Imaging chlorophyll fluorescence with an airborne narrow-band multispectral camera for vegetation stress detection

Progress in assessing the feasibility for imaging fluorescence using the O₂-A band with 1 nm full-width half-maximum (FWHM) bands centered at 757.5 and 760.5 nm is reported in this paper. Multispectral airborne data was acquired at 150 m above ground level in the thermal, visible and near infrared regions yielding imagery at 15 cm spatial resolution. Simultaneous field experiments conducted in olive, peach, and orange orchards (water stress trials), and an olive orchard (variety trial) enabled the detected variability in fluorescence emission to be examined as function of stress status. In a parallel modelling activity the coupled leaf-canopy reflectance-fluorescence model, FluorMOD, was used to assess fluorescence retrieval capability by the in-filling method, as well as by fluorescence indices from the published literature. Fluorescence retrievals using the in-filling method, the derivative index D702/D680 and reflectance indices R690/R630, R761-R757, and R761/R757 yielded the best results in the simulation study, while demonstrating insensitivity to leaf area index (LAI) variation. The fluorescence in-filling method, derivative index D702/D680, and R761-R757 were the indices least affected by chlorophyll a + b (Cab) variation. On the other hand, other published indices for fluorescence detection at leaf and canopy levels exhibited high sensitivity to variations in Cab and LAI, and therefore were considered less suitable for in-field fluorescence detection. The fluorescence signal extraction from airborne imagery using the in-filling method was validated through comparisons with field-measured steady-state fluorescence (Fs) using the PAM-2100 and GFS-3000 instruments, confirming simulation predictions. The water stress experiments conducted on olive and peach orchards demonstrated the feasibility of chlorophyll fluorescence (F) extraction at the tree level from the airborne imagery, yielding determination coefficients r² = 0.57 (olive), and r² = 0.54 (peach). Consistent results were obtained between airborne F and ground truth assimilation (A) measured in the olive variety field experiment under no water stress levels, yielding r² = 0.71.     

Influence of structure of cyclic urea derivatives on their reactivities with cotton

The structure of the cyclic urea influenced the rate of reaction with cotton cellulose and the mechanism by which reaction occurred. Reaction of N, N′-dimethylolethylene-urea (DMEU) and N, N′-dimethylolpropyleneurea (DMPU) with cellulose in presence of inorganic salt catalysts proceeded through methylol hydroxyls and at the same rate; but reaction mechanism differed. With DMEU, N → metal ion coordination occurred and S_N2 mechanism prevailed. With DMPU, O → metal ion coordination resulted. Reaction of dihydroxyethylene urea (DHEU), N, N′-dimethyldihydroxyethyleneurea (DMeDHEU), and N, N′-dimethyloldihydroxyethyleneurea (DMDHEU) with cotton cellulose proceeded through ring hydroxyls with the formation of a carbonium ion, indicating an S_N1 mechanism. The much faster rate of reaction with DMeDHEU than with DHEU was attributed to the more electronegative environment of its ring hydroxyl, while the much slower rate of reaction of DMDHEU was attributed to hydrogen bonding between its methylol and ring hydroxyls.     

Is it DSS or OLTP: automatically identifying DBMS workloads

The type of the workload on a database management system (DBMS) is a key consideration in tuning the system. Allocations for resources such as main memory can be very different depending on whether the workload type is Online Transaction Processing (OLTP) or Decision Support System (DSS). A DBMS also typically experiences changes in the type of workload it handles during its normal processing cycle. Database administrators must therefore recognize the significant shifts of workload type that demand reconfiguring the system in order to maintain acceptable levels of performance. We envision intelligent, autonomic DBMSs that have the capability to manage their own performance by automatically recognizing the workload type and then reconfiguring their resources accordingly. In this paper, we present an approach to automatically identifying a DBMS workload as either OLTP or DSS. Using data mining techniques, we build a classification model based on the most significant workload characteristics that differentiate OLTP from DSS and then use the model to identify any change in the workload type. We construct and compare classifiers built from two different sets of workloads, namely the TPC-C and TPC-H benchmarks and the Browsing and Ordering profiles from the TPC-W benchmark. We demonstrate the feasibility and success of these classifiers with TPC-generated workloads and with industry-supplied workloads.     

Built-in lubrication on cotton fabrics

Partial cotton esters of long chain fatty acids of low degrees of substitution (D.S.<0.20) have been prepared by a variety of methods. In particular, the effects of the introduction of a stearoyl or an oleoyl group into the cellulose matrix on fabric properties, such as softness of hand and wrinkle recovery, have been studied. Attempts have been made to compare fabric properties of partial esters of like D.S. prepared by various methods of esterification and effect of a chemically attached alkanoyl group with effect of the same group deposited or adsorbed on the surface of the cotton fabric. Consideration has been given to the size of the alkyl group, its orientation on the surface of the fiber and its hydrophobicity. Data indicate that resistance to abtasion of cottons chemically modified with long chain alkyl groups is reduced whenever the finished fabric has high dry wrinkle recovery. High dry wrinkle recovery is obtained after esterification of cotton in nonaqueous media. Improvement in resistance to abrasion is pronounced when the alkyl group has not been chemically combined with the cellulose matrix in the absence of water, and usually is obtained when the finished cottons possess only high wet wrinkle recovery. One of eight papers being published from the Symposium “Surface Active Agents in the Textile Industry,” presented at the AOCS Meeting, New Orleans, April 1970. So. Utiliz. Res. Dev. Div., ARS, USDA.     

The Whistle Blower

Captain Crunch has gone full circle, donning the white hat in preference to the black. Infamous for his discovery that the pitch of a toy whistle in the Cap’n Crunch cereal box could trick the telephone network into giving him free telephone calls, John T. Draper sees his latest venture as reparation to society for the clandestine use of the toy whistle.     

Wall Shear Stress in Transient Turbulent Pipe Flow by Local Velocity Measurement

The modeling of unsteady wall shear stress plays a crucial role in the analysis of fast transients in pressurized pipe systems, since it allows to evaluate transient energy dissipation properly. The main aim of this paper is to give a contribution to the understanding of transient pressurized flow dynamics in turbulent regime by measuring not only pressure but also the instantaneous axial velocity profile at two sections of the laboratory pipe. Specifically, by means of ultrasonic Doppler velocimetry—a completely nonintrusive technique—instantaneous velocity gradients at pipe wall are measured allowing to evaluate the time history of the actual wall shear stress by coupling velocity measurements to a two-zone stress model. As a result, the behavior of accelerating and decelerating flows with respect to the corresponding steady ones, i.e., with the same value of the discharge, is pointed out. Due to the characteristics of the laboratory pipe—a 352-m long high density polyethylene pipe—transients phenomena are investigated both at short and long time scales.     

Mary Poppins meets Hackerwhacker

Not usually one to go for the ‘big guys’, I thought I would take a concerted and deliberate step in reverse this month and review what I would consider to be a ‘shirt and tie’ site compared to some of the left of left, avant guard or liberated (not necessarily liberal) sites I have been accessing for the past year or so.