Combinations of steady-state visual evoked potential (SSVEP) and electromyography (EMG) are one of the most widely used hybrid brain-computer interfaces (BCI). For users who are suffering from severe motor impairments...
详细信息
Combinations of steady-state visual evoked potential (SSVEP) and electromyography (EMG) are one of the most widely used hybrid brain-computer interfaces (BCI). For users who are suffering from severe motor impairments and could only control muscles above their necks, the EMG of jaw clench is commonly used together with SSVEP. Traditional asynchronous signal collecting and serial processing method is time-consuming. This study explored the simultaneous classification of SSVEP and jaw clench-related EMG from the same occipital electrodes. A convolutional neural network (CNN) model was adopted to classify the fusion signal after extracting different time and frequency domain features. Synchronous 12-class identification from 3 jaw clench patterns and 4 stimulate frequencies was tested on ten subjects. The 10-folder cross-validation results showed that using only 4 occipital electrodes, the CNN model with continuous wavelet transform feature achieved the overall best 89.3±4.0% accuracy for sync 12-class. Besides, the parallel acquiring and analyzing method has the lowest consuming time. The proposed method could reduce the signal channels and shorten the collect-process time of the SSVEP-EMG hybrid BCI.
Brain-computer interfaces (BCIs) have been widely used to improve or restore neural functions. For stroke patients, BCIs based on motor training show a promising potential in motor rehabilitation. However, the neural ...
详细信息
Brain-computer interfaces (BCIs) have been widely used to improve or restore neural functions. For stroke patients, BCIs based on motor training show a promising potential in motor rehabilitation. However, the neural mechanism and the effects of different time course in motor rehabilitation remain unclear. To this end, our study focused on the BCI based neurofeedback training (NFT) design and its evaluation method. During motor imagery and execution (MI/ME) tasks, electroencephalogram (EEG) and electromyogram (EMG) were synchronously recorded and probed. We found the multi-band changes of coupling EEG-EMG features. Additionally, the longterm motor NFT significantly improved the cortical-muscle activation, while non-feedback training improved less. These relevant results give a theoretical basis to the development and application of new neural rehabilitation technology.
The main characteristic of a reflective semiconductor optical amplifier chip (RSOA) is that it does not generate optical resonance under electric pumping and maintains the operation state of spontaneous emission. In t...
详细信息
The main characteristic of a reflective semiconductor optical amplifier chip (RSOA) is that it does not generate optical resonance under electric pumping and maintains the operation state of spontaneous emission. In this paper, a Nb2O5/SiO2/Nb2O5/SiO2 (four-layer Nb2O5/SiO2) film system is employed as the coating material for the output facet of the RSOA. The 3 dB spectral width of the spontaneous emission spectrum from this RSOA reaches 79.4 nm, with a ripple of less than 1 dB occurring across this wavelength range. Notably, around the 1550 nm wavelength, the ripple is as low as 0.5 dB. This represents the best performance reported for this type of chip. The RSOA is packaged as a narrow-linewidth external cavity laser. Under test conditions of 25 degrees C and 180 mA, the external cavity laser produces an output power of 12.6 mW and achieves a linewidth of 299.8 Hz. Furthermore, by adjusting the Fabry-P & eacute;rot (FP) standard cavity, filtering, and other external cavity parameters, the lasing spectrum of the narrow-linewidth external cavity laser based on the RSOA is tunable across a wavelength range from 1535.83 nm to 1561.42 nm, which shows the usability of the proposed ROSA for a C-band external cavity narrow-linewidth laser.
Bronze holds immense artistic, historical, and scientific significance, representing a valuable component of humanity's cultural heritage. Despite its cultural value, bronze is susceptible to corrosion and damage ...
详细信息
Bronze holds immense artistic, historical, and scientific significance, representing a valuable component of humanity's cultural heritage. Despite its cultural value, bronze is susceptible to corrosion and damage caused by environmental factors. This paper prepared an environmentally friendly poly(vinyl alcohol)/ poly(ethylene glycol) diacrylate (PVA/PEGDA) microgel loaded with L-cysteine (Cys), which effectively protects fragile bronze artifacts. In this study, the color and microstructure of the bronze coatings were characterized using a camera, colorimeter and scanning electron microscope. The results showed that the PVA/PEGDA microgels loaded with Cys (PVA/PEGDA + Cys microgels coating) not only did not change the color and appearance of the bronze, but also adhered and bonded well to the bronze surface. Confocal microscopy confirmed the soft and self-healing properties of the PVA/PEGDA + Cys microgels coating. Electrochemical testing and analysis showed that the PVA/PEGDA + Cys microgels coating exhibited excellent corrosion inhibition performance, with a corrosion inhibition efficiency of as high as 95.66%. The compressive test shows that the PVA/PEGDA + Cys microgels coating has certain reinforcement properties for bronze. The complete removal of PVA/PEGDA + Cys microgels coating can be achieved by spraying ethanol solution, indicating the enormous potential of microgels coating in protecting corroded bronze artifacts in the short term.
Ceramic matrix composites(CMCs)structural components encounter the dual challenges of severe mechanical conditions and complex electromagnetic environments due to the increasing demand for stealth technology in aerosp...
详细信息
Ceramic matrix composites(CMCs)structural components encounter the dual challenges of severe mechanical conditions and complex electromagnetic environments due to the increasing demand for stealth technology in aerospace *** address various functional requirements,this study integrates a biomimetic strategy inspired by gradient bamboo vascular bundles with a novel dual-material 3D print-ing *** distinct bamboo-inspired structural configurations Cf/SiC composites are designed and manufactured,and the effects of these different structural configurations on the CVI process are *** method is utilized to characterize the relationship between interface bonding strength and mechanical *** results reveal that the maximum flexural strength and fracture toughness reach 108.6±5.2 MPa and 16.45±1.52 MPa m1/2,respectively,attributed to the enhanced crack propagation resistance and path caused by the weak fiber-matrix ***,the bio-inspired configuration enhances the dielectric loss and conductivity loss,exhibiting a minimum reflection loss of-24.3 dB with the effective absorption band of 3.89 *** work introduces an innovative biomimetic strategy and 3D printing method for continuous fiber-reinforced ceramic composites,expanding the ap-plication of 3D printing technology in the field of CMCs.
Seeking new energy sources, especially those with less environmental impact, has been a consistent effort in the field of energy harvesting. In this work, we present an innovative energy harvesting technique for colle...
详细信息
Seeking new energy sources, especially those with less environmental impact, has been a consistent effort in the field of energy harvesting. In this work, we present an innovative energy harvesting technique for collecting energy from clothing. In this convenient but powerful method, electrical energy is generated by simply sliding a zein film assembly on the surface of clothes by constructing zein/cloth direct current (DC) triboelectric nanogenerators (TENGs). These TENGs contain only one electrode, which is connected to the zein assembly, leaving the cloth electrode free. Therefore, the clothes avoid any modification or tailoring, allowing for typical washing after separating the zein. Upon testing many ordinary clothing made with typical fabrics, the proposed zein/cloth TENGs worked efficiently with the most studied fabrics. The zein/cloth DC TENGs could generate electrical signals with an output performance of V = 23.45 V and I = 113.12 nA, making it capable of easily powering at least 10 LED lights simultaneously. Thus, our pioneer work provides a promising method for designing a portable ultra-light nano-energy generator that can harvest energy for small electrical power demands using the simple friction between clothes and the flexible zein assembly, irrespective of the location and time. This technique damages the clothing only negligibly and extricates energy harvesting from environmental constraints, such as sunlight and wind.
A reasonable planting density is vital for wheat resource efficiency and yield enhancement. However, systematic research on the impact of spraying TiO2-NPs on wheat growth, metabolism, and stress tolerance cultivated ...
详细信息
A reasonable planting density is vital for wheat resource efficiency and yield enhancement. However, systematic research on the impact of spraying TiO2-NPs on wheat growth, metabolism, and stress tolerance cultivated in cadmium (Cd)-contaminated soil is limited, especially in integration with planting density, requiring a deeper understanding. Our study showed that spraying with 3.1 mg per plant TiO2-NPs (in pots) and 21.6 mg m-2 TiO2-NPs combined with high planting densities (in the field) both significantly reduced the Cd content in wheat grains by 27.9 and 35.7%, respectively. Immobilization of subcellular water-soluble Cd and the conversion of Cd into inactive plant components in leaves were the primary reasons for this reduction. Metabolomics further revealed the up-regulation of metabolites related to antioxidant activity, plant stress resistance, growth promotion, and the tricarboxylic acid (TCA) cycle, which promotes plant growth, enhances wheat antioxidant enzyme activity, and alleviates oxidative stress. Transcriptomic analysis validated the association between these responses and improved plant stress resistance, with genes such as MYB, WRKY, P450, and Cd membrane transport-related genes like ABCG2 and ABCC3 contributing to the decrease in Cd levels in wheat. Importantly, the Cd-associated human health risk index was also reduced via foliar TiO2-NPs application. Overall, foliar spraying of TiO2-NPs combined with high plant density was beneficial in alleviating Cd levels in wheat grains, limiting the risk of Cd exposure to human health via the food chain.
X-ray computed tomography (CT) was used to investigate the fatigue crack growth behavior of continuous SiC fiber reinforced Ti alloy (SiCf/Ti). Based on the three-dimensional morphology of the fatigue crack and the to...
详细信息
X-ray computed tomography (CT) was used to investigate the fatigue crack growth behavior of continuous SiC fiber reinforced Ti alloy (SiCf/Ti). Based on the three-dimensional morphology of the fatigue crack and the tortuosity of the SiC fibers, we investigated the fatigue crack growth behavior and their dependence on the tortuosity of the fibers. The results revealed that the fatigue crack tends to intersect fibers with higher tortuosity compared to their straighter counterparts, which could explain the crack initiation position and its propagation behavior in continuous fiber reinforced composites.
Mining dump trucks play an important role in engineering construction and resource extraction. Current research mainly focuses on the dynamic modeling and reliability analysis of the vehicle frame, suspension and over...
详细信息
Mining dump trucks play an important role in engineering construction and resource extraction. Current research mainly focuses on the dynamic modeling and reliability analysis of the vehicle frame, suspension and overall model. However, with the development of electric drive, the wheel hub system has become an important component in mining truck equipment. This paper investigates the multi-body modeling of a mining truck's hub drive reduction system in order to analyze its output characteristics including the stability of the angular velocity of its planetary carriers and the fluctuations in its meshing forces. A bench experiment was also conducted to verify the accuracy and stability of the proposed modeling. And the simulation results revealed that the fluctuations in the angular velocity of the planetary carriers were primarily influenced by the excitation from the hub motor's input and the meshing forces between the gears of the reducers, which were mainly determined by the contact stiffness, damping, and clearance value during gear contact.
Robust operability is one of the key properties of industrial processes with uncertain parameters, which helps the designers assess the operating performance and improve production reliability quite early. The objecti...
Robust operability is one of the key properties of industrial processes with uncertain parameters, which helps the designers assess the operating performance and improve production reliability quite early. The objective of this work is to develop a framework of operability analysis to depict the robust operational space and quantificationally assess the robust operability of the plant. First, a derivative-free optimization-based flexibility analysis model is designed to identify the largest flexibility space. Then, a line projection method is adopted to locate the boundary points of the operational space. Finally, the Delaunay triangulation and convex hull theory are combined to identify the robust operational space;meanwhile, the optimal operating condition is found, which provides operators with straightforward guidance to ensure reliable operations. After calculating the space volume, the ratio to the physical operational space can assess robust operability. Three case studies are considered to show the efficiency of the proposed method.
暂无评论