Review of Variable-Rate Sprayer Applications Based on Real- Time Sensor Technologies

Precision variable rate spray is one of the research hotspots in the field of modern agriculture spraying applications. Variable rate spraying of the canopy allows growers to apply adjusted volume rate of pesticides to the target, based on canopy size, and to apply plant protection products in an economical and environmentally sound manner. In the field of pesticide application, knowledge of the geometrical characteristics of plantations will guarantee a better adjustment of the dosage of the agrochemicals applied. This technology is integrated with intelligent real-time sensors, which have a high potential for agricultural precision spray applications. This book chapter presents the foundations and applications in agriculture of the primary systems used for real-time spray target detection of the geometrical characterization of tree plantations. Systems based on infrared, ultrasonic, light detection and ranging (LIDAR), and stereo vision sensors were discussed, respectively, on their performances to detect spray targets. Among them, laser scanners and stereo vision systems are probably the most promising and complementary techniques for achieving three-dimensional (3D) pictures and maps of plants and canopies. The advantages of data fusion applied in real-time target detection and its accuracy in density estimation of the plants were stressed

Mapping infectious disease hospital surge threats to lessons learnt in Singapore: a systems analysis and development of a framework to inform how to DECIDE on planning and response strategies.

BACKGROUND: Hospital usage and service demand during an Infectious Disease (ID) outbreak can tax the health system in different ways. Herein we conceptualize hospital surge elements, and lessons learnt from such events, to help build appropriately matched responses to future ID surge threats. METHODS: We used the Interpretive Descriptive qualitative approach. Interviews (n = 35) were conducted with governance and public health specialists; hospital based staff; and General Practitioners. Key policy literature in tandem with the interview data were used to iteratively generate a Hospital ID Surge framework. We anchored our narrative account within this framework, which is used to structure our analysis. RESULTS: A spectrum of surge threats from combinations of capacity (for crowding) and capability (for treatment complexity) demands were identified. Starting with the Pyramid scenario, or an influx of high screening rates flooding Emergency Departments, alongside fewer and manageable admissions; the Reverse-Pyramid occurs when few cases are screened and admitted but those that are, are complex; during a 'Black' scenario, the system is overburdened by both crowding and complexity. The Singapore hospital system is highly adapted to crowding, functioning remarkably well at constant near-full capacity in Peacetime and resilient to Endemic surges. We catalogue 26 strategies from lessons learnt relating to staffing, space, supplies and systems, crystalizing institutional memory. The DECIDE model advocates linking these strategies to types of surge threats and offers a step-by-step guide for coordinating outbreak planning and response. CONCLUSIONS: Lack of a shared definition and decision making of surge threats had rendered the procedures somewhat duplicative. This burden was paradoxically exacerbated by a health system that highly prizes planning and forward thinking, but worked largely in silo until an ID crisis hit. Many such lessons can be put into play to further strengthen our current hospital governance and adapted to more diverse settings

Analysis of the Effects of Different Factors on Damage Potential Ranking

A quantitative evaluation of the damage potential of ground motions to structures can provide a basis for the selection of input ground motions. To determine the main factors influencing the damage potential ranking of ground motions, the corresponding effect factors were analyzed. First, the structural period range from 0.05 to 10 s was divided into three types of period ranges based on an improved Newmark–Hall spectrum. The intensity measures (IMs) that can characterize the damage potential in every period range were determined. Second, the effect of yield strength coefficient (Cy), vibration period (T), and type of site on the damage potential ranking are explained. A recommended damage potential ranking is given in the same period range. Finally, to demonstrate the rationality of the recommended damage potential ranking in this paper, two representative reinforced concrete (RC) shear structure models are established for analysis. For the same type of structures, the damage potential rankings under different Cy and T conditions have high correlation with the recommended damage potential ranking, and the discreteness is very low. When considering the site factors, the corresponding correlation and dispersion change little. Based on the analysis of two typical structural models, the R2 between the recommended damage potential ranking and structural response ranking were 0.89 and 0.94, respectively. It is proven that the methods of Cy, T, and the type of site are reasonable when establishing the recommended damage potential ranking in this paper. This study provides a theoretical basis for simplifying the evaluation of ground motion damage potential and for selecting input ground motions

The Effect of the Yield Strength Coefficient and Natural Vibration Period on the Damage Potential Ranking of Ground Motions

To analyze the effect of structural parameters on the damage potential ranking of ground motions, the effect of the yield strength coefficient (Cy) and natural vibration period (T) on the damage potential ranking of ground motions is analyzed based on the bilinear model and the modified Clough model, which are the most commonly used hysteretic models in structural dynamic analysis. The displacement response (Sd) spectrum under nonlinear conditions is taken as the damage potential intensity measure (IM) of ground motions, and the effect of the Cy and T on the Sd mean spectrum is also analyzed for comparative analysis. The results show that: (1) in the short-period range, Cy has a great effect on the displacement response ranking. On the other hand, in the medium- and long-period ranges, Cy has little effect on the Sd ranking; (2) with the change of T in medium- and long-period ranges, the variation of Sd values is obvious when the change of T is small, but the variation of Sd ranking is very small. This conclusion can provide a theoretical basis for evaluating the damage potential of ground motions and selecting input ground motions

Simulation and verification for seed-filling performance of cell wheel precision seed metering device based on discrete element method

The cell wheel seed metering device was improved and a stirring seed-filling device was added to improve the seed-filling performance of cell wheel pseudo-ginseng precision seed metering devices. Using pseudo-ginseng seeds in Wenshan Prefecture, Yunnan Province as the objects for seed metering, the software application EDEM was adopted based on the discrete element method for the simulation calculation and analysis of the seed-filling performance of the seed metering device under 4 rotational speeds of the cell wheel and 6 rotational speeds of the stir wheel. The simulation results indicate that the filling ratio increases as the rotational speed of the stir wheel increases under a constant rotational speed of the cell wheel. Test verification of the simulation analysis results was conducted on the test bed of the seed metering device. The results indicate that increasing the rotational speed of the stir wheel can obtain a filling ratio of over 90%. The test results display a similar variation trend to that of the simulation analysis with an error of average filling ratio less than 5%. Therefore, it is feasible to analyze the seed-filling performance of the stirring and seed-filling device of the seed metering device with the discrete element method

Analysis of the Effects of Different Factors on Damage Potential Ranking

A quantitative evaluation of the damage potential of ground motions to structures can provide a basis for the selection of input ground motions. To determine the main factors influencing the damage potential ranking of ground motions, the corresponding effect factors were analyzed. First, the structural period range from 0.05 to 10 s was divided into three types of period ranges based on an improved Newmark–Hall spectrum. The intensity measures (IMs) that can characterize the damage potential in every period range were determined. Second, the effect of yield strength coefficient (Cy), vibration period (T), and type of site on the damage potential ranking are explained. A recommended damage potential ranking is given in the same period range. Finally, to demonstrate the rationality of the recommended damage potential ranking in this paper, two representative reinforced concrete (RC) shear structure models are established for analysis. For the same type of structures, the damage potential rankings under different Cy and T conditions have high correlation with the recommended damage potential ranking, and the discreteness is very low. When considering the site factors, the corresponding correlation and dispersion change little. Based on the analysis of two typical structural models, the R2 between the recommended damage potential ranking and structural response ranking were 0.89 and 0.94, respectively. It is proven that the methods of Cy, T, and the type of site are reasonable when establishing the recommended damage potential ranking in this paper. This study provides a theoretical basis for simplifying the evaluation of ground motion damage potential and for selecting input ground motions

Effects of Structural and Seismic Factors on the Constant-Strength Ductility Spectra Based on NGA-West2 Database

The constant-strength ductility spectrum is a nonlinear response spectrum that is commonly used to establish the demand curve of the seismic response during performance-based seismic design. It is affected by many factors. In this paper, to evaluate the effect of the major influencing factors, including the structural parameters and seismic factors, the constant-strength ductility spectrum is calculated under different conditions based on 5535 ground motion records. Conclusions are drawn based on the mean constant-strength ductility spectra. (1) With respect to the effects of structural factors, the variation trend of the ductility spectra is highly consistent with increasing T, and the ductility spectra are usually larger for larger ζ and smaller Cy and k2. (2) With respect to the seismic factors, the ductility spectra show obvious differences in different periods; however, some parameters, such as PGA, have no influence on the ductility spectra. The results of this study can provide a theoretical basis for the calculation of ductility demand in the seismic design of structures

Simulation and verification for seed-filling performance of cell wheel precision seed metering device based on discrete element method

The cell wheel seed metering device was improved and a stirring seed-filling device was added to improve the seed-filling performance of cell wheel pseudo-ginseng precision seed metering devices. Using pseudo-ginseng seeds in Wenshan Prefecture, Yunnan Province as the objects for seed metering, the software application EDEM was adopted based on the discrete element method for the simulation calculation and analysis of the seed-filling performance of the seed metering device under 4 rotational speeds of the cell wheel and 6 rotational speeds of the stir wheel. The simulation results indicate that the filling ratio increases as the rotational speed of the stir wheel increases under a constant rotational speed of the cell wheel. Test verification of the simulation analysis results was conducted on the test bed of the seed metering device. The results indicate that increasing the rotational speed of the stir wheel can obtain a filling ratio of over 90%. The test results display a similar variation trend to that of the simulation analysis with an error of average filling ratio less than 5%. Therefore, it is feasible to analyze the seed-filling performance of the stirring and seed-filling device of the seed metering device with the discrete element method

BIOINSPIRED IMBRICATED MICROTHORN SCALE SURFACES AND THEIR ABRASIVE WEAR PERFORMANCE

To solve the problem of abrasive wear failure of the soil-engaging components of agricultural machinery, the imbricated microthorn scale structure of the sandfish (Scincus scincus) epidermis surface was selected as a bionic prototype. By adopting a bionic engineering approach, nine bionic microthorn scale surface specimens with different geometric structure parameters were designed and prepared. Wear resistance tests were performed in a rotating abrasive wear testing system. The results of the wear tests showed that the imbricated microthorn scale structured surfaces had substantially less abrasion loss than a conventional smooth surface. The influence of the geometric structure parameters on the wear performance was also identified. Numerical simulations were performed to explore the wear resistance mechanism of the imbricated microthorn scale structured surfaces. The abrasion of the bionic surfaces mainly occurred at the edge of the microthorn that faced the abrasive particle flow. The trajectory of subsequent abrasive particle flow was modified by the large dispersion of particle flow; hence, the number of particles that impacted the surface decreased. Therefore, the wear resistance performance of the bionic surfaces was enhanced. This bioinspired surface can provide a technical reference to mitigate the abrasive wear failure of the soil-engaging components of agricultural machinery.National Natural Science Foundation of China [52065031, 51605210]; Analysis and Testing Foundation Project of Kunming University of Science and Technology [2019T20140038, 2019M20182214012, 2019M20182214014]The authors express their appreciation to Guangming Chen, Guangkai Zhang, Yin Li, and Xiaoyang Wang for their technical assistance throughout the experiments. This research was funded by the National Natural Science Foundation of China (Grant Nos. 52065031 and 51605210) and the Analysis and Testing Foundation Project of Kunming University of Science and Technology (Grant Nos. 2019T20140038, 2019M20182214012, and 2019M20182214014)

Method for Ranking Pulse-like Ground Motions According to Damage Potential for Reinforced Concrete Frame Structures

To rank the pulse-like ground motions based on the damage potential to different structures, the internal relationship between the damage potential of pulse-like ground motions and engineering demand parameters (EDPs) is analyzed in this paper. First, a total of 240 pulse-like ground motions from the NGA-West2 database and 16 intensity measures (IMs) are selected. Moreover, four reinforced concrete frame structures with significantly different natural vibration periods are established for dynamic analysis. Second, the efficiency and sufficiency of the IMs of ground motion are analyzed, and the IMs that can be used to efficiently and sufficiently evaluate the EDPs are obtained. Then, based on the calculation results, the principal component analysis (PCA) method is employed to obtain a comprehensive IM for characterizing the damage potential of pulse-like ground motions for specific building structures and EDPs. Finally, the pulse-like ground motions are ranked based on the selected IM and the comprehensive IM for four structures and three EDPs. The results imply that the proposed method can be used to efficiently and sufficiently characterize the damage potential of pulse-like ground motions for building structures