Reflectance calibration of aerial video imagery with automatic gain compensation on and off

Abstract

Video imaging systems are noi radiometrically calibrated, thus it is difficult to obtain quantitative remotely-sensed imagery for natural resource applications. Video camera automatic gain controls (AGC) present potential problems in calibrating video systems for quantitative analysis because they compensate for changing solar illumination conditions. In this experiment aerial video calibrations to ground reflectance standards were compared for AGC turned on and off, The calibrated aerial video was evaluated for guinea grass (Panicum maximum L.) biomass treatments on two dates. Results showed that there was more atmospheric light scattering in the red than in the NIR video band. Light scattering affects could be detected only when the AGC was ofT because when AGC was on light scattering affects were masked. These results also showed that video imagery produced significant correlations with guinea grass biomass that were comparable to ground reflectance measurements.     

Landscaping Attributes and Property Buyers' Profiles: Their Joint Effect on House Prices

This paper investigates the effect of environmental features on house values while focusing on the interactions between landscaping attributes and home buyers' profile. The originality of this study rests on the assumption that, while neighbourhood characteristics translate into distinct sub-markets and primarily set the structure of house prices, individual home buyers' preferences, under specific market conditions, also affect values. The study benefits from two distinct, although related data sets on the single-family segment of Quebec City's housing market: while landscaping features were obtained via an extensive field survey of houses sold between 1993 and 2000, a detailed phone survey of related homeowners' family status, age and income profiles is being conducted since 2000. Findings suggest that household profile and structure do shape landscaping preferences and that utility patterns of homeowners may be best understood by looking at interactions between the two sets of variables. Considering that population aging is a major issue for economic and social planners, such a conclusion should be accounted for in housing policy design.     

The Dyeing and Finishing of Circular-knitted Cotton and Cotton Blends

This paper reviews the major recent developments in the field of dyeing and finishing of knitted fabrics and the market and economic forces which have influenced them. These are identified as the fast growing demand for leisure and sports wear, with cotton and cotton blends finding major consumer preference, and the rapid escalation in costs for energy; water, effluent treatment and oil-based dyes and chemicals.     

Diurnal patterns of bidirectional vegetation indices for wheat canopies

The perpendicular vegetation index (PVI) and normalized difference vegetation index (NDVI) were calculated from Mark II radiometer RED (0.63-0.69 μm) and NIR (0.76–0.90 μ) bidirectional radiance observations for wheat canopies. Measurements were taken over the plant development interval flag leaf expansion to watery ripeness of the kernels during which the leaf area index (LAI) decreased from 40 to 2-5. Spectral data were taken on four cloudless days five times (09.30, 11.00, 12.30, 14.00 and 15.30 hours (central standard time, C.S.T.) at five view zenith, Zv (0, 15, 30,45 and 60°) and eight view azimuth angles relative to the Sun, A_v (0, 45, 90, 135, 180, 225, 270 and 315°). The PVI was corrected to a common solar irradiance (PVIC) based on simultaneously observed insolation readings.

The PVIC at nadir view (?=0°) increased as (l/cosZ_s) increased on all the measurement days whereas the NDVI changed little as solar zenith angle (Z_s) changed. Thus, the PVIC responded to increasing path length through the canopy, or the number of leaves encountered, as solar zenith angle changed whereas the NDVI, which has saturated by the time an LAI of 2 was achieved, was nonresponsive.

Off-nadir PVIC ratioed to nadir PVIC increased as the view zenith and solar zenith angles increased (reciprocity in Sun and view angles), and as the view azimuth, A angle approached the Sun position (back scattering stronger that forwardscattering). In contrast, the DNVI was very stable for all view and solar angles consistent with saturation in its response. Even though the PVI is subject to bidirectional effects, it contains more useful information about wheat canopies at LAI > 2 than does the NDVI. The NDVI of the plant canopies changed rapidly at low vegetative cover but its bidirectional sensitivity at low LAI was not investigated.     

THERMAL RESISTANCE OF BACILLUS STEAROTHERMOPHILUS SPORES IN DRIED PASTA AT DIFFERENT STAGES OF REHYDRATION

The thermal resistance of Bacillus stearothermophilus spores at different stages of rehydration was examined. Inoculation was achieved by rehydrating pasta samples in water containing 1‐mL spore crop (10⁶ spores/mL); the product was heat sealed in sterile pouches and processed in a laboratory retort. Thermal inactivation of spores was carried out using 10 time intervals at 121C for moisture contents, 70, 90, 105, 115, 125 and 145% dry basis. The death curves obtained consisted of two phases, an initial rapid decline (1.5 to 2.6 log reductions) followed by a slower, linear decrease of survivors from which the decimal reduction time (D value) was calculated. D₁₂₁ values were found to decrease with increasing moisture content and ranged from 4.6 to 6.5 min. The thermal resistance constant (z value) was examined to assess the effect of temperature (110–125C) on lethality. z values decreased with increasing moisture content and ranged from 10.7 to 15.6C. The results of this study demonstrate that temperature and moisture content influence the effectiveness of the intended heat process. For products that are rehydrated during heat treatment, the moisture content of the product is a critical factor. Therefore, if complete rehydration is not achieved, this may result in the heat process being less effective for the destruction of microorganisms, which may have implications in regard to food safety.     

OXIDATION OF HYDROCARBONS BY HEMIN1

A model system for cytochrome P-450 comprised of hemin, thiosalicylic acid, and solvent (acetone and water), oxidized cyclohemne and n-hexane at pH 2.7. Oxidation of cyclohexane yielded more cyclohexanol than cyclohexanone under mild reaction conditions, whereas the oxidation of n-hexane generated more 3- and 2-hexanones than 3- and 2-hemnols. Oxygen was a limiting factor in the reaction, and increased oxygen pressures increased the ratio of cyclohexanone to cyclohexanol formed. Lag time for product formation decreased in a linear fashion with an increase in temperature. In addition, cyclohexanone decreased relative to cyclohexanol as the temperature was increased. Antioxidants increased the lag time for product formation, but had little effect on the final quantity or ratios of the oxidative products generated. 1,3 Diphenylisobenzafiran had no effect on the lag time, whereas Tiron and catechol increased the lag time. In contrast to aliphatic thiols, aromatic thiols were capable of driving the oxidative reaction. The model hemin system was approximately 6% as active as natural cytochrome P-450. Hemin immobilized on glass beads effectively catalyzed the oxidation of cyclohexane.     

Region Recognition Using Area Method

Visual aids in the form of graphs and charts are often used in analysis and design procedures. Commonly, a graph is divided into regions of common characteristics, such as in a soil classification scheme in which a set of properties are located on a chart and the soil classification is given. Although these aids are useful in hand calculations, it is often difficult to implement these charts into a computer code. A general technique is described in this paper which can simplify both implementation and the regional coordinate analysis by the use of an area coordinate method. An example and a short Fortran code are also included to show how this technique can be used.     

Modelling planting configuration and canopy architecture effects on diurnal light absorption changes in cotton

Abstract

A simplified model that accounts for diurnal solar zenith and azimuth angle illumination changes and plant geometry effects on photosynthetically active radiation (PAR) was developed, h was tested using diurnal absorbed PAR (APAR) measurements acquired for cotton (Gossvpium hirsuium L.) grown at Weslaco, Texas, during the 1984 and 1986 growing seasons. Diurnal canopy reflectance and transmittance measurements were automatically collected at 3-minute intervals from about 9.00 to 14.50 local standard time (LST) using radiometers mounted 3·7m above the soil surface and PAR light bar sensors located beneath the crop canopy perpendicular to the crop rows. Plant growth measurements estimated by the model were significantly correlated with observed measurements during crop development. Model-estimated heliotropic leaf elevation trends agreed with published results for cotton canopies. APAR, relative to incident PAR, was generally lower for east-west rows than for north-south rows during crop development. The APAR response of cotton canopies for both east-west and north-south rows were found to be essentially flat when solar azimuth was between 90° and 270° so one observation close to noon would probably be representative of the diurnal APAR measurements.     

IMPROVED ESTIMATIONS OF TOTAL AND PSYCHROTROPHIC MICROFLORA IN RAW MILK USING REFLECTANCE COLORIMETRY AT 32°C1

A reflectance colorimeter with 32°C incubation/detection temperature successfully quantitated total and psychrotrophic microflora in raw milk. Correlations between reflectance colorimetry and the Standard Plate Count improved with preliminary incubation time: .50 (no preliminary incubation), .74 (24 h at 7°C), to .84 (48 h at 7°C). Correlations between reflectance colorimetry and the Psychrotrophic Bacterial Count were better than those achieved with the Standard Plate Count and improved: .53 (no preliminary incubation). 80 (24 h at 7°C), to .91 (48 h at 7°C). The 48 h preliminary incubation method would cost less and data would be available in 48 to 72 h compared to the 98 to 240 h for psychrotrophic plating methods. A second sample set (no preliminary incubation) could be analyzed to identify high-count samples in less than 24 h. Color detection times following sample refrigeration for 24 h at 0, 4. and 7°C were significantly different from samples tested before refrigeration. Identical sample time/temperature storage conditions are suggested