The ability to create scalable, thin magnetic structures based on nanosized particles/building blocks opens great opportunities for their application in a wide variety of optoelectronic and magnetic storage devices.
|
|
| 4. |
- Feng, Yanyue, 1993, et al.
(författare)
-
Applications of anodized TiO2 nanotube arrays on the removal of aqueous contaminants of emerging concern: A review
- 2020
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 186
-
Forskningsöversikt (refereegranskat)abstract
- The presence of contaminants of emerging concern (CECs) in various water bodies and the associated threats to eco-system and human society have raised increasing concerns. To fight against such a problem, TiO2 photocatalysis is considered to be a powerful tool. In recent decades, TiO2 nanotube array (TNA) fabricated by electrochemical anodization emerged as a viable immobilized catalyst and its applications on CECs removal have gained a considerable amount of research interest. We herein present a critical review on the development of TNA and its applications on the removal of aqueous CECs. In this work, the CECs removal in different TNA based processes, the CECs removal mechanisms, the role of TNA properties, the role of operational parameters, and the role of water matrices are discussed. Moreover, perspectives on the current research progress are presented and recommendations on future research are elaborated.
|
|
| 5. |
- Li, Kaihui, et al.
(författare)
-
Three‐dimensional discrete element simulation of indirect tensile behaviour of a transversely isotropic rock
- 2020
-
Ingår i: International Journal for Numerical and Analytical Methods in Geomechanics. - : John Wiley & Sons. - 0363-9061 .- 1096-9853. ; 44:13, s. 1812-1832
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of a three‐dimensional discrete element model using flat‐joint and smooth‐joint contact models to investigate the effect of anisotropy on the tensile behaviour of slate, a transversely isotropic rock, under Brazilian testing from both macro and microscales. The effect of anisotropy is further realised by exploring the influence of foliation orientations (β and ψ ) on the tensile strength, fracture pattern, microcracking and stress distribution of the transversely isotropic rock. The variation of tensile strength with foliation orientation is presented. The cross‐weak‐plane fracture growth observed in laboratory is reproduced, and the criterion for which to form is also given from the aspect of foliation orientation. Furthermore, the proportional variations of microcracks well account for the effects of foliation orientation on the tensile strength and failure pattern. Finally, it is found that the existence of weak planes increases both the heterogeneity and the anisotropy of stress distributions within the transversely isotropic rock, with the degree of influence varying with the foliation orientation.
|
|
| 6. |
- Luo, Zhengyi, et al.
(författare)
-
Demand Flexibility of Residential Buildings : Definitions, Flexible Loads, and Quantification Methods
- 2022
-
Ingår i: Engineering. - : Elsevier Ltd. - 2095-8099. ; 16, s. 123-140
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reviews recent research on the demand flexibility of residential buildings in regard to definitions, flexible loads, and quantification methods. A systematic distinction of the terminology is made, including the demand flexibility, operation flexibility, and energy flexibility of buildings. A comprehensive definition of building demand flexibility is proposed based on an analysis of the existing definitions. Moreover, the flexibility capabilities and operation characteristics of the main residential flexible loads are summarized and compared. Models and evaluation indicators to quantify the flexibility of these flexible loads are reviewed and summarized. Current research gaps and challenges are identified and analyzed as well. The results indicate that previous studies have focused on the flexibility of central air conditioning, electric water heaters, wet appliances, refrigerators, and lighting, where the proportion of studies focusing on each of these subjects is 36.7%, 25.7%, 14.7%, 9.2%, and 8.3%, respectively. These flexible loads are different in running modes, usage frequencies, seasons, and capabilities for shedding, shifting, and modulation, while their response characteristics are not yet clear. Furthermore, recommendations are given for the application of white-, black-, and grey-box models for modeling flexible loads in different situations. Numerous static flexibility evaluation indicators that are based on the aspects of power, temporality, energy, efficiency, economics, and the environment have been proposed in previous publications, but a consensus and standardized evaluation framework is lacking. This review can help readers better understand building demand flexibility and learn about the characteristics of different residential flexible loads, while also providing suggestions for future research on the modeling techniques and evaluation metrics of residential building demand flexibility.
|
|
| 7. |
- Tan, Zhifei, et al.
(författare)
-
Constitutive modelling and systematic evaluation of asphalt concrete’s viscoelastic tension-compression asymmetry effect on pavement performance
- 2024
-
Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 25:1
-
Tidskriftsartikel (refereegranskat)abstract
- Asphalt concrete (AC) exhibits significant tension-compression (TC) asymmetry, which is currently not considered in pavement design. This study develops a novel temperature-dependent dual viscoelastic model to quantitatively capture the viscoelastic behaviour of AC. Unlike the conventional viscoelastic constitutive model, the proposed model decomposes strain into tensile and compressive components to characterise AC’s TC asymmetry. Additionally, a systematic modelling framework with intrinsic TC asymmetry is developed for the first time to predict the response of pavement under moving tire load. The results illustrate that implementing the proposed dual viscoelastic model enlarges both the vertical deformation of pavements and the tensile and shear strains in the AC layers, bringing it closer to the realistic scenario compared to the conventional model that only considers compression properties. Furthermore, high temperatures and low vehicular speeds exacerbate the substantial effects of AC’s TC asymmetry on asphalt pavement. This study provides a valuable method to capture AC’s TC asymmetry and predict pavement response more accurately, giving better insight into pavement response and enhancing pavement design and maintenance.
|
|
| 8. |
- Wang, Anci, et al.
(författare)
-
Performance optimization of electric vehicle battery thermal management based on the transcritical CO2 system
- 2023
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 266
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal management of electric vehicles, especially battery thermal management, is critical to driving range and operational safety. To find a vehicle thermal management system with higher energy efficiency and environmental protection, an environmentally-friendly and efficient battery and cabin parallel cooling thermal management system was evaluated with CO2 as the working fluid. First, different control strategies of the evaporation temperature were compared regarding the battery cooling performance. Then, the effect of the battery cooling evaporation temperature on the coefficient of performance (COP) was explored. It was found that the maximum COP increased by 8.38% as the evaporation temperature decreased from 17 to 5.8 °C. Besides, it was found that the optimal battery cooling evaporation temperature range is 10.2–11 °C when the battery heating power is 0.4 kW. The vapor quality at the cold plate outlet should be lower than 0.95. Finally, the battery cooling performance under variable operating conditions was investigated. The influence of operating parameters on the battery cooling evaporation temperature and CO2 outlet vapor quality was also analyzed. Simulation results showed that the optimum evaporation temperature range varied significantly under different working conditions. The vapor quality at the cold plate outlet decreased slightly with the evaporation temperature.
|
|
| 9. |
- Wang, Anci, et al.
(författare)
-
Principle and performance optimization analysis of a frost-free control for electric vehicle heat pumps
- 2023
-
Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 226
-
Tidskriftsartikel (refereegranskat)abstract
- To avoid the attenuation of the electric vehicle driving range caused by the performance degradation of the heat pump during frost, a frost-free control strategy was developed which enables frost-free operation without adding any additional dehumidifying and drying components. Simulation analyses of the frost-free control principle and performance characteristics are carried out. Thermodynamic and response characteristics of evaporation temperature to valve openings of different heat pumps are compared. The results show that excessive pressure drops in evaporators severely hinder the realization of frost-free operation. Then, the effect of evaporator designs on frost-free operation is further investigated. A new comprehensive evaluation parameter (η) that can unify pressure drop and heat transfer is proposed. When η is between 0 and −2, the heat exchanger meets the requirements of frost-free control. In addition, the upper humidity range for frost-free operation at different temperatures is calibrated. When the ambient temperature is 0/-5/-10/-15/-25 °C, the corresponding maximum humidity that can achieve frost-free operation is 87/86/85/84/82 %, respectively. In low temperature and high humidity regions, the frost-free operation can be guaranteed by increasing the evaporator airflow volume rate and reducing the supply air temperature.
|
|
| 10. |
- Wu, Jing, et al.
(författare)
-
Interleukin-33 is a Novel Immunosuppressor that Protects Cancer Cells from TIL Killing by a Macrophage-Mediated Shedding Mechanism
- 2021
-
Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 8:21
-
Tidskriftsartikel (refereegranskat)abstract
- Recognition of specific antigens expressed in cancer cells is the initial process of cytolytic T cell-mediated cancer killing. However, this process can be affected by other non-cancerous cellular components in the tumor microenvironment. Here, it is shown that interleukin-33 (IL-33)-activated macrophages protect melanoma cells from tumor-infiltrating lymphocyte-mediated killing. Mechanistically, IL-33 markedly upregulates metalloprotease 9 (MMP-9) expression in macrophages, which acts as a sheddase to trim NKG2D, an activating receptor expressed on the surface of natural killer (NK) cells, CD8+ T cells, subsets of CD4+ T cells, iNKT cells, and gamma delta T cells. Further, MMP-9 also cleaves the MHC class I molecule, cell surface antigen-presenting complex molecules, expressed in melanoma cells. Consequently, IL-33-induced macrophage MMP-9 robustly mitigates the tumor killing-effect by T cells. Genetic and pharmacological loss-of-function of MMP-9 sheddase restore T cell-mediated cancer killing. Together, these data provide compelling in vitro and in vivo evidence showing novel mechanisms underlying the IL-33-macrophage-MMP-9 axis-mediated immune tolerance against cancer cells. Targeting each of these signaling components, including IL-33 and MMP-9 provides a new therapeutic paradigm for improving anticancer efficacy by immune therapy.
|
|
