All issues
Volume 58, Issue 1
Displaying 1-5 of 5 articles from this issue
- |<
- <
- 1
- >
- >|
-
Matthew LAURENSON, Akira OTUKA, Seishi NINOMIYA2002 Volume 58 Issue 1 Pages 1-9
Published: March 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSMetBroker offers consistent access for agricultural models to heterogeneous weather databases by using a mediated architecture. This paper discusses three approaches to developing software that uses the MetBroker system, namely Java applets, small bridging Java applications, and Java servlets. Working applications using these three approaches are presented as models for software development. All of the approaches except Java servlets require that the client computer have a copy of the Java 2 Runtime Environment. Applets have the advantage of flexibility and ease of updating, but require considerable memory and can be slow to startup. Small bridging Java applications run on the client's computer can be used to retrieve weather data from MetBroker and write it to a file, from which it can be read by models written in languages other than Java such as FORTRAN or BASIC. Models implemented as Java servlets take any input from users via HTTP requests, and output their results as HTML pages. Such models can be accessed via simple browsers such as Internet-enabled cellular phones. A fourth approach, creating ActiveX® controls from the Java beans, is being explored. Such controls would let developers using non-Java visual development tools such as Visual Basic or Active Server Pages directly include MetBroker-based components in their applications.View full abstractDownload PDF (7979K) -
Tomoaki KOMORI, Ryoko IKEMOTO2002 Volume 58 Issue 1 Pages 11-22
Published: March 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe CO2 mass transfer problem of the assimilation cell phase of the crop leaf in the gross photosynthesis process was solved by the use of analytical procedures for net photosynthesis in the previous investigation (Komori and Ikemoto, 1999).
The solutions were applied to evaluate the CO2 gross mass transfer coefficient kL0, the gross photosynthetic reaction rate constant k10 and the CO2 concentration profile CA(z, t) in the assimilation cell phase with a constant respiration rate k0 for the case of rice. The summary is as follows:
1) Exact solutions for CA(z, t), the CO2 flux NA0, kL0 and the gross photosynthetic rate RAT0 are simplified to Eq. (13) through Eq. (16). These approximate solutions are available to obtain the relation of the CO2 mass transfer mechanism between the gross and the net photosynthesis in the assimilation celll phase.
2) Equation (22) or Eq. (39) gives the correlation of the gross and the net photosynthesis with the CO2 mass transfer rate. Equation (22) suggests that k0 has no influence on the gas phase CO2 mass transfer coefficient kG and for the over-all CO2 mass transfer coefficient, Eq. (39) provides Eq. (40). Moreover, Eqs. (22) and (39) indicate that the graphical method (Komori and Ikemoto, 1999) is appropriate for estimation of kL and kG.
3) Figure 3, generated from Eq. (22) or Eq. (39), shows the relationship between k10 and the net photosynthetic reaction rate constant k1, and is also the graphical method to estimate k10 from the net photosynthetic rate RAT and k0. Following the analytical discussion of Eq. (21) through Eq. (29) the k10-RAT curve in Fig. 3, shows that for assimilation of the crop leaf, the practical gross photosynthesis is biophysically different from the substantial net photosynthesis.
4) In order to quantitatively evaluate the characteristics of the photosynthetic reaction, the assimilation cell effectiveness factor Ef0 (Bird et al., 1960; Ohtake, 1963), defined by Eq. (50), was introduced. The Ef0 curve in Fig. 9 indicates the equilibrium point, kGb=kGs, the transition point, kL=HkG for the CO2 mass transfer resistance and the terminal point of RATmax at the maximum RAT in the region of 0≤RAT≤RATmax. In addition, Ef0 suggests that the photosynthetic reaction is very fast and can be performed near the surface of the assimilation cell phase.View full abstractDownload PDF (1473K) -
Archana DUANGPAENG, Haruo SUZUKI, Keiko NAKANISHI, Nobuyuki OKUDA, Tos ...2002 Volume 58 Issue 1 Pages 23-32
Published: March 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThis experiment was disigned to clarify how the soil temperature beneath canopy cover and mulch differs between a prostrate canopy cover and an erect canopy cover. The experiment was conducted from October 1998 to March 1999. A total of 18 experimental plots were prepared. These plots had either black mulch or no mulch, prostrate or erect canopy, and different leaf area indices (LAI).
The plots without mulch and with an erect canopy had higher maximum soil temperatures than did the plots without mulch and with prostrate canopy, irrespective of their LAI. As for the minimum soil temperature, the effects of prostrate canopy and erect canopy were reversed, depending on the temperature of the control plots. Among such plots, those with larger LAI had higher minimum soil temperatures. At the minimum soil temperature, both types of canopy had an even greater heat insulating effect than did the control plot. Except for the plots with an LAI of 2.0, a prostrate canopy resulted in higher minimum soil temperatures than did an erect canopy.
The effect of mulch on the soil temperature was examined with the diurnal range ratio of soil temperature. In the plots without mulch, the prostrate canopy generally provided smaller daily range ratios than did erect canopy, regardless of the LAI of those plots (the difference in the ratio between the two types of canopy for the various LAI was about 0.16 on average). The plots with a 1.0 or larger LAI that were covered with mulch had an average diurnal range ratio that was about 0.04 larger than those plots without mulch. This indicates that mulch had a small effect on soil temperature fluctuations. The difference between the effect of an erect and a prostrate canopy on soil temperature fluctuations was insignificant; however, combining mulch with canopy generally reduced the diurnal range ratio and increased the effect of the mulch on soil temperature fluctuations.View full abstractDownload PDF (1285K) -
Evaluation of Unmixing Method in Laboratory ExperimentKazuo OKI, Kenji OMASA, Minoru INAMURA2002 Volume 58 Issue 1 Pages 33-39
Published: March 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSVarious information such as vegetation vigor and coverage affect a pixel of remotely sensed images observed in vegetation areas. The radiance value of each pixel is changed by differences of vegetation vigor and coverage. Therefore, considering mixed pixels is necessary for vegetation environmental assessment using remotely sensed images.
A vegetation measurement model based on the concept of a linear mixture model was proposed, and an unmixing method that estimates the subpixel cover of each category from mixed pixels was applied to estimate subpixel vegetation cover with different vigor from the mixed pixels through laboratory experiment. The unmixing method was found to be effective in estimation of the subpixel vegetation cover with different vigor from the mixed pixels when the spectral radiance of each cover type was known before carrying out the method. Furthermore, it was found that the accuracy of the unmixing method for estimating each category within a pixel of a remotely sensed image depends on the wavelength range used. If the spectral radiance of an endmember agreed well with that of the category within a pixel, the coverage of interest was estimated accurately.View full abstractDownload PDF (4350K) -
Toshiaki MUKAI2002 Volume 58 Issue 1 Pages 41-49
Published: March 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (738K)
- |<
- <
- 1
- >
- >|