small fields
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2022 ◽  
Thomas Wanger ◽  
Xueqing He ◽  
Wolfgang Weisser ◽  
Yi Zou ◽  
Shenggen Fan ◽  

Abstract Agricultural diversification of intensified farming systems is being proposed as a solution for achieving both food security and agricultural sustainability, but so far there has been little implementation of such policy at a larger scale. In China, major policies promote the “High-standard farmland consolidation” (HSFC) strategy to improve productivity and reduce environmental degradation in the world’s largest food production areas by simplifying instead of diversifying landscapes on large instead of small fields. As China’s Central government is asking for scientific innovations to improve its sustainable development strategy, we argue that China can become a role model to integrate agricultural diversification in its major policies, if HSFC builds on five decades of diversification research to achieve the national food security and sustainable development goals. We use text mining to analyze the past 17 years of China’s most important agricultural policy, the No. 1 Central Documents (1CD) policy and show that agricultural diversification at the field and supply chain level has received limited attention. Based on global synthesis studies covering five decades of research, we provide practical recommendations of how to integrate agricultural diversification in the China’s major policies from the national (the National 5-Year Plan and 1CD) to the provincial level. We use the major agricultural commodities rice, tea, wheat, and rapeseed in Zhejiang province as a case study to discuss how diversification can help to reach China’s sustainable agriculture targets. Diversification of China’s major food production areas on small fields could be an important example globally of how scientific progress informs policy and facilitates the food system transition.

Brennen Dobberthien ◽  
Fred Cao ◽  
Yingli Zhao ◽  
Eric Harvey ◽  
Genoveva Badragan

Abstract External beam radiotherapy often includes the use of field sizes 3 × 3 cm2 or less, which can be defined as small fields. Dosimetry is a difficult, yet important part of the radiotherapy process. The dosimetry of small fields has additional challenges, which can lead to treatment inconsistencies if not done properly. Most important is the use of an appropriate detector, as well as the application of the necessary corrections. The International Atomic Energy Agency and the American Association of Physicists in Medicine provide the International Code of Practice (CoP) TRS-483 for the dosimetry of small static fields used in external MV photon beams. It gives guidelines on how to apply small-field correction factors for small field dosimetry. The purpose of this study was to evaluate the impact of inaccurate small-field output factors on clinical brain stereotactic radiosurgery plans with and without applying the small-field correction factors as suggested in the CoP. Small-field correction factors for a Varian TrueBeam linear accelerator were applied to uncorrected relative dose factors. Uncorrected and corrected clinical plans were created with two different beam configurations, 6 MV with a flattening filter (6 WFF) and 6 MV without a flattening filter (6 FFF). For the corrected plans, the planning target volume mean dose was 1.6 ± 0.9% lower with p < 0.001 for 6 WFF and 1.8 ± 1.5% lower with p < 0.001 for 6 FFF. For brainstem, a major organ at risk, the corrected plans had a dose that was 1.6 ± 0.9% lower with p = 0.03 for 6 WFF and 1.8 ± 1.5% lower with p = 0.10 for 6 FFF. This represents a systematic error that should and can be corrected.

2022 ◽  
S. Y. Wang ◽  
Yijun Yu ◽  
Jinxiang Hao ◽  
Yang Feng ◽  
Jinjiang Zhu ◽  

Abstract Monolayers of a prototypical cuprate high transition-temperature (TC) superconductor Bi2Sr2CaCu2O8+δ (Bi2212) was recently found to show TC and other electronic properties similar to those of the bulk. The robustness of superconductivity in an ideal two-dimensional (2D) system was an intriguing fact that defied the Mermin-Wagner theorem. Here, we took advantage of the high sensitivity of scanning SQUID susceptometry to image the phase stiffness throughout the phase transition of Bi2212 in the 2D limit. We found susceptibility oscillated with flux between diamagnetism and paramagnetism in a Fraunhofer-like pattern up till TC. The temperature and sample size-dependence of the modulation period agreed well with our Coulomb gas analogy of a finite 2D system based on Berezinskii–Kosterlitz–Thouless (BKT) transition. In the multilayers, the susceptibility oscillation differed in a small temperature regime below TC in consistent with a dimensional-crossover led by interlayer coupling. Serving as strong evidence of BKT transition in the bulk, there appeared a sharp superfluid density jump at zero-field and paramagnetism at small fields just below TC. These results unified the phase transitions from the monolayer Bi2212 to the bulk as BKT transition with finite interlayer coupling. This elucidating picture favored the pre-formed pairs scenario for the underdoped cuprates regardless of lattice dimensionality.

2021 ◽  
Vol 12 ◽  
Zhenwang Qin ◽  
Wensheng Wang ◽  
Karl-Heinz Dammer ◽  
Leifeng Guo ◽  
Zhen Cao

To date, unmanned aerial vehicles (UAVs), commonly known as drones, have been widely used in precision agriculture (PA) for crop monitoring and crop spraying, allowing farmers to increase the efficiency of the farming process, meanwhile reducing environmental impact. However, to spray pesticides effectively and safely to the trees in small fields or rugged environments, such as mountain areas, is still an open question. To bridge this gap, in this study, an onboard computer vision (CV) component for UAVs is developed. The system is low-cost, flexible, and energy-effective. It consists of two parts, the hardware part is an Intel Neural Compute Stick 2 (NCS2), and the software part is an object detection algorithm named the Ag-YOLO. The NCS2 is 18 grams in weight, 1.5 watts in energy consumption, and costs about $66. The proposed model Ag-YOLO is inspired by You Only Look Once (YOLO), trained and tested with aerial images of areca plantations, and shows high accuracy (F1 score = 0.9205) and high speed [36.5 frames per second (fps)] on the target hardware. Compared to YOLOv3-Tiny, Ag-YOLO is 2× faster while using 12× fewer parameters. Based on this study, crop monitoring and crop spraying can be synchronized into one process, so that smart and precise spraying can be performed.

2021 ◽  
pp. 1-34
Jannik Dreier ◽  
Jean-Guillaume Dumas ◽  
Pascal Lafourcade ◽  
Léo Robert

In 1968, Liu described the problem of securing documents in a shared secret project. In an example, at least six out of eleven participating scientists need to be present to open the lock securing the secret documents. Shamir proposed a mathematical solution to this physical problem in 1979, by designing an efficient k-out-of-n secret sharing scheme based on Lagrange’s interpolation. Liu and Shamir also claimed that the minimal solution using physical locks is clearly impractical and exponential in the number of participants. In this paper we relax some implicit assumptions in their claim and propose an optimal physical solution to the problem of Liu that uses physical padlocks, but the number of padlocks is not greater than the number of participants. Then, we show that no device can do better for k-out-of-n threshold padlock systems as soon as k ⩾ 2 n , which holds true in particular for Liu’s example. More generally, we derive bounds required to implement any threshold system and prove a lower bound of O ( log ( n ) ) padlocks for any threshold larger than 2. For instance we propose an optimal scheme reaching that bound for 2-out-of-n threshold systems and requiring less than 2 log 2 ( n ) padlocks. We also discuss more complex access structures, a wrapping technique, and other sublinear realizations like an algorithm to generate 3-out-of-n systems with 2.5 n padlocks. Finally we give an algorithm building k-out-of-n threshold padlock systems with only O ( log ( n ) k − 1 ) padlocks. Apart from the physical world, our results also show that it is possible to implement secret sharing over small fields.

2021 ◽  
Syakira Saadon ◽  
Norhazrin Azmi ◽  
Prabagar Murukesavan ◽  
Norsham Nordin ◽  
Salman Saad

Abstract Petroliam Nasional Berhad (PETRONAS) is embarking on the implementation of the Design One Build Many (D1BM) concept, an integrated approach on design standardization, replication and volume consolidation for light weight fit for purpose wellhead platforms - also known as Lightweight Structure (LWS). The objective of the standardization is to enable monetization of marginal and small fields by improving project economics that are challenged with the high development costs and conventional execution schedules. Traditionally, projects are developed through a "bespoke" design which requires a specific engineering study during the Front End Loading (FEL) phase to cater for the field specific requirements. In addition, once the project has been sanctioned, it is a must to undergo tendering and bidding activities which can increase field monetization duration by four to five months. The current "bespoke" design has resulted in non-standardization, loss of opportunity for volume consolidation and ultimately longer time for field monetization. Although the Design One Build Many principles were known for a long time, but they were rather project oriented. Thus this emerging solution is a result of synthesizing multiple challenges with the goal to establish an end-to-end systematic approach in monetizing marginal and small fields by lowering development cost and monetization duration. There will be standardized sets of Base Design and a flexible Catalogue items to cater for standardized add on items. Lessons learned incorporation upon the repeated design and standardized execution strategy including Engineering, Procurement, Construction, Installation and Commissioning could also help in improving the delivery efficiency for the lightweight structure. The greater collaboration across fields and blocks will give significant added advantage through economies of scale efficiency and eventually increase in the overall project value.

2021 ◽  
pp. 301-324
Lin Liu ◽  
Bruno Basso ◽  

This chapter discusses existing yield forecasting systems in which the yield forecasts are driven by integration of different data sources, such as output of crop modeling, remote sensing and gridded climate datasets. It first provides overviews of the two predominant modeling approaches— crop simulation modeling and statistical modeling— to forecasting crop yield, with an emphasis on their respective use for operational crop yield forecasting systems. The chapter then briefly describes the accuracy and lead time of the existing yield forecasting models. Lastly, it provides a case study that integrates digital tools, field surveys, and crop modeling to provide on-time maize yield forecasts in small fields in Tanzania. The chapter concludes with a summary and future perspectives for research.

2021 ◽  
Vol 13 (23) ◽  
pp. 13354
Daniel Nilsson ◽  
Håkan Rosenqvist

Small arable fields are beneficial with regard to ecosystem services, e.g., concerning biodiversity. By selecting appropriate crops and cultivation practices, arable fields can also be used as carbon sinks. The objectives of this study were to investigate what impact field conditions (e.g., field size and shape) and payments (subsidies) for environmental benefits have on profitability. A dynamic simulation model was used to simulate machine operations in fields of two different shapes and five different sizes (from 0.75 to 12.00 ha). A wide range of crops cultivated in Sweden were investigated (fallow land and plantation of Norway spruce were also included). A perimeter-based subsidy was suggested in order to conserve and promote biodiversity, and an area- and crop-based subsidy was suggested in order to promote sequestration of soil organic carbon (SOC). The results showed that, without financial support and from a purely economic point of view, most field types investigated should be planted with Norway spruce. With currently available subsidies, e.g., EU Common Agricultural Policy (CAP) direct payments, hybrid aspen, poplar, fallow, and extensive ley cultivation are the most profitable crops. Perimeter-based subsidies favoured the net gain for small fields. As expected, a subsidy for sequestration of SOC favoured cultivation of specific SOC-sequestering crops such as ley, willow, and poplar. Our recommendation for future studies is to investigate a well-balanced combination of perimeter-based support and SOC sequestration support that benefits biodiversity and climate under different cultivation conditions.

Ileana Silvestre Patallo ◽  
Rebecca Carter ◽  
David Maughan ◽  
Andrew Nisbet ◽  
Giuseppe Schettino ◽  

Abstract Image-guided small animal irradiation platforms deliver small radiation fields in the medium energy x-ray range. Commissioning of such platforms, followed by dosimetric verification of treatment planning, are mostly performed with radiochromic film. There is a need for independent measurement methods, traceable to primary standards, with the added advantage of immediacy in obtaining results. This investigation characterizes a small volume ionization chamber in medium energy x-rays for reference dosimetry in preclinical irradiation research platforms. The detector was exposed to a set of reference x-ray beams (0.5 to 4 mm Cu HVL). Leakage, reproducibility, linearity, response to detector’s orientation, dose rate, and energy dependence were determined for a 3D PinPoint ionization chamber (PTW 31022). Polarity and ion recombination were also studied. Absorbed doses at 2 cm depth were compared, derived either by applying the experimentally determined cross-calibration coefficient at a typical small animal radiation platform “user’s” quality (0.84 mm Cu HVL) or by interpolation from air kerma calibration coefficients in a set of reference beam qualities. In the range of reference x-ray beams, correction for ion recombination was less than 0.1%. The largest polarity correction was 1.4% (for 4 mm Cu HVL). Calibration and correction factors were experimentally determined. Measurements of absorbed dose with the PTW 31022, in conditions different from reference were successfully compared to measurements with a secondary standard ionization chamber. The implementation of an End-to-End test for delivery of image-targeted small field plans resulted in differences smaller than 3% between measured and treatment planning calculated doses. The investigation of the properties and response of a PTW 31022 small volume ionization chamber in medium energy x-rays and small fields can contribute to improve measurement uncertainties evaluation for reference and relative dosimetry of small fields delivered by preclinical irradiators while maintaining the traceability chain to primary standards.

Ann‐Britt Schönfeld ◽  
Karl Mund ◽  
Guanghua Yan ◽  
Andreas Alexander Schönfeld ◽  
Hui Khee Looe ◽  

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