A Rapid Detection Method for Fungal Spores from Greenhouse Crops Based on CMOS Image Sensors and Diffraction Fingerprint Feature Processing

The detection and control of fungal spores in greenhouse crops are important for stabilizing and increasing crop yield. At present, the detection of fungal spores mainly adopts the method of combining portable volumetric spore traps and microscope image processing. This method is problematic as it is limited by the small field of view of the microscope and has low efficiency. This study proposes a rapid detection method for fungal spores from greenhouse crops based on CMOS image sensors and diffraction fingerprint feature processing. We built a diffraction fingerprint image acquisition system for fungal spores of greenhouse crops and collected diffraction fingerprint images of three kinds of fungal spores. A total of 13 diffraction fingerprint features were selected for the classification of fungal spores. These 13 characteristic values were divided into 3 categories, main bright fringe, main dark fringe, and center fringe. Then, these three features were calculated to obtain the Peak to Center ratio (PCR), Valley to Center ratio, and Peak to Valley ratio (PVR). Based on these features, logistics regression (LR), K nearest neighbor (KNN), random forest (RF), and support vector machine (SVM) classification models were built. The test results show that the SVM model has a better overall classification performance than the LR, KNN, and RF models. The average accuracy rate of the recognition of three kinds of fungal spores from greenhouse crops under the SVM model was 92.72%, while the accuracy rates of the LR, KNN, and RF models were 84.97%, 87.44%, and 88.72%, respectively. The F1-Score value of the SVM model was higher, and the overall average value reached 89.41%, which was 11.12%, 7.18%, and 5.57% higher than the LR, KNN, and RF models, respectively. Therefore, the method proposed in this study can be used for the remote identification of three fungal spores which can provide a reference for the identification of fungal spores in greenhouse crops and has the advantages of low cost and portability

Effect of the Severe Plastic Deformation on the Corrosion Resistance of a Tantalum–Tungsten Alloy

Tantalum and its alloys are regarded as equipment construction materials for processing aggressive acidic media due to their excellent properties. In this study, the influence of severe rolling (90%) on the dissolution rate of a cold-rolled Ta-4%W sheet in different directions was investigated during immersion testing and the corresponding mechanism was discussed. The results show that the dissolution rate of the cold-rolled sample is significantly lower than that of the undeformed sample. The corrosion resistance followed the sequence of “initial” < “90%-ND” < “90%-RD” < “90%-TD”, while the strength is in positive correlation with the corrosion resistance. Severe rolling promotes grain subdivision accompanied by long geometrically necessary boundaries and short incidental dislocation boundaries on two scales in the cold-rolled sample. The volume elements enclosed by geometrically necessary boundaries form preferential crystallographic orientations. Such preferential crystallographic orientations can greatly weaken the electrochemical process caused by adjacent volume elements, resulting in greatly reduced corrosion rates in the severely deformed sample. The unexpected finding provides a new idea for tailoring the structures of tantalum alloys to improve both their strength and corrosion resistance

Study on all solid-state 213 nm laser Raman spectrometer

Due to the adverse effects formed by fluorescence interference difficult to remove, intense interest has been directed towards the development of techniques and instrumentation to inhibit fluorescence. When the wavelength of Raman excitation light is less than 250 nm, we can completely separate the fluorescence noise from the Raman features in the UV spectrum. Based on this, we describe a new deep UV Raman spectroscopy system composed of a compact acousto-optically Q-switched diode-pumped solid-state (DPSS) neodymium-doped yttrium vanadate laser and a UV Raman spectrometer. The laser is capable of producing ∼140 mW of 213 nm power quasi-continuous wave as 9.6 ns pulses at a 20 kHz repetition rate. The UV Raman spectrometer with the incident slit of 50 μm width is based on Littrow structure, of which the spectral resolution is better than 0.05 nm in the band of 211.5 nm ∼ 235.5 nm meeting the requirements of 10 cm−1 Raman spectral resolution. We effectively reduce the volume of the test system and improve the robustness of the test system. We measure the deep UV Raman spectra of solution methanol, which verified the feasibility and rationality of the system

Effects of Nutrient Solution Irrigation Quantity and Downy Mildew Infection on Growth and Physiological Traits of Greenhouse Cucumber

Abiotic and biotic stresses both decrease the quality and quantity of cultivated plants. In this study, in order to see the responses of cucumber plants to drought stress and cucumber downy mildew infection, downy mildew infestation at different two levels, B1 (disease infestation) and B2 (no disease infestation), along with three fertigation requirement levels, full fertigation T1, moderate nutrient solution deficit T2 and severe nutrient solution deficit T3, were applied in a greenhouse. Thus, six treatments, i.e., B1T1, B1T2, B1T3, B2T1, B2T2 and B2T3, were set. The leaf gas-exchange parameters were significantly increased under CK (control experiment, B2T1: no disease infestation and full irrigation) treatment, and leaf photosynthesis rate, transpiration rate and stomatal conductance were significantly decreased under the B1T1 treatment. Leaf intercellular CO2 concentration was significantly increased under B1T1 treatment. Leaf photosynthesis rate, transpiration rate, intercellular CO2 concentration and stomatal conductance were significantly decreased under B1T2, B1T3, B2T2 and B2T3 treatments. Compared with treatment CK (B2T1), the plant height of cucumber under B1T1, B1T2, B1T3, B2T2 and B2T3 treatments decreased by 11.41%, 19.05%, 27.48%, 7.55% and 10.62%, respectively; the stem diameter of cucumber under B1T1, B1T2, B1T3, B2T2 and B2T3 treatments decreased by 5.70%, 13.45%, 23.03%, 9.46% and 15.74%, respectively; and leaf area of cucumber under B1T1, B1T2, B1T3, B2T2 and B2T3 treatments decreased by 22.79%, 38.68%, 58.28%, 13.76% and 29.96%, respectively. The root&ndash;shoot ratio of cucumber under B1T1, B1T2, B1T3, B2T1, B2T2 and B2T3 treatments was 3.16%, 2.99%, 4.11%, 3.92%, 3.13% and 3.63%, respectively. The root&ndash;shoot ratio of cucumber was the highest under the B1T3 treatment

Study on Corrosion Behavior and Mechanism of Ultrahigh-Strength Hot-Stamping Steel Based on Traditional and Compact Strip-Production Processes

Hot-stamping steel is a type of high-strength steel that is mainly used in key safety components such as the front and rear bumpers, A-pillars, and B-pillars of vehicles. There are two methods of producing hot-stamping steel, i.e., the traditional process and the near net shape of compact strip production (CSP) process. To assess the potential risks of producing hot-stamping steel using CSP, the microstructure and mechanical properties, and especially the corrosion behavior were focused on between the traditional and CSP processes. The original microstructure of hot-stamping steel produced by the traditional process and the CSP process is different. After quenching, the microstructures transform into full martensite, and their mechanical properties meet the 1500 MPa grade. Corrosion tests showed that the faster the quenching speeds, the smaller the corrosion rate of the steel. The corrosion current density changes from 15 to 8.6 μA·cm−2. The corrosion resistance of hot-stamping steel produced by the CSP process is slightly better than that of traditional processes, mainly since the inclusion size and distribution density of CSP-produced steel were both smaller than those of the traditional process. The reduction of inclusions reduces the number of corrosion sites and improves the corrosion resistance of steel

On the quest for impartiality: Design and analysis of a Fair Non-repudiation protocol

We design and model-check a simple optimistic fair non-repudiation protocol. Our protocol is considerably simpler than current proposals, due mainly to the avoidance of using session labels. Our analysis technique is supported by exposing several vulnerabilities on weaker versions of our protocol. Some of the properties we check are liveness properties. To verify these, we use an intruder that respects the resilient communication channels assumption

The Characteristic Microstructures and Properties of Steel-Based Alloy via Additive Manufacturing

Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid−state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel−based alloy and then some typical microstructures produced by metal additive manufacturing technologies with different components and processes are summarized, including porosity, dislocation cells, dendrite structures, residual stress, element segregation, etc. The characteristic microstructures may exert a significant influence on the properties of additively manufactured products, and thus it is important to tune the components and additive manufacturing process parameters to achieve the desired microstructures. Finally, the future development and prospects of additive manufacturing technology in steel are discussed

The austenite to polygonal ferrite transformation in low-alloy steel: multi-phase-field simulation

The austenite to ferrite phase transformation is a critical structural transformation in steel production, where the morphology and grain size of ferrite substantially influence the mechanical properties of steel materials. In this work, the influences of cooling rate, prior austenite grain size (PAGS), and Mn content on the microstructure evolution and component distribution of austenite-to-polygonal ferrite phase transformation are investigated by a multi-phase-field model. It is found that higher cooling rates intensify the driving force for austenite to polygonal ferrite phase transformations and delay the phase transformation process. As PAGS decrease, the increased proportion of austenite grain boundary offers more nucleation sites for polygonal ferrite and thus refines the polygonal ferrite grain. Additionally, increased Mn content results in significant grain refinement due to a reduction in the transformation temperature of austenite to polygonal ferrite. This work provides valuable insights into adjusting and designing desired microstructures of polygonal ferrite for enhancing the mechanical performance of steel

Enhancement of strength-ductility trade-off in a 2000 MPa grade press-hardened steel via refined martensite with stable high-density cementite

High-strength press-hardened steels (PHSs) are characterized by a martensite structure of high strength and adequate ductility. Strengthening PHSs with high C contents is usually accompanied by a loss of ductility and toughness. To overcome this inherent strength–ductility trade-off dilemma, we propose a novel strategy to achieve outstanding mechanical performance by introducing stable high-density Cr-rich cementite, which refines the martensite structure via Zenner pinning effect in a novel 2000 MPa grade PHS. Specifically, a high tensile strength of 2085 MPa with an appreciable total elongation of 10.1% is achieved in the novel PHS, which is far superior to commercial 22MnB5 steel (1519 MPa and 10%). The strength increase is predominantly induced by a high density of dislocations and cementite in the novel PHS, while the good ductility is attributed to the refined martensite structure coordinating plastic deformation and the enhanced work-hardening ability and dislocation storage capability mediated by massive cementite. The work can lay foundations for designing high-strength PHSs with good ductility