| 1. |
- Huang, Jing, et al.
(författare)
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Gas exchange in fruits related to skin condition and fruit ripening studied with diode laser spectroscopy
- 2016
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Ingår i: Journal of Biomedical Optics. - 1083-3668. ; 21:12
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Tidskriftsartikel (refereegranskat)abstract
- The concentration of the biologically active molecular oxygen gas is of crucial importance for fruits in the metabolic respiration, maturation, and ripening processes. In our study, oxygen content and oxygen transport in fruits, exemplified by apples and guavas, were studied noninvasively by gas in scattering media absorption spectroscopy. The technique is based on the fact that free gases typically have 10,000 times narrower absorption features than the bulk material. The technique was demonstrated in studies of the influence of the fruit skin in regulating the internal oxygen balance, by observing the signal response of the internal oxygen gas to a transient change in the ambient gas concentration on peeled and unpeeled fruits. In addition, the gas exchange rate at different ripening stages was also studied in intact guavas.
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| 2. |
- Li, Tianqi, et al.
(författare)
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Application of Tunable Diode Laser Spectroscopy for the Assessment of Food Quality
- 2017
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 71:5, s. 929-938
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Tidskriftsartikel (refereegranskat)abstract
- Adequate food packaging is important to ensure food quality and prolong the shelf life of food. Frequently, the method of modified atmosphere packaging (MAP) is used. We used a tunable diode laser spectroscopy technique to detect the oxygen content in food packages, e.g., in packaged milk and bread. Different detection geometries were adopted to be able to collect scattering light that had passed through the gas volume in the packages, and to avoid the disturbance of ambient air. Furthermore, studies of the bread-baking process have been performed by measuring the water vapor signals in a fermenting dough. The results demonstrate that the technique has a great potential for nonintrusive assessment of food quality and the bread-baking process.
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| 3. |
- Song, Ziwei, et al.
(författare)
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Application of lidar remote sensing of insects in agricultural entomology on the Chinese scene
- 2020
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 144:3, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- Insect pest management is a very important aspect for plant protection in crops production. Remote sensing provides a large number of techniques that are beneficial in entomological research. Although entomological radars have been used for studying migrations of insects for many years, most of entomological radar studies have been vertically tracing high-altitude migration behaviour of insects. Light detection and ranging (lidar) is a counterpart to radar, now operating in the optical part of the electromagnetic spectrum, which has been recently applied for monitoring of insects at low altitude. Such techniques, in particular low-cost continuous-wave (CW) bi-static systems based on the Scheimpflug arrangement, have been rapidly developing during the last decade. As a result, optical methods present new and fascinating possibilities. Based on experience from a 2-week field campaign in rice paddy fields, we here present an overview of lidar remote sensing applied to the Chinese scene. The capability of a CW Scheimpflug lidar system in monitoring the insects was studied. We present results on insect abundance in relation to time of the day and weather conditions. We also identified insect species by analysing wing-beat frequencies and studied their attraction to ultraviolet (UV) lamp located close to the horizontal laser sampling path during night time. Results showed that the insect species were abundant, that insects detected by the lidar system were attracted to light and that light rain increased the insect activity. The lidar detection system had a high read-out frequency, enabling the estimation of insect wing-beat frequencies.
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| 4. |
- Zhang, Hao, et al.
(författare)
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Non-invasive optical detection of oxygen content in food packages using gas in scattering media absorption spectroscopy
- 2016
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Ingår i: Guangxue Xuebao/Acta Optica Sinica. - 0253-2239. ; 36:2
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Tidskriftsartikel (refereegranskat)abstract
- Food quality is greatly dependent on the security of the food packaging process,which has been widely developed to inhibit food spoilage and to prolong the shelf life for food products. Gas in scattering media absorption spectroscopy is used as an optical noninvasive method to estimate the gas content in food packages. A diode laser with central wavelength of 760 nm is used to record an oxygen spectroscopic signal, and then to estimate the oxygen content by investigating the gas exchange in the package. The experimental results show that the technique can be used to determine the oxygen concentration and to assure the integrity and security of food packages.
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| 5. |
- Zhu, Shiming, et al.
(författare)
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Insect abundance over Chinese rice fields in relation to environmental parameters, studied with a polarization-sensitive CW near-IR lidar system
- 2017
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Ingår i: Applied Physics B: Lasers and Optics. - : Springer Science and Business Media LLC. - 0946-2171. ; 123:7
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Tidskriftsartikel (refereegranskat)abstract
- Effective monitoring of flying insects is of major societal importance in view of the role of insects as indispensable pollinators, destructive disease vectors and economically devastating agricultural pests. The present paper reports on monitoring of flying agricultural pests using a continuous-wave lidar system in a rice-field location in Southern China. Using a Scheimpflug arrangement, range resolution over several 100 m long observational paths was achieved. The system operates with two perpendicularly polarized near-infrared lasers, which are activated intermittently, and back-scattered radiation from insects was recorded by a linear array detector placed after a linear polarizer. Our polarization sensitive system was used to monitor the flying insect diurnal activity and also the influence of changes in weather conditions, e.g., the occurrence of rain. Activity strongly peaked at dusk and rose again, although to a lower extent, just before dawn. At the onset of rainfall, a strong increase in insect counts occurred which was interpreted as the rain-induced bringing down of high-altitude migrant insects.
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| 6. |
- Zhao, Guangyu, et al.
(författare)
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Reflectance and fluorescence characterization of maize species using field laboratory measurements and lidar remote sensing
- 2016
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Ingår i: Applied Optics. - 1559-128X. ; 55:19, s. 5273-5279
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced fluorescence is an important technique to study photosynthesis and plants. Information on chlorophyll and other pigments can be obtained. We have been using a mobile laboratory in a Chinese experimental farm setting to study maize (Zea mays L.) leaves by reflectance and fluorescence measurements and correlated the spectroscopic signals to the amount of fertilizer supplied. Further, we studied five different species of maize using the remote monitoring of the fluorescence signatures obtained with the same mobile laboratory, but now in a laser radar remote-sensing configuration. The system separation from the target area was 50 m, and 355 nm pulsed excitation using the frequency-tripled output from an Nd:YAG laser was employed. Principal component analysis and linear discriminant analysis were combined to identify the different maize species using their fluorescence spectra. Likewise, the spectral signatures in reflectance and fluorescence frequently allowed us to separate different fertilizer levels applied to plants of the same species.
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