Canopy bidirectional reflectance dependence on leaf orientation

Abstract

The bidirectional reflectance patterns of a complete (dense) canopy are examined as functions of canopy architecture, as specified by azimuth angle δ_e and zenith angle ψ for a leaf normal. The leaves are assumed to be opaque Lambertian reflectors, all with identical orientation and reflectance properties throughout the canopy, and randomly distributed with respect to the irradiation field and the viewing direction. Multiple reflections are not considered and irradiation is by direct beam only. Simple analytical expressions for the bidirectional reflectance factor are presented and analysed. The nadir reflectance (expressed as a fraction of the leaf reflectance) for canopies whose leaves face the sun, δ_e = 0, is bounded by cos ψ and 1/2; cos ψ. The nadir reflectance initially increases with increasing ψ, but then decreases when ψ reaches moderate to large values. For a δ_e = π canopy, on the other hand, the much lower nadir reflectance is bounded by ½ cos ψ and 0, and decreases with increasing ψ throughout the entire range of ψ (0 to ½π). The maximum bidirectional reflectance occurs at large viewing zenith angles (i.e. close to the horizon). The maximum reflectance is always higher for a δ_e = 0 canopy than for a δ_e = π canopy, but the differences become small when ψ approaches ½π. The bidirectional reflectance thus depends on the leaf azimuth as well as the zenith angle. Leaf-area azimuthal distributions should be considered when conducting model inversions to infer canopy characteristics and architecture.     

Real-time design of an adaptive nonlinear predictive controller

Based on real-time identification and using the concept of NARX (Nonlinear AutoRegressive with exogenous inputs) models, a new adaptive nonlinear predictive controller (ANPC) design is proposed. NARX models represent a natural way to describe the input-output relationship of severely nonlinear systems. From an initial batch of input-output data, a parsimonious NARX model is obtained using the Modified Gram-Schmidt (MGS) orthogonalization algorithm. Following this initial off-line identification and model reduction procedure, the control loop is closed. The ANPC directly uses the obtained structure and initial parameter estimates, which are updated each time step using recursive identification. The controller is designed similar to a typical linear predictive controller based on solving a nonlinear programming (NLP) problem. This paper shows how to solve this NLP problem on-line without the knowledge of the NARX model structure. The design is given for the multi-input multi-output (MIMO) case.     

Variable structure model following control for industrial robots

A variable structure model following control (VSMFC) strategy for the control of most types of industrial robots (according to a classification ofCoiffet 1983) has been presented. For 99% of the robots given in the classification of Coiffet (1983), the dynamics of each link can be represented by a simple model with the nonlinearities and coupling dynamics decoupled from the linear part (Stoten 1985). This facilitates the designer to have a modified VSMFC law, which will maintain sliding mode motion of the error and its derivative, referred to as the representative point (RP), on a user chosen switching line and to drive the RP to the origin of the error plane (error is defined as the difference between the states of the reference model and those of the plant). When in sliding mode the system remains insensitive to parameter variations and disturbances     

FATTY ACIDS AND MEAT CHARACTERISTICS OF DIFFERENT BIOLOGICAL TYPES OF BEEF CATTLE DEVELOPED UNDER A MANAGEMENT-INTENSIVE GRAZING SYSTEM

ABSTRACT

Beef steers representing four biological types were evaluated for fatty acid profiles and meat characteristics in muscle tissue developed on grazed forages. Biological types included six large‐framed, late maturing, nine medium‐framed, late maturing, nine medium‐framed, intermediate maturing, and nine medium‐framed, early maturing steers. Longissimus dorsi muscles were removed and frozen after 7 days of dry aging. Tenderness and cook loss were similar between biological types. Significant differences (P < 0.05) in fatty acid profiles were found between biological types. The medium‐framed, early maturing animals scored highest (P < 0.05) in marbling, had the highest (P < 0.05) concentration of total n‐3 fatty acids, and had the lowest n–6/n–3 ratio at 1.03:1. All biological types had a mean n–6/n–3 ratio well below the recommended <4:1 for human cardiovascular health. Under this dietary management system, medium‐framed, early maturing beef steers should be considered for producing grass‐fed beef based on both carcass merit and fatty acid composition.

PRACTICAL APPLICATIONS

Beef cattle that reach physiological maturity (i.e. puberty) earlier than their contemporaries should be selected for the production of grassfed beef if fully developed on forages. Those animals have the ability to deposit fat earlier than their later‐maturing contemporaries. Additionally, medium‐framed beef animals should be selected over larger‐framed animals as skeletal frame does not contribute to meat quality but requires more nutritional input for growth and maintenance. This ability to deposit fat exclusively on forage nutrients, without energy or protein supplementation, should be exploited when developing grassfed beef. Fat deposition, particularly intramuscularly (IM), contributes positively to meat quality. Fatty acids, especially the ratio of n‐6/n‐3, are optimized when beef animals have been fully developed on nutrient‐dense forages. Forages must be managed in such a way to capture those nutrients for animal intake and protect the plants for regrowth in a pasture setting.     

ALKALINE PHOSPHATASE FROM JAW ALA SHRIMP (ACETES INDICUS)

Alkaline phosphatase was isolated from Jawala shrimps (Acetes indicus), a tiny crustacean. The hepatopancreas (head region) is a good source of this enzyme. pH optima of the partial purified enzyme was found to he 9.5 and optimal temperature for maximal activity was 40C. Jawala phosphatase was completely inhibited by 1, 10‐phenanthroline and EDTA, indicating that it is a metalloprotein. The activity of inhibited enzyme was restored by Zn²⁺ and Mn²⁺ salts. Feed back inhibition of the enzyme by inorganic phosphate was also observed.     

FACTORS INFLUENCING PEPSINOLYSIS OF METHYL-, ETHYL- AND PROPYL- ESTER DERIVATIVES OF β-LACTOGLOBULIN

β‐Lactoglobulin was esterified with methanol, ethanol or propanol, yielding 100, 60 and 44% esterification, respectively. The kinetics of peptic hydrolysis of unmodified, methylated‐, ethylated‐and propylated‐fi‐lactoghbulin derivatives were followed under various conditions of time, temperature, and enzyme and protein concentrations. The resulting hydrolysates were analyzed by SDS‐PAGE and RP‐HPLC. Changes of temperature and enzyme concentration influenced strongly the rate of hydrolysis and the RP‐HPLC profiles while protein concentration had much smaller impact on reaction rates when tested in the range2.5–20mg/mL. Peptic hydrolysis of methylated‐β‐lactoglobulin derivatives could proceed at a temperature as low as 4C and at an enzyme/substrate ratio as low as 0.125%, Peptide profiles of the hydrofysates of methyl‐ and ethyl‐β‐lactoglobulin derivatives were gemratty quite similar except for the appearance of additional peaks in case of methyl‐p‐lactoglobulin. RP‐HPLC profile of propyl‐β‐lactoglobulin ester was slightly different from that of both the methyl‐and ethyl‐β‐lactoglobulin. The features of the peptide profiles of the different hydrolysates of esterified β‐lactoglobulin did not differ after long pepsinofysis. The population of small hydrophilic peptide increased, accompanied by a decrease of the large hydrophobic peptides (for methyl derivative) and the hydrolysis of intact protein (for ethyl‐ and propyl‐derivatives).     

Fundamental Study and Equipment for Sintering and Testing of Cermet Bodies: VI, Fabrication, Testing, and Properties of 72 Chromium-28 Alumina Cermets

Physical properties, including firing shrinkage, density, modulus of rupture from 75° to 2400°F., stress-rupture life in cross bending and in tension at 1800° and at 2000°F., modulus of elasticity, tensile strength from 75° to 2000°F., comparative impact resistance, oxidation resistance, thermal expansion, and thermal-shock resistance, for the composition 28% alumina-72% chromium combine to indicate the potential value of this material in high stress applications at elevated temperatures where severe thermal shock may be encountered. While the thermal-shock resistance is much better than that possessed by the low-chromium high-alumina bodies discussed in Part V, the mechanical properties at elevated temperatures do not appear to suffer as a result of the highly continuous metal phase in the more recently developed body.     

Influence of Preheating Skimmilk on Water-holding Capacity of Sodium Salts of Caseinates and Coprecipitates

The effect of different preheat treatments of milk on the water-holding capacity of the corresponding sodium caseinates made under laboratory conditions was investigated. Unheated skimmed milk, and milks heated under conditions ranging from 60°C to 120°C for 1 min, respectively, were used for the manufacture of the caseinates. Water-holding capacity was estimated using a method involving equilibration of the powder with excess water and measurement of the volume of released water. Water-holding progressively increased with heating, whereby with 120°C/1 min more than two-thirds of the dispersion volume tested was retained. The whey protein content of the caseinates also varied according to temperature and water-holding capacity.