With the development of artificial intelligence in recent years, deep learning has been widely used in mechanical system signal classification but the impact of different feature extractions on the ...efficiency and effectiveness of deep learning neural networks is more important. In this study, a vehicle classification based on engine acoustic emission signal in the time domain, the frequency domain and the wavelet transform domain for deep learning network techniques is presented and compared. In signal classification, different feature extractions will show in different decomposition levels and can be used to recognize the various acoustic conditions. In the experimental work, as engines from 10 different ground vehicles operate, the measured sound signal is converted into a digital signal, and the established data set is classified and identified by the deep learning method. The number of samples, identification rate and identification time in the various signal domains are compared and discussed in this study. Finally, the experimental results and data analysis show that by using the wavelet signal and the deep learning method, excellent identification time and identification rate can be achieved, compared with traditional time and frequency domain signals.
Typical lead‐based perovskites solar cells show an onset of photogeneration around 800 nm, leaving plenty of spectral loss in the near‐infrared (NIR). Extending light absorption beyond 800 nm into ...the NIR should increase photocurrent generation and further improve photovoltaic efficiency of perovskite solar cells (PSCs). Here, a simple and facile approach is reported to incorporate a NIR‐chromophore that is also a Lewis‐base into perovskite absorbers to broaden their photoresponse and increase their photovoltaic efficiency. Compared with pristine PSCs without such an organic chromophore, these solar cells generate photocurrent in the NIR beyond the band edge of the perovskite active layer alone. Given the Lewis‐basic nature of the organic semiconductor, its addition to the photoactive layer also effectively passivates perovskite defects. These films thus exhibit significantly reduced trap densities, enhanced hole and electron mobilities, and suppressed illumination‐induced ion migration. As a consequence, perovskite solar cells with organic chromophore exhibit an enhanced efficiency of 21.6%, and substantively improved operational stability under continuous one‐sun illumination. The results demonstrate the potential generalizability of directly incorporating a multifunctional organic semiconductor that both extends light absorption and passivates surface traps in perovskite active layers to yield highly efficient and stable NIR‐harvesting PSCs.
A near‐infrared (NIR)‐harvesting perovskite solar cell with a power‐conversion efficiency of 21.6% and an operational half‐life of 1900 h is achieved by directly incorporating a multifunctional organic semiconductor that both extends light absorption and passivates defects in the perovskite active layer.
Upconversion CeO2:Tm3+/attapulgite (ATP) nanocomposites intermediated by carbon quantum dots (CQDs) were synthesized by a facile deposition method using hexamethylenetetramine as precipitator. The ...products were characterized by various techniques. The photocatalytic degradation of dibenzothiophene (DBT) in simulated gasoline was conducted under visible light irradiation by taking advantage of CeO2:Tm3+/CQDs/ATP nanocomposites as catalyst. The influence of Tm3+ doping amount and the mass fraction of CeO2 to ATP on the desulfurization performance were investigated. Results indicated that the CeO2:Tm3+ nanoparticles were coupled uniformly on the CQDs/ATP surface. The desulfurization rate of DBT reached the highest 96% when the molar fraction of Tm3+ in CeO2 was 2% and the mass fraction of CeO2 to ATP was 20 wt%. The enhanced photocatalytic oxidative desulfurization was attributed to the upconversion property of CeO2:Tm3+ which transformed visible light into ultraviolet light increasing the utilization of solar energy, while CeO2:Tm3+ built indirect Z-scheme heterojunction with modified ATP mediated by CQDs, both favored the separation of the charges carriers and benefits the redox potentials.
Using fly ash (FA) and superabsorbent polymer (SAP) in construction promotes sustainability by reducing cement consumption and enhancing concrete durability. However, the mix design of FA concrete ...with SAP has to be improved due to the uncertainty of entrained water content and early strength (0–28 days). To fulfill this objective, a numerical study was conducted to assess the influence of FA on the computation of entrained water content, utilizing a model derived from Powers' model. Experimental and numerical assessments were then conducted to explore the effects of SAP on the mechanical properties, total shrinkage, and pore structure of concrete. Results revealed the modifications are crucial to accurately calculate the minimum entrained water content required for full hydration of the binder material in concrete. Moreover, the influence of SAP on cubic compressive strength (0–28 days) can be described by differences in porosity, and the conventional correlations were still applicable to describe the correlation between cubic compressive strength and other mechanical properties. Notably, pore refinements and shrinkage reduction of concrete were observed owing to the use of SAP. These findings would promote theoretical research, mix design, and practical applications of FA concrete with SAP.
•A developed model for calculating entrained water content of fly ash concrete.•A prediction model for the early strength of concrete with SAP was proposed.•The entrained water content significantly affected the mechanical properties.•Minor changes in particle size of SAP weakly affected the mechanical properties.•Conventional relations still existed between mechanical properties.
Display omitted
•Ternary CQDs/SmFeO3/attapulgite photocatalyst was fabricated.•Optimal CQDs led to form Z-scheme heterostructure.•Charge separation and redox ability was enhanced.•Outstanding NO ...removal achieved under solar light.
A novel photocatalyst integrated with carbon quantum dots (CQDs), SmFeO3 and attapulgite (ATP) clay mineral was synthesized by sol-gel/impregnation method which was successfully applied for NO removal under solar light irradiation. The textual and optical properties of the materials were analyzed by various characterizations. Results indicated the SmFeO3 nanoparticles were uniformed loaded on the ATP support and both coherently interacted with CQDs. The amount of CQDs had significant effect on the NO conversion, while 5 wt% incorporation achieved the highest 90% conversion rate. An indirect Z-scheme mechanism was proposed that the CQDs performed as an intermediate between SmFeO3 and ATP for the charge transfer while the high redox potential was maintained. In addition, the ATP fiber showed not only UV-responsive property in Z-scheme structure, but also excellent adsorption effect for gas molecules.
Thousands of DNA elimination events occur during somatic differentiation of many ciliated protozoa. In
Tetrahymena, the eliminated DNA aggregates into submacronuclear structures containing the ...protein Pdd1p, a member of the chromodomain family. We disrupted somatic copies of
PDD1, eliminating parental expression of the gene early in the sexual phase of the life cycle. Even though zygotic expression, from the undisrupted germline
PDD1 copy, is activated before DNA elimination normally occurs, the somatic knockout cells suffer defects in DNA elimination, genome endoduplication, and nuclear resorption, and eventually die, demonstrating that
PDD1 is essential and suggesting Pdd1p is directly involved in establishing a chromatin structure required for DNA elimination.
The cover feature image shows chemical species (in gold) rushing in to bind with receptors (in green) so that light signals of associated fluorophores (in blue) are switched from ‘off’ to ‘on’. ...Plastic chips containing such fluorescent PET sensor spots help medical personnel to save lives everyday worldwide. These ‘fluorophore‐receptor’ constructs also emulate logic gates (in orange) of the semiconductor IT revolution and they can operate in tiny living spaces where semiconductors fear to tread. Molecular information technology underpins all living systems. Cover design by Chao‐Yi Yao. More information can be found in the Perspective article by Chao‐Yi Yao and A. Prasanna de Silva.
Recently, region-based 3D video coding has been proposed. However, existing view synthesis distortion estimation (VSDE) methods are performed at the frame level. To guide the rate-distortion ...optimization process of region-based 3D video coding schemes, this paper proposes the first pixel-level VSDE (PL-VSDE) method. We first give the definition of the pixel-level view synthesis distortion. To estimate it, a backward prediction method is then developed, which starts from the pixels of interest (POIs) in the virtual view and finds their corresponding pixels in the reference view via a coarse-to-fine approach, denoted as coarse-to-fine backward prediction (CFBP) method. Additionally, the CFBP fully considers the details of 3D warping, the rounding operation and the warping competition in view synthesis, leading to improve accuracy of the prediction. Besides, a table-lookup method and a warping property are introduced to speed up the CFBP. After integrating the CFBP into the PL-VSDE, we can estimate the view synthesis distortion at the pixel level. Our method is carried out pixel-by-pixel independently, which is friendly for parallel processing. The experimental results demonstrate that our proposed method has significant advantages in both accuracy and efficiency compared with the state-of-the-art frame-level VSDE methods.
Paper and traditional books have been serving as useful tools in supporting knowledge-intensive tasks and school learning. Although learning strategies such as selective verbatim note-taking or ...question-asking may foster intentional recall or resolve comprehension difficulties in paper-based learning practice, improvement in learning may depend on the opportunity and quality of which students apply note-taking, review notes, or enhance comprehension through questioning. This study aims to complement a paper textbook with a mobile phone and to treat the combination as a whole to facilitate verbatim note-taking, resolving comprehension questions, and receiving reading recommendations. The textbook paragraphs were augmented with line numbers to facilitate coordination between the mobile phone and the paper textbook. An eight-week comparative study was conducted to explore the use of two reading vehicles. The results and findings show that using a mobile phone to augment paper-based learning is technically feasible and seems to promote the application of verbatim note-taking and posting comprehension questions for discussion. However, the results of two course tests indicate that consequent learning improvement seemed inconsistent among the students. A six-week case study was also conducted to explore the implications of the augmented support to students’ learning practice. The findings show that mobile phones as learning supportive tools to augment paper-based learning could support students’ planning and management of learning strategies or activities. The portability of mobile phones and paper textbooks and the ubiquitous connection of paper-based learning with an online learning community may provide the flexibility in planning ahead for suitable learning strategies or activities and may enhance students’ assessment for management of students’ learning goals.
The syntheses of adaptive camouflage devices based on novel side-chain engineered organic electrochromic materials have been demonstrated. Herein we report a molecule engineering approach for the ...tuning and syntheses of green-brown switchable electrochromic materials and also demonstrate their applications in chameleonic fabric devices. We have also successfully demonstrated the fabrication of chameleonic fabric devices.
PDF
